Platinum Metals Review

UK ISSN 0032-1400

PLATINUM METALS REVIEW

A quarterly survey of research on the platinum metals and of developments in their application in industry

VOL. 34 OCTOBER 1990 NO. 4

Contents

Palladium Supported Catalysts in CO +RON0 Reactions 24mm4 178 Destruction of Organochlorines 2 180 Quantitative Analysis of Molecular Oxygen Using Palladium Porphyrins 2 181 Progress in Catalytic Technology in Japan 2 184 Macromolecular Platinum Metals Chelates 2i85 Surface Studies of Osmium Alloy coatings 2191 Ternary and Complex Rhodium Alloys 2192 A Review of Cathodically Modified Alloys 2204 Oxidation-Resistant Alloys 2204 A Potential Opportunity for F’latinum Group Metals Catalysts 2205 Automobile Emissions Control Catalysts 2206 The Chemistry of the F’latinum Group Metals 2207 Further Studies of Platinum Mineral Deposits 24214 Alfomo cossa 24215 Abstracts 2 222 New Patents 2236 Index to Volume 34 24mm4

Communications should be addressed to The Editor, Platinum Metals Review Johnson Matthey Public Limited Company, Hatton Garden, London EClN 8EE Palladium Supported Catalysts in CO + RONO Reactions By X.-Z. Jiang Department of Chemistry, University of Zhejiang, Hangzhou, P. R. China In the past decade much effort has been This article is a summary of our recent studies directed towards the synthesis of dialkyl oxalates on palladium supported catalysts in CO + and dialkyl carbonates directly from carbon MeONO (or EtONO) reactions at atmospheric monoxide and alcohols over palladium supported pressure in the vapour phase (6 - 8). It was found catalysts, under mild reaction conditions (I -4). that the carbonylation reactions of RONO, Although the mechanism of the reactions has not where R represents a methyl or ethyl group, been fully elucidated, the key reactions can be were very sensitive to the support, and that the illustrated by the following equations: main product was particularly dependent on the ,0-R nature of the support, as illustrated in Figure I. CO + 2RONO O=C + 2NO (i) -. Monocarbonylation ‘0- R 0 = C-OR The monocarbonylation of methanol or ethanol 2CO + 2RONO- I + 2NO (ii) can be achieved by introducing the correspon- 0 = C-0-R ding nitrites (methyl nitrite, MeONO, with b.p. (where R represents an alcohol residue). -12OC, or ethyl nitrite, EtONO, with b.p. The conditions required for these chemical 17OC) which were prepared according to reactions to take place are quite mild; for exam- established procedures (9). The nitrite was then ple, dimethyl or diethyl carbonate and oxalate able to react directly with carbon monoxide to can be efficiently prepared in the vapour phase form dimethyl carbonate or diethyl carbonate by bringing carbon monoxide into contact with over fured catalyst beds of palladium supported methyl nitrite or ethyl nitrite, respectively, on on active carbon catalysts, in the gas phase and a palladium fixed bed catalyst, at atmospheric at atmospheric pressure. The reaction pressure and at a reaction temperature between temperature varied from 80 to 12oOC. Because 80- 12oOC. The reason that this reaction can be the alkyl nitrites are fairly sensitive to heat and carried out under such mild conditions could be ultraviolet irradiation ( IO), they decompose rationalised on the basis of the iso-electronic rapidly above I~oOC,but below IIOOC they are structure of +NOand CO, leading to a strong quite stable for a long period of time. The op- synergistic catalytic effect on the active centre timum reaction temperature for the formation of of palladium (5). On the other hand, the nitrogen dimethyl carbonate or diethyl carbonate from oxide liberated from the reaction in Equations (i) MeONO or EtONO, respectively, is in the or (ii) will generate alkyl nitrite in the presence region of 90 to I IoOC, the selectivity being about of alcohol and oxygen, as indicated in the 90 per cent and with a carbon monoxide conver- chemical Equations (iii) and (iv): sion about 25 per cent in a flow system with a differential reactor. The formation of carbon 2NO + Y202 - N203 (iii) dioxide was extremely low in the vapour phase. N,O, + 2ROH - 2RONO + H20 (iv) The nature of the active carbon support, which As a result, there is no loss of alkyl nitrite, was made from various kinds of raw materials, which appears to play a role in circulating the significantly affects the catalytic activity for reagent in the reaction system. It is therefore of dimethyl carbonate or diethyl carbonate forma- great interest to investigate the applicability of tion (6, 7). Kinetic studies revealed that the 2 these reactions to industrial processes. per cent palladiumkarbon catalyst, in which the

Platinum Metals Rev., 1990, 34, (4), 178-180 178 /OR 2"10 Pd/C 1%Pd/a-Alz03 O=C-OR I '=',OR c80-120*C, 1 atm e0-120*~,latm* O=C-OR Dial kyl- Dialkyl- I carbonate oxa late Fig. 1 The main product of the RONO + CO reactions was found to be dependent on the I nature of the support. R represents a methyl or ethyl group active carbon was made from coconut shell, ex- be achieved in the monocarbonylation of hibited relatively &her formation activities for methanol and ethanol over the catalysts M + 2 dimethyl carbonate (DMC) or diethyl carbonate per cent palladiundcarbon (where M represents (DEC), for instance rDMC = 15 mmol/gcat.h; lithium, copper or iron) at a pressure of I at- while for an active carbon support made from mosphere and temperature of 80 to IIOOC. coal rDMC = 9 mmol/gcat.h, and for an active carbon support made from wood rDMC = 4 Dicarbonylation mmol/gcat.h, all under the same reaction con- An alternative reaction which formed dialkyl ditions. The main reason for these differences oxalates from CO + RONO over a palladium in the catalytic activity may be attributed to the catalyst supported on a-alumina under at- dispersion of the palladium particles exposed on mospheric pressure and at reaction temperatures the surface of the catalyst. The average palladium between 8o-12o0C in the vapour phase, is il- particle sizes measured by transmission electron lustrated in Figure I. Where carbon monoxide microscopy (TEM) can be ranked as follows: couplug occurred to form carbon-carbon bonds, dmM = 70 hi for the coconut shell-made active the occurrence of the dicarbonylation reaction carbon supported palladium catalyst; dmM = was mainly attributed to a function of the sup- 180 A for coal-made support and dnM = 340 port, therefore, a-alumina was utilised for the hi for wood-made active carbon support. From support instead of active carbon (8, I I). An im- a comparison of the dispersions of the palladium portant feature of palladium catalysts supported particles with the corresponding catalytic activi- on a-alumina is a fairly low dispersion of the ty, it can be concluded that active carbon sup- palladium particles exposed on the surface of the ported catalysts with higher dispersions of catalyst. It may be due to the very small surface palladium particles demonstrate higher catalytic area of the a-alumina support, for example, the activity for the formation of dimethyl carbonate surface area will be less than 8 m'lg, and the and diethyl carbonate from CO + MeONO, or crystallites of a-alumina are quite large. EtONO, under the mild gas phase reaction con- After a comparison of a-alumina-supported ditions mentioned above. and active carbon-supported palladium catalysts In some cases, however, the competitive for- a valuable conclusion could be drawn: a-alumina- mation of dimethyl (or diethyl) oxalate with car- supported palladium catalysts with a very low bonate would occur, especially at reaction dispersion of the palladium particles favoured temperatures above I I o°C. This competitive dicarbonylation reactions for the formation of reaction gives rise to a selectivity problem. An alkyl oxalates from CO + RONO; while active attempt was made to direct the selectivity carbon-supported palladium catalysts with a fair- towards monocarbonylation, rather than carbon ly high dispersion of palladium particles favoured monoxide coupling, by the inclusion of a small the monocarbonylation reaction, forming dialkyl amount of additive, such as a salt containing carbonates as the dominant product, under the lithium, copper or iron (6). As a result of this same reaction conditions. No doubt this is due additive selectivitiesgreater than 90 per cent can to the effect of the support.

Platinum Metals Rev., 1990, 34, (4) 179 The addition of a small amount of iron, gallium of attention for prospective industrial application. or titanium promoter will increase the catalytic At present the production of diethyl oxalate from activity for the formation of dimethyl (or diethyl) CO + EtONO over M + Pd/a-Al,O, catalyst oxalate by 3 or 4 times (11). Therefore the syn- is being developed in a plant in Shanghai. It will thesis of dimethyl and diethyl oxalates by car- undoubtedly result in more industrial utilisation bon monoxide coupling in the vapour phase can of palladium catalysts in the manufacture of be successfully achieved over catalysts of M + valuable organic compounds, perhaps replacing I per cent palladium/a-alumina, with the selec- existing production methods. tivity of about 85 per cent, and with 35 per cent carbon monoxide conversion and 60 per cent References RONO conversion in the integrated reactors. I K. Nishimura, S. Uehiumi, K. Fujii and K. Nishihira, Am. Chem. SOC.,Prep. Div. Pet. Chan., The heat of reaction of the reaction of (-AH) 1979, 24, (I), 355 CO + RONO, Equation (ii), was estimated to 2 K. Nishimura, S. Uehiumi, K. Fujii and K. be 47 kcal/mol at IOOOC,therefore the design of Nishihira, U.K.Patent 2,003,872; 1979 an integrated reactor on an industrial scale must 3 U. Romano, R. Tesel, M. Massi Mauri and P. L. Rebora, Id.Eng. Chem., Prod. Res. Dev., 1980, pay much attention to the heat effect. 19, 396 So far the mechanisms of the reactions, Equa- 4 S. G. David and M. S. Staines, European Appl. tions (i) and (ii), have not been established. We 134,668; 1985 5 S.-Y. Xu, B. Xue, Z.-F. Lin and X.-Z. Jiang, 3. have proposed that a synergistic effect of the iso- Catal. (Dalian, China), 1989,10, (2), 187 (Chinese) electronic structure of +NOand CO might play 6 X.-Z.Jiang, Y.-B. Zhu and S.-Y.Xu, 3. Catal. an important role in the reaction procedure (6, (Dalian, China), 1989, 10, (I), 75 (Chinese) Sci. 8, I I). Nishimura and colleagues assumed that 7 Y.-B. Zhu and X.-Z.Jiang, Chin. Bull., 1989, 34, (IO), 875 an intermediate of alkoxy palladium, such as 8 X.-Z.Jiang and Y. Chen, Fine Chemicals, 1989, Pd(N0) (OR) is formed during the reaction (I, 6, (I), 37 (Chinese) 2); moreover Rivetti and Romano isolated alkoxy 9 A. H. Blatt, “Organic Syntheses, Collective Volume”, Wiley, London, 1950, Vol.2, p.363 carbonyl complexes of palladium (IZ), such as I0 K. Kornblum and E. P. Oliveto, 3. Am. Chem. Pd(COOCH,),(PPh,),. They reported that this SOC.,1949,71, 226; J. B. Levy, Id.Eng. Chem. complex was stable for several hours in methanol (Id.Ed.), 1956, 48, 762 under carbon monoxide at room temperature, I1 X.-Z.Jiang, Chinese Patent Applicahn 90103093.7 but quickly decomposed at 5ooC, and then I2 F. Rivetti and U. Romano, 3. Orgammer. Chem., 1978, 154, 323 dimethyl oxalate was detected in the solution. Clearly further investigation will be required to Destruction of Organochlorines explore the mechanisms for mono- or dicarbonylation of alcohols. Many organochlorine molecules are persis- tent environmental poisons, and after use they must be disposed of most carefully. Although Conclusions high temperature incineration is the generally This article has briefly described novel ways accepted method of destroying the for mono- and dicarbonylations of methanol polychlorinated biphenyls, for example, con- and/or ethanol in synthesising the corresponding cern about incomplete oxidation remains. carbonates and oxalates over active carbon or Now, a report from the University of Sydney a- outlines a relatively low cost process for the alumina supported palladium catalysts in both electrocatalytic oxidative destruction of academic and industrial research laboratories. organochlorines (J. K. Beattie, Pure Appl. The introduction of methyl or ethyl nitrite as a Chem., 1990, 62, (6), 1145-1146). Complete circulating reagent, which experienced almost no oxidation to carbonate and chloride is achieved loss during the process, was a key feature of the using oxygen in alkaline solution, however, oxygen is too weak an oxidant to regenerate the novel method. In addition the mild reaction con- ruthenium tetroxide which is the active ditions and high catalytic activity and selectivi- catalytic species, but this can be achieved using ty of these reactions have attracted a great deal a small applied voltage.

Platinum Metals Rev., 1990, 34, (4) 180 Quantitative Analysis of Molecular Oxygen Using Palladium Porphyrins By Anthony Harriman Center for Fast Kinetics Research, The University of Texas at Austin, Texas, U.S.A.

A simple optical method for the quantitative determination of dissolved oxygen under physiological conditions is described. The technique involves measurement of room temperature phosphorescence from palladiumfll) porphyrins. Such emission is rare for large organic molecules, and its long lifetime, together with the favourable absorption characteristics of the porphyrin receptor, ensure that the phosphorescence can be resolved easily, wen in heterogeneous media. Phosphorescence yields and lifetimes are shown to be highly sensitive to the concentration of dissolved oxygen, but do not depend upon the nature of the environment, and can be used separately or together to determine oxygen levels within a biological substrate. This technique should be applicable to all areas of clinical, medicinal and biomedical chemistry.

In order to facilitate development of novel and which exhibit mom temperature anti-cancer agents it is necessary to be able to phosphorescence. Recent work has shown that monitor their in-situ reactivity with molecular palladium(I1) porphyrins exhibit moderately O,, since activated forms of 0, (for example intense phosphorescence in solution at room superoxide ions, hydroxyl and peroxyl radicals, temperature, and this is quenched by 0,(5). singlet molecular 0,)are believed to be respon- We have since found that the phosphorescence sible for the initiation of the chemotherapeutic lifetime of the porphyrin can be used to give a process. This requires analytical determination direct measurement of the concentration of of dissolved 0, concentrations under dissolved 0, in the solution. Palladium(I1) por- physiological conditions. Several experimental phyrins, therefore, could be used as molecular methods have been devised to obtain such in- probes for determination of dissolved 0, con- formation, including membrane polarographic centrations in a wide range of environments, detectors (I), oxygen-dependent fluorescence including biomaterials. quenching (2), ESR active spin-labels (3), chemiluminescence (4), and phosphorescence Discussion and Results quenching (5). Each of these approaches has its Photophysical Studies in Water merits and disadvantages but, in terms of As an illustration of the proposed technique, universal application and simplicity of opera- we present recently obtained results describing tion, the luminescence quenching method is the the luminescence properties of a water-soluble most attractive. Because a long-lived triplet ex- palladium(I1) porphyrin (PdP) in dilute cited state will always be very much more sen- aqueous solution. The porphyrin used for this sitive towards 0,-quenching than the study was palladium(I1) tetrakis(4-sulphon- corresponding short-lived singlet excited state, atopheny1)porphyrin (PdTSPP), the structure the phosphorescence quenching technique is to of which is given overleaf. This compound be preferred over the fluorescence approach. shows prominent absorption bands in the However, very few dyes are known that are visible region, as shown, see Figure I. biocompatible, stable and easily derivatised Excitation of PdTSPP in N2-saturated

Plotinurn Metah Rev., 1990, 34, (4), 181-184 181 can be measured easily. Under these condi- S03Na tions, the yield of total luminescence is reasonably high and can be measured with any commercial spectrofluorimeter. 4 id b PdTSPP Fluorescence is unaffected by the presence of molecular oxygen, whereas both phosphorescence intensity and lifetime are quenched by added 0,. As shown in Figure 3, there is a linear correlation between the rate constant for decay of triplet PdTSPP, measured aqueous solution gives rise to the emission spec- by laser flash photolysis methods, and the con- trum given in Figure 2. Both fluorescence and centration of dissolved 0,. For the same solu- phosphorescence emission can be observed tions, there is a corresponding correlation under such conditions. Time-resolved between the ratio of phosphorescence-to- luminescence studies allow resolution of the fluorescence maximum intensities and the con- two emissions since fluorescence (T~= 0.I ns) centration of dissolved 0,, Figure 4. These is very much shorter lived than latter two plots can be used to determine the phosphorescence (T~= I ms). The two spectra concentration of dissolved 0, in an unknown are well separated, with minimal overlap, and solution by comparing values measured for the the relative ratio of their maximum intensities unknown solution with the calibration plots.

250 - I408 Fig. 1 The absorption spectrum of palladiumQ1) tetrakis (4-sulphonatophen- y1)porphyrin in water shows the prominent absorption in 2 150 the visible region z !! I! 100 w u Z 50 0 U +- $2 WAVELENGTH, nm

io FLUORESCENCE h

- 08 z I I \ I 3 n 06 W ?? A 04 m Fig. 2 The total emission 9 spectrum recorded for 02 PdTSPP in nitrogen- saturated water at room temperature shows both the 500 5b Sbo 650 700 750 800 fluorescence and the WAVELENGTH. nm phosphorescence spectra

Platinum Metals Rev., 1990,34, (4) 182 3 OE6. Fig. 3 The plot of the observ- TRIPLET SIGNAL ed rate constant for the decay 5 at 460nm of the PdTSPP triplet excited state versus the concen- ' tration of dissolved oxygen in 2 OE6. water at room temperature LL shows a linear correlation; 2 $ is the quenching rate constant, and r is the correlation 1 OE6 ' coefficient which indicates how close the plot is to a 5LL r = 0996 linear display (for a perfect E straight line r= 1) 00 00 50E-4 I OE-3 7 5E-3 20E--3 Z! -3 OXYGEN CONCENTRATION

Identical effects are observed with other tions, there is a corresponding decrease in the water-soluble PdP derivatives and with water- phosphorescence lifetime (zp); in the absence insoluble PdP compounds dissolved in organic of 0, the lifetime is about I ms. These quen- solvents. In all cases, the phosphorescence ching effects follow Stern-Volmer kinetics lifetime and total emission spectrum can be (6pr/+p)= (7pr/7p) = I + ICQ[O,IT~~(i) used to give a quantitative determination of the where and 4, (or T~~ and T~)refer to concentration of dissolved 0, in the system. phosphorescence yields (or lifetimes) recorded in the absence and presence of 0,, respective- Analytical Considerations ly, and k, is the bimolecular rate constant for The studies outlined above have shown that quenching the triplet excited state by 0,. Stan- dilute solutions of palladium(I1) porphyrins dard values representing the absence of 0, are (PdP) exhibit both fluorescence and obtained by saturating the solution with N, phosphorescence at room temperature. The and all other solutions were saturated with fluorescence yield remains independent of the known mixtures of O,M,(6). The concentra- concentration of dissolved 0,, since the tion of dissolved 0, in an unknown solution is fluorescence lifetime is too short for diffusional determined simply by comparing the observed quenching, but the phosphorescence yield (+p) T~ and +p values with the calibration curve. decreases progressively as the concentration of In aqueous solution T~ was found to be dissolved 0, increases. Under the same condi- independent of the concentration of PdP,

10-

P 6-

Fig. 4 The plot of the observ- Groalent 5 91 x 103M-' r = o 995 ed ratio of fluorescence to 2. phosphorescence intensities versus the concentration of dissolved oxygen in water at 0.0 05 10 15 room temperature OXYGEN CONCENTRATION /10-'M

Platinum Metals Rev., 1990, 34, (4) 183 solution pH, ambient temperature, ionic intact cells. The in-situ measurements were strength and light intensity over wide ranges. rendered difficult by the high levels of light The phosphorescence lifetime, therefore, gives scattering and the poor light transmitting pro- an accurate measure of the concentration of perties inherent with such samples. It is dissolved 0 *.By contrast, +,, is not an absolute desirable, therefore, to synthesise porphyrin value but depends markedly upon concentra- derivatives that absorb and emit at long tion of PdP and light intensity. These same wavelengths where biological tissue is relatively parameters affect fluorescence and transparent and light scattering is minimised. phosphorescence to an equal degree, however, Thus, the luminescence properties of so that the ratio of the yields of palladium(I1) phthalocyanines, naphthalo- phosphorescence and fluorescence can be used cyanines and “expanded porphyrins”, which to determine accurate concentrationsof dissolv- should absorb and emit in the near infrared ed 0 I, since the fluorescence yield can be used region, will be evaluated in further studies. as an internal standard. Also, it is important to ensure that the probe molecules do not perturb the biomaterial or in- Biological Environments duce photodestruction of the medium. These The above studies were extended to include studies will be described in full in a later paper. determination of the concentration of dissolved 0, in organic solvents, micelles, liposomes, Acknowledgements vesicles, viscous media and inside the pockets We thank the Texas Advanced Technology Program for financial support of this work. The Center for of serum albumins. These studies used a range Fast Kinetics Research is supported jointly by the of PdP derivatives of differing Biotechnology Resources Division of the NIH and by hydrophobichydrophillic character. The the University of Texas at Austin. Palladium(I1) teuakis(4-sulphonatophenyl) porphyrin can be pur- luminescence properties of each PdP were chased from Midcentury Chemicals, Posen, Illinois. determined, as above, and their reaction with molecular O1 was quantified using laser flash References photolysis methods. The effects of PdP concen- I M. Hitchman, in “Measurement of Dissolved Ox- ygen’’, Wdey-Interscience, New York, 1978 tration, temperature, medium, added reagents, z N. Opitz and D. W. Lubbers, Adv. Expt. Med. 0, concentration and dye stability were Bid., 1984, 180, 261 monitored in order to establish the ability of the 3 W. K. Subczynski and J. S. Hyde, Bwphys. J., technique to determine meaningful 0 concen- 1984, 45, 743 4 R. Oshino, N. Oshino, M. Tamura, L. Kobinlin- trations under such conditions. sky and B. Chance, Bwchim. Bwphys. Acta, 1972, The PdP derivatives were used subsequently ”73, 5 to stain a variety of biomaterials, including 5 J. M. Vanderkooi, G. Maniara, T. J. Green and D. F. Wilson, J. Bwl. Chem., 1987,262, 5476 membranes, mitochondria, macromolecular 6 A. Mills, A. Harriman and G. Porter, Anal. Chem., proteins, DNA, and both healthy and infected 1981,53, 1254

Progress in Catalytic Technology in Japan A review of the developments in catalytic type, which is now used in a newly industrialis- technology made in Japan in recent years has ed process, is described in some detail. been prepared by M. Misono and N. Nojiri These include a novel palladium-tellurium on (Appl. Cutul., 1990,64,(I-2), 1-30). It is sug- active carbon catalyst that has been developed gested that the close co-operation between for use during the diacetoxylation of academic and industrial chemists is one of the I ~-butadiene to I ,4-.&acetoxyl-2-butene, factors that has contributed to the progress. under mild conditions, wlde a new asymmetric Another is the effective application of new process for I-menthol production depends catalyst materials, such as heteropoly acids, upon the use of optically active rhodium- new zeolites, bimetals and chiral transition BINAP to catalyse the enantioselective metal complexes. One representative of each isomerisation of geranyldiethylamine.

Plarinum Merals Rev., 1990, 34, (4) 184 Macromolecular Platinum Metals Chelates By A. D. Pomogailo Institute of Chemical Physics, Academy of Sciences, Chernogolovka, Moscow Region, U.S.S.R. and I. E. Uflyand State Pedagogical Institute, Rostov-on-Don, U.S.S.R.

In this review the advances in and problems associated with the preparation, structure and practical applications of macromolecular platinum metals chelates (MPMC) are presented and assessed. The terminology, classijkation and nomenclature of MPMC are considered and special attention is paid to their preparation and structural features. Some applications of MPMC are described.

During the last two decades the chemistry of or where the chelates form crosslinks (II) (7) to macromolecular platinum metals chelates the chain are usually called macromolecular metal (MPMC) has received much attention. The chelates, as shown below. Here the symbol - chelation of platinum metals by polymeric denotes a polymeric chain. ligands is widely used, for example, for the In contrast to co-ordination polymers which preparation of efficient polymeric catalysts (I), are described in detail elsewhere (8, 9) MPMC for membrane filtration of solutions containing do not contain metal in the polymer backbone, low concentrationsof platinum metals (2,3), and thus the metal can be easily removed or in ion exchange (4,5). Important theoretical pro- substituted by other metals without breaking the blems in the polymeric and co-ordination main chain of the macromolecule. Similarly other chemistry of MPMC, such as macromolecular platinum metals complexes with chelates which reactivity, the nature of bonding in metal chelates act as ion-exchangeresins (3 - 5, 10)should also and the distortion of ligands have also been be related to macromolecular platinum metals investigated. chelates. The parameters used in MPMC classification, Terminology, Classification and the classes and typical examples of MPMC Nomenclature of the MPMC (I I - 21) are listed in Table I. It should be noted High molecular weight homo- and heterochain that pendant type MPMC may be formed when compounds with pendant metal chelates (I) (6) low molecular weight platinum metals chelates

Platinum MetaLs Rev., 1990, 34, (4), 185-191 185 Table I

Macromolecular Platinum Metals Chelates Classification

1. Parameter: nature of metal-ligand bonding

a. Molecular chelates b. Intramolecular compounds

2. Parameter: chelate node nature

a. N,N-chelates b. 0,O-chelates c. S,S-chelates

d. P,P-chelates e. N,O-chelates f. N,S-chelates CL.

3. Parameter: number of atoms in metal cycles

a. four-member chelates b. five-member chelates c. six-member chelates -C)Q \/ Pd (0 COCH3) 2

is a polymeric carrier surface

Platinum Metah Rev., 1990, 34, (4) 186 are bound with polymers, an example of which in suspension, but there are drawbacks with this is this ruthenium chelate (22): method: the synthesis of complexes takes from one hour (29) to several days (24), and as a rule, T a rise in temperature results in higher yields of the complex; reaction conditions including pH, intermixing intensity, and ratios of the reagents greatly affect the chelation process, although these conditions of MI’MC synthesis have not yet received serious systematic study. where bipy is 2,2’-bipyridyl. MPMC Structure Up to now the MPMC nomenclature has been The characteristics of the chelation of platinum inadequately described; basically the two ap- metals with polymeric ligands have been analys- proaches shown below have been used: ed previously (I, 30). It should be noted that as (i) the addition of the prefm “poly” to the a rule intramolecularchelates of type I are form- substance name, for example, polydioximate ed in dilute solutions and that intermolecular palladium(I1) of type I11 (23); chelates of type I1 are formed in concentrated (ii) separate descriptions of the metal ion (or its solutions and polymeric matrices. The compound MX,,) and ligand, for example, the stereochemistry of co-ordination in MPMC is complex of RhCl with the condensation product determined by the nature of the metal complex of 2,2’ -bipyridyl-q,4’-dicarbonylchloride and in the case of soluble polyligands, and the struc- 2,6-diaminopyridine of type IV (I I). tural arxangement of the ligands in the case of cross-linked polymers. In the majority of cases, Methods of MPMC Preparation the chelating fragments of macroligands behave Common methods and principles for the syn- in the same way as their low molecular weight thesis of complex compounds are widely used in analogues; therefore metal chelates of similar the preparation of MPMC. A description of these composition and structure are formed. Binding methods, with appropriate examples, is given in of MX, by polymer matrices has some features Table II. Depending upon the characteristics of in common with reactions involving low the polymer the chelation may be carried out in molecular weight reactants. Thus, for example, the homogeneous phase (soluble linear homo- if the polymeric chain imposes steric hindrance and copolymers) or in a heterogeneous mixture towards chelate formation then monodentate (cross-linked polymers, grafted polymers and MX, feof type V is observed (31). The gels). In the case of soluble polymers solutions chloromethylated copolymer of styrene and of hgand in organic solvents or mixed media, and divinylbenzene, modified by aqueous, organic or aqueous-organic solutions of 1,2-bis(diphenylphosphino)ethane, forms Mx, are used. In the case of insoluble polymers mononuclear MPMC of type VI (32) with donshave to be carried out with the polymer RhH(CO)(PF%,), ,while low molecular weight

0 0

Platinum Metals Rev., 1990, 34, (4) 187 Table II

Methods of Macromolecular Platinum Metals Chelates Preparation

1. Synthesis on the base of chelating macroligands a. Interaction of MX, -chelating macroligand (24)

\/ Ru(blpy)zC[ 2 b. Method of ligand exchange (14, 15)

2. Methods of assemblage a. Polymerisation of metal chelate monomers (25) r

b. Polycondensation (26) r -

NHqcH3NH-C I1 0

c. Method of arising reagents (27)

K2PdC14 + CHI QCH2 f PLVP I I i HCRz HCR? R2C -Pd-CRz If1

d. Fixing of metal chelates on polymers (21) (j Ru(blpy)ZC12 + PLVP PY N. 1 ,PY - (N/Riu.N NJ

Platinum Metals Rev., 1990, 34, (4) 188 Table II (continued)

Methods of Macromolecular Platinum Metale Chelates Preparation

3. Synthesis of polynuclear chelates a. Fixing of clusters on polymers (28)

OS,(C0),2 + PLVP

b. Dimerisation of mononuclear complexes (14.1 5) co I/- + Rh(CO),(acac- 0-Rh-0 Lo el 0-Rh-0 9 d acac is acetylacetonate anion, 4-VP is 4-vinylpyridyne. P4VP is poly-4-vinylpyridyne, Py is pyridine, NUN is 22'dipyridyl ligands, such as I ,3-bis(diphenylphosphho)pro- The immobilised Rh(1) is stable only in a pane and I ,4-bis(diphenylphosphino)butaneY hydrogen atmosphere. Second, in a similar way, form rhodium dime complexes (32), below. the reduction of Pd(I1) occurs as (26): It should be pointed out that coordination of MHs MX, by chelating polymers leads to the forma- jbipy.Pd(II)(OCOCH ]) I -)bipy.Pd(O) tion of rather more stable complexes than form- In the macromolecular complex, Pd(0) can be ed fmm the corresponding low molecular weight reoxidised by dilute nitric acid or by chelates. The chelates formed are often stable to (NH,12 &(NO 3) 6. the reduction of the transition metal (such as during catalysis). This can be demonstrated by two MPMC Applications examples: first, the reduction of Rh(III), fued Three different ways of looking at MPMC lead on polyamides with bipy groups, to Rh(1) by to diverse applications: (i) the effect of the metal hydrogen proceeds in two steps (I I): at first step on the operational parameters of polymers, (ii) Rh(1) is formed, see page 19,but at second step the effect of the macromolecular chain on metal autocatalytic reduction of Rh(II1) by Rh(1) pro- properties, and (iii) the synthesis of new ceeds according to the rate equation: polymeric materials, which differ substantially in dlRh(I)l/dt = kIRh(1II)I 'LRh(I)I their properties from the initial reactants, see

n /PPh

Rh H (CO)PPh3

01)

Plotinurn Metals Rev., 1990, 34, (4) 189 Table 111. This information has been concen- based on rhodium complexes with cross-linked trated mainly in the patent literature (33). One polystyrene containing bipy fragments, was of the most interesting examples involve effective for more than 300 cycles (31). platinum-containing polymers showing in- The chelation of platinum metals is important hibitory activity with respect to tumour cells for analytical purposes (3 - 5, I 0). As a rule, the L929, HeLa, Detroit, WISH (34). The selective uptake of metal ions is achieved by us- mechanism of the activity of this preparation is ing polymeric ligands where the structure of the probably based on the slow release of the active ligands is determined by the co-ordination component, which provides the prolonged action chemistry of the specific metal. The uses of of the anti-tumour preparation. MPMC for the preparation of electroactive During recent years a new direction in catalysis coatings (25), electroconducting(39, photocon- has developed, whereby the chemistry of im- ducting materials (25), and in systems for the mobilised catalysts combines the advantages of photochemical storage of energy (39, are also of homogeneous (high activity and selectivity) and interest. heterogeneous (technologically practical) catalytic Thus, analysis of the methods of preparation, systems (I). Chelation is one of the most simple structures and the applications of MPMC in- ways of overcoming the basic shortcomingof fN- dicate substantial progress in MPMC chemistry ed metal complex catalysts, which is the relatively has been achieved. There are still important pro- low stability of the metal-polymer bond during blems to be solved however, which would enable the catalytic reaction. Thus, for example, the the basic principles of MPMC chemistry to be catalyst for olefin hydrogenation, which is formulated. Further work needs to be done on:

Table 111 Fields of MPMC Applications

Applications I Metal chelate I Metal complex catalysis Pt, Pd, Rh, Ir, Os, Ru Improvement of thermal properties of polymers Pt, Pd, Rh, Ir, 0s. Ru Selective binding and separation of metal ions Pt, Pd, Rh, Ir. Os, Ru Electroconducting polymers Pd . 0s. Ru Photoconducting polymers 0s. Ru Electroactive coatings 0s. Ru Energy storage systems Ru Biological preparations Pt

Platinum Metals Rev., 1990, 34, (4) 190 (i) the elaboration of new methods of MPMC of the participating chelating macroligands; (iii) preparation; (ii) a detailed analysis of the an investigation of the stemchemistry of chelates influence of the metal and polymeric chain in the in MPMC; and (iv) problems of stereoregulation early stages of the chelation process and the role and supramolecular structure of MPMC. References I A. D. Pbmogailo, ‘‘Polymeric Immobilized Metal 19 A. D. hmogailo, A. P. Lisitskaya, D. A. Kritskaya, Complex Catalysts”, Nauka, Moscow, 1988,p.303 A. N. Pbwmarev and E S. Dyachkovski, in 2 K. E. Geckeler, V. M. Shklinev and B. Y. Spimkm, “Complex Metal Organic Catalysts of Olefm Angew.Maknnnol.Chem., 1987, 155, 151 Pblymerization”, ChemogAovka, Inst. Chem. Phys. Acad. Sci. USSR Publ., 1983,8, (2), 78 3 A. Warshawsky in “Ion Exchange and Sorbtion processes in ~~&,~~d~’~, john wiley and 20 A. Madelli, F. kagnolari, G. hnorta, A. Foffini Sons, Chichester, 1987, Ch.3 and S. Tormni, 3. Mol. Catal., 1984, 24, 361 4 G. V. MWW and S. B. sawin, “Chelate For- 21 B. Elman and c. 3- 0rga-r. &m.3 ming Sorbents”, Nauka, Mascow, 1984, p.173 1985, 294, 117 5 S. A. Shovaand Yu. N. Kukmhkm. ,lev,bSh. 22 K. Sumi, M. Fume and S. Nozakura, 3. Polym. Uchebn. Zawd. Khim. Khim. Technol. (USSR), Sci.: Polym. Chem. Ed., 1984, 22, 3779 1985, 28, (9, 3 23 S. J. Kim and T. mwa,Makml. Chem., 6 C. Methenitis, J. Morcellet and M. Morcellet, Eut: 1975, 176, 891, 1217 Polym. 3., 1987, 23, 403 24 M. Kaneko, A. Yamada, E. Tmchida and Y. 7 H. Yukimasa, H. Sawai and T. Takizawa, Kurimura,J. Polym. Sci.: Polym. Len. Ed., 1982, Maknnnol. Chem. Rapid Comma, 1980, I, 579 “3 593 Rhrle, Adv. Polym. Sci., 50, 25 A. D. Pbmogailo and V. S. Savostyanov, “Metal- 8 D. 1983, 45 Containing Monomers and Polymers on their 9 M. Kaneko and E. Tsuchida, 3. Polym. Sci.: Base”, Moscow, Khimia, 1988, 384 pp. Macnnnol. Rev., 1981,16, 397 26 K. Zhang and D. C. Neckers, 3. Polym. Sci.: 10 S. K. Sahniand J. Reedijk, Coord. Chem. Rev., Polym. Chem. Ed., 1983,21, 3115 1984, 59, 1 27 G. R. Newkome and A. Yoneda, Maknmrol. Chem. 11 Y. P. Wang and D. C. Neckers, React. Polym., Rapid Commun., 1985, 6, 77 1985, 3, 181 28 S. Bhaduri, H. Khwaya and B. A. Narayanan, 3. 12 A. D. Pbmogailo, A. P. Lisitskaya, A. N. Chem. Soc., Dalton Tmns., 1984, (IO), 2327 PbnOmareV and F. s. DyafhbSl6 in “Catalysts 29 F. SVM, E. Walova and J. Angew. Containing Fixed Complexes”, Novosibirsk Makml. Ch-., 1985,136, (USSR), ht- Catid. Sibir. Otdel. had. USSR, hbl., 1977, p.35 3o A. D. pbm0gailoand1.E. uflyand, cd.them., 1988, 13, (2)s 147 I3 T’ Nakahira and Makmmol’ Rapid commun., 1985, 6, 341 31 R. S. Drago, E. D. Nyberg and A. G. El’Amma, Inotg. Chem., 1981, 20, (8), 2461 Khmia and ‘4 s. Bhaduriy Khanwalker,3. R. Sanger, J.C.S., Dalton Tmns., Chem. SOC.,Dalton Tmns., 1982, (2), 445 32 A. 1977,(2), 120 33 A. D. Pomogailo and I. E. Uflyand, 15 S. Bhaduri and H. Khwaja, J. Chem. Soc., Dalton “Macromolecular Metal Chelates”, Moscow, Tmns., 1983, (21, 419 Khimia, IggI (in press) 16 J. Kiji and H. Koni~hi,M&md- them. Rapid 34 C. E. merJr, C. Ademu-John, D. J. Ghn Comwn., 1985, 6, 49 and J. J. Fortman, in “Metal-Containing Polymer 17 E. Baralt and N. L. Holy,3. Org. Chem., 1984, Systems”, Plenum Press, New York, 1985,p.197 49, 2626 35 T. A. Furstch, L. T. ‘hylor, T. W. Fritz, G. Fort- 18 T.M. Sejlhanov,E.E. ErgcehinandB.A.Utkelov, ner and E. Khor, 3. Polym. Sci.: Polymer. Chem. vjrsokomol. Soedin., 1986, z8B, 504 Ed., 1982,20, (9, 1287 Surface Studies of Osmium Alloy Coatings The thermionic emission from a surface coated made of osmium-rhenium-tungstencoatings on with a binary alloy has been shown to be superior impregnated tungsten cathodes (C. S. Ares Fang to that from a pure tungsten surface, or one and C. E. Maloney, J. Vuc. Sci. Technol., 1990, coated with a pure metal. As far as emission 8, (93 2329-2332)- enhancement is considered, surface chemistry Measurements from an uncoated area of the may have a more important effect than the cathode surface were compared to those from substrate. It has been reported that addition of three areas coated with different alloy composi- a small amount of a fare earth metal to a binary tions, and showed that the effective work func- alloy coating leads to a reduction in work function of a surface coated with 40 osmium-40 tion. For this reason a study has been rhenium-zo per cent tungsten was 1.76 eV.

Platinum Metals Rev., 1990, 34, (4) 191 Ternary and Complex Rhodium Alloys AN INVESTIGATION OF MECHANICAL PROPERTIES By J. R. Handley Johnson Matthey, Materials Technology Division

A previous study on binary alloys of rhodium 127, 99, 94 and 73 hours, respectively, at a has shown that the addition of small quantities of loading of 345 bar and at a temperature of suitable alloying elements produce useful com- 1200~C;but the rare earth alloys had poor mercial alloys (I).It was found that certain workability (I).The addition of tantalum or binary alloys did not colour liquid glass, had an rhenium to these alloys improved their workabili- acceptable creep life and could be fabricated in- ty. The addition of tantalum and rhenium to to products used in the production of glass fibre. binary alloys of the other refractory group metals, At high loading and high temperatures, some and certain other elements, improved their cold binary rhodium alloys had a superior creep life formability, as shown in Table 11. to zirconia grain stabilised (ZGS) 10 per cent The principal mode of oxidation in the binary rhodium-platinum. Binary alloys which contain alloys was by grain boundary diffusion and in- hafnium, zirconium and niobium form a protec- ternal oxidation. The addition of a spinel oxide tive surface oxide layer which prevents metal loss former, such as chromium, was made to improve by the evaporation that is normally associated the oxidation resistance of these alloys. At the with the platinum group metals. lower temperature of 120o0C chromium did im- This investigation of rhodium alloys was car- prove the oxidation resistance of binary alloys. ried out to see if the useful properties of binary This improvement was similar to that found in alloys could be enhanced by the addition of fur- stainless steels and nickel superalloys. At the ther alloying elements, and if the creep life could higher temperature of 140ooC, chromium no be improved by the addition of grain boundary longer formed a protective oxide spinel. The ox- strengthening elements, such as carbon, or by idation resistance of the more complex alloys was the formation of a gamma prime precipitate or similar to that found in the binary alloys where an oxidation-resistant oxide spinel. the addition of a strong oxide former prevented The concentration of the alloying elements us- rhodium evaporation. Most of the alloys revealed in this study was generally I weight per cent, ed a weight gain after oxidation, as a result of which for most alloys is below the solid solubili- the alloying element being converted to an ox- ty limit, thus preventing precipitation of a second ide, Table 111. The most resistant oxide layers intermetallic phase. The alloys were argon arc formed upon the ternary alloys containing tan- melted and fabricated into sheets, and their stress talum or niobium. rupture properties were determined at loadings Glass compatibility tests carried out on binary of I 10to 345 bar at temperatures of 1200,1300, alloys revealed that the addition of a strong ox- 1400 and I~xIOC. ide former, such as chromium or hafnium, The addition of a further alloying element to prevented rhodium from colouring liquid glass. the binary alloys only produced a small increase The effect of small additions of these elements of up to 50 Hv in the as-cast hardness of the ter- to those binary alloys which mildly coloured glass nary alloys, as shown in Table I. In the previous was to prevent them from colouring liquid glass paper it was shown that the binary alloys con- (Table 111). The addition of a third or fourth ele- taining scandium, holmium, zirconium and ment to most of the binary alloys did not reduce lutetium had the longest stress rupture lives of the contact angle of liquid glass. Only two of the

Platinum Metals Rev., 1990, 34, (4), 192-204 192 T.Mo I The As-Cast Hardness of Ternary Rhodium Alloys Containing 1 Weight

~ ~~ Per Cent Each of the Second~ and Third Elements, Compared to the Basic Binary Alloy hardness values, Hv

Element Binary Cr Hf" Nb Mo V Ta Ti Zr

Al 176 168 Ag 98 137 114 Au 128 115 Ca 152 153 co 130 130 Cr 117 117 163 209 152 128 163 143 206 DY " 158 164 Er 174 169 161 181 194 Fe 117 118 Gd " 157 160 Hf" 179 163 179 159 142 154 172 150 149 Ho 156 158 177 168 161 197 173 Ir 94 127 110 La 151 164 Lu 162 166 165 170 Mg 108 143 Mn 134 150 Mo 121 152 142 132 121 145 151 128 187 Nb 131 209 159 131 132 141 279 145 161 Nd 160 159 Ni 134 145 143 0s 111 136 104 Pd 109 133 131 Pt 110 119 109 Re 102 135 123 136 Ru 98 125 120 sc 189 167 199 185 176 189 205 Sm 156 161 Ta 126 163 172 279 151 138 126 172 Tb 168 142 Ti 118 143 150 145 128 128 118 216 Tm 167 169 v 164 128 154 141 145 164 138 128 193 W 116 129 121 145 121 170 122 164 Y 187 189 Yb 146 181 Zr -151 -206 -149 -161 -187 -193 -172 -216 -151 O0.5 wt.% dysprosium and gadolinium; 0.3 wt.% hafnium more complex alloys, lutetium-tantalum- metals, rare earth metals and indium produced rhodium and hafnium-rhenium-scandium- the longest stress rupture lives. MORa series rhodium, reduced the contact angle of liquid of ternary alloys was made to determine the ef- glass to below the 33O angle that occurs with fect of additions of 0.75 weight per cent niobium rhodium to 2oo and 27O, respectively. and I weight per cent tantalum to binary alloys, In the previous study it was shown that binary and the results are given in Tables IV and V. alloys formed by the addition of refractory group These results show that the most signifiit

Platinum Me& REV.,1990,34, (4) 193 Table II Cuping Tests of Rhodium Alloys Containing 1 Weight Per Cent Each of the Second and Third Elements, Compared to the Basic Binary Alloy ErichsenErichsen numbernumber ofof turnsturns ofof aa 2525 mmmm diameterdiameter disc,disc, depthdepth inin O.OlmmO.Olmm perper turnturn

Element Binary Cr Hf' Nb Mo v Ta Ti Zr

Al 11 41 Ag 41 57 Au 45 54 Ca 34 29 co 47 54 Cr 29 29 33 36 50 37 59 40 Er 28 29 32 29 19 Fe 46 57 Hf" 47 33 55 47 38 29 100+ 32 54 Ho 33 18 22 29 21 34 28 Ir 49 60 55 Lu 33 29 24 30 Mn 39 48 Mo 41 50 38 40 41 26 38 34 19 Nb" 38 36 47 38 40 48 75+ 43 40 Nd 19 31 Ni 52 33 55 0s 36 50 51 Pd 45 48 57 Pt 56 53 61 Re 54 102 59 64 Ru 53 42 54 sc 8 20 29 26 18 26 14 Sm 19 25 Ta 43 59 100+ 75+ 38 54 43 56 46 Tb 29 39 Ti 30 40 32 43 56 38 28 Tm 26 32 v 30 37 29 48 26 30 54 29 w 71 100+ 48 31 34 27 Y 21 31 Yb 35 29 Zr 42 54 4c 19 29 46 28 42

0.3 wt.% hafnium, '0.75 wt.% niobium improvement in creep life occurred in those content to be I per cent. The ternary alloys of alloys which contained either another refractory niobium-rhodium and tantalum-rhodium group metal, a rare earth metal, indium or which had the longest creep life were another platinum group metal. The addition of zirconium-niobium-rhodium, molybdenum- I weight per cent of osmium or iridium to a niobium-rhodium and tungsten-tantalum- 0.75 per cent niobium-rhodium alloy increased rhodium of 156, 151 and 106hours, respective- the stress rupture life from 56 to 105 hours. ly, at 345 bar and 1200OC. The effect of osmium concentration on the 0.75 Therefore a further series of ternary alloys in- per cent niobium-rhodium alloy is seen in cluding refractory group metals was made to Table VI, which shows the optimum osmium determine which combination would produce

Platinum Metals Rev., 1990, 34, (4) 194 Table 111 I Glass Compactibiity Tests and Oxidation of Complex Alloys of Rhodium Glass test Oxidation

Weight loss or weight gain, Contact mg/cm h Alloying angle, elements degrees Colour at 12OOOC at 140OOC - Ag-Ta v.v.1. brown - 16.2 AI-Ta clear 0.0 6.0 Au-Ta v.v.1. green - 18.7 Cr-Ta 64 clear 1.8 Cr-Mo 68 clear -4.7 Co-Ta d.. blue 8.1 Co-Ta-W d. blue 20.2 Er-Ta 46 I. brown 6.6 Fe-Ta v.v.1. brown - 3.0 Hf-Cr 47 v.1. brown - 4.6 Hf-Cr-Mo clear 13.1 Hf-Lu 45 brown 12.6 Hf-Re 54 I. brown 9.4 17.5 Hf-Sc 49 I. brown 0.5 Hf-Ta 62 clear 16.2 60.0 Hf-Ti clear 2.5 Hf-V clear 4.6 Hf-W 50 clear 7.6 15.7 Hf-Re-Mo 2.5 Hf-Re-Sc 27 - 5.6 Hf-Re-Ta 58 clear 5.6 Hf-Ta-W 46 clear 1.3 Hf-Cr-Mo-Ta 51 clear 11.1 17.4 Ho-Ta I. brown 5.0 Lu-Ta 20 clear 5.6 Mn-Ta clear - 2.4 Mo-Ta 81 I. blue -2.5

Nb-Cr 47 I. blue 6.1 Nb-Cr-Mo I. blue 6.1 Nb-Lu I. brown 4.0 Nb-Mo blue -1.0 Nb-Ni d. brown 0.0 Nb-Ni-Ti I. brown 18.2 Nb-Re-Sc 68 v.v.1. brown 2.5 Nb-Sc 34 I. brown 20.7 Nb-Ta 55 clear 11.0 16.6 Nb-Ta-lr 38 clear 6.8 6.1 Nb-Ti v.v.1. brown - 3.0 Nb-V I. blue 1.o Pd-Ta brown 5.6 Pt-Ta 47 v.1. brown Re-Ta 64 v.1. brown - 4.4 Ru-Ta - 6.4 Sc-Ta 57 clear 1.8 Ta-W clear 3.1 Ta-Zr 57 clear 12.3 39.2 V-Ta 68 clear 0.0 Y-Ta 56 v.I. brown 6.1 Zr-6 clear - 7.5 - 125.0

Element Cr Hf Nb Pt Re sc V Ta Contact angle, O 62 47 62 53 47 55 Glass colour CI cl cl v.l.br v.l.gr v.l.gr v.l.bl v.l.gr

.I. very light, v.v.1. very very lig d. dark, I. light, cI clear, k brown, gr green. bl blue

Platinum Metals Rev., 1990, 34, (4) 195 Table IV Stress Rupture Livea of Ternary Alloys of Rhodium-0.75 wt.%, Niobium Containing 1 Weight Per Cent of the Pbtimcm Third Element at a Loading of 345 bar and at Temperatures of 120OOC (upper) and 1400°C (lower) time to failure, hours

Metals Ti V Cr Mn Fe co Ni cu Zn Ga Ge As Se 103.3 23.8 23.7 39.4 50.7 39.8 Ca 1sc9.5 2.9 4.2 5.8 2.1 3.4 Rev., A Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te 3 156.5 56.2 151.9 54.8 56.2 22.9 12.0 100 1990, 7.3 9.1 12.6 3.7 9.1 4.6 4.9 10.4 Hf' Ta w Re 0s Ir Pt Au Hg TI Pb Bi Po 34, 92.9 64.2 98.6 76.2 20.3 104.6 105.6 48.8 38.1 (4) 7.2 8.8 13.0 6.3 0.6 10.0 6.9 6.9 5.5 Ce Pr Nd Pm Sm Eu Gd Tb DV Ho Er Tm Yb Lu 30.1 31 .O 85.5 3.7 2.4 11.2

Table V Stress Rupture Lives of Ternary Alloys of Rhodium Containing 1 Weight Per Cent Tantalum and 1 Weight Per Cent of the Third Element at a Loading of 345 bar and at Temperatares of 120OOC (upper) and 1400OC (lower) time to failure, hours Mg Al Si P S 18.5 19.7 2.4 1.8 Ca sc Ti V Cr Mn Fe co Ni cu Zn Ga Ge As Se 27.5 97.5 35.9 100 35.9 20.9 35.9 27.4 32.0 17.1 6.8 3.9 6.5 1.9 5.1 1.5 2.1 2.6 4.7 Sr Y Zr Nb' Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te 37.8 37.5 98.6 57.5 22.6 46.5 24.0 26.5 93.6 3.7 1.4 13.0 7.1 9.3 6.2 1.6 3.6 Ba La Hf' Ta W Re 0s Ir Pt Au Hg TI Pb Bi Po 82.9 46.5 106.6 55.5 34.8 24.3 20.9 9.0 17.2 6.2 7.5 6.7 0.7 4.3 2.2 0.7 Ce Pr Nd Pm Sm Eu Gd Tb DY Ho Er Tm Yb Lu 27.9 13.0 42.6 32.5 123.8 15.4 1.1 40.2 196 196 0.2 0.8 2.3 5.6 6.5 0.05 '0.3 wt.% hafnium. 0.75 wt.% niobium the longest creep life, and the results are seen binary alloys of scandium, holmium, erbium and in Table VII. This shows that some of the lutetium is seen in Table VIII. This shows that strongest alloys are produced from combinations most refractory group metals reduced the stress of elements on the same line of the Periodic Table rupture life of these rare earth-containing alloys. (zirconium/niobium/molybdenum and haf- However, the addition of hafnium to lutetium- nium/tantalum/tungsten). Two of these alloys, rhodium, chromium to scandium-rhodium and 0.75 per cent niobium-1 per cent zirconium and tantalum to erbium-rhodium, increased the stress 0.75 per cent niobium-1 per cent molybdenum, rupture life compared to that of the binary alloys, had a longer stress rupture life than a cobalt- while only chromium improved the formability. based superalloy at a loading of 345 bar and at The effect of the addition of osmium, iridium a temperature of 1z0o~C. . and rhenium upon the stress rupture properties The effect of the addition of a refractory group of ternary alloys is given in Table IX. Of these metal on the stress rupture properties of the elements, the addition of osmium and rhenium

Table VI Effect of Carbon and Osmium Concentrations on the Stress Rupture Properties of Ternary Alloys of Rhodium at a Loading of 345 bar

Alloying elements, Temperature, Element Concentration, weight per cent OC weight per cent I l%Crl%V C 0.0 0.01 1200 32.4 27.7 1400 1.7 1.2

0.75% Nb 1% Ag C 0.0 0.01 1200 12.0 48.2 1400 4.9 9.2

0.75% Nb 1% Er C 0.0 0.01 1200 31.0 29.6 1400 2.4 0.75% Nb 1% 0s C 0.0 0.01 1200 104.6 35.6 1400 10.0 4.7 1% Ti 1% Cr c I 0.0 1 0.01 1200 34.2 29.2 1400 1.7 4.0

1% Ti 1% Mo C 0.0 0.01 1200 43.5 33.8 1400 6.0 4.8

1% Ti 1% Zr C 0.0 0.02 1200 83.4 27.9

0.75% Nb 0s 0.0 0.5 1.o 2.0 1200 56.2 46.0 104.6 21.0 1400 16.6 10.6 10.0 -2.0

Platinum Metak Rev., 1990, 34, (4) 197 ~~~

TableTable VIIVII StressStress RuptureRupture PropertiesProperties ofof TernaryTernary AlloysAlloys ofof RhodiumRhodium andand thethe RefractoryRefractory GroupGroup Metals Metals atat aa LoadingLoading ofof 345345 barbar

Temper-Temper- ature,ature, OC TimeTime toto failure,failure, hourshours Element,Element, ' weightweight 1%1% 1%1% 0.3%0.3% 1%1% ).75% 1% 1% 1% 1% perper centcent TiTi ZrZr HfHf VV Nb Ta Cr Mo W 1%1% TiTi 1200 40.940.9 83.483.4 27.527.5 39.839.8 23.5 35.9 34.2 43.5 5.7 1400 3.83.8 9.69.6 6.56.5 4.74.7 2.9 3.9 1.7 6.0 2.4 1400 I I - 1% Zr 1200 83.483.4 94.494.4 58.758.7 52.252.2 153.5 37.5 46.9 55.9 34.9 1400 9.69.6 4.14.1 4.64.6 5.85.8 7.3 1.4 2.4 4.5 4.3

0.3% Hf 1200 27.5 58.7 49.8 53.8 62.4 82.9 50.7 75.6 48.5 1400 6.5 4.6 3.9 10.5 8.8 17.2 2.1 6.6 3.8 1% v 1200 39.8 52.2 53.8 47.2 23.7 100.0 32.6 28.0 10.5 1400 4.7 5.8 10.5 5.7 4.2 6.5 3.6 4.2 1.1 ~ - - - - - ~ - 0.75% Nb 1200 23.5 153.5 62.4 23.7 56.2 98.6 39.4 151.9 76.2 1400 2.9 7.3 8.8 4.2 9.1 13.0 5.8 12.6 6.3 ~ - 1% Ta 1200 35.9 37.5 82.9 100.0 98.6 46.5 35.5 57.1 106.6 1400 3.9 1.4 17.2 6.5 13.0 6.2 1.9 7.1 7.5 ~ - - - 1% Cr 1200 34.2 46.9 50.7 32.6 39.4 35.9 28.0 75.5 10.2 1400 1.7 2.4 2.1 3.6 5.8 1.9 2.1 2.1 0.2 ~ __ 1% Mo 1200 43.5 1 55.9 75.6 28.0 151.9 57.1 75.5 42.7 18.3 1400 6.0 4.5 6.6 4.2 12.6 7.1 2.1 2.8 0.1 - - - ~ - ~ ~ - 1%W 1200 5.7 34.9 48.5 10.5 76.2 106.6 10.2 18.3 11.1 1400 -2.4 -4.32.41 -fl3.8 1 - 1.1 -6.3 -7.5 -0.2 -0.1 -0.3 produced the most significant improvements in niobium, improved the stress rupture life; but the stress rupture life of these ternary alloys. at higher concentrations the stress rupture life The effects of the addition of non-metallic was decreased. elements carbon, boron, phosphorus, sulphur The effect of loading upon the creep life of and silicon on the creep lives of 0.75 per cent complex alloys is seen in Table XI. The addi- niobium-rhodium and I per cent zirconium- tion of 0.75 per cent niobium to 0.1 per cent rhodium alloys are seen in Table X. This shows silicon-rhodium alloy at a loading of I 10 bar at that even at low concentrations these elements 12m°C reduced the stress rupture life from 2147 can substantially reduce the stress rupture life to 2045 hours. Most of the alloy additions to the achieved by the binary rhodium alloys. A similar binary niobium-rhodium alloys substantially result produced by small additions of carbon to reduced the stress rupture life, at the loading of other ternary alloys is given in Table VI. Very IIO bar at 12moC, from 1919 hours. Only one low concentrations of carbon in alloys which con- alloy, the 0.3 per cent hafnium-1 per cent tain a strong carbide forming element, such as zirconium-rhodium, produced a significant

Platinum Metah Rev., 1990, 34, (4) 198 increase in the stress rupture life compared with that of the binary rhodium alloys containing haf- W nium or zirconium, at a loading of I 10 bar and 1% a temperature of 120oOC. Lives were increased from 869 and 677 hours to 1565 hours, respec- :? 1.4 1.0 9.3 - Mo 1% 16.2 17.0 tively. The stress rupture results show that at 72.0 7 high loadings the addition of a third element im- ?t 1.9 1.4 2.7 cc Cr 11.7

proves the creep life, but at lower loadings a fur- 1%

$6 c 43.6 136.8 ther alloy addition makes no significant Metals improvement. This lack of improvement in creep :: 5.6 2.3 6.8 Ta 1% 97.5 32.5 properties is due to the fact that the alloy addi- m 40.2 123.8 tion does not prevent the oxygen diffusion which -I- produces large oxide particles, which then act as Refractory 2.4 3.7 9.5 06 Nb 11.8 30.1 85.5 m 31.0

crack initiators. 103.3 0.75% It was found that the ternary alloy 0.75 per cent and

niobium-1 cent of tantalum-rhodium could V per 1.1 1% 24.8 hours

be used as a welding rod for rhodium alloys. Earths Stress rupture results obtained from welded 5.3 6.1 0.6 Hf

rhodium alloys of niobium-tantalum, hafnium- 15.2 66.1 Rare failure, 0.3% vanadium and hafnium-titanium at I 10 bar and 165.5 to with a temperature of 120oOC gave lives of 792,1919 bar Zr 1% and 869 hours, respectively. This ternary alloy Time

was used to weld fabricated rhodium spinner 345 of baskets. Vlll Ti 4.1 1% Rhodium Some alloys were made which contaiued a gam- 93.8 of ma prime precipitate, of either Ni,Ti or Nb,Ti, Table order effect

in to determine their upon rup- 1.5

stress Loading Lu 1% 72.9

ture properties. The results revealed that at 345 a Alloys

bar and a temperature of 120ooC, the gamma at Er 1%

prime precipitates produced only a small increase 4.35 in the stress rupture life of 51 hours for 3 per 52.9 cent nickel-titanium-rhodium and 48 hours for Ternary of 2.6 Ho 1%

3 per cent niobium-titanium-rhodium, when 99.8 compared to the values of 21 ,34, and 41 hours for the binary alloys nickel-rhodium, niobium-

of 5.2 Sc 1%

rhodium and titanium-rhodium, respectively. 127.5

Other possible hardening ternary alloys were Properties investigated. The addition of cobalt to a tungsten-rhodium alloy increased the stress rup- OC 200 1200 1 1400 1400 1400 1200 1400 1200

ture life from I I to 85 hours, at a loading of 345 Rupture

bar and at 120ooC. The addition of gallium and Temperature, indium, which are used to harden platinum, reduced the stress rupture life of indium- Stress rhodium from 40 to 16 hours, at 345 bar and cent per Ho Lu I200OC. sc Er The formation of an oxide spinel used to pro- 1.0% 1.0% 1.0% 1.0% Element, tect the low alloy steels of chromium, and weight molybdenum, together with the strong oxide

Platinum Metals Rev., 1990,34, (4) 199 TableTable IXIX II StressStress RuptureRupture LivesLives ofof ComplexComplex Alloys Alloys ofof RhodiumRhodium atat aa LoadingLoading of of 345345 barbar I Stress rupture lives, hours

TernaryTernary AlloyAlloy ComplexComplex AlloyAlloy

~ ~~ AlloyingAlloying Temperature,Temperature, OC "C AlloyingAlloying Temperature,Temperature, OCOC elementselements elementselements 1200 1400 12001200 1400 1400

CrCr HoHo 11.7 1.4 Cr Ho 0s 31.131.1 1.71.7 CrCr ScSc 136.8 2.7 Cr Sc 0s 48.048.0 CrCr ScSc 136.8136.8 2.72.7 Cr Sc Re 1.41.4 2.42.4 CoCo TaTa 27.427.4 2.1 Co Ta W 85.185.1 4.44.4 ErEr MoMo 16.216.2 1.31.3 Er MoMo ReRe 22.922.9 1.81.8

HfHf HoHo 15.215.2 6.16.1 HfHf HoHo ReRe 46.346.3 HfHf TiTi 27.527.5 6.56.5 HfHf TiTi IrIr 92.092.0 HfHf TiTi 27.527.5 6.56.5 HfHf TiTi 0s0s 26.326.3 7.37.3 HfHf NbNb 62.462.4 8.88.8 HfHf NbNb 0s0s 137.6137.6 7.07.0 HfHf MoMo 75.675.6 6.66.6 HfHf MoMo ReRe 99.999.9 21.221.2 HfHf VV 53.853.8 10.510.5 HfHf VV 0s0s 32.232.2 3.83.8 HfHf ZrZr 58.758.7 4.64.6 HfHf ZrZr 0s0s 135.8135.8 5.85.8 HfHf ScSc 66.166.1 5.25.2 HfHf ScSc ReRe 87.787.7 HfHf TaTa 82.982.9 17.217.2 HfHf TaTa ReRe 163.7163.7 5.05.0 HfHf TaTa 82.982.9 17.217.2 HfHf TaTa WW 50.750.7 4.24.2

~~ HoHo MoMo 17.017.0 11.o .o HoHo MoMo ReRe 39.239.2 1.11.1 NiNi TaTa 32.032.0 2.62.6 Ni"Ni" TiTi TaTa 51.451.4 3.03.0

~ NbNb CrCr 39.439.4 5.85.8 NbNb CrCr 0s0s 22.022.0 4.34.3 NbNb TaTa 79.579.5 8.08.0 NbNb TaTa IrIr 92.492.4 16.216.2 NbNb TiTi 23.523.5 2.92.9 NbNb NiNi TiTi 15.015.0 3.13.1 NbNb LuLu 85.585.5 11.811.8 NbNb LuLu 0s0s 40.640.6 4.84.8 NbNb VV 23.723.7 4.24.2 NbNb VV 0s0s 43.743.7 5.45.4

MoMo ZrZr 55.755.7 4.54.5 MoMo ZrZr 0s0s 88.288.2 4.24.2 MoMo ScSc 72.072.0 9.39.3 MoMo ScSc ReRe 89.289.2 4.54.5 MoMo VV 28.028.0 4.24.2 MoMo VV ReRe 2.72.7 1.91.9 ScSc TiTi 93.893.8 4.14.1 ScSc TiTi 0s0s 111.0111.0 YY TaTa 37.837.8 3.73.7 YY TaTa Ir Ir 61.161.1 HfHf CrCr MoMo -18.118.1 1.11.1 HfHf CrCr MoMo TaTa 156.4156.4 5.95.9 ill alloy additions contain 1 wt.% of element, except 0.3 wt.% hafnium, '3'3 wt.% wt.% nickel-1nickel-1 wt.%wt.% titaniumtitanium andand 0.750.75 wt.% wt.% niobium niobium

formers, hafnium and tantalum, produced one stress rupture lives of these alloys (2). The pre- of the longest lives of 156hours, when tested at sent investigation has shown that small additions a loading of 345 bars and at 120o0C. of boron, carbon, phosphorus, sulphur and silicon to a 0.75 weight per cent niobium- Discussion rhodium alloy all reduce the stress rupture life Studies of nickel and cobalt superalloys have of the binary alloy, see Figure I. This effect was shown that the presence of low levels of non- also found in a I weight per cent zirconium- metallic elements can significantly reduce the rhodium alloy, and in other ternary alloys. At

Platinum Metals Rev., 1990, 34, (4) 200 very low levels of carbon, alloys which form very sion. A similar improvement is found in the stress stable carbides, such as niobium, revealed an in- rupture properties of nickel supedoys with low creased stress rupture life at 345 bar and at carbon content. Studies of nickel superalloys 1200OC.This improvement in stress rupture life have shown that the carbon increases the grain may be due to the formation of fine particles of boundary adhesion, but at higher concentrations NbC which increased the grain boundary cohe- of carbon it forms large carbides at the grain

Table x Effect of Non-metallicNon..metallic Element Concentration on thethe Stress Rupture Properties of Binary Rhodium Alloys at a Loading of 345 bar

Temperature, Alloying Concentration of nonmetallic element, Element OC element weight per cent

Stress rupture life, hours

0.75% Nb B 0.0 0.02 0.05 0.1 I I I 1200 56.2 21.2 1400 9.1 0.8

I C I 0.0 I 0.02 I 0.05 I 0.1 I I I I I 1 I 1200 56.2 69.3 21.5 7.9 1400 9.1 6.3 4.3 1.o .o

P 0.0 0.02 0.05 0.1

1200 56.2 38.0 11.6 1400 9.1 4.8 2.1

I S I 0.0 I 0.02 I 0.05 I 0.1 I I I I 1200 56.2 29.0 22.6 1400 9.1 3.2 2.8

Si 0.0 0.02 0.05 0.1 1200 I 56.2 48.3 1400 9.1 5.0

1% Zr 0 0.0 0.1

1200 94.4 39.9 1400 4.1 5.4

C 0.0 0.01

1200 94.4 47.1 1400 4.1 . 6.3

Si 0.0 0.1

1200 94.4 61.4 1400 4.1 3.8

Plotinurn Metak Rev., 1990,34, (4) 201 Platinum

Table XI

Metals Stress Rupture Properties of Rhodium Alloys at Loadings of 110, 207 and 345 bar

Time to failure, hours

Reu., Loadinq, bar 110 207 345 P Bend Bend Bend P Alloying elements Elongation, angle, Elongation, angle, Elongation, angle, -1990, Temperature, OC SRL per cent degrees SRL per cent degrees SRL per cent degrees W\o 0 1%Er 0.75% Nb 34, 1200 896.2 5.2 30 31 .O 7.8 5 y 1% 1%V

(4) Cr v,-.P -1 200 ~~ 462.4 6.5 20 32.6 7.8 130 0.3% Hf 1% Zr I 1200 1565.5 5.2 25 58.7 6.5 30 1300 242.3 6.5 45 0.3% Hf 1% Mo 1% Re 1200 665.1 2.6 15 99.9 3.9 80 1400 44.6 5.2 85 21.2 9.2 50 1500 18.1 2.6 65 0.75% Nb 1% Cr 1400 66.3 1.3 35 5.8 6.6 80 0.75% Nb 2.0% 0s 1200 514.9 5.2 90 25.1 5.2 155 0.75% Nb 1% Mo

~ 1400 276.4 1.3 20 12.6 9.2 110 0.75% Nb 0.1% Si 1200 2045.0 3.9 25 48.3 6.3 110 0.75% Nb 1% Sc 1200 86.4 3.9 30 5.2 9.2 30 0.75% Nb 1% Ta 1200 787.6 9.2 5 188.6 11.8 45 79.5 11.8 105 1300 661 .O 7.9 50 168.6 10.5 55 24.6 13.1 45 1400 291.8 3.9 50 54.6 6.6 100 8.0 11.8 140 . 1500 103.0 6.6 70 1% Mo 1% Ti 1200 901.8 6.5 45 43.5 2.6 100 1% V 1% Zr 1200 829.4 3.9 35 52.2 2.6 40 1% V 1% Zr 0.01% C N 1200 444.3 6.5 10 62.1 7.8 20 0N Bend Test arounda 5mm radius strength of ternary alloys of refractory group -- I metals is produced by the large binding energies of the AB compounds between these metals. Metals from Groups I11 and IVYsuch as scandium and zirconium, produce the largest bindmg energies with rhodium, and also in ternary alloys containing these elements. The effect of the addition of a second platinum group metal, such as iridium or osmium, is to promote the formation of even more stable AB compounds, such 0.02 064 0.06 0 08 0.iO as IrHf, and ZrIr 3. Also the theory predicts ex- CONCENTRATION, weight per cent tremely strong bondmg of osmium with hafnium, Fig. 1 Variations in the stress rupture life of 0.75 weight per cent niobium-rhodium niobium and zirconium; and in those ternary and alloys with various concentrations of the quaternary alloys of rhodium which contain com- third, non-metallic constituent at a test binations of two or more of these refractory group temperature of 120OOC and a loading of 345 bar metals with osmium some of the longest lives at 345 bar at IZOO~Coccurred. At high loadings the creep properties of cer- boundaries which act as crack initiators pro- tain rhodium alloys are superior to those of ZGS moting premature failure. In addition, at high platinum, ZGS 10 per cent rhodium-platinum, temperature these elements are readily oxidised nickel and cobalt superalloys. At loadings of 345 to volatile gases which form voids, which then bar the principle mode of failure is by slip, which cause rapid failure. is easily made more difficult by internal oxida- The results of this investigation show that ad- tion of refractory group metals to a fine disper- ditions of non-metallic elements have a sion of oxides. At a lower loading of IIO bar deleterious effect upon the high temperature pro- failure is initiated by grain boundary sliding and perties of rhodium, and this effect may occur in cavitation. Under these conditions the easy dif- other platinum group metals or alloys. The use fusion of oxygen along the grain boundaries of of electron beam melting makes it possible to rhodium alloys promotes the formation of large produce alloys with a lower non-metallic content oxide particles. These large oxides prevent than can be achieved by conventional melting dynamic recovery and act as crack initiators pro- techniques. The use of such equipment for moting rapid failure of the alloys. Under condi- melting platinum group metals and their alloys tions of low stress this investigation could not for high temperature applicationswill reduce the find any rhodium alloys which had longer stress concentration level of non-metallic elements, and rupture lives than ZGS platinum or nickel and hence may improve their high temperature pro- cobalt superalloys. perties. The superior stress rupture lives of binary and Conclusions ternary rhodium alloys which contain additions The addition of one or more elements to binary of one or more refractory group metals can be alloys of rhodium can improve the properties of explained by the Lewis acid based stabilisation the bimq alloys. The formation of a stable pro- theory. If this theory is applied to the formation tective oxide coat can prevent liquid glass from of oxides (3) in rhodium alloys and those being coloured. The inherent grain boundary rhodium alloys which contain other platinum weakness of rhodium will limit its usefulness as group metals, it can explain the improvement in a high temperature material. The presence of the stress rupture properties of dilute solutions small additions of non-metallic elements of refractory group metals in binary and ternary significantly reduced the stress rupture life of alloys. It shows that the improvement in creep rhodium alloys. The longest creep lives in

Platinum Metals Rev., 1990, 34, (4) 203 rhodiumrhodium basedbased alloysalloys werewere obtained obtained fromfrom alloysalloys References containingcontaining mixturesmixtures ofof eithereither refractoryrefractory groupgroup I J. R. Handley, Platinum Metals Rev., 1989, 33, metals,metals, oror rarerare earthsearths andand refractory refractory groupgroup (’), ‘4 metal, or refractory group metal with the addi- 2 J. J. debrbadillo, Trans. AIME, 1983, 14A, 329 metal, or group l”letal with the addi- 3 J. K, Gibson, L. Brewer and K. A. Gingerich, tiontion ofof osmiumosmium oror iridium.iridium. Trans. AZME, 1984, 15A, 2075 A Review of Cathodically Modified Alloys The beneficial effects conferred on base bulk alloying, favourably influences the com- metals and their alloys by small additions of the mercial viability of cathodically alloyed steels. platinum group metals have been reported here In contrast, the alloying of titanium with frequently. In recent issues, for example, the platinum group metals has been shown to be literature on the enhancement of corrosion beneficial in both oxidising and reducing resistance in stainless steels has been reviewed media. Palladium has been the most studied ad- (I ,2); and that on amorphous chromium alloys dition, and the research has led to the develop- (3) and surface-implanted titanium alloys has ment of the widely used commercial also been reported (4). titanium-0.2 per cent palladium alloy which is The platinum group metals enhance the cor- particularly suited to service in reducing condi- rosion resistance of such alloys in corrosive tions. Surface alloying by, for example, ion- media by modifying the cathodic reaction, and implantation with palladium or platinum is also this has led to the description “cathodically effective in conferring enhanced corrosion modified alloys”. resistance as well as certain mechanical proper- Now, an extensive review of the literature on ties, such as fatigue. C.W.C. base metals cathodically modified with noble References metals has been published (5). This report I I. R. McGill, Platinum Metals Rev., 1~,34,(z), 85 surveys the literature on chromium, stainless 2 I. R. McGill, ibid., 1990, 34, (3), 14 steels and titanium. The author claims that it is 3 C.W.C., Platinum Metals Rev., 19,34, f2), 84 the first comprehensive review of the subject 4 IAnon.1 Platinum Metals Rev., 1990, 34, (z), 97 which, he considers, has been neglected as a 5 J. H. Potgieter, Report M397, Mintek, Randberg, topic in recent years-the only active groups be- January 1990, 13pp, ISBN 0-86999-876-5 ing Professor Tomashov’s team in the U.S.S.R. Academy of Sciences, Moscow and Dr. Higgin- Oxidation-Resistant Alloys son and his co-workers at Mintek. Tungsten and molybdenum possess high Several studies have been made on the effect melting points and good mechanical strengths of small additions of platinum group metals to at elevated temperatures, but even at moderate chromium in both oxidising and reducing temperatures both oxidise rapidly. Previous acids. In reducing conditions, platinum group studies have shown that tungsten-chromium- metal modified alloys self passivate easily and palladium alloys have remarkable oxidation their corrosion resistance is several orders of resistance when heated in air, and different magnitude higher than that of pure chromium. mechanisms have been proposed to explain the The effectiveness of the platinum group metals advantageous action of the palladium. is as follows: platinum>palladium>iridium A recent investigation of the oxidation >rutheniumhsmium. During the period of ac- mechanism and of the characteristics of this tive dissolution that precedes the onset of alloy system, and of some quaternary alloys passivation, an enrichment of the platinum produced by substituting large amounts of group metals occurs at the alloy surface. molybdenum for some of the tungsten, has now The work carried out on stainless steels in been reported (D.-B. Lee and G. Simkovich, J. reducing acids shows that platinum group Less-Common Met., 1990,163, (I),51-62). metal additions are more beneficial to ferritic Between 1000 and 125ooC, the oxidation steels than to austenitic steels, and that their ef- resistance of the alloys increases with fect is enhanced with increasing chromium con- temperature, the molybdenum-containing tent of the steel. When molybdenum is also alloys being the more resistant. The palladium present, there is a synergistic effect with the enhances the formation of a protective chromic platinum group metal addition. oxide scale, acts as a reservoir for chromium, More economic use of the platinum group facilitates the outward movement of chromium metals through surface alloying, rather than by and prevents oxygen diffusing inwards.

Platinum Metals Rev., 1990, 34, (4) 204 A Potential Opportunity for Platinum Group Metals Catalysts New Developments in Selective Oxidation, Studies in Surface Science and Catalysis, 55

EDITED BY G. CENTI AND F. TRIFIR~, Elsevier, Amsterdam, 1990, 892 pages, ISBN 0-444-88694-X, W.385.00, u.s.$I97.50 With the exception of a few important group metal centres in the oxidation of olefms examples platinum group metals catalysts have to ketones using hydrogen peroxide. Kinetic found little utility in commercial selective studies established that the oxygen transfer step oxidation processes. This is because the high is a bimolecular process involving nucleophilic specific activity of platinum group metals attack of a PtOOH species on an olefm catalysts tends to make them highly efficient for activated at a separate, distinct platinum group deep oxidation, hence their widespread use in metal centre. Thus in the presence of a I:I

pollution control. In the process chemical [(dppe)Pd(CF,)(CH,~,)I+ and (diphoe)- industry the requirement is for the high value Pt(CFj)(OH) catalyst mixture a variety of intermediate, and this prompts the question olefins were oxidised to the corresponding “IS it likely that there will be an expanded role ketones, with up to 38 per cent yield in the case for platinum group metals catalysts in this area of butylvinyl ether; (dppe = I ,z-diphenyl- in future years?” phosphinoethane, diphoe = cis-I ,z-diphenyl- The international symposium held in Rimini, phosphinoethylene). Italy, from 18th to 22nd September 1989, Homogeneous bimolecular action was also considered the whole field of selective inferred by N. I. Kuznetsova, A. S. Lisitsyn, oxidation, and so the recently published A. I. Boronin and V. A. Likholobov who used proceedings enables an assessment to be made platinum and palladium catalysts for the of both current research activity and the future epoxidation of cyclo-hexene by molecular potential for platinum group metals catalysts in oxygen in the presence of hydrogen. They this area. From the point of view of the number suggest the in-situ formation of hydrogen of papers presented at the conference peroxide over Pto followed by interaction of concerning these materials the question may peroxide and olefm over a platinum group seem rhetorical. Even if silver and gold are metal ion. Thus mixtures of K,PtCl, and included with the platinum group metals no H,PdCl,/SiO, or (CH,CN),PdCl, converted more than 15 per cent of the papers reported 63 per cent cyclo-hexene at up to 24 per cent studies using such materials as selective yield to epoxide. oxidation catalysts. However, in recent times Another interesting paper in the related area there has been an increasing interest in their of co-catalysis was provided by N. H. Kiers, B. use, particularly in the liquid phase, especially L. Feringa and P. W. N. M. van Leeuwen who since the successful commercialisation of used chemistry with a distinct analogy to Wacker chemistry and alkene acetoxylation, Wacker technology to oxidise olefms to both using palladium catalysts. Papers were aldehydes over (CH CN) ,PdClNO, KuCl , co- presented not only on the use of palladium but catalyst systems using molecular oxygen. also of platinum and ruthenium catalyst Papers dealing with heterogeneous oxidations systems in liquid phase selective oxidation in the liquid phase using platinum group metals processes. included that by P. Vinke, H. E. van Dam and A paper by G. Strukul, A. Zanardo and F. H. van Bekkum who used R/Al ,0 to oxidise Pinna describes a well exemplified case of 5-hydroxymethylfurfural to the dicarboxylic bifunctional catalysis involving two platinum acid using molecular oxygen. The objective

Platinum MetaLs Rev., 1990, 34, (4), 205-206 205 here was to oxidise materials obtained from N. Rajapakse, B. R. James and D. Dolphin renewables, rather than oil derived chemicals, describes the use of dioxo(porphyrinato)- to yield existing or new products; in this case a ruthenium(VI) species to oxidise thioether and product was obtained with potential as olefinic substrates using molecular oxygen. feedstock for new polymers. Another Thus the complex trans-Ru(porp)O, was shown interesting feature is the use of supported to transfer oxygen cleanly or remove hydrogen platinum to selectively oxidise the substrate. from several such substrates, albeit slowly, For the oxidation of hydrocarbons and (porp=dianion of ~,10,15,2c+tetramesityl- alcohols M. Hronec, Z. Cvengrosova, J. Tuleja porphyrin). and J. Ilavsky found that promotion of Pt/C An interesting paper by M. Bressan and A. and Pd/C by base metals gave higher catalytic Morvillo demonstrates that aliphatic acyclic activity and higher resistance against and cyclic hydrocarbons can be oxidised in deactivation. Thus the incorporation of cobalt, good yield from hydrocarbon substrates using bismuth, cadmium, zinc, or manganese into the homogeneous catalysts. tRu"CI(DPP) IPF, catalyst systems improved performance in the and truns-tRuxlC1,(DPP),I were effective for oxidations of numerous olefms, for example a- the oxidation of cyclo-octane, cyclo-hexane and pinene, to alcohols and ketones. n-hexane to the corresponding alcohols and The use of a tri-metallic Pd-Pt-Bi/C catalyst ketones, using sodium hypochlorite as oxidant to oxidise glucose to gluconic acid with high (DPP= I ,3-bis(diphenylphospho)propane). selectivity and space time yield was described In summary those papers dealing with the use by B. M. Despeyroux, K. Deller and E. of platinum group metals catalysts for selective Peldszus. Yields approaching 100 per cent at oxidation reactions demonstrate a growing 4000g/g/h were achieved. Platinum was shown awareness of the applicability of these elements to boost activity while bismuth improved to this important field. The selective oxidation selectivity. of commercially important substrates using In recent years there has been interest in cheap oxidants such as air or hydrogen peroxide biomimetic systems, particularly in attempts to and platinum group metals catalysts is the goal, use laboratory analogues of such enzymes as the and it is likely that in the future new processes monooxygenase Cytochrome P450 which incorporating such technology will emerge to promotes a range of oxidations in biological augment the few examples currently being systems with very high efficiency. A paper by operated on a commercial scale. E.S. Automobile Emissions Control Catalysts Now utilising more than one third of the oxidise the first two components while Western World's demand for platinum, it is simultaneously reducing the latter. Including interesting to recall that the use of platinum rhodium in the catalyst formulation enables this metals catalysts to control the emissions from to be achieved. Cerium oxide additions also gasoline fuelled, spark ignition engines has only improve the performance of these "three-way" arisen in the last twenty years. A concise catalysts, while engine controls ensure that the account of the major technical and scientific air-to-fuel ratio is maintained at the advances made during this time has recently stoichiometric composition, where platinum- been given by Kathleen C. Taylor, of the rhodium catalysts promote the conversion of General Motors Research Laboratories the three major pollutants simultaneously. Chmtech., 1990, 20, (91, 551-555). Further work is still required, for example, to Initially the control of carbon monoxide and improve catalyst activity under cold-start gaseous hydrocarbons was achieved by the use conditions and tolerance of high temperatures. of platinum and palladium. After 1981 more The development of catalytic converters has stringent standards were introduced, including already contributed to significantly lower a new requirement to decrease nitrogen oxides vehicle emissions and improved air quality, and emissions. The approach adopted was to to our knowledge of platinum metals catalysis.

Platinum Metals Rev., 1990, 34, (4) 206 The Chemistry of the Platinum Group Metals A REVIEW OF THE FOURTH INTERNATIONAL CONFERENCE By C. F. J. Barnard Johnson Matthey Technology Centre

Sponsored by the Dalton Division of the Royal Society of Chemistry, the fourth International Conference on the Chemistry of the Platinum Group Metals was held at the University of Cambridge on 9th to 13th July 1990. Previous meetings in this series have been held in Bristol (1 981), Edin- burgh (1 984) and Shefield (1 987). More than three hundred delegates, over one third from overseas, attended the meeting for a programme of twenty-seven lectures and almost two hundred poster presentations.

The opening lecture by Lord Lewis of the species and elemental mercury. More details on University of Cambridge set the main theme for the structures of these complexes and other the conference with a review of metal cluster clusters were given by Profasor M. McPartlin of chemistry, an area to which he has made a ma- the Polytechnic of North London. By studying jor contribution over many years. While concen- related series of compounds, an insight has been trating on the structural aspects of cluster gained into how smaller clusters react to form compounds, his lecture also illustrated a variety larger units. While early efforts to synthesise large of synthetic routes to the compounds, their redox clusters of osmium and ruthenium emphasised behaviour and the fluxionality of hgands in large the role of interstitial atoms in providing addi- clusters. tional electrons to stabilise the smcture, they are Careful analysis of the pducts of pyrolysis of not essential, as indicated by the recent [M,(CO),,I or tM,(CO),,(MeCN),I (M = Ru characterisation of the dianion tOs,,(CO),,12-. or 0s) has led to the identification of series of Cluster compounds stabilised by the incorpora- compounds ranging from M, species up to M,, tion of boron were described by C. Housecroft species. While the structures of small clusters of the University of Cambridge. These species, (M 46) can be predicted by electron counting for example [HRu,(CO),,(AuPPh,)BHI, may be rules as described by Mingos, for larger clusters characterised by mdtinuclear NMR smopy the rules do not predict a unique structure. Large ( H and B), and in addition by X-ray crystallo- cluster compounds can also undergo a slgnifcant graphy when suitable crystals can be formed. The number of redox changes without corresponding variation in reactivity of Ru, cluster compounds major structural changes, for example nine redox containing B, C or N atoms was illustrated by states have been identified for an [ 0s,, (CO) ,, I reactions with diphenylacetylene. Mixed metal core. In the search for larger metal clusters, clusters containing platinum were discussed by substitution reactions generating mixed metal Professor R. Adams of the University of South species have proved useful. The coupling of Carolina. A number of such compounds may be osmium or ruthenium clusters with mercury salts obtained from the reaction of bis(cyc1oocta- yields compounds such as [Ru18 Hg,C, (CO) ,* 1 ,- diene)platinum(o)with metal carbonyls M(CO), where two Ru, units are linked by a Hg, bridge. (M = Fe, Ru or 0s). Although the majority of The compounds readily undergo an unusual the products are small clusters (3 to 7 metal reversible rearrangement to form a Hg,-bridged atoms), reaction with [Os,(CO),,(MeCN),I,

Platinum Metals Rev., 1990, 34, (4), 207-214 207 where the acetonitrile ligands are readily water and do not show colloidal effects such as substituted, yields high nuclearity clusters such light scattering. For larger metal clusters (about as [Pt50s6(CO),,(COD),1. Reduction of 1000 atoms) low temperature (I K) NMR spec- ROs (CO) I ,with hydrogen yields three cluster troscopy provides information on the electronic products each containing six bridging hydrogen properties of the particles. This technique was atoms. described by P. I? Edwards of the University of The kinetics of substitution reactions of metal Cambridge for copper and platinum colloids. As carbonyl clusters were discussed by Professor A. the size of the particles decreases their electronic J. IW of the University of Toronto. The effect properties deviate from the normal metallic of phosphine ligands (L) in complexes behaviour associated with large arrays of atoms, [Ru,(CO),, Ll on the further substitution and so by studying a range of particles, details behaviour of these compounds can be analysed of this transition from metallic to non-metallic in terms of electronic and steric factors. Very behaviour may be obtained. good correlations between reaction rates and phosphine basicity (corrected where necessary for Catalysis steric effects) were obtained. Increased electron Low pressure hydroformylation using rhodium donation into the cluster promotes further catalysts (LP-0x0) was jointly developed during substitution as would be expected. A wide range the 1970s by Union Carbide, Davy McKee and of cluster complexes may be obtained by these Johnson Matthey and now accounts for over half reactions, providing many interesting oppor- of the world capacity for butyraldehyde produc- tunities for future investigations. tion. Recent developments in the extension of The molecular recognition processes con- this technology to butene feedstocks through the tributing to crystal packing and growth were use of novel phosphite ligands were described by discussed by Professor D. Braga of the Univer- D. Bryant of Union Carbide. Simple phosphite sity of Bologna, using metal cluster compounds ligands were initially discarded by Union Car- as examples. Differences in the solid state bide during their development work on the LP- structures of [Ru,(CO),(C,H,)I and 0x0 process due to their instability to hydrolysis [OS,(CO),(C6H6)1 may be attributed to Crystal under reaction conditions. The more stable packing and intermolecular interactions. In- phosphines, in particular triphenylphosphine, tramolecular interactions affecting solid state were selected to provide suitable reaction rates, motions such as the rotation of co-ordinated selectivity and catalyst stability. However a re- organic fragments were also considered. The examination of the factors responsible for motions of benzene and ethene ligands of phosphite hydrolysis led to the identification of [Os,(CO),(C,H,)(C,H,)l can be explained by novel ligands, see Figure I, highly resistant to the different shapes of the potential energy hydrolysis. Furthermore, using these ligands surfaces for rotation of the two ligands. hydroformylation rates were greatly superior to Recent advances in the characterisation of those for phosphine-based catalysts, thus allow- small metal particles were described by Professor ing these systems to be considered for hydrofor- J. M. Thomas of the Royal Institution. Using mylation of higher (C, +) olefin feedstocks. high angle Rutherford scattering rather than the Olefin isomerisation from internal to terminal normal low angle diffraction technique, electron double bonds is also catalysed in these reactions, microscopy can detect metal particles of only 3 allowing mixed butene feedstocks (now widely or 4 atoms. Information on particle structure can available as a by-product of MTBE production) also be obtained by temperature-dependentEX- to be used. Diorganophosphites (I) give low AFS. Using this technique the giant metal straight:branched aldehyde ratios, lower than clusters [Pd56,L6,(OAc),,,1(L = bipy or phen) those achieved with triphenylphosphine, but the first described by Russian workers have been bisphosphites (11) yield very high isomer ratios. characterised. These molecules are soluble in The production of n-valeraldehyde by a

Platinum Metals Rev., 1990, 34, (4) 208 Fig. 1 Novel ligands diorganophosphites (I) and bisphosphites (11) were identified as being highly resistant to hydrolysis. For rhodium-catalysed hydroformylation (I) gives low 8traight:branched aldehyde ratios, lower than those achieved with triphenylphoephine, while (II) yields very high isomer ratio8

bisphosphite-modzied rhodium catalyst is thus 10 years significant impmements have been an economically attractive proposition. The made to the performance and durability of the aldehyde would find a market as a precursor to catalyst through better understanding of the con- 2-propylheptanol used in the preparation of tribution and interaction of the various com- didecylphthalate which has advantages over ponents of the catalytic system; namely the dioctylphthalate in its use as a plasticiser. platinum group metals, promoters and the sup- Development work is continuing at Union port. A key feature in maintaining NO, reduc- Carbide with the aim of commercialising this tion performance while also achieving carbon process over the next few years. monoxide oxidation through the water-gas shift The use of other chelating ligands with the reaction has been an increase in the use of ceria. potential for promoting chiral selectivity in With ever tighter specifcations proposed for homogeneous catalysis was discussed by Pmfessor future legislation, the difficulties in obtaining L. Venanzi of ETH, Zurich. Rhodium good catalyst performance under cold start con- pyrazolylborate complexes have been examined ditions will become more important. This may in alkene hydrogenation reactions and their per- eventually lead to a requirement for heating the formance compared with rhodium-phosphine catalyst (for example, electrically) before starting systems. Catalysis of acetalysation reactions, the engine. Equation (i), by rhodium-triphos complexes Hydrocarbon oxidation mctions repment one of the major uses of heterogeneous catalysis in RzCO+2R'OH-RzC(OR1)z+HzO 6) the chemical industry. These reactions general- allows such reactions to be carried out on acid ly involve the use of oxygen-rich catalysts (like sensitive molecules with significant diastereo- metal oxides), a point that has generally been ig- chemical selectivity. nored in mechanistic studies to date. An attempt Developments in the field of heterogeneous toovemmethisdeficiencywaspresentedbyPro- catalysis for automobile exhaust emission con- fessor W. G. Klemperer of the University of 11- trol were described by T. J. True of Johnson linois. Model compounds were synthesised by the Matthey. The oxidation catalysts (for converting reaction of organometallic cations with polyox- hydrocarbons and carbon monoxide to carbon oanions such as [(C,Me,)TiW,O,,l 3+ and dioxide and water) introduced in 1975 were (P309)3-.Studies of reactions with molecular replaced by three-way catalysts (which in addi- oxygen were illustrated for the case of a cyclooc- tion achieves simultaneous duction of nimgen tadiene iridium complex. This reaction results in oxides, NOJ in the early 1980s. Over the past the initial formation of a 4-membered oxygen-

Plotinurn Metak Rev., 1990, 34, (4) 209 lithium isotope ratio in material deposited on the electrode surface during electrolysis. As long as the possibility remains of energy generation by this technique, whatever the mechanism, ex- perimentation will continue to identify the numerous factors that need to be controlled before the phenomenon can be obtained (111) reproducibly. Fig. 2 Other molecules can be readily co- Professor J. Grobe of the University of ordinated by substitution reactions with this Munster described the electrochemical genera- acetonitrile complex tion of platinum group metals compounds active for homogeneous catalysis. The inertness of the platinum group metals can be overcome giving bonded metallocycle which subsequently re- reasonable current yields by three methods: arranges to give a hydroxyl-substituted low temperature cathodic dissolution, high C-bonded metallocycle. temperature anodic dissolution in the presence Mechanistic studies of carbon chain growth of halide ions, and dissolution using a biased which may be applicable to Fischer-Tropsch alternating current (DCimposed on AC). Typical catalysis were discussed by Professor S. A. R. electrolyte/solvent combinations found useful Knox of Bristol University. Di-ruthenium were MeOHNaOMe and DMF/NBu,Cl. Low p-vinyl complexes were chosen as model com- valent complexes such as [RhCl(CO)(PPh J) I pounds with l3 C labelling of one of the atoms of were obtained when the electrolysis was carried the vinyl group allowing the point of linking for out in the presence of CO and PPh, ligands. C-C bond formation to be established. By substitution reactions with the acetonitrile com- Oxidative Addition plex, see Figure 2, other molecules can be readily RDutes to the intramolecular activation of co-ordinated. Reaction with diazomethane leads C-H bonds have only recently been identified. to carbene addition at the 0-carbon of the vinyl Studies of iridium and rhodium complexes which group, and alkynes also link to this carbon to undergo C-H oxidative addition to yield stable yield p-butadiene complexes. However, ethene alkyliridium hydride products were described by links to the a-carbon of the vinyl group. The Professor R. G. Bergman of the University of spatial arrangement of the ligands may contribute California. Irradiation of dihydride complexes to this change in point of attachment but the such as [Ir(C,Me,)(H),(PMe,)l at low situation is complicated by the possibility of temperature results in the elimination of migration of the vinyl group from one metal hydrogen and the formation of a solvent-stabilised centre to the other. intermediate. This intermediate reacts with C-H A third, less conventional, area of platinum bonds (IO %-2O>3O)to yield stable products. group metals catalysis that was discussed by D. A consequence of this high level of activity T. Thompson of Johnson Matthey is the effect was that the choice of an inert solvent for kinetic first claimed by Fleischmann and hns as involv- studies was difficult, and liquefied inert gases ing low temperature nuclear fusion. Detailed (xenon or krypton) were finally selected. Even analytical studies of palladium electrodes obtain- these solvents interact with the irradiation pro- ed from cells reported to have genemted “excess” ducts to form intermediates which may then heat in “cold fusion” experiments showed undergo an exchange reaction with the alkane various anomalous features. These included followed by the C-H insertion reaction. Through changes in the microstructure of the rods, sug- the use of inert gas solvents, iridium complexes gesting high thermal stress (temperatures of up were shown to activate adamantane (2O C-H to at least 300OC) in local areas, and an unusual insertion) and cubane (3O C-H insertion).

Platinum Metals Rev., 1990, 34, (4) 210 The effect of metal-metal bonds on the ox- central Ru,(CO), unit were studied at low idative addition reactions of dimeric compounds temperature with the process occurring much was considered by J. l? Fackler of Texas A and faster for the trans-(SS) isomer than the other M University and Professor M. Cowie of the forms. At higher temperatures the cis and trans University of Alberta. Reactions of gold(1) forms interconvert due to rotation about the cen- dimers were reviewed by J. l? Fackler. A range tral metal-metal bond. Finally, at higher of starting materials for this work was readily temperatures still, the SS and SR isomers available in dithiocarbamate and phosphorus interconvert by an intermolecular process ylide complexes. Although the stable species thought to proceed via cleavage of the central isolated were Au - Au asymmetric products, Ru-Ru bond. these were formed by rearrangement of Professor Cotton dealt with a series of chloride- Au" -Au" intermediates. The interaction bet- bridged dimeric and trimeric complexes. Struc- ween the metal atoms is also evidenced by the turally these complexes may be viewed as aris- reductive elimination from ALI"~-Aulll dimeric ing from edge-sharing or face-sharing of complexes which in the absence of metal-metal octahedra formed around each metal atom by the bonding is forbidden by orbital symmetry rules. chloride ligands. In general these complexes do Professor Cowie presented the results of the not contain metal-metal bonds, although the mix- study of low dent dimeric metal compounds ed oxidation state Ru" -Rulll dimeric com- containing bis(dipheny1phosphino)methane pounds have short Ru-Ru distances consistent (DPM). The short bridging ligand allows interac- with a bond order of one half. EPR studies of tion between the metal atoms, which for a series Ru have allowed characterisation of the three of rhodium complexes is best described as a isomers of [Ru,Cl,(PR,),l. For trimeric species dative bond giving the rhodium a formal representatives of all four oxidation states oxidation state of +I, for example in (RuII -Ru" -Ru" Rull -Rull' -Rull, [Rhl(CO)(DPM), M(CO),l. This interpretation bill -&,I1 -Rulll and hill -Rulll -,Ill) is supported by X-ray crystallography which have been characterised and their interconversion shows the rhodium atom to have essentially by redox reactions investigated. square planar co-ordination. Oxidative addition The development of novel polymers contain- reactions occur readily at this rhodium centre and ing metal-metal bonds was discussed by Professor subsequent interaction with the second metal M. H. Chisholm of Indiana University. A yields the fdproducts. Thus hydrogen sulphide number of metals (for example rhodium, reacts to yield sulphur-bridged products. ruthenium, molybdenum and tungsten) form dimeric compounds of the type [M (0, CR),] . Linear Clusters Liquid crystal phases exist for some of these com- The properties of different types of linear pounds, but this is metal dependent, discotic ruthenium cluster compounds were discussed by regions being formed by molybdenum and Professor K. Vrieze of the University of Amster- ruthenium complexes but not by those of dam and Professor F. A. Cotton of Texas A and tungsten. When reacting molybdenum carbox- M University. Professor Vrieze described the ylate complexes with oxalic acid, ligand exchange structures and fluxional behaviour of a series of yields polymeric materials. The products have a tetranuclear compounds containing monoaza- perpendicular arrangement of the metal dimers dime ligands, RICH=CH-CH=NR (MAD). relative to the direction of the chain. Products The complexes are readily prepared by the where metal dimers are linked in a parallel ar- reaction of the ligand with [Ru,(CO) Four rangement can be prepared using anthracene enantiomeric forms of the product dicarboxylates. Molybdenum and tungsten [Ru,(CO),,(MAD),I exist and have been polymers give different degrees of conductivity separated and characterised. The interconversion on oxidation. While the molybdenum materials of terminal and bridging carbonyl groups of the give products with only partial delocalisation of

Platinum Meiah Rev., 1990, 34, (4) 211 the metal-metal bonding, the tungsten analogues prepared for a variety of metals. On extending are more easily oxidised and give fully delocalis- the study to more complex ligands, incorporating ed systems. Ligand exchange reactions with thiophene rings, the products formed continue rhodium complexes are unsuccessful due to their to show a preference for cyclometallation rather inertness and therefore rhodium-based polymers than co-ordination through the heteroatom. cannot be prepared in this my. However, studies The application of 2d NMR spectroscopy to of complexes containing weakly bound ligands the study of tertiary structure in solution was ([Rh2(0,CR),(MeCN),l2+) showed that the discussed by Professor P. S. Pregosin of ETH, rate of substitution in the equatorial sites can be Zurich. Cross-peaks are observed in the 2d pat- significantly enhanced by the presence of poten- terns when nuclear Overhauser effects influence tially bidentate ligands in the axial sites, which peak intensity. This occurs when two protons may provide a suitable opportunity for are less than 2.5A apart but is negligible for further investigations. distances greater than 3 A. By complexing “marker” ligands, such as phenanhline, where Monomeric Complexes some protons are held close to the metal, the The chemistry of RhlLwas further explored spatial arrangement of the atoms around the by Professor K. R. Dunbar of Michigan State metal can be determined. Comparisons with X- University. Reaction of [Rh,(MeCN),,14+with ray crystallography can identlfy structural dif- tris(2,4,6-trimethoxyphenyl)phenyl)phosphine (TMPP) ferences between solution and the solid state. The

yields a monomeric complex [Rh(TMPF‘) 1 + use of the technique was illustrated by a study where each ligand is bound through one of palladium ally1 complexes where the relative phosphorus and two oxygen atoms. The oxygen positions of the syn- and anti-protons, with bonding is weak and dissociation provides respect to palladium, were identified. binding sites for other ligands. Mononuclear complexes of Rh” are rare and this compound Metal Films therefore offers a useful starting material for ex- The formation of thin metal films is a topic of ploring the chemistry of this oxidation state of increasing interest in the electronics industry. The rhodium. Reaction with carbon monoxide generation of platinum group metals films by involves a series of reversible steps including metal organic chemical vapour deposition oxidation of the starting material by (MOCVD) was described by Professor H. D. t Rh(C0) (TMPP) I + . Loss of carbon monox- Kaesz of the University of California. Early ide from the Rh(1) dicarbonyl complex yields a product which has a lower oxidation potential and can be re-oxidised by [Rh(TMPP) I + . A study of the varying co-ordination modes of a group of substituted pyridine ligands was presented by E. C. Constable of Cambridge University. This work arose from an interest in the use of bipyridine complexes as catalysts for the photolysis of water. Careful analysis of the products obtained from the attempted preparation of [Ir(bipy) + identified one compound I L -J which was surprisingly found to contain one (IV) bipyridyl hgand bound through nitrogen and car- Fig. 3 This compound produced during the bon rather than through two nitrogen atoms, see attempted preparation of [Ir(bipy)s13+ Figure 3. Using phenylpyridinemercury chloride contains one bipyridyl ligand bound as a ligand transfer reagent, similar complexes through nitrogen and carbon rather than through two nitrogen atoms bound through nitrogen and carbon may be

Platinum Metals Rev., 1990, 34, (4) 212 attempts using [Pt(acac), 1, [PtCl ,(CO) ,1 or platinum group metals, although for platinum [Pt(PF,),I gave films contaminated with carbon sensitive cases there may be some cross reaction or phosphorus. Organometallic platinum group on skin testing. metals complexes are suitable alternatives when In the closing lecture Professor S. J. Lippard hydrogen is used to react with the carbon species of the Massachusetts Institute of Technology ad- formed to prevent contamination of the film. dressed the question of the mechanism of action Compounds such as [PtCpMe,] and [Pt(Cp- of platinum anti-cancer complexes, and in par- Me)Me,I give bright reflective fims composed ticular why there is a marked difference in the of small crystallites. Bright films can also be made activities of the cis and trans isomers of for rhenium, rhodium, iridium and nickel but IPtCl2(NH,),1. The key cellular target for are amorphous in structure. The problem of alloy platinum complexes was identified as DNA some formation between a coating and gallium is a 20 years ago. The exact details of this interac- significant problem for the use of gallium tion have now been identified using 195 Pt NMR arsenide as a semiconductor material. This could spectroscopyand X-ray crystallography. Studies be avoided by depositing alloy films such as CoGa of the reaction of the two ~PtCl,(NH,),Iisomers or RGa,. The synthesis of novel compounds with nucleosomes indicated that there is little dif- containing the metals in these ratios should allow ference in the rate at which they form difunc- these fims to be prepared. tional adducts. Cisplatin binds most readily to two adjacent guanines on a smgle strand of DNA Biological Aspects while trans-IPtCl,(NH,),l binds to purines The fmal lectures of the conference were (guanine and adenine) separated by one or two devoted to the biological aspects of platinum other bases. By studying the way in which DNA group metals compounds. The allergic response duplex oligomers combine to form extended which can occur as the result of exposure to ionic units it was shown that cisplatin binding causes platinum halogeno-complexes was discussed by DNA to bend by 30-40°, while there is no C. W. Bradford of Johnson Matthey. Sensitisa- directed bending for the trans isomer. Binding tion by platinum salts is restricted to this class of both the cis and trans complexes to DNA in- of compounds but is none the less important as hibits replication and it seems likely that the in- these are key species in the refining of platinum activity of the trans isomer is due to these lesions and are common starting materials for the syn- being more readily repaired. thesis of co-ordination compounds. The symp- Further work has now identifed a protein pre- toms of the allergic response are mainly rhinitis, sent in normal cells which binds to cisplatin- conjuctivitis and asthma, and sensitisation can DNA lesions. Efforts are now being made to be confirmed by a simple skin test. Smokers and determine the structure of this protein and assess those sensitive to common allergens such as grass its level in different types of cell. It may be that pollen and house dust are more at risk of being this will contribute to the understanding of the sensitised by platinum salts. The routine health spectrum of activity of cisplatin and suggest how monitoring carried out for workers in platinum compounds active against Werent tumours may handling areas of Johnson Matthey sites was be developed. described, these procedures now having been adopted into regulatory guidelines. The Posters mechanism of the sensitisation is believed to in- In addition to the oral presentations almost 200 volve binding of platinum to protein via sulphur posters were exhibited in three sessions during atoms in methionine groups. The platinum- the conference. Although the display area was protein conjugate is the antigen which stimulates restricted, the posters attracted considerable in- lymphocytes to produce Pt-specific IgE and interest from participants at all levels and con- duces the symptoms on re-exposure. The sen- tributed greatly to a successful conference. Most sitisation is not produced by salts of the other of the posters described new chemimy which was

Platinum Metals Rev., 1990, 34, (4) 213 principally of academic interest, but some presented by C. E J. Bamard of Johnson Matthey also had applications in mind. R. J. Haines of Technology Centre, while a display by the University of Natal described the use of S. G. Warren of Johnson Matthey Materials substituted ruthenium carbonyl cluster systems Technology Division featured advances in the in- as electrocatalysts for the reduction of carbon dustrial applications of tetraammine platinum(I1) dioxide to methanol, formaldehyde, and carbon compounds for use both as catalyst precursors monoxide, the product ratios being dependent and for electroplating systems. both on the potential of the electrode and the pH Throughout the conference a high standard of of the electrolyte. Applications for platinum presentation was maintained by the lecturers, metals as catalyst systems in phosphoric acid fuel with their willingness to deviate from their cells were described by G. A. Hards and col- previously submitted abstracts to present recent leagues of Johnson Matthey, who have studied research results much to be welcomed. The the impact of surface area on the activity of dominance of multi-nuclear chemistry at this platinum alloy catalysts compared with sup- conference might suggest that the study of the ported platinum systems. I? G. Pitcher of organometallic and co-ordination chemistry of Johnson Matthey has demonstrated that super- mono-nuclear species is of declining interest and conducting YBCO films (TS = 100 K) have been it is to be hoped that this will be seen as a produced on polycrystalline alumina substrates challenge to workers in these fields to redress the coated with 2000 A thick DC sputtered balance at the next Royal Society of Chemistry platinum films; the platinum interlayer acts as International Platinum Group Metals Conference. an effective diffusion barrier to substrate Current plans are for the next conference to be aluminium. A poster on the development of held in 1993 at the University of St. Andrews, orally active platinum(1V) anti-turnouragents was in Scotland.

Further Studies of Platinum Mineral Deposits Although this Journal does not set out to pre- Thus geologists from each of these countries sent a comprehensive record of the available contributed to the first paper. Three major information on the occurrence, geology, platinum-group element-bearing mineralisation mineralogy or extraction of the platinum-group zones have been found in the early Proterozoic elements, from time to time an opportunity is Penikat layered intrusion, and a separate paper taken to draw the attention of readers to some was devoted to each. It is suggested that the significant new contribution to the literature traditional concepts of platinum genesis cannot concerning these topics. The proceedings of the explain these deposits, where the platinum- Fifth International Platinum Symposium, sulphide association is apparently not essential, which was held in Helsinki, Finland, from 1st to and where platinum-group minerals may or 3rd August 1989, have recently been published may not be associated with chromite. There and will be of interest to researchers seeking followed significant contributions on platinum- up-to-date information on the results of recent group element mineralisation and distribution investigations of platinum deposits world-wide. in the Bushveld Complex of Southern Africa, Edited by E. F. Stumpfl and H. Papunen, the Dumont Sill in Quebec, Canada, the eighteen papers have now appeared in the jour- Duluth Complex of Minnesota, U.S.A., and nal Mineralogy and Petrology, 1990, 42, (1-4). the Munni Munni Complex of Western Reflecting the recent success of Finnish Australia. This 195 page section was concluded geologists in identifying several platinum-group with a paper on the mineralisation potential of element concentrations the first four papers in the Longwood Igneous Complex of South the major section devoted to “Layered Igneous Island, New Zealand. Complexes” were concerned with the Pro- Occurrences of platinum-group minerals in terozoic intrusions which are widespread over a ophiolite suites in Cyprus, Morocco, Norway large area of the northeastern part of the Fen- and Spain are featured in the second, 67 page, noscandian Shield, and which are encountered section, while placer deposits in Burma and in Finland, Sweden and the Soviet Union. France are included in the final section.

Platinum Metah Rev., 1990, 34, (4) 214 Alfonso Cossa THE MAN AND HIS PLATINUM SALTS By Professor George B. Kauffman and Ester Molayem California State University, Fresno, U.S.A.

Almost every co-ordination chemist or platinum chemist is familiar with Cossa’s $rst and second salts, K[PtCl,(NH,)l.H,O and K[PtCl, (NH3)l.H20,respectively, yet the lge and work of their discoverer is virtually unknown outside of Italy. Cossa made outstanding contributions not only to the chemistry of platinum and to inorganic chemistry in general, but also to agricultural and plant chemistry, mineralogy, petrography, medicine, botany, forensic chemistry, and the analysis of soils and rocks, especially those of his native land.

Alfonso Cossa was born in Milan, Italy on Reference to the Investigations Instituted in November 3, 1833,the son of Giuseppe Cossa, England) (1855) (7) and “Uber Theorie und librarian of Milan’s famous Biblioteca di Brera Praxis in der Landwirtschaft” (On Theory and and an authority on paleography and Practice in Agriculture) (1856)(8). diplomacy, and his wife Maria. He completed Cossa was that rare type of scholar who with his classical studies in Milan and in 1852 went the passing years enters fields of knowledge in to Pavia, an ancient town 20 miles south of which he did not have formal training. After his Milan known as the Oxford of Italy because of education as a physician, he became successive- its many colleges (x - 5). Here he studied at the ly a botanist, an agricultural chemist, a Collegio Borromeo, and in November, 1857 he mineralogical chemist, and an inorganic and co- received the degree of Doctor of Medicine from ordination chemist. When his favourite branch the Universith di Pavia with a dissertation on the history of electrochemistry (6). Even before receiving his degree Cossa, at the early age of 23, had translated into Italian two of Justus Liebig’s books “Die Grundsatze der Agricultur-Chemie mit Rucksicht auf die in England angestellten Untersuchungen” (The Principles of Agricultural Chemistry with

Alfonso Coma 1833-1902 Born in Milan, Cossa had an illustrious career as a chemist and lithologist. He founded, published and edited, from 1872 to 1882 the journal, Le Stuzioni sperimentali agrorie italiane. He was President of the Turin Academy of Sciences and for some faeen years was Director of the Reale Scuola di Applicazione degli Ingegneri di Torino. He died in Turin

Platinum Metals Rev., 1590, 34, (4), 215-221 215 of chemistry, mineralogical chemistry, under- Like the government of the Papal States, the went many changes as a result of new absolute governments that existed in the Pied- physicochemical theories, Cossa, although a monte region of north-westem Italy before the mature scholar with a substantial reputation, 1848 revolution and in the rest of Italy before returned to school to learn the mathematical 1859 not only failed to promote scientific pro- ideas now essential to modern chemistry. This gress but actually discouraged it. Thus, during continual evolution of his intellectual develop- the eighteenth century and the first half of the ment characterised him throughout his life. nineteenth century, great scientists born in Ita- From an early age Cossa was interested in ly such as Joseph Louis Lagrange, Pellegrino chemistry, especially applied chemistry. He Rossi, Macedonio Melloni and Faustino had unusual scientific and didactic talents, but Malaguti deserted their native land for other at the beginning of his career he was forced to countries because of uncaring governments, learn much completely by himself. In an political reasons or lack of means for study. autobiographical letter to the chemist Ar- Cossa confessed that in 1858 he did not know cangelo Scacchi, Cossa admitted: where to go to study chemistry. In an 1893 lec- “Concluding my confession by telling you that ture he recalled: the little that I have done, I have done by myself “the idea of collecting information on the life and with the fmwill to overcome the obstacles that works of Angelo Sala arose in me a long time ago, presented themselves to me at every step”(2). going back to the year 1858. Fond of chemistry but compelled to a platonic love because at that The state of science and chemistry in Italy time at the Universiti di Pavia young students during the decade 1850- 1860 forced Cossa to were not allowed to dedicate themselves to ex- study chemistry by himself, initiating research perimental researches in a laboratory, I tried to satisfy my inclination by applying myself, as I that had only an indirect relationship to knew and was able, to the study of the history of chemistry and later becoming a good self- science. ” taught scholar. At this time, Dumas, Laurent, There was a great shortage of teachers in Italy Gerhardt, Cahours, Wurtz, Berthelot and at the time that Cossa received his medical Saint-Claire Deville were active in France; Ger- degree, so he remained at the Universita di many had Liebig, Wohler, Bunsen, Kolbe, Pavia, becoming professore di chimica and Hofmann, Strecker and Kekule; and England direttore of the Istituto Tecnico in 1861. His had Graham, Williamson, Frankland and Od- outstanding qualities as a researcher and ling. Excluding Faustino Malaguti teacher were recognised by Quintino Sella (1802-1878)~who had fled to Paris in 1831 as (1827- 1884), the statesman and a political refugee, the only notable chemists in crystallographer who helped place the new na- Italy were Rafaelle Piria (1815-1869, tional government on a fmfooting after Italy’s Francesco Selmi (I 8 I 7 - I 88 I) and Ascanio unification. Thus when Venice was united to Sobrero (1812-1888), and of these only Piria the newly formed kingdom of Italy in 1866, occupied a university chair. Furthermore, none Sella commissioned Cossa to organise and of these chemists established a school; they found in Udine, an Istituto Tecnico, where he each worked on their own and had very few remained until 1872 as professore di chimica students. In the words of Icilio Guareschi “they and direttore. were like bright points in a dark night” (2). After a short stay (I872 - I 873) in the Reale At that time most university positions were Scuola Superiore di Agricoltura at Portici, in occupied by men whose teaching was purely 1873 Cossa was appointed direttore of the Sta- theoretical and who failed to consider the great zione Agraria and insegnante di chimica progress in chemistry being made in other mineraria at the Reale Museo Industriale, both countries. Indeed, the teaching of chemistry in in Turin. In 1882 he succeeded Ascanio Italy was comparable to that existing in other Sobrero, the discoverer of nitroglycerin, as pro- countries sixty years earlier. fessore di chimica docimastica e mineraria at

Platinum Metals Rev., 1990, 34, (4) 216 Turin’s Reale Scuola di Applicazione degli In- Auer, Baron von Welsbach). Cossa found these gegneri di Torino, of which in 1887 he became elements to be widely distributed in nature direttore, a post that he retained until his death (16). He assumed that the association of three on October 23, 1902 after a short illness. rare earth elements, yttrium (17), cerium (17) and didymium (18) with calcium in various Cossa’s Early Research minerals supported his supposition that these The subject of Cossa’s early works was large- elements are dipositive, as did his preparation ly agricultural and plant chemistry. His first and characterisation of cerium molybdate (19) research paper dealt with absorption by roots and didymium molybdate (20). (10), and much of his work concerned the chemistry of plant seeds, soils, water supplies, Platinum-Ammines manures, sugar beet roots, the must of grapes, Long interested in biography and the history the ash of the leaves and fruit of lemon trees of chemistry, Cossa wrote articles on the life and asparagine in vetches, some of which work and work of a number of chemists, one of overlapped his mineralogical studies. which led him to undertake a new field of Throughout his career mineralogical research, the platinum-ammines. chemistry was Cossa’s primary field of interest, with almost half of his works being devoted to Cossa’s First Salt, this subject, from his fust mineralogical work, K[PtCl, (NH,)l.H,O published in 1869 (II), to his last, published In 1885 the Accademia dei Lincei asked thirty years later in 1899 (12). He classified, Cossa to commemorate the life and work of his characterised the properties of, determined the friend Quintino Sella (21), who had died the compositions of and proposed mineralogical previous year. In the course of his formulae for dozens of minerals and rocks from bibliographical research, Cossa encountered many sources. One of the minerals that he Sella’s “Sulle forme di alcuni sali di platino a studied, a variety of paragonite-a sodium mica base di platinodiamina” published in of composition H NaAl (SiO ,) - was named 1856-1857 (22), and he decided to carry out cossaite in his honour. Cossa analysed minerals experimental studies on platinum-ammine and rocks of Vulcano in the Lipari Isles, and in compounds. Beginning on May 3, 1885 (23) the stalactiform concretions in the Vulcano and continuing until 1897, he made a long crater he discovered and analysed a new series of investigations-his most important mineral of composition K, SiF, ,which he nam- chemical contributions. At this late stage of his ed hieratite (13). Cossa also analysed cinders career, he was fortunate to have the Minister0 and lava from the eruption of Mount Etna on della Pubblica Istruzione and the direttore of June 28th and July 2nd, 1879 (14). the Reale Museo Industriale Italian0 di Torino A number of Cossa’s petrographic and furnish sufficient funds for him to procure a mineralogical works on Italian rocks and half-kilogram of metallic platinum from minerals were published in a 304-page volume Kahlbaum in Berlin. He also had at his disposal in 1881 (IS). The collection of thousands of the excellent equipment and facilities of the these specimens ordered and classified by Cossa Stazione Agraria di Torino, equalled by few is now housed in the Politecnico di Torino. university laboratories in Italy. Closely related to his mineralogical studies One of the most famous and important co- were Cossa’s investigations of several lan- ordination compounds to be named after its thanides or rare earths, namely, lanthanum, discoverer is Magnus’ green salt, tetraam- cerium and didymium (a supposed rare earth mineplatinum(I1) tetrachloroplatinate(II), element discovered by Carl Gustav Mosander in tPt(NH,),I[PtCI,l, discovered in 1828 (24) in 1841, but subsequently separated into Berzelius’ laboratory by Heinrich Gustav neodymium and praseodymium in 1887 by Carl Magnus (1802-1870) (25). As the first

Platinum Metals Rev., 1990, 34, (4) 217 The fwst page of Cossa’s article published in 1890 entitled “On a New Isomer of Magnus’ Green Salt”, Gazz. chirn. ital., 1890, 20, 725, in which Cossa discusses platinum-ammines

discovered platinum-ammine, it is among the earliest known co-ordination compounds and played a significant role in the history of co- ordination chemistry because of the great stability and retention of the configuration characteristic of platinum compounds. It serv- ed as the starting point for a vast amount of research on the so-called platinum bases, not only by Cossa but also by Gros, Reiset, Berzelius (I 841)~Jules Reiset (I844), Charles Peyrone, Raewsky, Gerhardt, Cleve and many Frederic Gerhardt (1850)~August Wilhelm von other chemists. Its constituent cation and anion Hofmann (1851)~Carl Ernst Claw (1856) and are the most important ions of dipositive August Kekule (1864)and most successfully by platinum. It has the same empirical formula as Christian Wilhelm Blomstrand’s chain theory five other platinum(I1) compounds, namely (I 869) as subsequently modified and developed cis-~RCl,(NH,),I (Peyrone’s chloride) (26, by Sophus Mads JGrgensen (35). Although 27), ~runs-[I’tCl,(NH,),l (Reiset’s second Cossa interpreted his data in terms of the now chloride) (27, 28), [PtCl(NH,) I[PtCl ,(NH,)] obsolete Blomstrand-JGrgensen chain theory (291, [PtCKNH,),] ,[PtCl,I (30) and (36) and named his compounds according to [Pt(NH,) 1[PtCl , (NH 3)1 ,(3 I). The last com- Cleve’s obsolete nomenclature system (37), his pound was discovered by Cossa. This series is experimental results are in no way invalidated. a classic example of what Alfred Werner called In attempting to reconcile some discrepancies Koordinationspolymerie (co-ordination between the work of Reiset (28) and Cleve (39), polymerism) (32, 33), a type of structural Cossa treated solutions of tetraammine- isomerism in which the isomers have the same platinum(I1) chloride and sodium hexa- composition but formula weights that are dif- chloroplatinate(1V) in stoichiometric amounts ferent multiples of the same formula weight. at o°C and obtained a precipitate of yellow Before the advent of Werner’s co-ordination amorphous tetraammineplatinum(I1) hexa- theory in 1893 (34), theories of the constitution chloroplatinate(1V) (23, 39). He established of so-called complex compounds were advanced the constitution of this substance by treating its by Thomas Graham (1837), Jons Jacob solution with one of potassium

Platinum Metals Rev., 1990, 34, (4) 218 tetrachloroplatinate(II), whereupon the well- platosemiammine (PtCl.NH,Cl) (31, 40). He characterised Magnus’ green salt and potassium thus formulated the compound as hexachloroplatinate(1V) were formed: 2 NH,Cl ,Pt(NH,),Cl,. The orange-red Pt(NHi),Clz,Ptcl, + (KWzJ’taz + 6 ) Pt(NH1),C12,PtC12 + (KCl),,PtCl,, that is, “potassiochloride” of this new base, now known Cossa’s first salt, [Pt(NH,),I[PtCI,I + Kz[PtCl,I + as [Pt(NH,),l[PtCl,l + K,[PtCl,I (modem). KtPtCl,(NH,)l.H,O, is readily soluble in water and yields the new isomer of Magnus’ Continuing his work, Cossa discovered a fifth green salt on treatment with platosodiammine isomer of Magnus’ green salt, in addition to the chloride: four isomers already known. By treating Magnus’ green salt with a boiling solution of 2(Pt(NHl)C12,KCl) + Pt(NH,),Cl, -. ammonium nitrate, he obtained a mixture of 2Pt(NH1)Cl,,Pt(NH1),Cl, + 2KCl, that is, trans-[PtCl, (NH,) ,I (platosammine chloride), 2K[PtCl](NH])l + [Pt(NHi),lClz + trans- t PtCl ,(NH , ,](NO ) , (platinodiammine ~Pt(NHl),l~PtCI,(NHl)l,+ 2KCl (modem). chloronitrate), and the new yellow isomer, [Pt(NH,),l[PtCl,(NH,)l ,, which he regarded Co8sa’s Second Salt, as a compound of one molecule of K[PtCI, (NH,)].H,O platosodiammine chloride (Pt(NH,),Cl, , By oxidising K[PtCl,(NH,)l.H,O (Cossa’s modern [Pt(NH,),ICl,) and two molecules of first salt) in aqueous solution with either the chloride of a new base, which he called chlorine or potassium permanganate, Cossa obtained the corresponding yellow platinum(1V) salt, IUPtCl,(NH,)l.H,O, now known as Cossa’s second salt, which he called platinosemiammine potassium chloride and formulated as Pt(NH,)Cl,,KCl (31). In solution treatment of this compound with [Pt(NH,),]Cl, produced a vermilion-red precipitate of unstable

[Pt(NH3)4I[PtCl, (NH,)l 2 (31). Cossa confirmed his view that one atom of platinum(I1) could combine with one molecule of a base to form compounds analogous to his

The announcement of the conversion of K[PtCl,(NH,)l.H,O, Cossa’s first salt, to the yellow salt K[PtCl,(NH,)l.H,O, Cossa’s second salt, as it appeared in Gazz. chim. ital., 1890, 20, 749

All photographs are by carney of Rof. Luigi Cermri.

Platinum Metals Rev., 1990, 34, (4) 219 I Some Platinum Compounds Prepared by Cossa Formula Modern Nomenclature

2PtpyCI,. Pt(NH,),CI, 2Pt(EtNH, ICI,, Pt(NH, ),CI, 2PtNH3C12, Pt(EtNH,),CI, 2PtpyCI,, Pt(EtNH,),CI, CI, Pt(EtNH, )4C12, PtCI, 2Pt(EtNH2)CI,, Pt(EtNH,),CI, 2Pt(EtNH,)CI,, Ptpy,CI, 2PtPVCI2, PtPV,CI, CI,, PtPV,CI,, RCI, PtpyCI,, KC1 PtpvCI,. pyHCl

I py = C,H,N: EtNH, = C,H,NH,

already prepared monoammine compounds last article on platinum-ammines Cossa (41, 42). In this work he prepared, among criticised Werner’s views of the constitution of others, the compounds listed in the Table. both platinum(I1)- and platinum(1v)-ammines. The Scottish chemist Thomas Anderson He concluded: found that when aqueous solutions of “I put an end to this note by declaring that if I (pyH) ,[PtCl,] and the corresponding still adhere to Blomstrand’s theory, I do not compounds of pyridine derivatives are boiled, disown the fact that it too does not explain clearly hydrogen chloride is eliminated with the the constitution of the ammoniacal derivatives of platinum; but this theory at least is not in formation of cis-[PtCl,py,l (Anderson’s opposition to the majority of the facts ascertained, platinic compound) or the corresponding that characterise this important and numerous compounds of pyridine derivatives, a reaction series of compounds, that certainly deserves to be known as Anderson’s reaction Cossa illustrated with new and varied experimental (4). researches in order to be able to succeed in finding showed that a similar reaction occurs with an even more satisfactory explanation of their platinum(I1) compounds (43, 45). He first structure.” (47) prepared (pyH) ,[RCl, 1 by cooling a mixture of solutions of K,[PtCl,I and pyHC1. Boiling an Acknowledgements aqueous solution of the compound or heating We wish to acknowledge the assistance of the following in locating source materials: Lanfranco the solid to 13oOC produced cis-[PtCl,py,l. Belloni, UniversitP degli Studi di Milano; Luigi Cer- Cossa also prepared platosomonodiammine ruti, Universiti di Torino; Vittorio Cirilli, Politecnico compounds, such as platosomonodiammine di Torino; and Guido Donini, Accademia delle Scienze di Torino. We are also indebted to Helen J. platinosochloride, 21’t(NH3) C1 ,PtCl I Gigliotti and Wendy M. Wheat, California State (modern [PtCl(NH3),l,[PtCI,l) (46). In his University, Fresno, for technical assistance.

References I L. Gabba, Ann. SOC.Chim. Milano, 1902,8, 184; 5 Cossa Family, Ed., “In Memoria di Alfonso reprinted in Ref. 5, p. 37-43 Cossa nel primo anniversario della sua morte”, z I. Guareschi, Mem. R. Accad. Sci. Torino, 1903, Vincenzo Bona, Turin, 1903 [zl, 53, 79; reprinted in Ref. 5, pp. 58-79 6 A. Cossa, “Notizie relative alla storia dell’elettro- 3 A. Piccini, Rend. R. Accad. Lincei, CIasse sci. fk, chimica; Dissertazione inaugurale che dava in mat., nat., 192, 11, (2), 235; reprinted in Ref. 5, luce Alfonso Cossa di Milano alunno dell’almo PP. 33-37 Collegio Borromeo per ottenere la laurea dottorale 4 M. Zecchini, La Chimica Industriale, 1902, 4, in medicino nell’I. R. Universita di Pavia, con ag- (21), 321; Arm. Accad. Agr. Torino, 1902,45, 145; giunte le tesi da difendersi, nel mese di gennaio reprinted in Ref. 5, pp. 44-52 1858”, Bizzone, Pavia, 1858

Platinum Metals Rev., 1990, 34, (4) 220 7 G. Liebig, “I prinapii fondamentali della chimica 27 G. B. Kauffman and D. 0. Cowan, Inorg. Syn., agraria in relazione alle ricerche istituite in In- 1963, 7, 239 ghilterra”, Prima traduzione italiana eseguita 28 J. Reiset, Ann. chim. phys., 1844, 131, XI, 417; sulla seconda edizione tedesca per cura di Alfonso Compt. rend., 1844, 18, 1100 Cossa, F. Vallardi, Milano, 1856 29 M. Peyrone, Ann. Chem., 1845, 55, 205 8 G. Liebig, “La teoria e la pratica della 30 P. T. Cleve, SvenskaAkad. Handl., 1872, [A, 10, agriCOlNra”, Prima edizione italiana con note 64; L. A. Chugaev, 3. Chem. SOC., 1915, 107, eseguita sull’originale tedesco per cura di Alfonso 1247; H. J. S. King, J. Chem. Soc., 1948, 1912 Cossa, F. Vallardi, Milan, 1857 31 A. Cossa, “Sopra un nuovo isomer0 del sale verde 9 A. Cossa, ‘‘Angel0 Sala, medico e chimico vicen- del Magnus”, Carlo Clausen, Turin, 1890; tino del secolo XVII. LetNra tenuta all’Ac- Memorie R. Accad. Sci. Torino, 1891, [21, 41, 3; cademia Olimpica di Vicenza nella tornata del 3 Gazz. Chim. ital., 1890, 23, 2503 aprile 1893”, Paroni, Vicenza, 1894 32 A. Werner, “Neuere Anschauungen auf dem 10 A. Cossa, Num Cimento, 1859, 9, IZI Gebiete der anorganischen Chemie”, Friedrich 11 A. Cossa, “Ricerche di chimica mineralogica”, Vieweg, Braunschweig, 1st Edn., 1905; pp. Stamperia Reale, Turin, 1869; Am’ R. Accad. Sci. 159-162; 2nd Edn., 1909; pp. 252-256; 3rd Torino, 1869, 4, 187; Ann. Sci. R. Ist. Tecnico di Edn., 1913; pp. 319-324; 4th Edn., 1920; pp. Udine, 1868, 2, 83; Z. anal. Chem., 1869, 8, 141 328-333; 5th Edn.9 1923; PP. 330-335 12 A. Cossa, “Lezioni di chimica applicata ai prodot- 33 G. B. Kauffman, Coord. Chem. Rev., 1973, XI, ti minerarii. Prime nozioni elementari di elet- 161 trochimica generale”, Carlo Giorgis, Turin, 1899 34 A. Werner, Z. anorg. Chem., 1893, 3, 267; for an 13 A. Cossa, “Sulla presenza del tellurio nei prodotti annotated English translation see G. B. Kauff- del cratere dell’isola Vulcano (Lipari)”, Carlo man, “Classics in Coordination Chemistry, Part Clausen, Turin, 1898; Atti R. Accad. Sci. Torino, I: The Selected Papers of Alfred Werner”, 1897, 33, 449 Dover, New York, 1968; pp. 9-88 14 A. Cossa, Atti R. Accad. Sci. Torino, 1881, 17, 35 G. B. Kauffman, 3. Chem. Educ., 1974, 51, 522. 325; Atti R. Accad. dei Lincei, Transunti, 1881, Annotated English language translations of [3], 6, 141, 181; Compt. rend., 1882, 94, 457; crucial papers by Graham, Claus, Blomstrand, Jahrbuch Min., 1883, 2, 11 and Jegensen are found in Kauffman, Ref. 24 36 G. B. Kauffman,3. Chem. Educ., 1959, 36, 511; 15 “Reale Stazione agraria sperimentale di Torino. Ricerche chimiche e microscopiche su roccie e Chymia, 1960, 6, 180 minerali d’Italia”, V. BOM, Turin, 1881 37 P. T. Cleve, Svenska Akad. Handl., :872, [A,10, 16 A. Cossa, Ani R. Accad. dei Lbtcei, Transunti, I 38 P. T. Cleve, Nova Acta SOC. Sci. Upsaliensis, 1878, [3l, 2, 191; 1879, [3l, 3, 25; “Sulla dif€u- sione del cerio, del lantano e del didimio”, 1866, 131, 6, (9,I Salviucci, Rome, I 879; Atti R. Accad. dei Lincei, 39 A. Cossa, “Ricerche sopra le proprieth di alcuni Memorie, 1879,131, 3, 17; 1880, [3l, 4,232; Ricer- composti ammoniacali del platino”, Ermanno che chimiche, 1881,272; Gaze. chim. ital., 1879,9, Loescher, Turin, 1887; Atti R. Accad. Sci. 118: 1880. 10. 465 Torino, 1886-1887, 22, 323; Gaze. chim. ital., 1 ,.< 17 A. Cossa, Atti R. Accad. dei Lincei, Transunti, 1887, 17, I 1883, [31, 7, 34; Gazz. chim. ital., 1883, 13, 326 40 A. Cossa, Ani R. Accad. dei Lincei, Rendiconti, 18 A. Cossa, Atti R. Accad. Sci. Tmh, 1882, 18, 1891, [41, 7, i, 3 41 A. Cossa, “Riassunto di alcune lezioni sul platino 174; chim. ital., 13, 280 Gazz. 1885, e sue principali combinazioni”, Carlo Giorgis, 19 A. Cossa, Compt. rend., 1886, 102, 1315, 1316 Turin, 1891 20 A. Cossa, Atti R. Accad. dei Lkcei, Transunti, 42 A. Cossa, “Sopra una nuova serie di combinazioni 1884, [3l, 8, 223; Compt. rend., 1884, 98, 990 basiche del platino”, Carlo Clausen, Turin, 1892; 21 A. Cossa, “Sulla vita ed i lavori scientifici di Atti R. Accad. Sci. Torino, 1892, 27, 973; Gazz. Quintino Sella”, R. Accad. dei Lincei, Rome, chim. ital., 1892, 22, ii, 620; Z. anorg. Chem., 1885; Atti R. Accad. dei Lincei, Memorie, 1885, 1892, 2, 181 [41, 2, 5 43 A. Cossa, Am’ R. Accad. dei Lincei, Rendiconti, 22 Q. Sella, Memorie R. Accad. Sci. Torino, 1857, 1893, 151, 2, 332; Gaze. chim. ital., 1894, 24, i, 121, 17, 337 393 23 A. Cossa, Atti R. Accad. dei Lincei, Rendiconti, 44 T. Anderson, Proc. Edinburgh SOC.,1850/1857,3, 1885, [4l, I, 318 309; Ann. Chem., 1855, 96, 199 24 G. Magnus, Ann. Phys. Chem., 1828,14, 239; for 45 A. Cossa, Atti R. Accad. dei Lincei, Rendiconti, an annotated English translation see G. B. Kauff- 1896,[51, 5, i, 245 man, “Classics in Coordination Chemistry, Pan 46 A. Cossa, Atti R. Accad. dei Lincei, Rendiconti, 2: Selected Papers (1798-1899)”, Dover, New 1894, [5l, 3, 360; Gaee. chim. ital., 1895, 25, ii, York, 1976; pp. 11-16 505 25 G. B. Kauffman, in “Dictionary of Scientific 47 A. Cossa, “Sulla costituzione delle combinazioni Biography”, ed. C. C. Gillispie, Scribner’s, New di platosemiammina”, Carlo Clausen, Turin, York, 1974; Vol 9, pp.18-19; Platinum Metals 1897; Atti R. Accad. Sci. Torino, 1896, 32, 388; Rev., 1976, 20, 21 Gaze. chim. ital., 1897, 27, ii, 11; Z. anorg. 26 M. Peyrone, Ann. Chem., 1844, 51, I Chem., 1897, 14, 367

Platinum Metals Rev., 1990, 34, (4) 22 1 ABSTRACTS of current literature on the platinum metals and their alloys

PROPERTIES Electrical Resistivity of High Pressure D,-Loaded Pd and Ti at Low Thermal Stability of Coevaporated AI-Pt Temperatures Thin Films on GaAs Substrates M. KITAJIMA, K. NAKAMURA and M. FUJITSUKA, Solid B. BLANPAIN, G. D. WILK, J. 0. OLOWOLAFE, 1. W. State Commun., 1990, 75, (z), 159-161 MAYER and L. R. ZHENG, Appl. Phys. Lett., 1990, 57, The absorption and desorption of the D in Pd and Ti (4), 392-394 has been studied at pressures 5-90 atm by measuring Coevaporated thin films of Al-Pt on GaAs with Al their electrical resistivity under cyclic conditions of concentrations between 45-70 at.% have suitable temperature from 77 K to room temperature. D starts thermal stability in the composition range between to be absorbed in the bulk of Pd metal at >270 K and AlPt and Al ,Pt for use in self-aligned gates on GAS. is not absorbed in Ti below the room temperature. The AlR thin fims have excellent adhesion properties, and increased stability compared to Al-Ni alloys. The Adsorption of CO on Pd Thin Films Formation of Single-Phase PtAs , Films on Ta( 1 10) on GaAs by Selective Oxidation and B. E. KOEL, R. J. SMITH and P. J. BERLOWITZ, surf Etching SCi., 1990, 231, (3), 325-332 Studies of CO adsorption on Pd overlayers on a E. WEISS, R. C. KELLER, M. L. KNIFFIN and C. R. Ta(1 10)single crystal substrate were performed using HELMS, Appl. Phys. Lett., 1990, 56, (25), 2557-2559 TPD of Pd, AES and LEED. By directly using CO The oxidation of pre-reacted Pt fims on (100) TPD, the Pd monolayer (ML) only weakly adsorbs oriented n-GaAs substrates was studied at 550-750°C CO. The CO adsorption energy increases with Pd using Auger electron spectroscopy and Xe+ ion pro- film thickness, returning to the value for bulk Pd for filing. The GaRPtAsJGaAs structure formed dur- a 3 ML Pd film. Pd was shown to grow in a layer-by- ing annealing in H, was oxidised using a mixture of layer mechanism at 775 K. Pd films annealed to 1075 H ,0 vapour and H ,. The GaPt phase can be oxidised K resulted in extensive alloy formation. However, the totally, whereas the inner RAs, and GaAs interfaces alloy is capped by a Pd monolayer that has a structure are left unoxidised. The oxidation of the Pt-Ga phase and surface chemistry identical to the as-deposited is self-limited by the diffusion of the Ga through the I ML Pd film formed at lower temperatures. Ga oxide overlayer. The oxide can be etched off to leave PtAs, on the GaAs substrate. Solution of Hydrogen in Cold-Worked Reaction between Cu and PtSi with Cr, and Annealed Pd95Ag5Alloys Ti, W, and C Barrier Layers S. KISHIMOTO, M. YOSHIDA, Y. ARITA and T. B. FLANAGAN, Ber. Bunsenges. Phys. Chem., 1990, 94, C.-A. CHANG, 3. Appl. Phys., 19,67, (IO), 6184-6188 (9, 612-615 The effect of cold-working and subsequent annealing Studies of the reaction and thermal stability between on the H solubility of a Pd,,Ag, random substitu- Cu and PtSi with several barrier layers, Cr, Ti, Wand tional alloy has been examined. A correlation between amorphous C showed that Cu reacts with PtSi around physical properties such as electrical resistance and 35Ooc. The low thermal stability of the Cu/PtSi hardness with H solubility has been made. Detailed structure is attributed to the high affinity of Cu to Si, data have been presented for the solubility at 323 K with the Cu silicide formation starting around zoo0C following annealing from 373 to 1073 K. The solubili- for a Cu/Si structure. Using an amorphous C barrier ty correlates with mechanical property changes. for the CuPtSi structure, a small amount of Cu silicide is observed at 40o0C, but not at 660OC. Laser Vaporization Generation of PdCH,, "JSPdCH,, and PdI3CH, for Specific Heat of a New Dense-Kondo Electron Spin Resonance Neon Matrix System CeTIn (T=Ni, Pd, Pt) Study at 4 K K. SATOH, T. FUJITA, Y. MAENO, Y. UWATOKO and H. L. B. KNIGHT, J. 0. HERLONG, S. T. COBRANCHI and T. FUJII, 3. Phys. soc. Jpn., 1990, 59, (z), 692-700 KIRK, 3. Chem. Phys., 1990, 92, (II), 6463-6468 Specific heat of a newly-found dense-Kondo system The title radicals have been generated by reactive CeTIn (T=R, Pd, Ni) was measured at 60mK-8oK. laser vaporisation and isolated in neon matrices at 4 For CePdIn and CePtIn, the ratio of specific heat to K for ESR investigations. The results allow an ex- temperature, C/T, increases greatly below IOK, in- perimental description of the electronic structure in dicating the heavy-fermion nature. the valence region to be obtained.

Platinum Metals Rev., 1990, 34, (4), 222-235 222 Auger Studies of the Effect of Mo, V and A Study of Chemisorption Behavior of Pd Additions on the Oxidation Carbon Monoxide on Rhodium Surfaces Characterisitics of Fe-24Cr Alloy D. M. REN and w. LIU, surj Sci., 1990, 232, (3), S. C. TJONG and J. B. MALHERBE, Appl. sutf. sci., 316-322 1990, 44, (31, 179-183 A study of the chemisorption behaviour of CO on Studies of the effect of Pd, Mo and V additions on the Rh( I I I), (001)and (I 13) planes and their vicinal step- oxidation behaviour of the Fe-zqCr alloy oxidised in ped surfaces at low coverage was performed using a air at 500OC were performed. The addition of I wt.% high resolution voltage-pulsed atom-probe. The of Pd to the Fe-qCr alloy was sufficient to promote results showed that CO is adsorbed only molecularly the formation of a thinner oxide fhthan on the alloy on the R~(III)and (001) planes and with a trace of without the Pd addition. There was no synergistic ef- dissociation on the hlgher index (113) plane. It was fect between Pd and Mo, or Pd and V in reducing the found that closely spaced step and kink sites play a oxidation rate of the Fe-z4Cr alloy. major role in promoting dissociation of adsorbed CO under the experimental conditions. Phase Relations in the Pd-Te System Study of the Fe-Rh-S Phase Diagram in W. S. KIM, G. Y. CHAO and L. J. CABRI, J. Less-Common Met., 1990, 162, (I), 61-74 Fe-Rh-Rh, S -FeS . o9 Field The Pd-Te system was studied using differential ther- V. A. BRYUKVIN, B. A. FISHMAN, V. A. REZNITCHENKO, mal analysis, X-ray diffraction, electron probe v. A. KUKOEV and N. A. VASIL’EVA, I..Akad. Nauk microanalysis and reflected light microscopy. New SSSR, Met., 1990, (z), 23-28 phase relations in the 0-50 at.% Te portion of the The Fe-Rh-S phase diagram was studied in the com- binary system are proposed. Eight binary phases exist position range Fe-Rh-Rh,S,-FeS, .@ by physico- in the system: Pd,,Te,, Pd,Te,, Pd,Te,, Pd,Te,, chemical analysis and the existence of non- and Pd,Te,, Pd,Tez, PdTe and PdTe,. Crystal struc- monovalent eutectic and peritectic equilibria were tures, physical and optical properties of the phases in observed. Studies performed in a broad range of the system are reported. temperatures and phases showed the presence of a Rh-containing pyrrhotinic solid solution of Crystallization of Amorphous Ti-Pd (Fe,Rh) I A. F. JANKOWSKI, M. A. WALL and P. E. A. TURCHI, 3. Less-Common Met., 1990, 161, (I), 115-124 Interfacial Reactions in the Ir/GaAs Studies of the phase formation in the Ti-Pd alloy System system performed by a physical vapour deposition K. J. SCHULZ, 0. A. MUSBAH and Y.A CHANG, J. &PI. technique showed the production of an amorphous Phys., 1990, 67, (II), 6798-6806 phase at 65 at.% Ti. Upon heating this thin film Interfacial reactions between Ir and GaAs in thin film amorphous structure, a direct transformation to a and bulk forms were studied at 400-1000~C using high temperature b.c.c. phase occurred, followed by TEM, energy dispersive X-ray analysis and electron ordering and phase separation. The amorphous struc- probe microanalysis. The diffusion path was found to ture and transformation were analysed using X-ray be Ir/IrGa/IrAs,/GaAs and is consistent with the diffraction, hot stage transmission electron phase diagram between the initial stages of reaction microscopy, Auger electron spectroscopy and dif- (thin film) and long term annealing (bulk). For thin ferential scanning calorimetry. films, where the Ir supply is limited, the final configuration is Ir ,Ga, /IrAs, /&As. Interfacial reactions Glass Transition Behavior of an Amor- between Ir and GaAs resulted in void formatioh at the phous Pd48Ni32P20Alloy Produced by GaAs interface. Mechanical Alloying Formation of Powder of Bi,Ru,O, dur- A. INOUE, K. MATSUKI and T. MASUMOTO, Mater. Thermolysis of Products of Trans., JIM, 1990, (z), 148-151 ing 31, Hydrolytic Deposition of Ruthenium and A pre-alloyed Pd,,Ni,P, ingot with mixed compound phases was amorphised by mechanical alloying Bismuth (MA) for periods longer than 72 ks (zoh). The amor- w. s. SHORIKOV, s. K. SMIRKOV, N. s. SHARINOVA and phous powder exhibits a large exothermic reaction v. L. SBITNEV, Zh. Prikl. Khim. (Leningrad), 19,63, due to irreversible structural relaxation, followed by (4, 769-773 a distinct glass transition to a supercooled liquid Studies were performed of formation of BizRu ,0 , before crystallisation. Compared with the data on an powder during thermolysis of 0.1 M solution of amorphous Pd,Ni,,P, alloy prepared by liquid K,[RuzOCIl,l in HCI (pH=o.9), and Bi (NO,), in quenching, the onset temperature of structural relax- HNO, (pH=o.4), which were mixed in ation decreases with an increase of the heat of struc- equimolecular ratio followed by addition of a 20% tural relaxation at low temperatures <450 K. The solution of NaOH until the pH was 9.5-10.0. The results showed that the MA-induced amorphous heating of hydrolytic Ru and Bi deposits to 32oOC phase has a disordered structure with more pro- resulted in their dehydration, retaining their nounced short-range ordering and contains a larger mesoporous structure. At 3zo-500°C, formation of milling-induced stored energy. mixed phases Bi,Ru,O, and Bi,Ru,O,, occurred.

Platinum Metals Rev., 1990, 34, (4) 223 CHEMICAL COMPOUNDS Coadsorption of Bismuth with Electro- catalytic Molecules: A Study of Formic Formation of Platinum and Palladium Acid Oxidation on Pt(100) Clusters with Carbonyl Phosphine N. KIZHAKEVARIAM and E. M. smm, J. Vac. Sci. Ligands Technol. A, 19,8, (3), 2557-2562 N. K. EREMENKO and s. P. GUBIN, Pure Appl. Chem., The adsorption of Bi and coadsorption with CO, 0,, 19,62, (6), 1179-1182 H,O and HCOOH on Pt(10o) surfaces was in- A general method for the synthesis of Pt and Pd car- vestigated by LEED. The “hex” reconsuuction of bonyl phosphine clusters has been found. Under mild clean Pt( I KO)is gradually and completely lifted by in- conditions zenvalent Pd derivatives can form Pd, creasing Bi coverage to 0.25 monolayers (ML); clusters with a carbonyl phosphine ligand shell of saturation coverage is 0.5 ML. Bi <0.25 ML has nuclearity between 3 and 38. The fmt high-nuclear moderate attractive interactions, but repulsive in- carbonyl-phosphme Pt cluster has been synthesised teractions occur for higher coverages. Each adatom by addition of phosphines to an oligomeric “Pt dicar- blocks two CO molecules and two 0 atoms. Bi is not bonyl” [Pt(CO),l, in solution. However, this hydrated by coadsorbed H20and a Pt(10o) surface method only gives clusters with nuclearity not more with 0.2 ML Bi is hydrophobic. Clean and Bi covered than 5 atoms. Thermolysis of Pt,(CO),(PEt,), in Pt(10o)are inert to HCOOH. decane under inert atmosphere leads to Pt,,@- CO),(CO), in 14% yield. Multilayer Oxide Growth on Platinum under Potential Cycling Conditions. - I. Kinetics and Mechanism of Reductive Sulphuric Acid Solution Elimination of Hydrocarbons from (p- L. D. BURKE, J. J. BORODZINSKI and K. J. O’DWYER, H)~Ru~@~-CX)(CO),(X=Ph, Et, C1, Electrochim. Acta, 19,35, (6), 967-973 C02Me, SEt, CHPhCH2Ph) Hydrous oxide growth on Pt under potential cycling T. P. DUGGAN, M. J. GOLDEN and 1. B. KEISTER, conditions in 1.0 mol/dm’ H, SO, yielded either a Organometallicr, 19,9, (9, 1656-1665 single or a two component product; the latter gave A study of the mechanism of reductive elimination of rise to two major reduction peaks in the region below C-H bonds from the title compound under CO, 0.4 V. The Pt electrode was conditioned before use yielding Ru carbonyls and alkanes or alkenes is by a preliminary etch in aqua regia, followed by presented. With /3-hydrogens present alkenes and repeated hydrous oxide growth and reduction runs. H,Ru,(CO),, are products. Rate laws for each X substituent are given and activation parameters were Differential Electrochemical Mass Spec- determined. For X = F’h, Cl and Et inverse deuterium trometry Using Smooth Electrodes: Ad- isotope effects were measured. The proposed sorption and H/D-Exchange Reactions of mechanism involves a sequence of C-H reductive Benzene on Pt eliminations, each of which is preceded by reversible T. HARTUNG and G. BALTRUSCHAT, hngnruir, 1990,6, migration of H from Ru-H-Ru bridging to Ru-H-C (51, 953-957 bridging. The rate determining step at high CO The use of a smooth electrode for DEMS is discuss- pressures is cleavage of the first Ru-H-C bond. ed. A new design thin-layer cell is presented and its feasibility is demonstrated for the cathodic desorption ELECTROCHEMISTRY of benzene adsorbed on annealed R in 0.5 M HISO,. Partial desorption in the H region occurred and com- Changes in the Surface Morphology of plete desorption was only achieved under hydmgena- Platinum Electrodes Produced by the tion to cyclohexane at more negative potentials. Application of Periodic Potential Studies with C,D, showed that no C-D bond rup- Treatments in Alkaline Solution ture occurs upon adsorption. Various degrees of H/D exchange occur in the adsorbate. A. VISINTIN, w. E. TRIACA and A. J. ARVIA, J. Elec- troanal. Chem. Interfacial Electrochem., 1990, 284, Rapid Redox Reaction of Hemoglobin at (21, 465-480 Methylene Green Modified Platinum The development of preferentially oriented crystalline surfaces of Pt with rough topographies in Electrode alkaline solution, produced by the application of a Y. ZHU and S. WNG, Electrochim. Acta, 1990,35,(7), potential periodic square wave, is described. The ef- I 139-1 I43 fect of electrical variables is studied, and the different The electrochemical processes of methylene green growth modes are followed by voltammetry in the H (MG) were studied using spectrwlectrochemistry by atom electrosorption potential range and by SEM in situ measurements in an optically transparent thin micrographs. Strong OH- ion-metal surface interac- layer cell with the working electrode made of a piece tions are thought to favour the formation of hydrous of Pt gauze. A Pt auxiliary electrode and a Ag/AgCl Pt oxide layers. The electroreduction of the latter reference electrode were used. A well-defined cyclic yields F’t overlayers with distinguishable growth voltammogram of haemoglobin at the MG modified modes and preferred crystalline orientations. Pt electrode was observed.

Platinum Metals Rev., 1990, 34, (4) 224 The Influence of Electrode Porosity and Thermal Neutron Measurements on Elec- Temperature on Electrochemical Gas trolytic Cells with Deuterated Palladium Evolution at Platinum and Rhodium Cathodes Subjected to a Pulsed Current H.-J. HEIDRICH, L. MthLER and B. I. FODLOVCHENKO, J. R. GRANADA, R. E. MAYER, G. GUIW, P. C. FLORIW, 3. Appl. Electrochem., 1990, 20, (4), 686-691 A. LARRETEGW, V. H. GILLFITE, N. E. PATINO, J. Electrodes of smooth Pt, platinised Pt, smooth Rh CONVERTI and s. E. GoMEZ, J. Nucl. sci. Technol., and Pt coated with an electrochemically plated layer 1990, 27, (31, 222-229 of Rh were used to examine electrochemical gas The design of a highly efficient thermal neutron evolution, using o.gM H,SO, for H evolution and detection system is presented and the measurements @INaCl for Cl evolution. The pores are only effec- are performed with it on electrolytic cells containing tive for an irreversible gas evolving process (as with LiH dissolved in D,O with Pd cathodes. A clear cor- 0),but its rate can be accelerated by increasing the relation between neutron production response and porosity of the electrode surface layer and by increas- the pulsing of the electrolytic current through ing the temperature. For Cl or H evolution, which are deuterated Pd cathodes is observed in a repeatable reversible, the small pores of the surface layer do not manner. The patterns are strongly dependent on the operate if the overvoltage is determined by the gas previous charging history of the cathodes. The supersaturation. Temperature dependencies of the technique appears to be useful in studies of the dif- rate of the Cl and H processes are different; the rate ferent variables of the cold fusion phenomenon. for c1 evolution increases with rising temperature. Electrocatalysie on Microprecipitates of Oxide Formation and Reactivity for Palladium on Glassy Carbon Deposited at Methanol Oxidation on Platinised Carbon Various Potentials Anodes A. A. VEDENYAPIN, T. I. KUZNETSOVA, N. G. B. 1. KENNEDY and A. HAMNET& 3. Elecmanal. Chem. GEORGADZE and M. D. BATUROVA, Im. Akad. Nauk Interfacial Elecmchem., 1990, 283, (I&& 271-285 SSSR, Ser. Khim., 19,(6), 1263-1265 A XPS study of Pt and Pt + Ru PTFE bonded C elec- Studies of the catalytic properties of Pd precipitates trodes for methanol oxidation in acid solution was deposited on glassy C during various deposition performed. The role of Pt oxides in deactivating the potentials were performed during cathodic reactions Pt:C electrodes is discussed. Ru was found to act by of H2 evolution and electrohydrogenation of promoting the formation of Pt-OH groups on acetophenone. The results showed a strong effect of Pt+Ru:C electrodes and a possible mechanism is Pd deposition potentials on the activity of the presented. The effect of periodic potential relaxation catalysts. The most effective catalysts were deposited steps on the life performance of the electrodes is at potential E=o.6 V. presented. The results also showed that formation of inactive oxides groups on Pt:C electrodes appears to Pt-Ru Anodes for Methanol Electrooxida- be improved by the presence of methanol. tion: A Ruthenium-99 Mossbauer Study Electroreduction of Gaseous Ethylene on A. HAMNETT, B. J. KENNEDY and F. E. WAGNER, 3. a Plathized Nafion Membrane Caul., 1990, 124, (I), 30-40 P. s. FEDKIW, I. M. POTENTE and w.-H. HER, J. Elec- 99 Ru Mossbauer spectra were obtained for a series of tmchm. SOL., 1990, 137, (9,1451-1460 Pt-Ru methanol oxidation anodes. The presence of Ru(1V) species with a small quadruple splitting was The electroreduction kinetics of gaseous C,H, on a observed for the most catalyticallyactive sample. For platinised Nafion 117 membrane was studied at I highly dispersed samples the data indicate that the Ru atm, 20 or 100 mole % and 3o°C

Platinum Metals Rev., 1990, 34, (4) 225 Formation and Properties of Highly Mechanism of Simultaneous Reaction of Dispersed Electrolytic Deposits of Acid-Base Ligands in [Ru(bpy),NOOH1 *+ Iridium on Carbon Fibre A. B. NIKOL’SKII, N. I. VELETSKII and A. YU. ERSHOV, z. A. ZIKRINA, T. D. GLADYSHEVA and B. I. PODLOV- Vestn. Leningr. Univ., Fiz., Khim., 1990, (2), 39-42 CHENKO, Elektrokhimiya, 1990, 26, (4), 460-465 Studies of the mechanism of simultaneous reaction of Studies of the effect of deposition conditions on the acid-base conversion of [Ru(bpy),NOOHI 2+ to formation and properties of Ir deposits on C fibre [Ru(bpy),NO,H,OI+ were performed under showed a strong effect of state of oxide groups on the pseudo-monomolecular conditions ([OH -1 =const). surface of the C fibre. Highly dispersed Ir deposits The reaction mechanism proposed includes a stage of were obtained during electrodeposition of IT3+ on conjugated interaction of co-ordinated NO and OH fibre subjected to reductive treatment. Elec- with H,O. trocatalytic activities of Ir/C electrodes, obtained under various conditions, during the electro- PHOTOCONVERSION oxidation of methanol and formic acid were compared. Preparation and Characterization of Pt(Ru02)/Ti02Catalysts: Test in a Con- A Lead-Iridium Pyrochlore Based tinuous Water Photolysis System Bifunctional Oxygen Electrode J. c. ESCUDERO, s. CERVERA-MARCH, J. GIMBNEZ and R. A. M. KANNAN, A. SHULKA and S. SATHYANARAYANA, K. SIMARRO, 3. Catal., 19,123, (2), 319-332 Electmanal. Chem. Interfacial Electrochem., 1990, 3. Aqueous suspensions of Pt(RuO,)/TiO, 2817 (1&2), 339-344 photocatalysts, with Pt reduced by different techni- Pb-Ir pyrochlore displays no change in its cyclic ques, were irradiated with UV light in a photoreactor voltammogramover repetitive scans and can function with a continuous gas phase composed of Ar and as a stable bifunctional air electrode catalyst in a photoproducts. Performance of the catalysts in the specific electrode configuration, thus preventing the H,O-splitting process was related to the different erosion of the electrode by 0 evolution under high reduction methods by considering the physical oxidation potentials during the recharge of metal/air characteristics of the powders, both the deposits and cells. Thus this pyrochlore may be useful for energy supports, such as crystal structure, specific surface storage in a secondary metal/& cell. area, particle size, quality of the metal dispersion and Study of Energy Saving Anodes in Metal also of the oxidation state and doping changes caused Electrowinning by the techniques. The catalytic role of RuO, was specifically studied in connection with the X. LIU, Y. LIANG and N. LI, Youse Jinshu (Jikan), preparative treatments followed. 1990, (21, 61-66 The lifetime of newly prepared IrO, -PAN coated Ti Characteristics of Photoelectrochemical activated anodes was measured by an accelerated Cells Based on nh+-Siand ph+-Si Pho- lifetime test method at the anodic current density toanodes Modified by Metal Films 20,000 A/mz in a Zn electrowinning electrolyte. An excellent activated anode with low 0, evolution over- s. WANG, G. LI, H. LI and N. GETOFF, Z. Naturforsch., potential (15% H,SO,/I, 35OC, i=sm Alm’, 1990. 45% (9,695-701 q=0.316 V) and long lifetime (i=zo,ooo Alm’, Photoelectrochemical cells composed of different T = I I 8.4 h) was developed. The anodes can be used epitaxial n-Si photoanodes coated with evaporated in metal electrowinning due to them being relatively metal films of F’t, PtNi, Ni, and immersed in solu- cheap to produce and can save about 20% of the tion with redox couple Br,/Br- or energy needed in the electrolyte cell. Fe(CN), -/Fe(CN) ‘ - were investigated. The open circuit photovoltage and short circuit current density Triruthenium Cluster-Polypyrrole Films: under optimum conditions were 0.494 V and 45.8 A Remarkably Stable Immobilized Relay mA/cmz, respectively. at Highly Positive Potentials. Its Applica- tion to the Electrocatalytic Oxidation of Photolysis of Azomethane Adsorbed on Benzyl Alcohol Pd(ll1) S. COSNIER, A. DERONZIER and A. LLOBET, 3. Elec- L.L. HANLEY, x. GUO andand I.I. T. YATES, Surf. Sci.,Sci., 1990, troanal. Chem. Interfacial Electrochem., 1990, 280, 232, (I/& 129-137 (I), 213-219 The photolysis of azomethane (CH, N = NCH ,) Ru clusters, of general formula [Ru,O(OOC- adsorbed on Pd(III) was studied under ultrahigh CH,),L,]+, as thick or thin film modifiers on Pt or vacuum conditions using TPD. In the condensed C disc electrodes perform bulk electrocatalytic reac- multilayer, photolysis breaks the C-N bond of tions. Thin polypyrrole films covalently substituted azomethane, producing .CH, radicals and N,. The by p-0x0-carboxylate clusters show high chemical and N, desorbs directly during photolysis at 87K. The electrochemical stability, especially in the positive reaction of photolytically generated .CH , radicals potential region. Thus, successful redox catalysis of with chemisorbed D atoms on Pd(II1) has been the oxidation of benzyl alcohol was achieved. observed to yield CH,D below 15oK.

Platinum Metals Rev., 1990, 34, (4) 226 Competitive Hydrogen Production and Application of Ru-(11)-PolypyridineSen- Emission through the Photochemistry of sitizers in the Reduction of C02 to CH, Mixed-Metal Bimetallic Complexes and Hz-EvolutionUsing Ru-Colloids D. B. MACQUEEN and J. D. PETERSEN, znorg. Chem., H. Dm, H.-P. TRIERWEILER, I. WILLNER and R. 1990, 29, (I2), 2313-2320 MAIDAN, NmJ. Chem., 1990, 14, (9,317-320 The monometallic dihydride complexes The photophysical properties of Rubhen), + are

RhH, (PPh,) ,L+ undergo photochemistry and compared to those of Ru(bpy) , + for the reduction photophysics from two different excited states. of C02 to CH,. The former is a superior photosen- Photophysics occurs from metal-to-ligand charge- sitiser for H, evolution and CO, reduction in the transfer (MLCT) excited state generated by pro- presence of Ru colloid as catalyst, with improved moting a r-symmetry electron from Rh(II1) into a ** quenching of the excited state and effective charge orbital on L. When L is 2,2’-bipyrimidine (bpm), separation of the primary encounter cage complex. 2,3-bis(2-pyridyl)pyrazine (dpp) or 2,3-bis(2-pyridyl)- quinoxaline (dpq), a second RhH,(PPh,), fragment can be bound to L to form a homonuclear, bimetallic ELECTRODEPOSITION AND complex, [RhH,(PPh,),I ,Lz+.Couplingthe Rh(II1) SURFACE COATINGS dihydride to a highly absorbing Ru(bpy), fragment through bpm, dpp, or dpq results in the homonuclear Catalytic Anodes for High-Speed Elec- bimetallic complexes (bpy),RuLRhH,(PPh,), ’ +. troplating and Electrogalvanizing K. L. HARDEE, L. K. MITCHELL and E. J. RUDD, Plat. Photoreduction of Rhodium(II1) Ions in Su~Finish., 19,77, (4), 68-71 Water with Ultraviolet Light Aiming to A comparison is given of insoluble anodes for high Prepare the Dispersions of Ultrafine Par- speed plating and electrogalvanising using valve ticles metals with a coating of oxide mixtures, including l’t M. OHTAKI and N. TOSHIMA, Chem. Lett. Jpn., 1990, group metals oxides. It emphasises the advantage of (41, 489-492 catalytic anodes over Pb alloys. For electrolytic pro- The photoreduction of aqueous Rh(II1) chloride by cesses involving the anodic evolution of 0, ,catalytic UV irradiation was achieved in the presence of a solu- anodes such as the dimensionally stable anode (DSA) ble polymer or a surfactant as a protective agent. electrode are capable of stable, extended performance Stable ultrafme dispersions of Rh particles of average over a wide range of current densities. By comparison with Pb or PbO,, the catalytic anode can substantial- diameter 20 A were produced. The reduction was accelerated by addition of primary or secondary ly reduce the cell voltage and the energy required for alcohols, and the photoreduction became possible electrolytic processes. even on irradiation with visible light by addition of EtOH or 2-propanol. Electrodeposition of Silver onto Elec- trodes Coated with [Os(bipy) - Photochemistry of (v -C H,)Rh(CO) in (PVP) l~cllcl Phosphine Solutions: Evidence for an R. WANG, R. J. FORSTER, A. CLARKE and J. G. VOS, Elec- Associative Photosubstitution Mechanism trochim. Acta, 19,35, (6), 985-988 D. P. DROLET and A. J. LEES, J. Am. Chem. soc., 1990, Electrochemical deposition of Ag onto glassy C elec- 1123 (19,5878-5879 trodes modified with the redox polymer The solution photochemistry of the title compound in [Os(bipy),(PVP),,CllCl, where bipy is 2,2’-bipyridyl the presence of excess scavenging PPh, ligand shows and PVP is poly-4-vinylpyridine, was studied using that the photoreaction proceeds via an associative cyclic voltammetry. For electrodes coated with the mechanism, and a possible route is suggested. Laser analogous Ru containing polymer [Ru(bipy), - powers of 50-200 mW were used and determined by (PVP) ,,ClICI no electrodeposition was observed. means of a calibrated external power meter. Mechanism of the Photochemical APPARATUS AND TECHNIQUE Dehydrogenation and Transfer- Application of Pd Silicide in the Process Dehydrogenation of Alkanes Catalyzed by of Silicon Detectors trans-Rh(PMe3) (C0)Cl z. LI, w. CHEN and H. w. KRANER, ZEEE Trans. Nucl. J. A. MAGUIRE, w. T. BOESE, M. E. GOLDMAN and A. s. Sci., 1990, 37, (21, 192-197 GOLDMAN, Coord. Chem. Rev., 1990, 97, 179-192 A self-aligned metal-silicide process is described The title catalyst catalyses the photochemical which improves detector leakage current, detector dehydrogenation of alkanes to alkenes, yielding H, , yield and junction contact resistance. A method of or in the presence of potential H acceptors such as implanting impurity ions into Pd, Si uses a lift-off t-butylethylene and styrene, H, can be transferred technique for fabrication of Si detectors for high to the olefms. Both reactions proceed via a single energy physics. The method does not need a new photochemical step, the photoextrusion of CO from mask step in the existing detector fabrication process, the catalyst. and may be used with other refiactory metal silicides.

Platinum Metah Rev., 1990, 34, (4) 227 HETEROGENEOUS CATALYSIS Influence of Hydrogen Chloride Addition on the Catalytic Isomerization Activity of Gas Phase and Catalytic Ignition of Chlorinated Alumina and Chlorinated Methane and Ethane in Air over Platinum Platinum-Alumina Solids. Superacid T. A. GRIFFIN and L. D. PFEFFERLE, AIChE J., 1990, Behaviour 36, (6), 861-870 P.-M. BERNARD and M. PRIMET, J. Chem. SOL, Fara- Fine wire experiments have been used to determine day Tram., 1990, 86, (3), 567-570 the kinetic rate data for C,H, and CH, oxidations on Pt/Al,O, and Al,O, were chlorinatedby CCI, at 573 Pt at high temperatures. Under ultra lean conditions K. Adding HCI in the early stages of the n-butane the oxidations have different mechanisms. Gas phase isomerisation at 573 K increases the catalytic activity. ignition of fuel-air mixtures by heated catalytically ac- Preadsorption of HCI at 573 K converts the strongest tive surfaces involves dynamic surface and gas phase Lewis acid sites into superacid ones able to isomerise processes, and the independent monitoring of these n-butane at temperatures as low as 373 K. At 573 K, two is discussed. The sharp maximum in surface the role of the Pt is to produce important amounts of temperature needed for gas phase ignition observed HCI by dechlorination of the support and to con- previously is caused by transient heating of the sur- tribute to the formation of superacid centres. face as ignition occurs. Sintering-Redispersion of Pt-RelAl, 0 Carbon Deposition on Supported during Regeneration Platinum Particles C. L. PIECK, E. L. JABLONSKI and 1. M. PARERA, Appl. T. s. CHANG, N. M. RODRIGUEZ and R. T. K. BAKER, J. Catal., 1990, 62, (I), 47-60 Caul., 1990, 1239 (2), 486-495 The effect of temperature and gas flow rate on total Studies of coke formation and the associated changes metallic dispersion and specific surface area of Pt- in Pt particle morphology in real and model reform- Re/Al,O,reforming catalysts was studied during the ing catalysts were performed by a combination of burning of coke deposited on its surface. The actual electron microscopy and thermogravimetric techni- temperature inside the catalyst during coke burning ques. Decoking studies showed that the deposit was is the main parameter affecting the total metallic predominantly isotropic in nature and did not contain dispersion. The metallic phase is redispersed during any filamentous or graphitic components. During the catalyst oxychlorination and the total dispersion at catalytic hydrogasificationthe Pt particles undergo a values of 0.9-I% chloride on the catalyst is the same. wetting and spreading action with the carbonaceous residues on the support and thus maintain a small Hydrocarbon Conversion over Pt- average particle size. Re/AI 0 -ZSM-5 Bifunctional Catalysts. 11. Sulfur Resistance of Pt-Re/Al,03 Structure Sensitivity of Methane Oxida- Modified with ZSM-5 tion over Platinum and Palladium J. N. BELTRAMINI, S. BHATIA and R. FANG, React. R. F. HICKS, H. QI, M. L. YOUNG and R. G. LEE, J. Kinet. Catal. Lett., 1990, 41, (I), 199-203 Catal., 1990, 122, (9, 280-294 Sulphur resistance of Pt-Re/Al ,0, and Pt-Re/Al, 0 ,- A series of supported F’t and Pd catalysts were tested ZSM-5 was studied during n-heptane reforming. On for CH, oxidation at z60-370°C, 50 Torr CH, , I 10 the basis of selectivityand product distribution, it ap- Torr 0 ,, goo Torr He and conversionbelow 2%. The pears that the incorporation of S improves the intrinsic rate varies by >5mfrom the least active to aromatics performance of both catalysts. It is con- the most active catalyst, thus indicating that the reac- cluded that while S acts as a poison for the existing tion is structure sensitive. The catalytic activity of Pt reforming catalyst, it can play an important role in ac- depends on the distribution of the metal between a tivity maintenance and aromatics production when dispersed and a crystalline phase, while the catalytic ZSM-5 zeolite is present in the reforming catalyst activity of Pd depends on the metal particle size. The bed. mean steady state turnover frequency at 335OC and the mean apparent activation energy are given for the Liquid-Phase Dehydrogenation of different classes of catalysts. Cyclohexanol with Supported Noble Metal Hydrogenation Catalysts Dispersion of Platinum on Silica and Y. SAITO, M. YAMASHITA and Y. ICHINOHE, Nippon Alumina by Chemical Extraction Kagaku Kaishi, 1990, (3), 325-327 J. YANG, J. PAN, N. ZHENG, X. LIU and J. ZHANG, Appl. Cyclohexanol dehydrogenation and cyclohexanone catal., 1990, 61, (I), 75-87 hydrogenation were performed with suspended noble Chemical extraction combined with transmission metal particles. The orders of initial dehydrogenation electron microscopy (TEM) was used to study the rates are Pd>Rh-Pt>>Ru and Rh>Pd-Pt>>Ru dispersion of Pt in a series of Pt/Al,O,and Pt/SiO, obtained for the catalysts supported on C and Al,O,, catalysts. The results obtained with standard EuroPt- respectively, were different from those for I catalyst showed that the “percentage extracted” of hydrogenation. The suspended states of catalyst Pt after oxidation at -4wOC was identical with the metal/(=were stable. Pt catalysts were most active for “percentage exposed” of Pt evaluated by TEM. hydrogenation.

Platinum Metals Rev., 1990, 34, (4) 228 Hydrogenolysis and Related Reactions of ‘*’Xe NMR Proof for the Distribution of Hydrocarbons (C, to C,) on Silica- Platinum Species during Pt/NaY Supported Rh-Pt Bimetallic Catalysts Preparation by H PtCl Impregnation 1. A. OLNERandc. KEMBALL, Proc. R. Soc. Lond. A, and Pt(NH,), ’+ Cation Exchange 19909 429, (187613 17-43 Methods The reactions of propane, butane, 2-methylpropane, 0. B. YANG, s. I. woo and R. RYOO, J. Catal., 1990, pentane, mnethylbutane, 2,z-dimethylpropane and 1239 (21, 375-382 cyclopentane with H, have been studied in a static The distribution of Pt species during the preparation reactor using highly dispersed Rh-Pt/SiO, catalysts. of PtiNaY catalysts by the impregnation of H,PtCI, The main reaction was hydrogenolysis with C-C bond or the cation exchange of Pt(NHl),z+ into a NaY breakage. Most compounds reacted at similar rates zeolite was measured by Iz9XeNMR spectroscopy. over Pt with activation energies in the range 132-144 More uniform distribution of Pt species in the im- kJ/mol. With Rh the rates varied with hydrocarbon pregnation were achieved by longer thermal structure by factors of >1o2. Rh was more active than treatments in a I~O%relative humidity chamber Pt by factors of -200 for branched hydrocarbons and before calcination. However, the cation exchange of 10’ or more for straight-chain compounds. At method gave uniform distribution of Pt species in the temperatures >455 K there was evidence of a change zeolite channel throughout the ion exchange, calcina- of rate-determining step over Rh, with the rate of tion and reduction. The result was consistent with the CH, desorption controlling the overall reaction. rate of H,PtCl, adsorption on the NaY zeolite in aqueous solution and the Pt metal dispersion of the Isomerisation of n-Pentane on Pt/NaY samples. Pt/S04/Zr02: Role of Platinum and Reaction Mechanism Hydroconversion of n-Heptane on T. HOSOI, s. KITADA, T. SHIMIZU, T. IMAI and s. Catalysts Containing Platinum, Rhenium NOJIMA, Shokubai, 1990, 32, (z), 117-120 and Platinum-Rhenium on Sodium Studies of the catalytic characteristics of Mordenite Pt/SO ,/ZrO ,during n-pentane isomerisation by H ,- A. K. ABOUL-GHEIT, M. F. MENOUFY and A. K. EL- TPD showed that the H adsorption ability of MORSI, Appl. catal., 1990, 61, @), 283-292 Pt/SO,/ZrO, is much lower than that of Pt on Al,O, The hydroconversion of n-heptane on catalysts con- or ZrO,, but that it has enough activity for the taining Pt, Pt-Reand Re on Na mordenite (NaM) was hydrogenation of ethylene and cyclopropane under 61, 25 and 22 wt.%, respectively, at 40o0C, 3.0 MPa, H, atmosphere. It is concluded that the role of Pt is F/W= I .2 (vol. n-heptane (vol. catalyst)- Ih- I) and to hydrogenate the coke precursor which causes the a Hmheptane molar ratio of 10: I. The production of catalytic deactivation. heptane isomers was 38 wt.% on PtMaM but

Platinum Metals Rev., 1990, 34, (4) 229 Relationship between Selectivity and Catalytic Oxidation of GSorbose on Pd- Hydrogen Sorption of Carbon-Supported BilAdsorbing Resin Catalysts Palladium Catalysts 2.-M. LI and M.-Z. ZHANG, 3. Catal. (Dalian, China), E. POLYANSZKY and 1. PETR6, Appl. Catal., 1990,62, 1990, 11, (2), 106-114 (219 335-347 Supported bimetallic Pd-Bi catalysts were prepared The relationship between the catalytic activity, selec- by impregnating the non-polar polystyrene-divinyl tivity and the H content of C-supported Pd catalysts benzene crosslinked adsorbing resin (D3520) with a was studied by examining how certain parameters, solution of PdC1, and BiCI,. The Pd-Bi/D35zo such as the duration and the medium (liquid or gas catalyst had good activity and selectivity for the ox- phase) of the prehydrogenation of the catalyst, con- idation of L-sorbose, which could be oxidised in one trol the amount of H sorbed on 10% Pd/C catalysts. step into 2-keto-L-gulonic acid. Pd and Bi in the The hydrogenation of ally1 alcohol was studied at catalyst were identified as PdBi, or Pd,Bi phases by room temperature and I bar in 0.05 mol/dm' H, SO, XRD measurements. The interaction between sup- or Na sulphate solution. It was found that there is a port and metals was confmed; the active centre of

relationship between the H content of a catalyst and the catalyst being in the form of Pd' + - 0 - - Bi' + . the proportions of reduction and isomerisation. Sur- faces poor in H favour isomerisation and those rich in Hydrocarbon Conversions with Some H favour reduction. Under certain conditions the Intermetallic Catalysts proportion of isomerisation may be as high as 70%. A. BAKIA, J. M. BROWN, I. T. CAGA, I. R. HARRIS, C. E. KING and J. M. WINTERBOTTOM, 3. Chem. Technol. Metal-Support Interaction in the Pd/SiOz Biotechnol., 1990, 48, (3), 351-360 System: Influence of the Support The intermetallic pseudo-binary alloys ZrRh, -xPd, Pretreatment and ZrRh, -,Ru, (O

Platinum Metals Rev., 1990, 34, (4) 230 Oxydehydrogenation of Alkylbenzenes HOMOGENEOUS CATALYSIS on Rh/AlPO, Catalysts F. M. BAUTISTA, J. M. CAMPELO, A. GARCIA, D. LUNA A Highly Efficient Method for the and J. M. MARINAS, React. Kinet. Cad. Lett., 1990, Preparation of 2-41 Substituted Car- 41, (2)s 295-301 bapenems Exploiting a Pd(0) Mediated The oxidative dehydrogenation of several Cross-Coupling Reaction alkybenzenes was performed at 673-823K on T. A. RANO, M. L. GREENLEE and F. P. DININNO, Rh/AlPO, . The reaction mechanism is described by Tetrahedron Lett., 1990, 31, (zo), 2853-2856 the transfer of two H atoms to an activated triplet 0 molecule due to the action of the Lewis acid sites of A remarkably mild procedure for the synthesis of the catalyst. This may explain the higher degree of 2-aryl substituted carbapenems via a Pd catalysed coupling reaction of a vinyl triflate with aryl stan- AIPo, activity with respect to Rh/AIPO,, caused by nanes is described. Pd,(DBA),.CHU,, where DBA the higher number of acid sites in the support. is trisdibenzylideneacetone, was used as catalyst, and tris (~,4,6-trimethoxyphenyI)phosphineas the ligand Surface-Bound Organometallic Rhodium provides generous yields of the desired 0-lactams. Precursors for 1-Hexene Hydrogenation Reaction times are brief while reaction temperatures J. HERRERO, C. BLANCO, M. A ESTERUELAS and L. A. never exceed ambient. ORO, Appl. Organornet. Chem., 1990,4, (z), 157-162 Rh precursor catalysts supported on palygorskite, Desulfonylative Carbonylation of montmorillonite and SiO, were obtained from an Arylsulfonyl Chlorides Catalyzed by organometallic cationic Rh species and evacuated Palladium Complexes supports at different temperatures. From results of li- K. ITOH, H. HASHIMOTO, M. MIURA and M. NOMURA, quid phase hydrogenation at atmospheric H pressure J. Mol. Catal., 1990, 59, (31, 325-332 the supported Rh species were found to vary with the Carbonylation of arylsulphonyl chlorides with Pd support and its dehydration temperature. Very stable complex catalysts in the presence of metal alkoxides complexes are obtained under ambient humid condi- M(OR), (M=B, Al, and Ti) yielded the correspon- tions, and if the support is natural palygorskite. ding esters along with diary1 disulphides. Among the Pd catalyst precursors tested, PdCl (PPh ,) and Promoter Effect of Alkali Metal Oxides Pd(PPh,), showed good catalytic activity. The reac- and Alkali Earth Metal Oxides on Active tion could also be completed with Pd(PPh,), and Carbon-Supported Ruthenium Catalyst Ti(0-i-Pr), at x6o0C but decreasing the reaction for Ammonia Synthesis temperature reduced the product yield. With metal K.-I. AIKA, T. KAWAHARA, s. MURATA and T. ONISHI, carboxylates M(OCOR), (M=Na, K, Ca, Mg and Bull. Chem. SOC.Jpn., 1990, 63, (4), 1221-1225 Zn), free acids are also obtained. Promoter effects of alkali metal nitrates (&NO,, Palladium-Catalyzed Asymmetric Allyla- KNO,, RbNO,) and alkalineearth (Mg, Ca, Sr, Ba) nitrates on Ru/A.C. (active C) were studied in order tions of Chiral Enamines Bearing to prepare an effective catalyst for NH , synthesis. On Phosphine Functionality. Effects of active C, RuU,.3H,O and [Ru(NH,),lCl, were Anionic Counterparts of Allylating found to be effective perecursors of Ru catalysts. Reagents on Asymmetric Induction Alkali earth metal nitrates, especially Ba(NO,),, K. HIROI and J. ABE, Tetrahedron Lett., 1990, 31, (25), were found to be as effective as alkali metal nitrates 3623-3626 on Ru/A.C. Asymmetric allylations of chiral enamines bearing a phosphine group were catalysed by Pd(PPh,), using Partial Hydrogenation of Benzene with various allylating reagents to produce optically active Ruthenium Catalysts Prepared by a a-ally1 carbonyl compounds. A great effect of anionic Chemical Mixing-Spray Drying Pro- counterparts of allylating reagents on the asymmetric cedure induction was observed. This is the fvst example of S.-I. NIWA, F. MIZUKAMI, M. TOBA, T. MURAKAMI and the importance of anionic counterparts of allylating M. UEDA, Nippon Kagaku Kaishi, 1990, (3), 284-290 reagents in Pdcatalysed asymmetric allylations. Catalyst I w~.%Ru-o.Iwt.% Cu/SiO, for cyclohex- Phenyl-Phenyl Coupling Triphenylan- ene formation from benzene was prepared by in chemical mixing and spray drying. Optimal condi- timony Catalysed by Palladium(0) tions for catalyst preparation and source of support D. H. R. BARTON, J. KHAMSI, N. OZBALIK and J. were found in order to increase cyclohexene yield. REIBENSPIES, Tetrahedron, 1990, 46, (9), 3111-3122 The most effective solvent for preparing the catalysts The Pd(o) induced coupling of phenyl groups in was ethylene glycol, at optimum amount 2.5-3.8 triphenylantimony(I) to give diphenyl and Sb(o) has times in molar ratio to silica. When the catalysts were been studied for possible intermediates. Two com- activated under H at 400OC for 5h, the cyclohexene plexes containing Sb and Pd have been isolated, and yield was 34.7%. Adding 1,4-butanediol and benzyl their structures determined. One complex is made up alcohol increased the cyclohexene yield to 40%. of (I) co-ordinated to Pd diacetate.

Platinum Metals Rev., 1990, 34, (4) 23 1 Palladium-Catalyzed Carboannulation of Synthesis, Characterization, and Kinetics 1,3-Dienes by Aryl Halides of Functionalized Polybutadiene Using a R. c. LAROCK and c. A. FRIED, 3. Am. Chem. soc., Homogeneous Rhodium Hydroformyla- 1990, 1x2, (Is), 5882-5884 tion Catalyst The coupling of two reactions to produce a simple P. L. MILLS, S. J. TREMONT and E. E. REMSEN, hd. arylannulation of 1,3dienes by 5% Pd(OAc), by Eng. Chem. Res., 1990, 29, (7), 1443-1454 functionally substituted aryl halides uses readily The liquid-phase hydroformylationof a commercially available starting materials and proceeds under mild available low molecular weight polybutadiene whose conditions in high yield, completely stereo- and microstructure consists of 12 wt.% ~~-polybutadiene regioselectively giving a wide range of functionally and 88 wt.% cis/t~ans-1,4-polybutadiene using substituted carbocycles. Rest results were obtained Wilkinson’s homogeneous Rh catalyst with excess by using 5% Pd(OAc),, I equiv. of n-Bu,NCl, and PPh , is examined. ‘I C and H NMR studies showed carbonate or acetate bases in dimethylformamide at that this catalyst system results in a polymer product 60-80OC. whose olefm units are selectively converted to the corresponding internal and terminal branched aldehydes New Applications of Organopalladium with negligible formation of hydrogenation products. Compounds in Organic Synthesis R. c. LAROCK, Pure Appl. Chem., 1990, 62, (4), Oxidation of 2-Methylnaphthalene to 653-660 2-Methyl- 1,4-Naphthaquinone with Am- The Pdcatalysed arylations and vinylations of cyclic monium Dichromate Catalysed by RuC13 alkenes provides a new route to 3-arylcycloalkenes S. CHOCRON and M. MICHMAN, Appl. catal., I990,62, and cyclic 1,q-dienes. This can be applied to syn- (I), 119-123 thesise inhibitors of blood platelet activating factor The oxidation of 2-methylnaphthalene (I) to and prostaglandins. Pd can migrate along C chains 2-methyl-1,4-naphthaquinone(2), by tetraalkylam- and thus long chain aromatic aldehydes, ketones and monium dichromate and ammonium dichromate in other carbonylcontaining compounds can easily be acidic solutions of acetonitrile-H,0 catalysed by Ru- prepared. Pd-promoted cyclisation also affords novel C1, was performed at 20-5oOC. Increasing the new routes to unsaturated lactones, bicyclic acetals, temperature improves both the rate of oxidation of (I) benzofurans, indoles, quinolines and isoquinolines. and selectivity for (2) whereas increasing the concen- Pd-catalysed hetero- and carboannulation provides tration of RuCl, increases the selectivity rather than another convenient route to hetero- and carbocycles. the rate of oxidation. Pdadium(0)-Catalyzed Carboxylative Oxidative Carbonylation of Cyclohexyl- Cyclized Coupling of Propargylic Alcohol amine to Cyclohexylurethane Catalysed with Aryl Halides by Dicblorobis-(S alicylaldehy de)-0- Y. INOUE,Y. ITOH, I.-F. YEN and S. IMAIZUMI, 3. MOI. Phenylenediiminato Ruthenate(II1) Catal., 1990, 60, (I), LI-L~ M. M. TAQUI KHAN, S. B. HALLIGUDI and B. SUMITA The reaction of CO, with Na RAO, 3. Mol. Cat~l.,19, 59, (I), 303-309 2-methyl-3-butyn-2-olateand aryl halides catalysed The complex [Ru(saloph)CI,l (where saloph is by a Pd(o) complex, Pd(PPh,), to yield cyclic bis(salicy1aldehyde-o-phenylenediimine)catalyses the vinylidene carbonates was described. The Pd(o)- oxidative carbonylation of cyclohexylamine in ethanol catalysed reaction is different in the reaction pathway medium to cyclohexylurethane selectively at 160Oc from the PdCl ,(CH,CN) ,-catalysed carboxylative and at a CO+O, (1:0.50) pressure of 21 atm. A tur- coupling of propargylic alcohols with ally1 chloride, nover number of 30 mol per mol catalyst per hour was but it mechanistically resembles the previously observed. The rate of oxidative carbonylation of reported Pd(o)-catalysed cyclisation followed by cyclohexylamine at 7-21 atm is first order with allylation of allylic alkynoates. respect to catalyst, cyclohexylamine and dissolved CO concentrations and one-half order with respect to Oxidative Coupling Reaction by Pd- dissolved 0, concentration. Catalyst and Its Industrial Development H. YAMANE, Shokubai, 1990, 32, (2), 121-122 New Chiral Ruthenium Complexes for Asymmetric Catalytic Hydrogenations Two new synthetic processes were developed by using an oxidative coupling reaction with Pd catalyst. H. TAKAYA, T. OHTA. K. MASHIMA and R. NOYORI, Pure The first process selectively synthesises Appl. Chem., 1990, 62, (6), 1135-1138 biphenyl-3,3’,4,4‘-tetracarboxylic tetraester by Mononuclear complexes, Ru(OC0R) ,(binap) where dimerising phthalic ester in the presence of binap is bis(diphenylphosphin0)-I, I I-binaphthyl, 1,Io-phenanthroline Pd complex and Cu salt, while and cationic [RuX(binap)(arene)lY have been the other process produces diester oxalate by ox- prepared and characterised. These complexes and idative coupling of CO with Pd/C catalyst in the their derivatives are highly efficient catalysts for presence of alcohol and alkylnitrite, and a combina- asymmetric hydrogenation of enamides, alkyl- and tion of alkylnitrite and Pd catalyst. The technologies aryl-substituted acrylic acids, &y-unsaturated car- are used in the coupling of various aromatics. boxylic acids, allylic and homoallylic alcohols, etc.

Platinum Metals Rev., 1990, 34, (4) 232 FUEL CELLS Selective Synthesis of Acetaldehyde Ap- plying a Fuel Cell System in the Gas Electrochemical Evaluation of Bis(tri- Phase fluoromethylsulfonyl) Methane as a Fuel K. OTSUKA, Y. SHIMIZU and I. YAMANAKA, J. Elec- Cell Electrolyte mchem. Soc., 1990, 137, (7), 2076-2081 H. SAFFARIAN, P. ROSS, F. E. BEHR and G. L. GARD, 3. The partial oxidation of C, H, using a fuel cell system Eh~chem.Sm., 1990, 137, (9, 1345-1348 with (C,H,+H,O, Pd/silica wool disk holding The kinetics of 0,reduction on Pt were studied in a H,PO,(aq.)/Pd or Pt, 0,) produces CH,CHO very new type of perfluorinated acid, (CF,SO,),CH,, selectively, at >97% in the gas phase, and also containing acidic C-H bonds. The conductivity of cogenerates electricity. The electrode prepared by 1.15 M (CF,SO,),CH, was 0.6 n-lcm-l at w°C, hot-pressing a mixture of Pd black or Pt black with which is the same as that of 98% H,PO, at 17oOC. graphite and Teflon powder improved the current Even the room temperature conductivity of this acid and the rate of formation of CH ,CHO, as compared was higher than that of 85% H,PO, at I~oOC.Using to an electrode of the metal black alone. The op- standard fuel cell electrodes, the room temperature timum C,H, pressure in the anode compartment is polarisation in I. I gM (CF, SO,) ,CH, was 40-60 mV 30 kPa, while the 0, pressure should be as high as lower than with the same electrodes used in 85% possible. The optimum reaction temperature is H ,PO, acid at 7oOC. 373K. At an applied potential of 0.15 V the yield of CH,CHO increased to 10.8%without decreasing the The Partial Oxidations of Benzene and current efficiency. Cyclohexane during Fuel Cell Reactions of O2 and €I2 GLASS TECHNOLOGY K. OTSUKA and I. YAMANAKA, Chem. Len. Jpn., 1990, (41, 509-SI2 Improved High Temperature Strength The partial oxidations of C6H6and cyclohexane oc- Claim for ZGS Platinum Material curred in the cathode during a 0,-H, fuel cell reac- P. RITCHIE and R. McGRATH, Glass, 19,67,(7), 278 tion at 298K. The anode was Pt-blacWgraphite and The requirements and developments which led to zir- the cathode, of Pd-black/graphite, catalyses the for- conia grain stabilised Pt alloy for extensive use in the mation of phenol from C6H6and cyclohexanol and glass industry, and its new sister alloy E300 ZGS 10% cyclohexanone from cyclohexane. The H, 0, Rh-Pt are discussed. The E3oo ZGS Pt, which is a generated at the cathode through the 0,-H, fuel cell new structural material, has been developed to sup- reaction reacts with C6H, and cyclohexane produc- plement the existing range of ZGS Pt alloys. ing their oxygenates. The Use of Platiuum and Its Alloys in the Platinum Dispersed on Carbon Catalyst Glass Industry for a Fuel Cell: A Preparation with Sor- bitan Monolaurate F. A. THOMPSON, Gh,19, 67, (7), 279-280 The range of physical properties of Pt which make it A. HONJI,T. MORI and Y. mm~um, Elecmhem. 3. invaluable in the glass manufacturing industry and SOC., 1990, 137, (7), 2084-2088 those of an oxide dispersion strengthened Pt alloy are A highly dispersed Pt catalyst on acetylene black was reviewed. Their uses in thermocouples, optical glass, formed by the reduction of chloroplatinic acid with crystal glass and glassfibre manufacture, and other MeOH containing sorbitan monolawate (SM).Elec- applications are discussed. trodes with the highest performance for 0 ,reduction in phosphoric acid at rw0C were formed when the concentration of SM was 5 gA and the catalyst was ELECTRICAL AND ELECTRONIC then heat treated at 5oo°C to decompose residual SM. ENGINEERING The Pt particle diameter is hardly changed after 400 h at 0.8 V vs. RHE in phosphoric acid at zq0C. Czochralski Crystal Growth in the System PtmSb2 -x Standard Gibbs Energies of Formation of R. A. LAUDISE, W. A. SUNDER, R. L. BARNS, G. W. Ru02(s) and LaRuO,(s) by Oxide e.m.f. KAMMLOIT, A. F. WIlT and D. J. CARLSON, 3. Cyst. Measurements hth,19, 102, (I/&, 21-30 C. MALLIKA and 0. M. SREEDHARAN, 3. Less-CommOn Czochralski growth of crystals in the title system was Met., 1990, 162, (I), 51-60 investigated for semiconductor properties. Single The e.m.f. of the galvanic cells Pt, Ru, RuOl I IS crystals of ptype PtSb,, with -10" carriers/cm3 YSZ 1 0, (PO,=0.21 am), Pt and Pt, Cu, Cu,O I were produced from BN crucibles. On doping with 8YSZI RuO,,Ru,PtwhereYSZisY,O,-stabilised Te, n-type materials were formed. Melts of composi- ZrO,, were measured at 1005-1106K and tion F'tMnSb crystaUised as PtMnSb single crystals. 751-1200K, respectively, yielding the least squares Single crystals of PtSb, were obtained from a melt expressions and the standard Gibbs energy of forma- composition of PtMn, .LI Sb ,. ,$, and several different tion of RuO, was determined. phases subsequently formed.

Platinum Metals Rev., 1990, 34, (4) 233 Au/Pt/Ti Contacts to p-In,,, 3Gao,,,As Formation of Palladium Oxides by and n-InP Layers Formed by a Single Mechanochemical Reaction on Pd and Metallization Common Step and Rapid Ag-Pd Alloy Contacts Thermal Processing M. HASEGAWA and K. SAWA, IEEE Trans. Components, A. KATZ, B. E. WEIR and W. C. DAUTREMONT-SMITH, 3. Hybrids, Manuf: Tecknol., 19,13, (I), 33-39 Appl. Pkys., 1990, 68, (3), 1123-1128 Pd contacts operated in mechanical break-make Viable Au/Pt/Ti contacts on p-InGaAs and n-InP actions in air without switching load current showed have been produced by elecmn gun evaporation of the formation of Pd oxide on 70% Pd-Ag and 50% three layers of Ti(5o nm), Pt(60 nm) and AU(I pm) Pd-Ag contacts after 100,000 operation tests. The under the same pumpdown process, followed by a products show the non-linearity of contact resistance single sintering by rapid thermal processing at according to measuring current in both dynamic and 40-450°C. The lowest resistivities of these ohmic static measurements. contacts were 0.11 and 0.13 Izmm for p and n contacts, respectively, achieved after heating at 450°C The Effect of Annealing Temperature on for 30 s. Electrical Properties of Pdln-GaSb Schottky Contacts Effect of Energetic Bombardment on the Y. K. SU, N. Y. LI, F. S. JUANG and S. C. WU, 3. Elec- Magnetic Coercivity of Sputtered PtlCo truchem. Soc., 1990, 68, (2), 646-648 Thin-Film Multilayers The thermal stabilities for Pd/n-GaSb Schottky con- P. F. CARCIA, s. I. SHAH and w. B. ZEPER, Appl. Pkys. tacts have been analysed, and at room temperatures Lett., 199% 56, (23), 2345-2347 they have a better performance than other metal/n- The best magneto-opticalproperties have so far been GaSb Schottky diodes, such as higher breakdown achieved in vapour-deposited Pt/Co multilayers voltages and good adhesive properties on GaSb. because fhs sputter-deposited in Ar have cwr- However, when the annealing temperature is increas- civities too small (100-350 Oe) to be practical in ed to 300-45o~C for 30 min the contacts gradually recording. However, the above studies showed that become ohmic. Interdiffusion between Pd and Ga by sputter depositing multilayers in Kr or Xe instead forming Ga,Pd is the dominant factor for degrading of Ar, coercivities of - 1000 Oe are achieved, which the properties of the diodes. are suitable for recording. The lower Coercivity of Ar- sputtered fhs is attributed to interfacial mixing of Pd/Ge Ohmic Contacts for GaAs Metal- Pt and Co layers by energetic bombardment from Ar Semiconductor Field Effect Transistors: gas atoms which recoil from the Pt target. Technology and Performance A. PACCAGNELLA, L. C. WANG, C. CANALI, G. Film Thickness Dependence of Magneto- CASTELLANETA, M. DAPOR, G. DONZELLI, E. ZANONI Optical and Magnetic Properties in Copt and s. s. LAW, Thin Solid Films, 1990, 187, (I), 9-18 and Co/Pd Multilayers Non-alloyed Pd/Ge ohmic contacts were studied S. HASHIhiOTO, Y. OCHIAI and K. AS0,J. Appl. Phys., for applications to GaAs metal-semiconductor 1990, 67, (91, 4429-4431 field effect transistors (MESFETs)and compared Studies of Co/R and CoiPd multilayers prepared by with conventional AuGeNi alloyed contacts. The two source DCmagnetron sputtering showed that Pd/Ge metallisation has a lower contact resistivity magneto-optical and magnetic properties of the with a narrower spread than AuGeNi, and the lowest multilayers are affected by total fhthickness. Kerr values were obtained when a Ti/Pt/Au overlayer was rotation angle of the fhs was greatly enhanced at used. Similarly, parasitic source and drain resistances fdm thicknesses below several hundred A. The in 0.25 W MESFETs are slightly lower. A Ti/Pt/Au theoretical calculation showed that the increase of overlayer improves the thermal stability of the Pd/Ge Kerr rotation was due to optical interference and metallisation at 30o0C, giving a long-term degrada- multiple reflection. tion rate. Magnetization and Aniuotropy of Co/Pd Reactivity of Ceramic Superconductors Multilayer Thin Films with Palladium Alloys D. G. STINSON and S.-C. SHIN, 3. Appl. Pkys., 1990.67, J. L. PORTER, T. K. VETHANAYAGAM, R. L. SNYDER and (9)1 459-4461 J. A. T. TAYLOR, 3. Am. Ceram. Soc., I-, 73, (6), Multilayered Co/Pd thin fhwere prepared by 1760-1 762 sequential electron-beam evaporation of Co and Pd Pd alloy compositions were investigated for suitabili- onto Si substrate at morn temperature with ty as a non-reactive material for the processing of thicknesses of $e Co and Pd sublayers of 2.0-10.3 cersmic superconductors. Ba-based superconductors and 4.3-22.3 A, respectively. Broad maxima in the were tested on Pd-Au and Pd-Ag alloys, and Bi-based saturation magnetisation M, and intrinsic perpen- superconductors were tested on a Pd-Ag alloy. For dicular anisotropy ener K,, were observed at a Pd Ba-based high-temperature superconductors 70% thickness of about 10 f At this maximum, 5 per Pd-30% Ag was the least reactive, and 30% Pd-70% Co volume is larger than the saturation magnetisauon Ag was the least reactive for Bi-based high of bulk Co. temperature superconductors.

Platinum Metals Rev., 1990, 34, (4) 234 Stable and Shallow Pan Ohmic Contacts MEDICAL USES to n-GaAs L. C. WANG, X. 2. WANG, S. S. LAU, T. SANDS, W. K. Biophysical Studies of the Modification of CHAN and T. F. KUECH, Appl. Phys. Len., 19,56, DNA by Antitumour Platinum Coordina- (21), 2129-2131 tion Complexes A thermally stable, low-resistance PdIn ohmic con- V. BRABEC, V. KLEINWACHF~R,TER, J.-L. BUTOUR and N. P. tact to n-GaAs was developed based on the solid phase JOHNSON,Bwphys. chem., 19,35, (2, 3), 129-141 regrowth mechanism. Rapid thermal annealing of a The modifkation of DNA by cisplatin has been Pd-In/Pd metallisation induces a two-stage reaction examined. Anti-tumour active Pt compounds induce resulting in the formation of a uniform single-phase in DNA, at low levels of binding, local conforma- fhof PdIn, an intermetallic with a melting point > tional alterations which have the character of non- IZOOOC.Specific contact resistivities and contact denaturing distortions. These changes in DNA occur resistances of I x IO-~ Q cm’ and 0.14 il mm, due to the formation of intrastrand cross-links bet- respectively, were obtained for samples annealed at ween two adjacent purine residues. Conformational 600-65ooC. The addition for a thin layer of Ge (2 alterations induced in DNA by anti-tumour active Pt nm) to the fvst Pd layer extends the optimum anneal- compounds may be reparable with greater difficulty ing temperature window down to ~ooOC.Specific than those induced by the inactive complexes. contact resistivities remained in the low IO-~il cmz However, the non-denaturation change induced in range after annealing at 4m°C for over two days. DNA by anti-nunour Pt drugs could represent more significant steric hindrance against DNA replication TEMPERATURE as compared with inactive complexes. MEASUREmNT Bending Studies of DNA Site-Specifically Modified by Cisplatin, tram- comparison of Resistance Versus Ther- diamminedichloroplat(II) and modynamic Temperature of Platinum cM-[Pt(NH,) (N3cytosine)Cll+ Resistance Thermometers with the ITS-90 s. F. BELLON and s. J. LIPPARD, Bwphys. Chem., 19, 35, (2, 31, 179-188 J. J. coNNOLLY, T. P. and J. TAPPING, JONES Duplex oligonucleotides containing a single intra- Merologia, 19,27, (z), 83-88 strand {F’t(NH,),}’ + cross-link or monofunctional Experiments that relate the resistances of a group of adduct and either 15 or 22 bp in length were syn- five high temperature Pt resistance thermometers to thesised and chemically characterised. The Pt- thermodynamic temperatures at 600-yk0C are modified and unmodified control DNAs were reported. Within the accuracy of the photoelectric polymerised in the presence of DNA ligase and the pyromeuy involved, +0.40°C at the freezing point of products and the extent of the DNA bending caused Ag, the measured thermodynamic temperatures by the various Pt-DNA adducts was shown by their agreed with the temperatures obtained using the gel mobility shifts relative to unplatinated controls. ITS-9 (International Temperature Scale of 1990). In When modified by the monofunctional adduct a 1.5 year period the typical random uncertainties, ~is-[pt(NH,)~(N3-cytosine)(dG)lQ the helix re- evidenced by variations in the resistance of Pt mains rod-like. These structural differences in DNAs resistance thermometers at the triple point of H,0, modified by cisplatin and its analogs could be im- were equivalent to 20.01 5% at the Ag freezing point. portant in biological processing of adducts in vivo.

A High Temperature (1200 O C) Probe for Synthesis and Antitumor Activity of PtO NMR Experiments and Its Application to Complexes of Benzyl-1,%-diaminoethane Silicate Meha Liganda S. SHIMOKAWA, H. MAEKAWA, E. YAMADA, T. H. BRUNNER, P. HANKOFER and B. TREIT~INGER, MAEKAWA, Y. NAKAMURA and T. YOKOKAWA, Chem. Chem. Ber., 1990, 123, (9,1029-1038 Len. JP., 1990, (4), 617-620 Twelve new diamine ligands were synthesised and A high temperature NMR probe has been developed characterised in which a benzyl group and another and used to measure the nSi nucleus in Na silicate vicinal substituent or a benzyl group, a 4-Q-benzyl glasses and melts. The probe uses Pt wire threaded group, and a 4-MeO-benzyl group, respectively, and through a two-hole tube of high purity alumi~SW- two other geminal substituents are attached to the rounding a core alumina tube. The heater current 1,z-diaminoethane skeleton. The diamine ligands are flows through two Pt wires in the alumina tube, op transformed into the dichoroplatinum(1I)complexes. posite in direction so as not to produce an additional The chloride ligands of four complexes are replaced magnetic field across the sample volume. Sample by the lactate anion. Polyvinylpplidone and a- temperatures were measured by a Pt:Pt-Rh ther- cyclodextrin are used to increase the water solubility mocouple, attached below the bottom of the capsule. of the Pt(I1) complexes. The antitumour activity of The highest temperature attained was IZOOOC.The the complexes was tested for P388 leukaemia, and NMR spectra show narrowing above the glass transi- compounds with small alkyl substituents show higher tion temperam. antitumour activity than that of cis-platinum.

Platinum Metak Rev., 1990,34, (4) 235 NEW PATENTS METALS AND ALLOYS ELECTROCHEMISTRY Gold Coloured Alloy for Dentistry and Composite Platinum Electrode for Jewellery Galvanic Coils D. DAVITZ U.S. Patent 4,865,809 PEROXID-CHEME G.m.b.H. European Appl. 350,895A A gold coloured alloy which is Cu-free contains A 5-100 pm thick Pt foil and a refractory metal elec- 22-28 wt.% Pd, 22-26 wt.% In, 8-20 wt.% Au, and trode of 0.1-10 mm thick Ti or Ta sheet, are bonded balance Ag, and may have a specific gravity of 9.35 by hot isostatic pressing at 650-90o0C, at a pressure 0.5 g/cm’. The alloy has improved tarnish of IOO--IZOO bar, for 0.5-3 hours. The Pt foil and the resistance and good corrosion resistance. electrode are surrounded by layers of inert separation foils. High quality Pt coated electrodes for use in Production of Magnetic Ornament from galvanic coils are produced, with good contact bet- Gold and Platinum-Cobalt Alloy ween Pt and the base metal, which gives increased efficiency. CITIZEN WATCH K.K. Japanese Appl. 2/54,783 Raw material which is in a dual phase dispersion state Platinum Black Air Cathode of Au and Pt-Coalloy is heated in an atmosphere containing 0, to form a surface layer of Co oxide, which ELTECH SYST. CORP. European Appl. 357,077A is removed. Further heating disperses the remaining A Pt black air cathode consists of a conductive, segregated Pt, so that a single Au-Pt phase is present porous, hydrophobic support layer which is a mixture in the uppermost surface. This method is used to of C particles and a hydrophobic polymer, and an form an ornament or accessory. electrolyte porous active layer of frnely divided Pt catalyst particles blended with a halogenated polymer Palladium-Gold Alloy for Jewellery Use binder. Expensive active ingredients are economically FORSCHSINST. EDELMET. GmnAppl. 3,826,607 used, and the electrode is used in metal-air batteries, acid and alkaline fuel cells, and ozone generators. A Au alloy for use as jewellery contains Pd, Au and Ga, and may also contain Ag, Cu and Zn. An example Corrosion Resistant Electrode for of a composition for an 18 carat Au alloy is 75% Au, Electrolysis 19% Pd, 5% Cu, and I% Ga. The Ga increases the strength and hardness of the alloy without requiring JAPAN CARLIT K.K. Japanese Appl. 11298,189 the replacement of some Pd by Ni, which tends to An electrode consists of a valve metal substrate; an produce an embrittling effect, poor colour and may ion-irradiated intermediate layer of at least one of Pt, have an allergy effect on the skin. Pd, Rh, Ir, Os, Ru, Ti, Ta, Nb or others, or an oxide; with a coating of a Pt group metal and/or oxide. An electrode having longer life is obtained, since the CHEMICAL COMPOUNDS corrosion resistance of the intermediate barrier layer is improved compared with those formed by conven- Preparation of High Purity Hexamine tional methods. Iridium Chloride TANAKA KIKINZOKU KOGYO Japanese Appl. 2/38,320 Electrode Manufacture for Electrolysis Higher purity hexamine Ir chloride of formula TANAKA KIKINZOKU KOGYO Japanese Appl. 11301,877 (Ir(NH3)6)C13is prepared by reaction of a solution An electrode is made by plating an elecuoconductive containing Ir(II1) choloride with NH,, addition of substrate of Ti, Ta, Nb or Zr with a precious metal HCI to form precipitates, dissolving the precipitates selected from Pt, Pd, Rh, Ir, Os, Ru, Au, Ag, and in aqueous NH, at 100-1 50°C under pressure, fdter- alloys thereof, followed by heat treatment and rolling. ing, and adding acetone to effect crystallisation. The electrode has a coating of uniform thickness, without pinholes, and is widely used in electrolysis of Layered Structured Transition Metal alkali halides and organic materials, and for elec- Chalcogenide trochemical processes. HAHN-MEITNER-INST. German Appl. 3,826,281 A new layer structure chalcogenide is of formula Electrolytic Manufacture of Ozone MX, where M is Rh, Ir, Os, Ru, Mo, W or Re, and SASAKURA KIKAI SEIS. Japanese Appl. 1/312,092 Xis S, Se or Te, and has a particle diameter of several A porous electrode has a 5-100 pm thick Pt layer on hundred nm down to a few nm. Ultrasound is used one side, to which a perfluorosulphonic acid type ca- to obtain the chalcogenide as a colloidal solution, tionic exchange resin is pressure-adhered. This elec- which is very stable and suitable for hrther process- trode is used as the anode in the manufacture of ozone ing. The MX, is used as a lubricant, a corrosion in- by electrolysing water, giving 0.05-0.5 wt.% of high hibitor, and for production of material layers with purity ozone, at reduced cost. Ozone suitable for photochemical or electrochemical properties. commercial use in food and healthcare is obtained.

Platinum MetaLs Rev., 1990, 34, (4), 236-243 236 Anodes Electroplated from Melts Non-Toxic Palladium Plating Solution Containing Noble Metal Salts NIPPON ELECTROPLAT. Japanese Appl. 2143,393 BAYER A.C. German Appl. 3,829,119 A Pd plating solution consists of 1-50 gA (in Pd base) Dimensionallystable valve metal anodes are activated of palladous amine chloride, 0.5-30 gA of by electroplating with noble metals andlor their com- pyridinesulphonic acid or its salt, and 0.1-100 ppm pounds, preferably with Pt, Ir or their compounds or in metal base of a soluble salt of a lanthanide metal, alloys, from melts containing noble metal salts. The for example Ce. This non-toxic Pd plating solution anodes are used in the economical production of has advantageous handling, and gives Pd precipitates alkali dichromates and chromic acid by electrolysis of which have excellent lustre and low stress, improved alkali mono- or &chromate solutions. adhesibility and elongation, and resistance to crack generation on repeated bending. Dimensionally Stable Anode for Chlor-Alkali Electrolysis Ruthenium Plating Solution for Electrical HUMBOLDT-UNIV. BERLIN Contacts East German Patent 272,315 NIPPON MINING K.K. Japanese Appl. 2154,792 A dimensionallystable anode for electrochemicalpro- A plating solution contains 3-10 gA Ru as an in- cesses consists of a Ti substrate, an intermediate layer organic Ru salt, 6-20 gA of acid, and a Group I11 and an electrochemically active layer based on metal salt preferably of In, SC, Y, or Ga, at 0.5-3 gA RuO,/TiO, or RuO,/IrO,/TiO,. The intermediate of metal. The solution is capable of forming platings layer is precious metal-free, and has high electrical of 2 pm or more in thickness, which are free from conductivity and good adhesion; consisting of TiN, cracks. The plating solution is useful for electrical (xis 0.1-1.2)up to IOO pm thick. The anode is used contacts, giving excellent brightness and reliability. especially in chlor-alkali electrolysis.

ELECTRODEPOSITION AND APPARATUS AND TECHNIQUE SURFACE COATINGS Humidity Resisting Gas Sensor TOSHIBA K.K. Japanese Appl. 11316,650 Platinum Platinum Alloy Plating Bath or A fued SnO, type semiconductor gas sensor consists JOHNSON M~YP.L.C. European Appl. 358,375A of an insulating base plate of for example Al, a pair A Pt or Pt alloy electroplating bath used for providing of thin fhAu conductor electrodes, and a gas sens- conducting parts in electrical circuits contains an ing membrane, on which is a catalyser membrane of alkaline aqueous solution of a complex Pt(I1) salt. porous metal oxide of 38-152 fl particle size, pro- The Pt salt is preferably complexed with NH, or duced by fuing Al powder, chloroplatinic acid and primary or secondary amines, and the anionic compo- Rh chloride. The gas sensor is stable for a long nent is -SO,, -NO,, -CO,, benzoate, citrate or period, has good humidity resistance, and good selec- others. The bath is more efficient and stable than tivity for gases, for example methanol. known baths, is versatile and easy to use. Measuring Formaldehyde Concentration Platinum Colloid Pretreatment Solution MA DENPA KOGYO K.K. Japanese Appl. 211,542 NIPPON ELECTROPLAT. Japanese Appl. 11319,683 A cell for measuring formaldehyde concentration has A Pt colloid solution contains 0.01-30 gA of a Pt salt, a Pt anode and a Ag cathode, with the area of cathode 0.1-100 gA of a polysaccharideas a protective colloid contacting the sample liquid set at 20 times that of the agent, and 0. I -100 gA of a reducing sugar as a reduc- anode, and with each electrode covered with a thin ing agent. The Pt colloid solution is best suited for membrane permeable to formaldehyde but not larger pretreating material for electroless Pt plating, since Pt molecules. The cell measures current from the anodic particles are adsorbed uniformly and in high purity. oxidation of formaldehyde, the concentration of which can be simply and speedily measured with high Platinum Plating Niobium or Tantalum accuracy, without being influenced by metallic ions. Substrates TANAKA KIKINZOKU KOGYO Oxygen Sensor for Internal Combustion Japanese Appls. 2111,785and 2111,794 Engine Exhaust Gas A process for Pt plating Nb or Ta substrates involves: JAPAN ELEC. CONTROL ms. Japanese Appl. 2147,546 (a) mechanically roughening the substrate surface, for An 0, sensor has an electrode formed on both sides example by sand blasting, (b) electrolytic polishing to of a solid electrolyte, with one side in contact with etch the surface, or chemical etching of the roughen- standard air and the other in contact with exhaust ed surface, (c) effecting activation treatment, and Pt gas; the latter side having a Pt oxidation catalyst plating, preferably by electroplating. The pretreat- layer, a SiO, decomposition-adsorption layer on the ment provides tightly adhered Pt plated fdms, useful catalyst layer, and a porous AI,O, protective layer. in manufacturing electrodes which consume Pt with The sensor detects the 0, concentration in engine ex- time, as the Pt may be re-coated using this process. haust gas to determine the &fuel ratio.

Platinum Metals Rev., 1990, 34, (4) 237 Gas Sensor with Noble Metal Catalyst Ruthenium Catalyst for Production of Layer Cyclohexylamines TOSHIBA K.K. Japanese Appl. 2154,157 BAYER A.G. European Appl. 351,661A A gas sensor consists of a pair of opposite electrodes A Ru catalyst having improved service life is produc- on an insulating substrate, and a metallic oxide ed by adding a total of 0.05-8 wt.% of rare earth semiconductor gas-responsive fdm, covered with a metal compounds, preferably Ce or La, and Mn com- catalyst layer consisting of 0.2-3.0 mol% of at least pounds to an Al ,0, support, heating to 2oo-450°C, one of Pt, Pd and Rh carried on A1203.Catalyst and applying 0.05-5 wt.% Ru. The catalyst is used deterioration can be effectively prevented. for production of cyclohexylamines and dicyclohex- ylamines by hydrogenation of anilines at 80-240°C Determination of Volatile Ruthenium under elevated pressure, and enables the products to Tetroxide be formed in a desired ratio. ISHIKAWAJIMA-HARIMA JUKO Japanese Appl. 2169,658 Solventless Preparation of Volatile RuO, is measured by passing sample gas through a fmt fdter to capture RuO,, reducing Acetoxyphenylmethylcarbinol RuO, in the sample gas to RuO,, passing the reduc- HOECHST CELANESE CO. European Appl. 353,898A ed gas through a second fdter to capture RuO, ,and Preparation of 4-acetoxyphenylmethylcarbinolis ef- measuring this amount of RuO, using a Geiger fected by heating 4-acetoxyacetophenone at counter or scintillation counter to determine the 54-12oOC with H,, in the presence of a Pd/C or amount of RuO, present. activated Ni catalyst, but using no solvent. Poly(4-hydroxystyrene)can be prepared from the car- Determination of Ruthenium in Solutions binol compound, and is used in adhesives, coating MOSCOW LOMONOSOV. UNIV. Russion Patent 1,495,713 compositions, and photoresists. Problems caused by A more efficient determination of Ru in solutions is solvents used in previous hydrogenation methods are by treating the sample with 1,Io-phenanthroline, eliminated with this solventless preparation. hydroxylamine hydrochloride, NaCI, and NaOH, to pH 5.5-8.0, adding siliceous sulphocationite, shak- Platinum-Lanthanum Catalyst for ing, cooling, decanting, drying and then determining Oxidation of Carbon Monoxide Ru by luminescencespectroscopy. Using this method W.R. GRACE CO. Eumpean Appl. 354,525A the time of determination is reduced. A catalyst for CO oxidation contains 50-1000 ppm Pt and 4-30 wt.% lanthana on an Al,O, substrate of surface area 45-450 m’lg. The catalyst may be used JOINING to control CO emissions from a variety of sources, especially by adding to a cracking catalyst to reduce Brazing Alloy Containing Palladium and CO emissions from the regenerator stack. It remains Gold active for a long time when subjected to multiple GTE PRODUCTS COW. U.S. Patent 4,903,890 regenerations. A brazing alloy consisting of 15-35 wt.% Pd, 5-30 wt.% Au, 10-30 wt.% Ni, 20-48 wt.% Cu and 5-25 Palladium-Charcoal Hydrogenation Catalyst wt.% 1Mn has a solidus temperature above 1000Oc and a liquidus temperature above 1018~C.The alloy BEECHAM GROUP P.L.C. European Appl. 355,986A is used for brazing metal parts made of a superalloy Preparation of 2-aminopurine is by catalytic having a solution heat treating temperature of hydrogenation of 2-amino-6-chloropurine using Pd 1025-1080~C,to form a uniform fillet at the joint. on charcoal as the catalyst, in aqueous solution, in the The alloy has good gap-filling and good high presence of a base, at 5o°C and 70 kPa. The process temperature properties. is a simple and inexpensive method of preparing ~-aminopurine,which is used in the preparation of 6-deoxy guanine nucleoside anti-viral agents. HETEROGENEOUS CATALYSIS Palladium Catalyst for Waste Gas Dehydrogenation Catalysts for Purification from Alcohol Engines Production of AUcenes DEGUSSA A.G. European Appl. 358,123A BRITISH PETROLEUM P.L.C. A catalyst for purification of waste gases from internal Eumpean Appls. 351,&6-67A combustion engines driven mainly with alcohol, con- Dehydrogenation catalysts for converting 2-IOC sists of 0.03-3 wt.% Pd, 0.5-70 wt.% of rare earth paraffm to alkenes consist of (a) up to 10 wt.% of Pt metal oxides, and 0.5-30 wt.% of MoSi,, an Al,O, (preferred), Pd, Rh, Ir or Ru, and 0.05-20 wt.% Zn carrier, and optionally a monolithic or honeycomb on a support having a silicalite structure, the support. The catalyst is used for removal of framework of the support being mainly Si and 0 aldehydes, alcohols, CO, NOx and hydrocarbons atoms, or Si, Zn and 0 atoms; or (b) a Pt group metal from the waste gases, having low initial reaction and Sn on a silicalite support. temperature, high conversion and better ageing.

Platinum MetaLs Rev., 1990, 34, (4) 238 Waste Gas Purification Catalyst for Palladium Hydrogenation Catalysts Reduced Hydrogen Sulphide Emission GAF CORP. U.S. Patents 4,885,410-11 DEGUSSA A.G. European Appl. 358,125A Supported catalysts consistingof (a) 0.05-5 wt.% Pd, A catalyst for purification of waste gases from internal 8-40 wt.% Cu, and 1.5-10 wt.% alkali(ne earth) combustion engines consists of a honeycomb support metal; or (b) 0.05-5 wt.% Pd, 10-90 wt.% Ni, and with an Al,O, carrier having 0.01-3 wt.% of Pt, Pd 0.03-10 wt.% Re, are used for hydrogenation of (a) and/or Rh with wt. ratio of Pt and/or Pd:Rh of lactones to diols or (b) unsaturated/carbonyl group 2-30:1,2-70 wt.% GO,,0-20 wt.% ZrO,, 0.2-25 containing organic compounds to alkanediol pro- wt.% B,O,, and optionally oxides of Fe, alkaline ducts. In case (a) products such as I ,q-butanediol and earths and/or rare earths. Using this catalyst, which I ,Chexanediol which are useful as monomers are ob- is free from Ni, emission of H, S and accumulation of tained with improved selectivity, and in (b) the pro- S oxides are reduced. ducts are useful for pharmaceuticals and cosmetics. Selective Preparation of Glycols Efficient Method for Regenerating GAP COW. U.S. Patent 4,7953733 Sintered Catalysts A new hydrogenation catalyst consists of 0.05-5 DOW CHEMICAL. CO. U.S. Patent 4,891,346 wt.% Pd and/or Rh, 10-90 wt.% Ni, and 0.03-10 Redispersing and reducing a deactivated Pd, Rh, 0s wt.% metallic Re on a support in fluted extended or Ru catalyst on a refractory support is achieved by form, which has 5-90 wt.% of Al,O,. The catalyst contact with a reducing agent to partially reduce the can be used for hydrogenation reactions, in particular catalyst, (2, or Br, to redispene the metal, and a I ,4-butynediol and I ,q-butenediol to I ,q-butanediol, reducing agent to complete the reduction. After having higher activity and selectivity to the product. regeneration the catalyst has at least 110% of its Glycols such as 1,4-butanediol are useful as original activity for converting ~-chloroprene, monomers for thermoplastics, and in the phar- CH,OH and CO to methylmethacrylate and maceutical industry. chloromethane. This is a simple, cheap and efficient method of regenerating sintered catalysts. Palladium Hydrogenation Catalyst for Butanediol Preparation Palladium Catalyst for Olefin GAF CORP. U.S. Patent 4,797,382 Isomeristion A new hydrogenation catalyst consists of 0.05-5 SHELL OIL co. U.S. Patent 4,895,997 wt.% Pd or a mixture of Pd with another metal hav- A double bond isomerisation process for conversion ing defmed properties, 8-40 wt.% Cu, and 1.5-10 of an a-olefm feedstock to internal olefins uses a wt.% of an alkali metal or alkaline earth metal on a catalyst which incorporates 0.01-10 wt.% Pd into an magnesium silicate support at 45-97% of the total Al,O, hydrogel, to give a surface area of at least 275 composition. The catalyst is used for preparation of m’/g and a specified pore structure. The catalyst 1,4-butanediol from 7-butyrolactone in high yield shows diminished dimerisation reactions. and selectivity. Novel Catalyst for Production of Catalyst Composite for Hydrocarbon Polymethylenes Dehydrogenation BROOKHAVEN NAT. LAB. U.S. Appl. 7,175,781 UOP U.S. Patent 4,880,764 A novel catalyst of Fe, together with Pt and/or Pd op- A catalyst composite consists of 0.1-2.0 wt.% Pt, tionally on an inorganic refractory oxide support, is modifiers of: 0.1-5.0wt.% Li, 0.1-2.0 wt.% Ir, and used for the synthesis of long chain hydrocarbons 0.1-5.0 wt.% Sn; all on an Al, 0, support of nominal from mixtures of CO and H, and/or H,O. diameter 850-2500 pm. The Ir is surface im- Polymethylenes are produced which could substitute pregnated on the catalyst, while the Pt, Li and Sn for commercial HD polyethylene. The novel catalysts components are uniformly impregnated. The catalyst are less expensive than prior-art Ru catalysts, can be Composite is used for conversion of hydrocarbons, used at moderate pressures, are stable, and can be us- especially for dehydrogenation of 2-1 gC paraffms or ed in slurry type reactors. olefms. Palladium Catalyst for Ally1 Acetate Naphtha Reforming Catalyst Preparation MOBIL OIL COW. U.S. Patent 4,882,040 DAICEL CHEM. IND. K.K. Japanese Appl. 1/299,253 A naphtha feedstock of low Octane value is reformed A Pd catalyst is used in the preparation of ally1 acetate to give a high octane value and aromatics content by by reaction of propylene with acetic acid and 0, , in contacting with a catalyst consisting of a Group VIII the vapour phase at 100-300~C. The catalyst con- metal, especially 0.1-10 wt.% Pt, in combination tains 0.1-5 wt.% Pd with a specific surface area of with Q zeolite containing 0.1-10 wt.% TI or Pb. 50-150 m’/g and alkali metal acetate(s), supported Selectivity for aromatics is high, and for on SiO, of specific surface area 20-200 m’/g with hydrogenolysislow; and aromatic gasoline is obtained defmed pore characteristics. The catalyst has an im- in good yield. proved life span and gives improved yield.

Platinum Metals Rev., 1990, 34, (4) 239 Palladium-Perovskite Waste Gas HOMOGENEOUS CATALYSIS Purification Catalyst MATSUSHITA ELEC. IND. K.K. Oxidative Carbonylation to Prepare Japanese AM. 11307,453 Organic Carbonates A waste gas purifying catalyst consists of a GENERAL ELECTRIC GO. honeycomb support having an Alz0 , coating loaded European Appls. 350,697A and 350,700A with Pd, then perovskite type double oxide fme Organic carbonates are prepared by reaction of an powders of formula ABO,, where A is a rare organic hydroxy composition, CO and 0, at eanhlalkaline earth metal and B is a transition metal. ~o-I~oOC,in the presence of a catalyst consisting of The embedded Pd is protected from poisoning, and Pd, Co or diltrivalent Mn, tetraalkylammonium the catalyst maintains higher activity over a long time halide(s), and a quinone andlor aromatic diol reduc- for purification of combustion exhaust from cars, or tion product. The organic carbonates produced are industrial or domestic combustors. used to prepare polycarbonates. This reaction does Palladium Catalyst for Preparation of not require bases, drying agents or solvents, so Aromatic Chlorides catalyst recycle is more practical. KUREHA CHEM. IND. K.K. Japanese Appl. 1/311,032 Ruthenium Catalyst for Transvinylation Aromatic chlorides are preparrd by trans- UNION CARBIDE COW. Eumpean Appl. 351,603A chlorination of polychlorinated aromatic compounds A new process for the transvinylation of a vinyl at 2oo-~w°Cover a catalyst consisting of 0.01-30% derivative of a Bronsted acid, for example vinyl Pd chloride and rare earth metal chlorides on active acetate, with a different Bronsted acid, involves mix- C. The chlorides are preferably one or more of Y, La ing in the liquid phase at 50-200 OC, in the presence and Ce chlorides, with a ratio of other molar of CO and 30,000-0.5 ppm of a Ru carbonyl carbox- chlorides:Pd chloride of O.OI-IOO. Useful aromatic ylate catalyst, to produce the vinyl derivative of the chlorides can be prepared effriently, in high yield, different Bronsted acid. The Ru catalysts are non- using this method. volatile, thermally stable, exhibit high activity only at Selective Preparation of Benzene elevated temperatures, are not toxic, and allow a high yield of product to be obtained. NIPPON KOKAN K.K. Japanese Appl. 1/311,033 Benzene is prepared by reaction of alkylbenzenes Pahdium-phoephine complex Catalyet with CO, over a catalyst of 0.01-50 wt.% Pd and for Hydrogenolysie 0.1-50 wt.% of one or more oxides from akaline RH~NE-POULENCCHIMI. European Appl. 352,164A earth and rare earth metal oxides, on an Al,O, support. The preferred catalytic component is Pd/CeO,, A chlomaromatic derivative such as chlombenzene is PdN,O,, Pd/La,O,, Pd/MgO with atomic ratio of hydrogenolysed with H, in the presence of a catalyst based Pd and a phosphine having a pKa of at least Pdlmetal oxides of 0-5-50. Benzene and useful CO on 6. The process takes place the homogeneous liquid and H, are prepared using this method, with high in wlmivitv tn hen7~nr phase. Exhaust Purification Catalyst Preparation Palladium-Phosphine Complex for NIPWN SHOKUBAI KAGNCU Japanese ApPl. 1/315,340 Carbonylation Reactions A monolithic honeycomb carrier is coated with RH6NE-WUL.ENC CHIhU. 0.1-10 gA total of Pt and/or Pd, and Rh, 1-150g/l European AppLF. 352,166-67A GO,, and 20-200 gA activated Al,O,, dipped into Akoxycarbonylation or hydrocarbonylation of an aqueous Sn solution, and dried and/or sintered to chlorinated aromatic compounds are effected by con- give 0.01-50 gA SnO,. The catalyst can be used for tacting with a Pd based catalyst and a phosphine, in simultaneous removal of hydrocarbons, CO and the presence of a base, an alcohol or H,, COYand a nitrogen oxides from internal combustion engine ex- solvent, at IOO-ZW~C and 10-100 bars pmsure. haust at lower temperatures. Prior-art processes start with bromo- and iodo- compounds, while this process allows alkoxycar- Domestic Stove Exhaust Purification bonylation or hydrocarbonylationof aromatic chloro- Catalyste compounds using a Pd-phosphine complex in the MATSUSHITA ELEC. IND. K.K. Japanese Appl. 2/9,452 presence of an amine. A Curved plane with honeycomb SVUCtllre is prepared Ruthenium Catalystcatalyst for for EpoxyE~~~ AcidAcid from a mixture of Al,O,, fused SO,, K salts or Production fibrous K titanate, cellulose ether, a surface active production agent and water, and is impregnated with Pt group a-NAT. ELF- AQWW world APPl. 90/o,I67A elements. It is used for catalysts for purifying exhaust A Ru salt is used to catalyse the oxidation of epoxy gases from various combustion devices, especially alcohols to epoxy acids using a solid oxidant in a domestic kerosene or gas stoves. The curved medium containing water and an organic solvent. honeycomb catalyst can be assembled to form a The process is used for preparation of low molecular tubular catalyst with large surface area. weight epoxy acids which are highly water soluble.

Platinum MeeraLC Rev., 1990,34, (4) 240 Ruthenium Catalyst Composition for Platinum-Gallium-Chromium Ternary Oxidation Reactions Fuel Cell Catalyst UNIV. OF FLORIDA U.S. Patent 4,885,377 UNITED TECHNOLOGIES CORP. U.S. Patent. 4,806,s I 5 A new Ru perfluoroalkyl carboxylate composition is A ternary metal catalyst contains at least 50 at.% Pt, used as a catalyst in olefin and alkane oxidations. 5-20 at.% Ga, and one of 0,Co, Ni or a mixture, Other catalytic oxidations involve high temperatures preferably Cr or a Co/G mixture, on a carbonaceous and pressures, but oxidation of cyclohexane and nor- support. The catalyst has a high mass activity for the bornene for example, using the catalyst, can take electrochemicalreduction of 0,, and is useful for fuel place at 65OC using 0, at 40 psi, in acetonitrile. cells, showing resistance to sintering and chemical dissolution during use. The operating life of the fuel Preparation of Glycol Monoethers Using cell is prolonged, with more stable output voltage. Ruthenium Catalysts SUN REFINING & MARK ET. U.S.Patent 4,895,987 Ternary Fuel Cell Catalyst Containing Glycol monoethers are prepared by dealkoxyhydroxy- Platinum and Gallium methylation of aldehyde acetals by reaction with INTER FUEL CELLS CO. U.S. Patent 4,880,71 I syngas in the presence of a novel catalyst system hav- A noble metal ternary alloy catalyst consists of at least ing a phosphonite or phosphinite promoter and a Ru- 50 at.% Pt, 5-20 at.% Ga, and at least one of G,Co, Co metal cluster compound or a mixture of Co and Ni and mixtures, preferably G, or Co and G;all on Ru compounds. The novel catalyst allows reaction a carbonaceous support. A stable, long-life catalyst is under milder conditions, and gives better rates and obtained for fuel cell electrodes and other catalytic selectivities. The glycol ethers obtained are useful, structures. The catalyst resists sintering and chemical for example, as jet fuel additives. dissolution during operation, thus improving the long term use of the fuel cell. Preparation of a-Keto Esters AGENCY OF IND. XI. TECH. Japanese Appl. 1/30~.053 CORROSION PROTECTION a-Keto esters are prepared by reacting a-hydroxy esters with a bromic acid salt in the presence of a Ru Anode for Cathode Protection catalyst, an onium salt and Na or K orthophosphate, As. USSR PHYS. CHEM. Russian Patent 1,497,280 in a two phase medium, preferably at 0-8o°C. The An anode has an inert support base, and a working method gives an industrially applicable process for part consisting of an electrochemical active element producing a variety of a-keto esters under mild con- shaped as a strip and made from an amorphous alloy ditions and in high yield; useful as intermediates in based on Pd. The anode is used for cathode protec- the preparation of drugs and agrochemicals. tion, and can be used for metal corrosion protection such as construction in water; giving increased operational efficiency and reduced energy consumption. FUEL CELLS High Temperature Fuel Cell Reforming CHEMICAL TECHNOLOGY Catalyst JOHNSON MATTHEY P.L.C. European Appl. 351,123~4 Removal of Platinum Group Metal A fuel containing a hydrocarbon is reformed in a high Compound from a Liquid temperature fuel cell by contacting a gas stream con- GAF CHEMICALS CORP. U.S. Patent 4,900,520 taining the fuel with a catalyst consisting of a Pt An acidic Pt group metal compound present at group metal and/or a noble metal from F’t, Rh, Ru or 1-5000 ppm is removed from a liquid product mix- Au, on a support of rare earth oxide, ZrO, ,GO, or ture by agitating with basic macroreticular anion ex- MgO. The catalyst has better corrosion resistance and change resin particles of size 60-1000 mesh. The resistance to deactivation of the electrolyte of a high process is used to purify organosilanes or silicones temperature fuel cell. derived from the reaction of a hydropolysiloxane. Platinum Alloy Electrocatalyst for Acid Fuel Cell GLASS TECHNOLOGY NE. CHEMCAT. CORP. European Appl. 355,853A Stirring Rod for Molten Glass A supported F’t alloy electrocatalyst used for an electrode for an acid electrolyte fuel cell consists of a con- TANAKAKIKINZOKU KOGW Japanese Appl. 2/48,422 ductive C powder carrier and 0.1-30 wt.% of a A rod for stirring molten glass consists of a hollow dispersed ordered F’t-Fe-Cu ternary alloy having support shaft formed so that cooling gas is blown into 40-60 at.% Pt, 13-40 at.% Fe and 13-40 at.Cu. The the rod. There is a Pt or Pt alloy outer surface layer alloy has a face-centred tetragonal or cubic structua, which contacts the molten glass, and the stirring and an avarage crystallite diameter not above 50 A. blades are mounted on the shaft. The stirring rod is The electrocatalyst has higher activity and longer life. used for glassware production facilities.

Platinum Metals Rev., 1990, 34, (4) 241 ELECTRICAL AND ELECTRONIC Silver-Palladium Composite Fine Powder ENGINEERING TANAKA KIKINZOKU KOGYO Japanese Appl. 1/319,609 A Ag-Pd composite fine powder is made by adding Cast Sputtering Target Containing hydrogenated sodium bride to an aqueous solution Platinum or Palladium of a Pd compound, for example Pd nitrate, to form a colloid, adding L-ascorbic acid, then an aqueous EASTMAN KODAK CO. U.S. Patent 4,885,134 solution of a Ag compound. The Ag-Pd composite A sputtering target used in the production of fine powder is used for electrical conductive paste us- magneto-optic recording media is formed of an alloy ed in thick film circuitry. The paste has improved containing Tb, Fe and Co together with 2.5-15 at.% characteristics such as no migration of Ag, and no of F’t, Pd, Cr, Ni, Ta or Hf, and especially contains solder cracking. 21-27 at.% Tb, 70-79 at.% Fe, 6-9 at.% Co, and 5-10 at.% of the fourth metal. Addition of the fourth Magnetic Recording Medium with metal produces fine grained physically sound bodies Palladium Thin Film having uniform composition and structure. Alloy MATSUSHITA ELEC.IND. K.K.Japanese Appl. 11320,619 Improved Silicone Gel Encapsulant for A magnetic recording medium consists of a high Electronic Devices molecular film such as polyethylene terephthalate, a sputtered thin film (150-500 A) such as Pd, Pd-Ag AMERICAN TU. & TELEG. co. U.S. Patent 4,888,226 or Pd-Si with more than 60% Pd in the alloys, a ver- Electronic devices, especially wire-bonded integrated tically magnetised film of Co-G, GI-Mo, Co-G-Rh, circuits, are encapsualted by a material consisting of or others, and a protective fh. The medium has 15-30 wt.% silicon gel which contains a Pt catalyst, good durability for vertical magnetic recording, and 50-80 wt.% SiO,, and 5-20 wt.% of a silicone high density recording can be performed without be- hydride composition. The uncured encapsulant is ing affected by environmental conditions. capable of flowing to encase an electronic device, and after curing it has appropriate adhesion, thermal, and Laser Beam Marking of Resin shock-resistant properties. Compositions Japanese Appl. 2145,125 Polycryetalline Platinum-Cobalt Magnetic FUJI PHOTO FILM K.K. Film Laser beams are used for cutting or marking a resin composition containing Pt, Pd, Ni, Cu or Co; an C. F. BRUCKER U.S. Patent. 4,902,583 alkyl, aryl or heterocyclic group; cations, and other A hexagonal polycrystallinemagnetic CqPt layer con- components. The method gives a fine finish to cut sists of a substrate, a 3000--10,000 A Copt film portions, and is used to engrave model names and whose c-axis throughout the film thickness is at 29O manufacture or lot numbers of IC packages, or to ac- to the plane of the film, and may include an in- curately cut masking tapes bonded to car bodies for termediate layer of G or W. A thin usable CoPt film painting. is deposited as a single homogeneous structure, preferably by controlled sputtering pmess, with a High Density Storage Magnetic coercivity of 1300-2000 Oe. Recording Medium MTSUSHITA ELEC. IND. K.K. Japanese Appl. 2156,717 Sulphiding Resistant Electrical Contact A magnetic recording film of oriented magnetisation UOY axis consists of a substrate, an intermediate layer op- TECHNOPOLICEHAKODA Japanese Appl. 11298,125 tionally of F’t group elements, Ni, Cu, or others, and A sulphurising resistant contact material consists of a a magnetic recording layer which is a ferromagnetic Ag or Ag alloy matrix and I -40 wt.% Ru02particles thin film of Fe carbide or Fe oxide. The magnetic dispersed in the matrix. The material is produced by recording film has high density storage by raising the pressing a mixture of Ru powder and Ag powder to rectangular ratio of the medium, which is for example form a compact, and sintering in an oxidising at- 0.90, and is used for video tapes. mosphere. The sulphurising resistance of the material is improved without reducing the contact properties. Magnetic Recording Medium Containing Platinum Magnetic Recording Medium Containing HITACHI K.K. Japanese Appl. 2158,723 Rhodium and/or Ruthenium The medium has a nonmagnetic base with a HITACHI K.K. Japanese Appl. I I31 2,724 magnetic layer containing Co and Pt, at least one of A magnetic recording medium consists of a non- Ni, 0,Mo and W, at least one of Rh, Ru, Ti, Zr, magnetic base material, an intermediate Cr, Mo or W Hf, Ta and Nb, and at least one of Al and Si. The layer, and a 500 A magnetic layer made of a thin noise level of high density reproduction and recor- film of an Fe-Ru system alloy containing 3-10 at.% ding can be reduced without loss of magnetic proper- Ru, an Fe-Rh system alloy containing 3-7 at.% Rh, ties of the Co alloy thin fdm. The medium has good or an Fe-Ru-Rh alloy. A protective layer may be pre- anticorrosion properties, high reliability, and can be sent. The magnetic layer has high coercive force. used in a magnetic memorising device.

Platinum Metals Rev., 1990, 34, (4) 242 Superconducting Paste for Thick Film MEDICAL USES Formation MITSUI MINING & SMELTING Japanese Appl. 2172,510 New Platinum Anti-Tumour Agents Superconducting paste consists of sintered powder Suitable for Encapsulation containing constituent atoms of a superconducting LIPOSOME co. INC. European Appl. 356,332A composite oxide of Bi, Pb, Sr, Ca and Cu, and New Pt complexes consist of qco-ordinate planar powder of one or more of Pt, Pd, Au, Ag or their ox- Pt2+ complexes and Cco-ordinate octahedral ides. The paste used for forming a superconducting Pt'+complexes with neoalkyl carboxylic acids such as thick film oriented to a spec54 direction, which is 2,2-dimethyloctanoic acid. The complexes are useful dense and contains a high ratio of a high Tc phase as anti-tumour agents, or anti-bacterial agents, (Tc = I IoK). especially suitable for encapsulation in liposomes. Improved Magnetic Recording Medium Platinum-Diamine Complexes with with Cobalt-Platinum Layer Anti-Tumour Activity SONY cow. Japanese Appl. 2/73,51 I NEDERLAM) ORG. TNO. European Appb. 357,108-9A A magnetic recording medium consists of a ground A Pt(1I) diamine complex (TN-56) and a Pt(1V) layer having at least one of Pt, Pd, Rh, Ir, Os, Ru, diamine complex (TNO-40) are both prepared from Au, Ag, Sb, Bi or others, with a magnetic thin layer K,PtCI,. The complexes have outstanding anti- of Copt or CoPtO containing at least one of Ti, Zr, tumour activity against diverse types of tumour, and V, Mo, G, Nb, Ta and W,or B. The magnetic strong actlvity against cells which have become resis- characteristics of the medium are improved, and the tant to cis-platinum. production cost is reduced. Indium-Free Dental Alloy Irradiation Treatment to Improve Corrosion Resistance of Workpieces ENGELHARD LTD. European APP~.357,335A A dental alloy consists of 60-85 wt.% Pd, 5-20 wt.% W.C. HERAEUS G.m.b.H. Appl. 3,830,539 German Cu, 3-15 wt.% Ga, 0.5-7 wt.% Au, 1-5 wt.% Sn, The corrosion resistance of workpieces made of Pd, 0.2 wt.% Ni, and o.oo5-0.02 wt.% of a grain refiner Ag and their alloys is improved by electromagneticir- of Ir, Ru, Re or mixnues of these metals. The novel radiation of their surfaces using a beam of pulsed alloy is used for dental restorations by casting and radiation of wavelength 140-360 nm, and a radiation then bonding a ceramic coating to part of the surface. time of I 11s to I ms. The workpieces are used in the It does not discolour dental ceramics, does not cause electronic industry as lead frames and contacts. bubbling of the porcelain during tiring, can undergo cold rolling, and is relatively inexpensive. High Reliability Metal-Ceramic Joint NGK SPARK PLUG K.K. German Appl. 3,931,156 Cis-Platinum Complexes for Inhibiting A ceramic is joined to a metal by inserting an in- Tumour Growth termediate member between them and heating the UNIV. OF TEXAS SYSTE. World Appl. 90/2,131A assembly to form an intermediatelayer which consists Four-co-ordinatecis-Pt(I1) complexescan be combin- of 20-70 wt.% Pd, 10-fio wt.% Ni, 1-10 wt.% Ti, ed with phospholipids to form liposomes which are and optionally up to 10 wt.% Cu. The joint has high reliability even at high temperatures, and is used for useful in inhibiting both the growth and metastatic valves, pistons, turbocharger rotom, or turbines, spread of tumours. A typical example of a Pt complex especially between a ceramic turbine wheel and a is cis-bis-neoheptanoato (ethylenediamine) Pt(I1). metallic rotor component. Platinum Complexes Used as Carcinostatic Agents TEMPERATURE CHUGAI PHARMACEUTICAL K.K. MEASUREMENT Japanese Appb. 2128,134-35 A dicarboxylate diamine Pt complex or its optically High Temperature Platinum Resistance active compound is prepared by reaction of (a) a Thermometer tetravalent platinum acid salt with 2-aminomethylpyrrolidine ISOTHERMAL m.LT. British Appl. 2,223,100A and its optically active compound to give tetrahalo(diamine)Pt(IV),followed A high temperature Pt resistance thermometer con- by treatment with Ag oxalate and the Ca salt of sists of a Pt winding in an elongate quartz be, with 1,I-cyclobutane dicarboxylic acid, or (b) cis- a positive potential offset voltage of 6-10 volts ap- dichloro(2-aminomethylpyrrolidine)Pt(I1) or its op- plied to the winding; the measured resistance of Pt tically active derivative with the Ag salt of I,I,- which is indicative of the temperaNre. The ther- cyclobutane dicarboxylic acid. mometer is calibrated using a graphite crucible to which a positive offset voltage is applied. High temperature standard Pt resistance thermometers and The New Patents abstracts have been prepared from high purity freezing point cells are obtained. material published by Derwent Publications Limited.

Platinum Metah Rev., 1990, 34, (4) 243 AUTHOR INDEX TO VOLUME 34

Page Page Page Page Abbas, N. M. 40 Barton, D. H. R. 231 Cabri, L. J. 223 Cottington, I. E. 14, 24, Abe, J. 23 1 Bassett, J.-M. 161 Cachet, H. 39 25, 35, 70, 76, 97, Abell, G. C. 156 Battezzati, L. 36 Caga, I. T. 230 141, 154, 180, 184, 191, Abend, G. 100 Baturova, M. D. 225 Cai, N.-C. 38 204,206 Abernathy, C. R. 165 Bautista, F. M. 231 Calais, C. I66 Cox, J. A. 38 Abilov, G. S. 110 Bautista, R. G. 25 Caliendo, C. I59 Crosley, D. R. 41 Aboul-Gheit, A. K. 229 Baxter, D. C. 104 Cameron, D. S. 26, 80 dkman, D. 158 Adlof, R. 0. 163 Bay6n, J. C. 101 Campelo, J. M. 231 Addriz, H. R. 161 Beanotti, A. 159 Canaday, J. D. 38 Ahmad, A. 38 Beattie, J. K. 107, 180 Canali, C. 234 Daneliya, E. P. 36 Aika, K.4. 23 1 Beaver, R. N. 47 Cannon, K. C. 106 Dapor, M. 234 Aizawa, M. 164 Bebelis, S. 122, 42 Capehart, T. W . 44 Dautremont-Smith, Alam, K. 40 Beck, D. D. 44 Carballo, L. M. 105 w. c. 234 Alandis, N. 44 Becker, K. 160 Carcia, P. F. 165, 234 Davey, D. E. 104 Albanesi, G. 45 Beeston, R. F. 39 Carlson, D. J. 233 Davies, J. A. 157 Albano, V. G. 100 Beghi, M. 159 Castellaneta, G. 234 de Alwis, A. A. P. 24 Albers, P. 158 Behr, F. E. 233 Centi, G. 205 De Armond, M. K. 103 Aldebert, P. 47 Bein, T. 99 Cervera-March, S. De Gronckel, H. A. M. Aleksif, B. K. 229 Bellon, S. F. 235 102. 226 99 Aleksif, B. R. 229 Beltramini, J. N. 228 Chalganov, E. M. 41 De Jonge, W. J. M 99 Allongue, P. 47 Belyi, A. S. 41 Chan, W. K. 235 Debenedetti, P. G. 35 Amblard, J. 39 Ben-David, Y. 46, 107 Chandra, S. I08 Dedieu, A. 72 Ameta, S. C. 102 Bergbreiter, D. E. 45 Chang, C.-A. 222 Delahay, G. 44 Amouyal, E. 39 Berlowitz, P. J. 222 Chang, T. S. 228 Delcourt, M.-0. 39 Anders, K. 160 Bernard, P.-M. 228 Chang, Y. A. 223 Dennehy, M. 161 Antonione, C. 36 Berndt, E. 36 Chang, Y.-S. 70 Dermietzel, J. 160 Aparina, N. P. 38, 101 Besenhard, J. 0. 110 Chao, G. Y. 223 Deronzier, A. 226 Appleby, A. J. 163 Bhatia, S. 228 Chaudron, G. 154 Desilvestro, J. 37 Arai, G. I57 Bider, J. W. 104 Chekhova, R. V. I07 Devilbiss, T. D. 101 Arai, H. 104 Blackburn, D. W . 143 Chen, F. L. I55 Dick, G.-B. 159 Aratani, M. 101 Blanco, C. 23 1 Chen, H. I56 Dimitriadis, C. A. 109 Ares Fang, C. S. 191 Blanpain, B. 222 Chen, W. 227 DimitrijeviC, N. M. I58 Arita, Y. 222 Block, J. H. 100 Chen, Y.-J. I03 Dimitrov, D. A. 166 Arvia, A. J. 157, 224 Bloor, L. J. I59 Chen, Y.-W. 106 Dimitrov, Kh. 105 Asakura, K. 230 Bockris, J. O’M. Cheon, S. H. 46 Dininno, F. P. 23 1 Asakura, Y. 104 101, 225 Chernova, G. P. 38 Diyachenko, N. 0. 36 Ash, D. H. 42, 43 Bodnariuk, P. 161 Chin, V. W. L. 165 Dong, Q.-H. 38 Ashton, S. V. 130 Boese, W. T. 227 Chiou, B. S. 40 Dong, S. 224 Aso, K. 48, 76. 99, 234 Bogomolov, D. 8. 38 Chocron, S. 232 Dong, S.-J. 40 Astrov, D. N. 110 BogYay, I. 162 Choi, D.-H. 159 Donzelli, G. 234 Ataka, Y. 162 Bond, A. M. 104 Chou. M.-L. 70 Doperchuk, M. I. 36 Auffermann, G. 156 Bond, G. C. 73 Chou; T. C. 155, 156 Dossi, C. 42 Auroux, A. 160 Bondareva, S. 0. 46 Choudary, B. M. 162 Doumain, C. 47 Avaca, L. A. 47 Bordeaux, F. 155 Chung, W.-Y. 104 Doyle, M. L. I43 Avnir, D. 103 Borodzinski, J. J. 224 Clarke, A. 227 Drolet, D. P. 227 Boronin, A. I. 43 Clauson, S. L. 100, 110 Drozdov, V. A. 41 Bahenkova, L. V. 161 Bowman, R. C. 156 Clechet, P. 109, 166 Diirr, H. 227 Baciocchi, M. 159 Brabec, V. 235 Cobranchi, S. T. 222 Dufaud, V. 161 Backman, A. L. 98 Braga, D. 100 Cocco, R. A. 106 Duggan, T. P. 224 Baglin, E. G. 25 Braichotte, D. 109 Cogan, S. F. 100, 110 Duh, J. G. 40 Bahia, A. 230 Briot, P. 160 Cohen, R. E. 166 Duplyakin, V. K. 41 Bai, X.-L. 106 Bronger, W. I56 Colbourne, A. P. 157 Duprez, D. 44 Baker, R. T. K. 228 Brossard, L. 37 Comrie, C. M. 99 Durand, R. 47 Bakirov, M. Ya. 101 Brown, J. M. 72, 230 Connolly, J. J. 235 Dutartre, R. 162 Baltruschat, G. 224 Briining, R. 155 Converti, J. 225 Dyer, C. K. 80 Bandi, A. 225 Bruneaux, J. 39 Conway, B. E. 156 Dyer, M. J. 41 Banse, B. A. 98 Brunner, H. 235 Coombes, J. S. 141 D’Amico, A. I59 Baranovskii, I. B. 46 Bryukvin, V. A. 223 Coq, B. 162 Barendrecht, E. I57 Buchanan, R. A. 97 Corti, C. W. Barnard, C. F. J. Bukhtiyarov, V. I. 43 84. 135, 204 Eigenson, I. A. 105 15, 207 Bukun, N. G. 37 Cosnier, S. 226 Eisman, G. A. 47 Barns, R. L. 233 Burke, L. D. 157, 224 Costa, B. 35 El Azhar, M. 160 Baron, J. 44 Butour, J.-L. 235 Costa Garcia, A. 40 Elfenthal. L. 102

Platinum Metals Rev., 1990, 34, (4), 244-248 244 Page Page Page Page El-Morsi, A. K. 229 Garnier, F. 40, 156 Haraya, K. 47 Imamura, H. 143 Emel’yanova, G. I. 105 Garrido, C. 109 Hardee, K. L. 227 Inamoto, Y. 162 Enayetullah, M. A. Gautney, J. 42, 43 Harriman, A. 181 Inoue, A. 223 101, 163 Genovese, L. 105 Harris, I. R. 230 Inoue, H. 37 Enyo, M. 156 Gentili, M. 159 Harris, T. 157 Inoue, Y. 232 Eremenko, N. K. 224 Georgadze, N. G. 225 Hartung, T. 224 Inui, T. 42 Ershov, A. Yu. 226 Georgopoulos, M. 39 Hasegawa, M. 234 Inukai, T. 48 Escudero, J. C. 226 Getoff, N. 226 Hashimoto, H. 162, 231 Isaeve, V. I. 46 Esteruelas, M. A. 231 Ghosh, A. K. 161 Hashimoto, S. Ishida, M. 101 Esumi, K. 100 Gigola, C. E. 161 48, 76, 99, 165, 234 Ishihara, S.4. 109 Evans, W. D. J. 71 Gilard, R. D. 48 Hatanaka, Y. 107 Ishikawa, S. 98 Gillette, V. H. 225 Hatwar, T. K. 48 Itaya, K. 155 Falconer, J. L. 229 GimCnez, J. 102, 226 Hayashi, T. 40 Ito, s. 43 Falendish, N. F. 36 Giordano, N. 105 He, Z. X. 103 Itoh, K. 162, 231 Faltemier, J. 159 Girushtin, G. G. 43 Heidrich, €3.-J. 225 Itoh, N. 47, 165 Fang, R- 228 Gladysheva, T. D. 226 Helms, C. R. 222 Itoh, Y. 232 Fanwick, P. E. 37 Glaubitz, D. I08 Henderson, R. S. 84 Itzhak, D. 164 Farmer, J. 155 Gningue, D. 40 Hensley, D. A. 229 Ivanov, P. s. 105 Farrell, N. 15, 110 Gold, J. 40 Hepburn, J. S. 44 hey, D. G. 109 Fateev, V. N. 101 Golden, M. J. 224 Her, W.-H. 225 Iwasaki, F. 43 Faulkner, L. R. 158 Goldman, A. S. 227 Herlong, J. 0. 222 Iwasawa, Y. 230 Fedkiw, P. S. 225 Goldman, M. E. 227 Herrero, J. 23 1 Iyoda, J. 105 Feller, H. G. 155 Goldoni, S. 110 Herrmann, J.-M. 103 Fernandes, M. G. Golodov, V. A. 45 Hertz, J. 36 109, 157 G6mez, R. 45 Henog, F. 108 Jablonski, E. L. 228 Fernaindez Alvarez, Gomez, S. E. 225 Hewett, C. A. 109 Jablohki, J. M. 43 J. M. 40 Gonzalez, E. R. 47 Hicks, R F. 98, 228 Jaccaud, M. 38 Feurer, E. 36 Goodenough, J. B. 163 Higgiion, A. 102, 154 Jacobs, B. A. J. 165 Fielder, W. L. 164 Gorbabevich, M. F. 42 Hildebrandt. B. W. 38 Jaeger, N. 229 Fierro, J. L. G. Gore, E. S. 2 Hirai, Y. 46 Jain, P. K. 102 47, 62, 106 Griitzel, M. 39 Hirano, H. 98 Jankowski, A. F. 223 Figoli, N. S. 161 Granada, J. R. 225 Hiroi, K. 23 1 JarmakoWiez, J. 44 Figueras, F. 162 Granger, R. M. 158 Hirose, Y. 164 Jaworski, R. K. 38 Filonenko, G. V. 43 Green, M. A. 165 Hishinuma, Y. 108, 233 Jean, G. 108 Fishman, B. A. 223 Greenlee, M. L. 231 Hiyama, T. 107 Jenkins, J. W. 73 Fitzgerdd, M. C. 39 Greidanm, F. J. A. M. Harber, J. K. H. 110 Jian, C.-Y. 38 Flanagan, T. B. 155, 222 165 Hofhan, N. W. 42.43 Jian, P. 109 Florido, P. C. 225 Grepioni, F. 100 Hoffman,R. W. 44 Jiang, X.-Z. 178 Forchione, J. 166 Griffin, T. A. 41, 228 Hofhano, J. E. 25 Jiq, Y. 105 Ford, T. E. 157 Griftith, A. 166 Hofhano, P. 110 Jintoku, T. 107, 163 Forster, R. J. 227 Gritsenko, V. I. 43 Holtzhawn, D. J. 155 Jackisch, W. 160 Fouche, V. 160 Gubm, S. P. 224 Hombo, J. 109 Johnson, N. P. 235 Franke, H. 160 Guczi, L. 162 Homeyer, S. T . 162 Johnston, P. 106 Frech, W. 104 Guenin, M. 160 Hoqji, A. 108, 233 Jones, D. 160 Fried, C. A. 232 Guerrera-Ruiz, A. Horiba, T. 108 Jones, T. P. 235 Froment, M. 39 45, 106 Horowitz, G. 40 Jou, J. W. 40 Frusteri, F. 105 Guevezov, V. 166 Hosoi, T. 229 Joyner, R. W. 106 Fujii, H. 222 Guido, G. 225 Hosokawa, H. 162 J-9 F*S. 234 Fuju, N. 39 Guisnet, M. 160 Hosokawa, K. 108 Juszezyk, W. 42 Fujimori, H. 98 Gulens, J. 38 Hosokawa, T. 162 Fqjita, T. 222 Gunasingham,H. 40 Hoye, P. A. T. 76 Fujitsuka, M. 222 Gundiler, I. H. 25 Hsu, L. 24 Kackley, N. 164 Fujiwara, Y. 107, 163 Guo, X. 226 Hsu, W.C. 106 Kaeriyama, K. 41 Fukumoto, Y. 40 Guseva, M. I. 38 Hu, Z. 230 Kaesz, H. D. 98, 103 Fukusbima, S. 107 HUot, J.-Y. 37 Kainthla, R. C. 225 Fumagalli, A. 100 Kajiwara, Y. 162 Furukawa, M. 155 Hacker, M. P. 110 Kalinina, G. E. 43 Furuya, N. 155 Hllnninen, H. E. 154 kOM, F. 105 bat,P. V. 158 Futsuhare, M. 143 Hahn, T. 105 Ichikawa, M. 106 Kameda, N. 45 wligudi, S. B. Ichikawa, S. 44 won,G. w. 233 Gachon, J. C. 36 46, 107, 232 Ichinohe, Y. 228 Kanani, N. 110 Gahler, S. 36 Hamnett, A. 163. 225 Igarashi, R. 39 Kandyba, G. I. 36 Galindo, M. C. 157 Handley, J. R. 192 Iitaka, Y. 156 Kannan, A. M. 226 Gao, S.Q. 41 Hankofer, P. 235 xmada, Y. 46 Karasali, H. 122 Garcia, A. 231 Hanlev, L. 226 Imni. T. 229 Knrpihki, 2. 42, 162 Gard, G. L. 233 Han&ton, N. A. 16 Imaizurm.. s. 232 K&mo, B. 143

Platinum Metals Rev., 1990, 34, (4) 245 Page Page Page Page Kashnikova, L. V. 45 Krozer, A. 143 Lipihski, J. 110 Matsumoto, K. 157 Katayama, T. 165 Kruse, N. 100 Lippard, S. J. 166, 235 Matsumoto, Y. 109 Katsman, E. A. 107 Krylova, A. Yu. 105, 161 Liu, H. 105 Matsumura, M. 38 Katz, A. 165, 234 Kubiak, C. P. 37, 158 Liu, W. 223 Matsuoka, M. 48 Kauffman, G. B. 215 Kuech, T. F. 235 Liu, X. 226, 228 Matsushima, S. 130 Kavan, L. 39 Kukoev, V. A. 223 Llobet, A. 226 Matusek, K. 162 Kawahara, T. 23 1 Kulesza, P. J. 158 Liiwendahl, L. 160 Mayer, J. W. 222 Kawamoto, Y. 105 Kul’evskaya, Yu. G. 161 Loktev, S. M. 107 Mayer, R. E. 225 Kawata, I. 163 Kumura, E. 156 Mpez, J. A. 101 Mazzone, D. 36 Kawauchi, T. 163 Kunai, A. 43 Mpez, T. 45 McCabe, R. W. 44 Kaziro, R. W. 107 Kunimori, K. 230 L6pez-Gaona, A. 45 McGill, I. R. 85, 144, 154 Keister, J. B. 224 Kupcha, L. A. 42 Lu, z. 102 McGrath, R. 233 Keller, R. C. 222 Kurauchi, T. 164 Lucchesini, A. 159 McKervey, M. A. 163 Kemball, C. 229 Kuriacose, J. C. 158 Lukco, D. B. 84 McLeod, J. E. 99 Kennedy, B. J. 225, 163 Kuriakose, A. K. 38 Lukehart, C. M. 100 McNicholl, R.-A. 81 Kennedy, M. 163 Kuroda, C. 101 Luna, D. 23 1 McPhail, A. T. 100 Kepiliski, L. 43 Kuroda, Y. 43 Luscombe, D. L. 104 McPhail, D. R. 100 Kesmodel, L. L. 229 Kuznetsova, T. I. 225 Lyman, C. E. 44 Meguro, K. 100 Kevan, L. 161 Lyudimov, A. P. 43 Meier, G. H. 24. 164 Khamsi, J. 23 1 L’Argentiere, P. C. 161 Menoufy, M. F. 229 Khan, S. U. M. 39 Laborde, H. 156 Meubus, P. 108 Khare, N. 108 Laconti, A. B. 166 Meyer, H. 110 Khodkevich, S. D. 37 Lahoz, F. J. 101 MacQueen, D. B. 227 Meyer, 0. 102 Kibasova, N. A. 107 Lakshmanan, V . I. 25 Maekawa, H. 235 Michaels, J. N. 101 Kiley, D. M. 110 Lamber, R. 229 Maekawa, T. 130, 235 Michman, M. 232 Kim, G. M. 24 Lambert, R. M. 161 Maeno, Y. 222 Mieth, J. A. 45 Kim, W. S. 223 Lamy, c. 156 Magnoux, P. 160 Mikhailova, A. M. 37 Kim, Y. K. 103 Lang, E. 24 Maguire, A. R. 163 Mikhailova, L. A. 37 Kimura, E. 156 Lange, H. I08 Maguire, J. A. 227 Millet, J. C. 38 Kimura, K. 48, 166 Lapidus, A. L. 105, 161 Maidan, R. 227 Millet, P. 47 King, C. E. 230 Larock, R. C. 232 Maistrenko, V. N. 46 Mills, A. 36 Kira, A. 101 Larreteguy, A. 225 Majumdar, D. 48 Mills, P. L. 232 Kirk, T. 222 Larson, S. L. 39 Majumder, S. A. 39 Milstein, D. 46, 107 Kishimoto, S. 222 Lattes, A. 44 Makie, Y. 161 Milton, D. 36 Kitada, S. 229 Lau, S. S. 109. 234, 235 Malcolme-Lawes, D. J. Minami, M. 101 Kitajima, M. 222 Laudise, R. A. 233 159 Misono, M. I84 Kiwi, J. 158 Le Penven, R. 159 Malherbe, J. B. 99, 223 Mitchell, F. R. G. 24 Kizhakevariam, N. 224 kohier, B. 108 Mallika, C. 233 Mitchell, L. K. 227 Klein, J. D. 100, 110 Lecohier, P. 110 Mallouk, T. E. 80 Mitchell, R. 157 Kleinwachter, V. 235 Lee, c. P. 109 Maloney, C. E. 191 Miura, K.4 41 Klempin, J. 160 Lee, D.-B. 204 Malykh, 0. A. 105 Miura, M. 162, 231 Kniffin, M. L. 222 Lee, D.-D. 104, 159 Mal’chikov, G. D. 100 Miura, N. 130 Knight, L. B. 222 Lee, G. M. 45 Manko, D. J. 163 Miyagi, H. 165 Knobler, C. B. 98 Lee, I.-s. 97 Manoharan, R. 163 Miyahara, Y. 165 KnSzinger, H. 43 Lee, R. G. 228 Mansot, J.-L. I03 Miyama, H. 39 Koch, H. 163 Lees, A. J. 227 Mao, T. F. 229 Miyamura, M. 98 Kochubei, D. I. 41 Leger, J.-M. 156, 159 Marazza, R. 36 Mizukami, F. 231 Kodrat’ev, L. T. 161 Lehn, J.-M. 159 Mari, C. M. 159 Mizukoshi, T. 164 Koel, B. E. 98, 222 Lemke, F. R. 158 Marinas, J. M. 231 Moata, A. 105 Kojima, H. 105 Le6n, B. 109 Marino, F. 36 Moggi, P. 45 Kondo, T. 46, 163 Leroux, F. 38 Marinova, T. S. 229 Mohamed, A. Y. A. 48 Kopinga, K. 99 Lessner, P. 166 Markovit, B. Z. 229 Moiseev, 1. I. 43 Korneeva, G. A. 107 Levason, W. 159 Martin, J. R. 109, 166 Molayem, E. 215 Kosanit, M. M. 158 Lewis, F. A. 81 Martinengo, S. 100 Moller, K. 99 Kostov, K. L. 229 Li, G. 226 Martins, M. E. 157 Moran, G. 103 Kotachi, S. 163 Li, H. 226 Martynova, L. M. 107 Morgenstern, D. A. 158 Kotani, T. 107 Li, N. 226 Masel, R. I. 98 Mori, T. 108, 233 Kounaves, S. P. 131 Li, N. Y. 234 Mashima, K. 232 Morikawa, A. 108 Kovachev, V. T. 166 Li, Z. 227 Mason, R. 36 Morita, M. 37 Kowalski, Z. 40 Li, 2.-M. 230 Masuda, T. 163 Mortreux, A. 45 Kozlov, N. S. 42 Liang, Y. 226 Masumoto, T. 223 Mostafavi, M. 39 Kozlova, G. V. 161 Licci&dello, A. 105 Mathew, J. P. 230 Miiller, H.-J. 103 Kraner, H. W. 227 Lin, C. 109 Matson, L. K. I56 Miiller, L. 225 Kraus, S. 36 Lin, C.4. 106 Matsuda, A. 163 Murahashi, S.4. 46, 162 Krausz, E. 103 Lin, G. H. 225 Matsuda, H. 165 Murakami, T. 23 1 Krebber, U. 110 Lintz. HA. 105 Matsuki, K. 223 Murata, K. 163

Platinum Metals Rev., 1990, 34, (4) 246 Page Page Page Page Murata, S. 23 1 Oro, L. A. 231 Praliaud, H. 230 Saitoh, Y. 161 Murayama, A. 98 Ostrovskii, N. M. 41 Prashad, M. 46 Sakagami, M. 104 Murinov, I. Yu. 46 Otsuka, K. 108, 163, 233 Predieri, G. 45 sakamoto, Y. 155 Murofushi, T. 157 Otterstedt, J.-E. 160 Preston-Thomas, H. 166 Sakurai, K. 37 Musbah, 0. A. 223 Ottolenghi, M. 103 Pretorius, R. 99, 155 Sands, T. 235 Myrick, M. L. 103 Owen, M. D. 100 Primet, M. 160, 228, 230 Sappa, E. 45 Myshenkova, T. N. 161 Ozbalik, N. 23 1 Price, A. 135 Sarangapani, S. 166 O’Dwyer, K. J. 224 Pringle, P. G. 74 Sarma, D. H. R. 100 O’Sullivan, E. J. M. 157 Priyantha, N. 103 Sasaki, K. 43 Nagamoto, H. 37 Procter, R. P. M. 102 Sashikata, K. 155 Nagase, K. 48 Psaro, R. 42 Sathyanarayana, S. 226 Nagase, M. 104 Paccagndla, A. 234 Pudney, P. D. A. 106 Sato, N. 105 Najafi, K. 154 Packham, N. J. C. 225 Pyatnitskii, Yu. I. 43 Sato, S. 102 Nakabayashi, S. 101 Pakhomov, V. P. 101 Satoh, K. 161, 222 Nakagawa, N. 101 Palacios, J. M. 47, 62 Savitskii, E. M. 135 Nakamura, K. 48, 222 Palanisamy, P. 100 Sawa, K. 234 Qi, H. 228 Nakamura, Y. 235 Palumbo, A. C. 99 Sbitnev, V. L. 223 Nakao, Y. 41 Pan, J. 228 Schaeffer, J. 24 Nakato, Y. 38 Papaconstantopoulos, Schmidt, L. D. 41 Nakayasu, S. 107 D. A. 166 Ragimov, K. 0. 101 Schmidt, W. 110 Nakazski, Y. 42 Papadopulos, S. 45 Ragohha, G. A. 105 Schultze, J. W. 102 Neibecker, D. 46 Papunen, H. 214 Ramakrishnan, V. 158 Schulz, G. 155 Nemoto, H. 48 Parera, J. M. 228 Rano, T. A. 23 1 Schulz, K. J. 223 Neubauer, H.-D. 160 Paripatyadar, S. A. 230 Ratajczykowa, I. 42 Schulz-Ekloff, G. 230 Newman, R. C. 102 Parmaliana, A. 105 Razhba, I. A. 110 Schwan, J. A. 45 Nguyen-Du 109 Patiiio, N. E. 225 Real, J. 101 Scott, K. 157 Ni, J. 37 Patzelt, T. 102 Rhu, R. 46 Searson, P. C. 157 Nieuwenhuys, B. E. 98 Paul, D. K. 42, 43 Redwan, D. S. 40 Sekido, S. 40 Nikol’skii, A. B. 226 Paumard, E. 45 Reibenspies, J. 23 1 Seko, T. 48 Nishihara, Y. 165 Pearton, S. J. 165 Reinking, M. K. 37 Selhaoui, N. 36 Nshimura, s. 41 Pedrosa de Jesus, J. D. Remsen, E. E. 232 Sen’kov, F. M. 42 Nitsche, S. 105 48 Ren, D. M. 223 Shah, S. I. 234 Nitta, F. 109 Peled, P. 164 Reznitchenko, V. A. 223 Shaposhnikova, E. R. 37 Niwa, 0. 37 P6rez-Amor, M. 109 Richardson, J. T. 230 Shaprinskaya, T. M. 43 Niwa, S.4. 23 1 Perry, S. D. 157 Rickard, J. M. 105 sharf, v. z. 46 Nizovskii, A. I. 41 Petersen, J. D. 227 Rico, I. 44 Sharinova, N. S. 223 Nodasaka, Y. 156 Petit, F. 45 Ridge, S. J. 47 Sharma, D. 102 Nojima, S. 229 Petr6, J. 229 Riesen, H. 103 Sheu, L.-L. 42, 43 Nojiri, N. 184 Pettit, F. S. 24, 164 Ritchie, F. 233 Shiga, T. 164 Nomura, K. 39 Pfeffer, M. 72 Robertson, N. L. 101 Shimabukuro, M. 104 Nomura, M. 162, 23 1 Pfefferle, L. D. 41, 228 Rodriguez, N. M. 228 Shimizu, T. 229 Nosaka, Y. 39 Phelps, J. C. 45 Ro~~~~uQ-R~~os,I. 106 Shimizu, Y. 104, 233 Novel-Cattin, F. 47 Pieck, C. L. 228 Roewer, G. 36 Shimokawa, S. 235 Noyori, R. 232 PigMhrO, s. 105 Rogin, N. Ya. 100 Shin, S.-C. 99, 165, 234 Pilipenko, A. T. 36 Rond, J. 40 Shindo, Y. 47 Pillai, S. M. 106 Roos, G. H. P. 163 Shinohara, H. 164 Obata, K. 47 Pineri, M. 47 Root, D. I03 Shionoya, M. 156 Ochiai, Y. ping, G. 156 Roslonek, G. 158 Shorikov, Yu. S. 223 48, 76, 99, 165, 234 Pirogova, G. N. 43 Ross, P. 233 Shreve, G. A. 84 Ohmori, T. 156 Pitchon, V. 230 Roux, J. P. 155 Shuh, D. K. 98 Ohnishi, R. 106 Pizzini, S. 159 Rozovskii, A. Ya. 105 Shukla, S. 46, 107 Ohno, E. 166 Pletcher, D. 159 Ruben, G. C. 104 Shulka, A. K. 226 Ohta, T. 232 Podlovchenko, B. I. Rudd, E. J. 227 Shutt, E. 205 Ohtaki, M. 227 225, 226 Rufus, I. B. 158 Siera, J. 98 Ohtsu, S. 161 PolyBnszky, E. 230 Rusakov, I. A. 46 Sieve, M. 155 oka, Y. 98 Pomogailo, A. D. 185 Russell, M. J. H. 143 Smarro, R. 102,226 Okada, A. 164 Pong, W. 103 Ryder, J. 25 Simkovkh, G. 204 Okada, T. 161 Pons, s. 37 Ryndin, Yu. A. 43 Singer, J. 164 Okumoto, H. 107 Popova, N. N. 43 Ryoo, R. 229 Singh, D. 166 Okuno, K. 166 Popovskii, V. V. 41 Sigh, R. P. 40 Oliver, B. M. 156 Porter, J. L. 234 Skrigan, E . A. 42 Oliver, J. A. 229 Portnoy, M. 46, 107 Sabat6, J. 102 Slams-Schwok, A. 103 Olowolafe, J. 0. 222 Potarin, M. M. 107 Sachtler, W. M. H. Slivinskii, E. V. 107 Onishi, T. 23 1 Potente, J. M. 225 42, 43, 162 Smeltzer, W. W. 157 0110, K. 48 Potgieter, J. H. 204 Saffarian, H. 233 Smirkov, S. K. 223 Ormerod, R. M. 161 Praiash, J. 164 Saito, Y. 39, 228 Smith, H. C. 46

Platinum Metals Rev., 1990, 34, (4) 247 Page Page Page Page Smith, M. B. 74 Tapping, 1. 235 Van Den Bergh, H. Witt, A. F. 233 Smith, R. J. 222 Taqui Khan, M. M. 108. 109, 110 Wolcyrz, M. 43 Smolikov, M. D. 41 46, 107. 232 van Koten, G. 72 Wong, C. 44 Snyder, R. L. 234 Tatarchuk, B. J. 106 van Roode, M. 24 woo, s. I. 229 Soma, M. 230 Taylor, J. A. T. 234 Vargaftik, M. N. 43 Worley, S. D. 42. 43 Sominskii, S. D. 161 Taylor, K. C. 206 Vasil’eva, N. A. 223 wu, s. c. 234 Somorjai, G. A. 160 Tazi, T. 162 Vayenas, C. G. 42, 122 Souteyrand, E. 47 Tenhover, M. 84 Vedenyapin, A. A. 225 Spasskaya, E. K. 37 Terunuma, Y. 161 Veletskii, N. I. 226 Spruit, J. H. M. 165 Terzijska, B. M. 166 Velev, 0. 225 xu, Y.4. 106 Sreedharan, 0. M. 233 Thivolle-Cazat, J. 161 Verona, E. 159 Xue, Z. 98, 103 Srinivasan, M. 230 Thomas, J. M. 14 Vershkov, A. V. 100 Srinivasan, s. 163 Thomas, W. 160 Vest, R. W . 100 Stanasiuk, Z. 42 Thompson, D. T. 136 Vethanayagam, T. K. Stasevich, V. P. 43 Thompson, D. A. 157 234 Yagasaki, Y. 98 Steele, D. F. 10 Thompson, F. A. 233 Vieweg, H.-G. 160 Yakimenko, L. M. 37 Steinmeyer, R. H. 156 Ticianelli, E. A. 47 Vilche, J. R. 157 Yamada, E. 235 Stenger, H. G. 44 Tjong, S. C. Villani, R. 45 Yamada, T. 98, 99 Stenin, M. V. 43 99, 101, 223 Visintin, A. 224 Yamagata, S. 101 Stinson, D. G. 234 Toba, M. 23 1 Viswanathan, B. 158 Yamakawa, F. 230 Stonehart, P. 77 Tolstikov, G. A. 46 Vladimirov, B. G. Yamamoto, A. 38 Storey, J. W. V. 165 Tom&, F. 47, 62 38, 101 Yamamoto, Y. 48 Stremsdoerfer, G. Tomashov, N. D. 38 Vork, F. T. A. 157 Yamamura, Y. 40 109.166 Tomashov, N. S. 158 Vos, J. G. 227 Yamanaka, I. Strom-Olsen, J. 0. 155 Tomesch, J. C. 46 VukoviC, M. 158 108, 163, 233 Strouse, M. J. 98 Topalov, A. S. 158 Yamane, H. 232 Struve, E. M. 224 Torii, S. 107 Yamashita, M. 228 Struzhko, v. L. 43 Tonna, A. E. 25 Yamazoe, N. I30 Stumpfl, E. F. 214 Toshima, N. 227 Wada, S. 156 Yang, J. 228 Stytsenko, V. D. 105 Treittinger, B. 235 Wada, Y. 108 Yang, 0. B. 229 Su, Y. K. 234 Tremont, S. J. 232 Wagner, F. E. 225 Yanokura, M. 101 Sugawara, S. 155 Triaca, W. E. 224 Wakabayashi, K. 47 Yassar, A. I56 Sugimoto, N. 48 Trierweiler, H.-P 221 Wakasugi, T. 230 Yasumori, I. 157 Sugimoto, T. 165 Trifir6, F. 205 Wall, M. A. 223 Yates, J. T. 226 Suhr, H. 36 Trost, B. M. 162 Wandt, M. A. E. Yavari, A. R. I55 Sumita Rao, B. 232 Tryk, D. 164 99, 155 Yeager, E. 164 Sunder, W. A. 233 Tsang, C. M. 42 Wang, G.-W. 106 Yen, I.-F. 232 Sundquist, W. I. 166 Tsiakaras, P. 122 Wang, J. 1 02 Yentekakis, I. V. 35, 122 Sdnjevif, D. t. 229 Tsou, Y. 41 Wang, L. C. 234, 235 Ykshe, E. A. 37 Suzuki, N. 38 Tsubomura, H. 38 Wang, R. 227 Yokokawa, T. 235 Suzuki, Y. 165 Tsuchiya, S. 143 Wang, R.-H. 106 Yokoyama, M. 39 Sviridov, V. V. I05 Tsuji, J. 162 Wang, S. 226 Yoshida, M. 222 Swette, L. 164 Tsuji, Y. 46, 163 Wang, X. Z. 235 Yoshino, K. 162 Swiiste, C. H. W. 99 Tsukada. K. 165 Wang, Y. 105 Yoshioka, H. 101 Szustakowski, M. 44 Tsunashima, S. 48 Wani, T. 43 Young, M. L. 228 Tsuruta, N. 161 Wareing, J. R. 46 Yue, L. 25 Tsuzi, E. 164 Watanabe, M. 77, 98 Tsyrul’nikov, P. G. 41 Watanabe, Y. 46, 163 Tabei, H. 37 Tuil6n Blanco, P. 40 Webb, G. 73 Tachibana, H. 40 Turchi, P. E. A. 223 Weeks, S. A. 163 Zagarodnikov, V. P. 43 Takahashi, T. 156 Tyson, D. R. 25 Weir, B. E. 234 Zaikovskii, V. I. 43 Takaishi, N. 162 Weiss, E. 222 Zalavutdinov, R. Kh. 38 Takanashi, K. 98 Wheat, T. A. 38 Zanoni, E. 234 Takaya, H. 232 White, G. E. 156 Zeper, W. B. 165, 234 Takeuchi, S. I08 Uchida, S. 104 White, J. M. 106 Zhai, R.4. 99 Tamaki, J. 130 Uchida, Y. I07 White, R. E. 47 Zhang, J. 228 Tamaru, K. 99 Uchihara, T. 38 Wickham, D. T . 98 Zhang, M.-Z. 230 Tamura, K. 108 Uchijima, T. 230 Wienreb, S. M. 45 Zheng, L. R. 222 Tan, C. B. 40 Uchiyama, S. 48 Wilk, G. D. 222 Zheng, L.-B. 106 Tanaka, A. A. 47 Ueda, K. 38 Wilkins, A. J. J. 16 Zheng, N. 228 Tanaka, K.4. 98 Ueda, M. 23 1 Williams, J. M. 97 Zhilyaev, A. N. 46 Tanghe, S. J. 154 Uehara, Y. 43 Williams, R. S. 98, 103 Zhil’tsova, 0. A. 38 Taniguchi, H. 163 Uflyand. I. E. 185 Willner, I. 227 Zhu, Y. 224 Tanihata, I. 101 Ugo, R. 42 Winterbdtom, J. M. 230 Zielinski, J. 42 Tano, T. 100 Ustinskii, E. N. 158 Winzer, A. 36 Ziessel, R. 159 Tantayanon, S. 46 Uwatoko, Y. 222 Wise, K. D. 154 Zikrina, Z. A. 226

Platinum Metals Rev., 1990, 34, (4) 248 SUBJECT INDEX TO VOLUME 34 a = abstract Page Benzene (conrd.) Page Absorption, H,. in Pd-Cia, thermodynamics, a 155 hydrogenation, a 45, 160, 231 Acetaldehyde, synthesis, in fuel cell, a 233 oxidation, a 43 Acetalisation, alkenes. a 162 in fuel cell, a 108, 233 Acetals, formation, a 43 Benzoic Acid, formation, a 107 Acetophenone, electrohydrogenation, a 225 Benzoquinone, production, a 43 Acetylene, reactions, a 43, 161 Biaryls, synthesis, a 107, 162 Acrylic Acids, asymmetric hydrogenation, a 232 Bismuth, coadsorption on Pt on HCOOH Adsorption, ammethane, on Pt( I11). a 226 oxidation, a 224 CO, on Pd(100)-S, a 99 Book Reviews, 5th Int. Platinum Sym. 214 on Pt/Ti02,methanation sites, a 229 Catalysis or Organic Reactions 143 on Rh, a 223 Catalysis Volume 8 73 C,H,,on Pt, a 98, 229 Handbook of Precious Metals 135 HI, on PtlTiO ,. methanation sites, a 229 New Developments in Selective Oxidation 205 nitrogen oxides, on polycrystalline Pt, a 98 “Platinum 1990” 141 NO, on Rh, a 100 Transition Metal Complexes as Drugs Alcohols, allyl, hydroformylation, and Chemotherapeutic Agents 15 hydrogenation, a 107. 230 Butadiene, reactions, a 105, 160, 184, 230 allylic, asymmetric hydrogenation, a 232 Butane, detector, a 159 benzyl, electrooxidation, a 226 hydrogenolysis, isomerisation, a 229, 228 cyclohexanol. oxidation, dehydrogenation, a 107,228 Butane-1,4401, production, a 107 ethyl, methyl, carbonylation 178 methyl, decomposition, a 42. 161 Cancer, anti-tumour Pt complexes, a 110, 235 synthesis, a 43, 162 book review on drugs 15 catalytic oxidation, NEMCA effect 122 drugs, neutron capture therapy, a 48, 166 electrooxidation, a 156, 225. 226 Capacitors, RuOiionomer composite, a 166 formation from CO,, a 225 Carbapenems, 2-aryl substituted, a 23 1 fuel cell, a 163 Carboannulation, 1,3-dienes, a 232 production, a 46, 162 Carbocycles, production, a 232 propargylic, coupling with aryl halides, a 232 Carbon Oxides, CO, adsorption, sensor 130 on Pt. Pd, a 43, 99. 222, 229 Aldehyde, linear, formation, a 45 adsorption with H2. on Ru/C black, a 45 Aldol, production, a 107 catalytic oxidation 45, 122 Alfonso Cossa, history 215 chemisorptions, a 106. 162, 223, 230 Alkanes, catalytic formation, a 230 detection, a 40,104 dehydrogenation, photochemical, a 39, 227 for aromatic acid synthesis, a 163 hydrogenolysis, a 41, 162 for hydrocarbon synthesis, a 161 oxidation, a 41 for isocyanate production, a 42, 43. 106 production by reductive elimination, a 224 for MeOH synthesis, a 43, 162 Alkanes, n-, reforming, a 160 hydrogenations, a 105, 106 Akenes, acetalisation, a 162 reaction with NH,, a 43 catalytic formation, a 230 reaction with NO,0, , a 105 chlorocarbon addition, a 45 CO , activation by Ir ,(CO) (dmpm) ,, a 37 cyclic, reactions, a 232 cycloaddition to propyne, a 106 from alkanes, a 39, 227 for CH, reforming, a 230 hydroformylation, a 45 for formate photoproduction, a 159 hydrogenation, a 46, 105, 230 methanation, a 44 oxypalladation, a 162 reduction, a 37, 46, 107, 225, 227 production by reductive elimination, a 224 Carbonylation, reactions, a 2, 46. 161, 178, 231, 232 Alkyl Formates, decarbonylation, a 46 Carboxylation, cyclohexane, a 107 Alkylbenzenes, oxydehydrogenation, a 23 1 Carboxylic Acids, formation, a 46 Allylations, asymmetric, of chiral enamines, a 231 hydrogenation, a 162, 232 Allylhenzene, conversion, a 46 Carburisation, Pd/AI2O3,a 43 Amides, formation, a 46 Catalysis, book review 73 Ammonia, isocyanate production, a 42, 43 by tris (hydroxymethyl) phosphine, complexes 74 oxidation plants 47, 62 for organic reactions, book review 143 reaction with CO, a 43 heterogeneous, a 4145,105-106,160-162,228-231 synthesis, catalyst, a 45, 231 homogeneous, a 45-46. 107, 162-163, 231-232 Amorphisation, of AI,R, a 155 industrial, conference 207 Aromatic Acids, synthesis, a 163 phase transfer 2 Aromatisation, naphtha, paraffin, a 41, 160 selective oxidation, conf. review 205 Aryl Chlorides, reactions, a 46, 107, 161, 232 Catalysts, automotive, a 44 Aryl Halides, for carboannulation of 1,3-dienes, a 232 effect of fuel additives 16, 97 Arylations, cyclic alkenes, a 46, 232 history 206 Arylcycloalkenes, production, a 232 new Johnson Matthey plant 71 Arylsulphonyl Chlorides, reactions, a 162, 231 recovery 25 Autocatalysts, contamination by fuel additives 16, 97 electrochemical modification, NEMCA effect 122 recovery of spent, book review 25 EuroF’t-I, dispersion, a 228 Azomethane, photolysis, a 226 for phase transfer reactions 2 gauzes, in NH, oxidation plant 62 Benzaldehyde, production, a 107 Iridium Complex,. IIr(bpy) 2(C’, N’)bpyI’ + in, Benzene, conversion from acetylene, a 161 glass, H2 evolution, a 103 desorption from Pt, a 224 0s-Re, carboxylic acid hydrogenation, a I 62

Platinum MetaLr Rev. 1990, 34, (4), 249-256 249 Catalysts (contd.) Page Catalysts (contd.) Page Palladium Complexes, I, 10-phenanthroline- Pd'+/Pd-Ag+/Ag-H,PO, -.thermodynamics, a 105 Pd + Cu, ester synthesis, a 232 Platinum Complexes, rrans-PtHX(PEt,),-CCI, , for arylations, vinylations, a 232 polymerisation, a 45 Pd cursors, carbonylations, a 23 1 [L,Pt(H)(p-L,)Pt(H)L,l' +,synthesis, a 45 PdCI,(MeCN),, + BiCI, + LiCI, Platinum Metals, cycloolefin, enol ether, acetalisation, a 162 hydrogenation, a 41 PdCI(PhCN), , for biaryls, a 162 Platinum, CH,/C,H6 ignition, a 41 Pd(O), cycloisomerisations, a I62 polycrystalline, CO/NO,CO/O, reaction, a 105 phenyl-phenyl coupling, a 23 1 0, modification, a 42 Pd(0)lHCOOH/W3N, hydrogenolyses, a 107 surface states, a 41 Pd(bis)(diisopropylphosphine) propane, wire, C2H,, CH, oxidations, kinetic data, a 228 carbonylations, a 46 Pt, Pt+RhlAl,O,, hydrothermal treatment, a 160 Pd(dippp), , for aryl chloride formylation, a 107 Pt, Pt-Re, RelNaM, n-heptane Pd(II), oxypalladation, a 162 hydroconversion, a 229 aromatic acid synthesis, a 163 Pt particleslc, coking, morphology, a 228 salts, CO oxidation, a 45 Pt,Pd,Rh,Ru hydrosolslion-exchange resin, Pd(OAc),, double Heck arylation, a 46 cyclohexene hydrogenation, a 41 diene carboannulation, a 232 Pt(RuO,)/TiO,, water photolysis, a 226 cyclohexane carboxylation, a 107 Pt+Re+Crly-Al,O,, surface properties, a 42 Pd(PPhl),, asymmetric allylations, a 231 Pt-AI, oxidation of, activity, a 41 in B-nucleoside synthesis, a 48 Pt-CeO, -Ni, MeOH decomposition, a 42 cyclic vinylidene carbonates, a 232 Pt-RelAl,O,, CI- detection, a 40 Pd,(DBA) .CHCI ,, reforming, metal dispersion, regeneration, a 228 carbapenem formation, a 23 1 moving bed reformer, a 160 (Ph-CH(OH)CH,HgCI)+PdCl,, Pt-RelAl,O,, AI,01-ZMS-5, reforming, styrene oxidation, a 107 S resistance, a 228 Palladium, black, giant clusters, Pt-Rh, in NH, oxidation plant 62 acetal formation, a 43 Ptlacetylene black, in fuel cells, a 108, 233 for electroles Cu deposition, a 110 Ptlacidic suppoft, butadiene hydrogenation, a 160 membrane, cyclohexane dehydrogenation, a 47 PtlAI,O,, chlonnated, isomerisation activity, a 228 modified Ag, a 44 dispersion, a 228 polycrystalline, COlNO,COIO, reaction, a 105 model catalyst, a 105 Pd,Rh,Ru/Al,O, ,SO,,TiO,, isocyanate particle size effects, a 160 production, a 42 with Herionite, n-alkane cracking, a 160 PdCI,, Wacker process, a 44 PtlAI,O,, C, cyclohexanone hydrogenation a 228 PdCI, + CuSO, ISiO, , benzene oxidation, a 43 Pt//3"-AI,O1, C,H, oxidation, NEMCA effect 122 PdO, C,H, to C,H, conversion, a 161 PtlCdS, Pt loading effect, a 38 PdO-PVPlSiO,, alkene hydrogenation, a 230 Pt/H-Mordenite, coking, ageing, a 160 Pd+alkalilSiO,, particle size, H effects, a 230 PtlNafion 117, C,H, electroreduction, a 225 Pd+ColAI,O,,SiO,AI,O,, HC synthesis, a 161 PtlNaY, preparation, Pt distribution, a 229 Pd+K,Cr,O,/C, aryl chloride carbonylation, a 161 PtlNaHY, activity, a 42 Pd+Pt/stainless steel, furnace gas purification, a 229 PtlPVPlmercapto-SiO, gel, activity, a 105 Pd-Bim3520 adsorbing resin, L-sorbose PtlSiO, , dispersion, a 228 oxidation, a 230 PtlSiO, -TiO,, photodeposition, a 103 PdCu, catchment gauze 62 PtlSO,/ZrO,, n-pentane isomerisation, a 229 Pd-Rb-Zr, powder, hydrocarbon conversions, a 230 Ptlsupport, C,H, adsorption, a 229 Pd-Tclsupport, synergism in HC structure effects, a 228 dehydrogenation, a 43 PtiTiO,, H, photoevolution, a 32, 102 Pd-TelC, 1.3-butadiene acetoxylation 184 methanation sites, a 229 Pd/AI,O,, butadiene hydrogenation, a 105, 184 Pt/ultrastable zeolite HY, coking, ageing, a 160 carburisation, H, reduction, a 43 Ptly-Al I 0,, sputtered, a 105 characterisation, by neopentane, a 42 PtlZrO,, CH,, MeOH, C,H, oxidation, poisoning, on styrene hydrogenation, a 161 NEMCA effect 122 Pdla-Al,O,, dialkyl oxalate formation 178 Rhodium, polycrystalline, ethyne hydrogenation, a 161 CO/NO,COIO, reaction, a 105 PdlC, dialkyl carbonate formation 178 Rhodium Complexes, RhCI(CO)(PR,), , for dispersion effects on activity, a 43 alkene dehydrogenation, a 39 H sorbed effects, a 230 RhCI,L,, hydrogenations, a 46 Pd/C fibres, CO/H, reaction, a 105 Rh(II) carboxylates, homochiral, PdlC-THF, aldol synthesis, a 107 C-C bond formation, a I63 Pdlglassy C, microelectroprecipitates, a 225 Rh-phosphole, hydroformylations, a 46 PdlKF, biaryl synthesis, a 107 Rh, (CO) CO hydrogenation, a 163 PdlMgO, SiO,, zeolite-X, +La, MeOH Rhacac(CO,), hydroformylations, a 107 synthesis, a 43, 162 Rh, (CO) quinoline reactions, a 46 Pd/SiO,, NCO movement, a 43 trans-Rh(PMe ,), (CO)Cl, SMSI, a 230 alkane dehydrogenation, a 227 Pdlsupport, structure effects, a 228 Wilkinson's for polybutadiene PdiTiO,, formate, HI production, a 158 hydroformylation, a 232 PdlNaY zeolite, with carbonyl clusters, a 43 (Ph,P),RhCI(I), deuterations, a 163 KPdlY-zeolite, in C,H, polymerisation, a 106 [Rh, (0,CCH, ), 1 + NaBH, , [Rh, (hfacac), - LiPd/Y-zeolite, in C2H, polymerisation, a 106 (H,O) ,I-Ph ,P, allylbenzene NaPdlY, CaPdN zeolites, Pd migration, a 161 conversion, a 46 NaF'dlY-zeolite, in C,H, polymerisation, a 106 Rh complexeslSiO,, Co-No reaction, a 106 Pdlzeolite, chemisorption, neopentane catalysis, a162 RhOJCdSlNa, S, photocatalysts, a 158 PdlZrO,, MeOH decomposition, dispersion, a 161 Rh(acac) ,, in hydrogenolyses, a I62

Platinum Metals Rev., 1990, 34, (4) 250 Catalysts (conrd.) Page Composites (contd.) Page Rh-BINAP, in 1-menthol production 184 SPE-electrocatalysts, in fuel cells, a 47 Rb-Ce/Al,O,, Ce valence, a 44 Conferences, 12th on Catalysis of Organic Reactions, Rh-F’t/SiO, , hydrocarbon hydrogenolysis, a 229 San Antonio, April 1988 143 Rh-V, oxygenate synthesis, a 106 4th Int. Conf. Chem. Plat. Group Metals, 1990 207 RMAIPO,, alkylbenzene oxydehydrogenation, a 231 5th Int. Platinum Sym. 214 RMAI ,0 , , coking, a 44 Cold Fusion, Salt Lake City, March 1990 136 HF impregnated, a 44 First International Fuel Cell Workshop 77 high temperature oxidationlreduction, a 44 Precious and Rare Metal, autocat recovery 25 reactions with CO+H,, a 106 selective oxidation 205 RhlCdS, Rh,S,/CdS, photocatalytic activity, a 158 Copper, determination in urine, a 104 Rh/PVP/mercaptoSiO, gel, activity, a 105 electroless deposition, a 110 RhlSiO,, alkane hydrogenolysis, a 41 film growth on Pt clusters, a 108 highly dispersed, a 44 reaction with PtSi, a 222 structure, activity, a 44 Corrosion, a 164 Rh double oxidcslSiO,, morphology, a 230 alumina on superalloys + Pt, a 164 Rh precursorslpalygorskite, formation, a 231 amorphous Cr-Pt-P alloys 84 RhNbO,/SiO,, hydrogenolysis, a 230 cathodic modification of stainless steel 154 Rhly-Al ,0 , , reforming CH, , a 230 double pressed, sintered stainless steel, a 164 Rh, carbonyl/support, CO, +propyne, a 106 in stainless steel-PGM alloys 85, 144 Ruthenium, resulphidisation effexts, a 106 Pd in oxidised Ti electrodes, a 38 Ruthenium 8omplexes, KIRunl(EDTA-H)CII.- platinised Ti electrodes, NaCl electrodialysis, a 37 2H,O, CO, reduction, a 46, 107 prevention by cathodic modification, 204 K ,[RuCI,l, cyclohexanol in Fe-Cr, hy Pd, Pt, a 99, 164, 223 oxidation+ ferricyanide, a 107 in turbines 24 [Ru(byp),l’+, photophysics, a 103 Rh-Ti, for surgical implants 97 [Ru(bpy),lz+2Cl-, formate, Ru-Cr alloys in HISO,, a 158 photoproduction, a 159 Crystallisation, amorphous Ti-Pd, a 223 RuCl, [PE-PPh,I ,, preparation, reactions, a 45 Crystals, Czochralski, PtMnSb, p-PtSh,, a 233 RuCl, (PPh ,)), N,N‘-diphenylurea, a 163 Cyclic Voltammetry, a 38, 224 RuCl 2-methylnaphthalene-~ oxidation, a 232 Cyclisation, reactions, a 232 Ru(bpy),’+, a 39 Cyclohexane, formation, a 23 1 Ru(0COR), (binap), preparation, reactions, a 41, 47, 107, 230, 233 asymmetric hydrogenations, a 232 Cyclohexanecarhoxylic Acid, a 107 RU3 (CO) 81 -(CH 3) 3 NO.2H 2 0, Cyclohexanol, a 107, 228 decarbonylations, a 46 Cyclohexanone, a 107, 228 [RuX(binap)(arene)lY, preparation, Cyclohexene, hydrogenation, n 41 asymmetric hydrogenations, a 232 Cyclohexylamine, oxidative carbonylation, a 232 IRu(saloph)Cl,I, cyclohexylamine Cyclohexylurethane, formation, a 232 carbonylation, a 232 Cycloisomerisations, enynes, review, a 162 Ru-Cu/SiO, , benzene hydrogenation, a 23 1 Cycloolefins, hydrogenations, a 41 Ru/AI ,0 , , dispersion, a 45 Cyclopentane, hydrogenolysis, a 229 Ru/AI,O,-K, from Ru,(CO),,, a 45 Cyclopentene, arylation, a 46 Ru/C black, for CO-H, co-adsorption, a 45 RulC with oxide promoters, a 106 Decarbonylation, alkyl formates, a 46 RulSiO,, alkane hydrogenolysis, a 41 Dehydrocyclisation, n-heptane, a 42 sol-gel preparation, a 45 Dehydrogenation, alkanes to alkenes, a 227 RdY-zeolite, cation effect in Fischer-Tropsch, a 106 alkylbenzenes, a 23 1 Cells, electrochemical, hydronium cells, a 38 cyclic hydrocarbons, synergism in, a 43 electrowinning, a 226 cyclohexane, a 41, 47, 230 galvanic, emf, a 233 cyclohexanol, a 228 photoelectrochemical, a 226 Depolarisers, concentration measuring, a 40 secondary, a 226 Detectors, alcohol 130 solid state DC ECL, a 39 CO, using SnO,, a 40,104 thermoelectrochemical, a 102 Cu in urine, a 104 YSZ electochemical, 0 exchange kinetics, a 37, 101 DNA, a 105 Chemical Vapour Deposition, a 36, 98, 103 electrical conductivity, a 104 Chemisorptions, a 106, 162, 223, 230 food testing 24 Chloralkali, electrolysis, cathode for, a 38 for CI- sensing in Pt-RelAl ,0 ,, a 40 Chloride, ion detection in Pt-Re/Al,O,, a 40 Hg in H,O, a 104 Chlorine, electrochemical evolution, a 156, 225 humidity, a 104 Chlorobenzene, formylation, a 107 imaging single molecules, a 104 Chromium Alloys, Cr-Pt-P, corrosion resistant 84 NMR, high temperature, a 235 Cisplatin 15, 235 0,.in physiological media 181 Clusters, linear, conference 207 Pd,Si for high energy physics, a 227 Coal, direct gasification 35 pH, a 40, 159, 165 Coatings, for superalloys, a 164 SO,, a 159 0s-Re-W, on thermionic coatings 191 stoichiometric composition of flame, a 40 Pd on metal hydrides 142 temperature, a 40, 110, 166, 235 Pt for turbine components 24 thermal neutrons, u 225 Coking, in Pt/C particles, a 228 Deuterium, in Pd, Ti, a 101, 222 Rh/Al,O,, S effect, a 44 Diacetoxylation, 1.3-butadiene 184 Cold Fusion, 101, 136, 225 Dialkyl Carbonates, formation 178 see also Solid State Fusion Dialkyl Oxalates, formation 178 Colloids, Ru, for CO, reduction, a 227 Diarylcyclopentenes, synthesis, a 46 Composites, AI-Pt cold rolled, a 155 a-Diazoketones, C-C bond formation, a I63

platinum Metals Rev., 1990,34, (4) 25 1 Page Electrodes (contd.) Page Dienes, 1,3-, carboannulation, a 232 in electrical conductivity monitor, a 104 Dienes, 1,4, cyclic, production, a 232 in fuel cells, a 163, 233 Diodes, a-Si:H/Pt, a 109 in humidity sensor, a 104 Pt-Pdp-CaFe, 0,. a 109 in solar cells, a 38, 102, I08 Pt-PdlRhlp-CaFe,O, , a 109 in solid electrolyte, a 37, 38 Diols, for alkenes acetalisation, a 162 in YSZ cells, a 101 N,N'-Diphenylurea, synthesis, a 163 organic waste destruction 10 DNA, action of Pt anti-tumour complexes, a 166, 235 smooth, benzene desorption, a 224 imaging, a 104 surface morphology changes, a 224 probe with Ru, a I05 Pt, activated, pH response, a 40 Pt, methylene green modified, E300 ZGS Rh-Pt, a 233 haemoglobin redox reaction, a 224 Electrical Conductivity, monitor, a 104 Pt, platinised Pt, porosity effects, a 225 Electrical Contacts, Au/Ge, -Pd,Pt/n-GaAs. ohmic, a 109 Pt black C-PTFE, in H3P0, fuel cells, a 47 AulPdlZnlPdlp-InP, a 109 Pt black-Teflon, in PEM cell, a 47 AulPtlTi to p-1nGaAs.n-InP, a 234 Pt disk microelectrodes, for Cu in urine, a 104 Pd low resistance ohmic, a 166 Pt foil + In + Pb, Au, MeOH oxidation, a 156 Pd-Ag, Pd oxide formation, a 234 Pt microelectrodes, 0 reduction kinetics, a 101 Pd-In, -Au/n-GaAs, ohmic, a 109, 235 Pt modified copolymer, H,, HCOOH, MeOH, Pd/Ge ohmic, in MESFETs, a 234 oxidations, a 156 WTi ohmic, to pGaAs, C doped, a 165 Pt + RulPTFElC, MeOH oxidation, a 225 Electrical Resistivity, D in Pd, Ti, a 222 Pt-polymer, 0, reduction, a 157 Electrocheduminence, in solid-state cell, a 39 Pt-Ru, fuel cell catalyst, a 108 Electrochemistry, a 37-38, 101, 156-158, 224-226 Ptlglass conducting polymer, a 164 Electrodeposition, a 103, 159, 227 WNafion 117, film morphology, a 225 Ag on 0s polymer-C, a 227 PtlNafionlglassy C, glucose enzyme sensor, a 40 Ag-Pd, pulse-plating, a 40 PtlNilp-Si, water photosplitting, a 39 electroless, 0s. Ru, Cu 70, 90, 110, 166 RIPTFEIC, deactivation, a 225 electroless codeposition, Pd, In. Au, a 109 p-SilSi0,lPd. HI photoproduction. a I03 Ir3+ on C fibre, a 226 Rh, RhlPt, porosity effect on gas evolution, a 225 Pd, on polymer filmslglassy C electrodes, a 157 Ru cyanidelglassy C, hydrazine detection, a 102 on vitreous C, a 159 Ru modifiedlPt, C, stability, a 226 Pd, Pt, on stainless steel, a 229 Ru pyrochlore. in fuel cell. a 164 Pd, Pt, spontaneous, on stainless steel RuO; + TiO,, MeOH production, a 225 support, furnace gas purification, a 229 Ru(bpy) +/Nafion/TiO, , a 39 Pt, a 159 IOs(bipy),(PVP) ,,CIICI/Ag/C, a 227 pulse plating, a 40 Electrolysis, chloralkali, a 38 Electrodes, anodes, CdS, CdSe, H,O for H, production, a 47 polymer-coated + RuO,, HI splitting, a 40 KOH, by Pt cathodes, HER, a 37 electroplating, a 227 Electrolytes, solid, with Pt electrodes, a 37

110,-PANlTi, Zn electrowinning, a 226 (CF,SO,),CH,. in fuel cell. a 233~~ ~ Pt, in fuel cells, a 163 Electroplating, high speed, anodes, a 227 Pt, CI, evolution, a 156 Electrowinning, Zn, IrO-PANlTi electrode for, a 226 Pt-Ru, MeOH oxidation, a 225 Emission Control, autocatalyst contamination 16, 97 Ptlporous C, in MeOH fuel cell, a 163 autocatalyst recovery, symposium 25 cathodes, H-permeable, automotive catalysts 206 Pd blacWPdlAgNlPd-CulNaINaH, a 108 new autocatalyst plant 71 Pd, in cold fusion, a 225 Enamides, asymmetric hydrogenation, a 232 Pd blacklgraphite, in fuel cell, a 233 Enamines, chiral, asymmetric allylations, a 23 1 Pt, in ECL cell, a 39 Energy, solar, conversion, systems, a 32, 102. 108, 158 Pt pure, Fe effect on HER, a 37 Enynes, cycloisomerisation, a 162 Pt-W,CH! polymerisation, a 108 Epoxyketone, a, 0-, hydrogenolysis, a 107 RuO,lNi, in chloralkali cell, a 38 Esters, a 46, 107, 232 composite polynuclear films, a 158 Ethane, reactions, a 41, 228, 230 fuel cells, a 47, 80 Ethanol, see Alcohols, ethyl interdigitated array, Pt, a 37 Ethers, cyclic enol, hydrogenations, a 41 Ir aggregates on doped SnO, , electrochemistry. a 39 Ethylbenzene, catalyst poisoning in production, a 161 Ir oxide film, neural prostheses 154 Ethylene, adsorption on PI, a 98, 229 Ir-Pb pyrochlore, a 226 catalytic oxidation, NEMCA effect 42, 122 IrK, activities, a 226 electroreduction, electrode morphology, a 225 Ir/Hg, film, depolariser concentration, a 40 oxidation, in fuel cell, a 233 ultramicroelectrodes 131 polymerisation, a 106 WTi, a 158 Ethyne, hydrogenation, a 161 NaPtO, rechargeable alkaline fuel cell, a 164 E.E.C., emission control 16, 97 Pd, in cold fusion, a 101 organopalladium chemistry project 72 Pd, Ir, filmlglassy C, H,O, reduction, a 38 Pd-Ti, corrosion in acids, a 101 Faraday Lecture, 1989, Pt history 14 Pdpolymer filmslglassy C, a 157 Films, CulPt, growth, a 108 Pd in oxidised Ti, corrosion electrochemistry, a 38 Ir, for laser writing, a I10 photoanodes, a 47, 226 multilayers 48, 76, 98. 99 platinised Ti, corrosion in NaCl electrodialysis, a 37 Pt, porous, in coal gasification plant 35 glyoxylic acid synthesis, a 157 Pt as substrate for a-Si:H, a 109 Pt, biomimetic machine, a 164 PtAs,, formation on GaAs. a 222 CO, reduction in CHjCN. a 37 Fiseher-Tropsch, a 106 hydrous oxide growth, a 224 Food, testing meter 24

Platinum Metals Rev., 1990, 34, (4) 252 Page Page Formaldehyde, production, decomposition, a 44.46, 107 Hydrogen Peroxide, production, via fuel cell, a 163 Formanilide, reaction with aniline, a 163 reduction, a 38 Formate, photochemical generation, a 158, 159 Hydrogenation, alkenes, a 46, 105, 230 Formic Acid, formation, decomposition, a 46, 107 allyl alcohol, on Pd/C, H effects, a 230 oxidations, on Pt(100) + Bi, a 156, 224, 226 allylbenzene, a 46 Formylation, aryl chlorides, a I07 asymmetric, enamides, acrylic acids, Fuel Cells, a 47, 108, 163-164, 233 carboxylic acids, alcohols, a 232 alkaline, a 164 benzene, a 45, 160, 231 First International Workshop, Tokio 77 butadienes, a 105, 160 for ethylene oxidation, a 233 buta-l.3-diene. oct-I-yne, a 230 Grove Symposium 80 carboxylic acids, a 162 H201,a 233 CO, a 43, 105, 106, 163, 229 in coal gasification 35 cyclohexanone, a 228 MeOH, a 108, 163 cyclohexene, a 41 phosphoric acid, a 233 cycloolefins, cyclic enol ethers, a 41 SPE, low Pt loadings, a 163 CIH,, vinylacetylene, a 43 thin film device 80 ethyne, a 161 world review 26 I-hexene, a 23 1 Furnace, Pt lined graphite, a 104 isoquinolines, quinolines, a 46 styrene, a 161 Gas Turbines, protective coatings 24 Hydrogenolysis, alkanes, a 41, 162 Gauzes, in NHI oxidation plant 47, 62 a,fi-epoxyketone, esters, a 107 Geology, 5th Int. Platinum Sym. 214 ethane, a 230 Glass, Pb borosilicate + A1,03, RuO, solubility, a 100 hydrocarbons, a 229 Glass, a 233 n-pentane, a 230 Glasses, metallic, Pd,,,Ni,Pm, relaxation, a 155 Hydronium Cells, a 38 Glucose, enzyme electrode, a 40 Clyoxylic Acid, synthesis, a 157 International Temperature Scale-1990, a 166 Grove Fuel Cell Symposium 80 Ion Beam Mixing, on Pt-Fe alloys, a 157 Ion Chromatography, for CI- detection, a 40 Haemoglobin, cyclic voltammetry on Pt, a 224 Iridium, electrodeposition on C fibre, a 226 Helium, release from PdT., a 156 for HIphotoevolution, a 103 Heptane, n-, reactions, a 42, 228, 229 in Ir-Hg film electrodes, a 40 Heterocycles, production, a 232 in Ir-SnO, electrodes, a 39 Hexane, reactions, a 43, 162 in Ir/Ti electrode, a 158 Hexene, 1-, hydroformylation, hydrogenation, a 46, 23 1 in Pd film/glassy C electrode, a 38 History, Alfonso Cossa and Pt salts 215 in ultramicroelectrodes 131 Faraday Lecture 14 Ir/GaAs interfacial reactions, a 223 Humidity, sensor, a 104 laser writing, a 110 Hydrazine, detection, by Ru cyanidelglassy C Pb-Ir pymhlore, air electrode catalyst, a 226 electrodes, a 102 Iridium Alloys, Ir-Al, oxidation, a I56 Hydrides, for H storage 142 Iridium Complexes, lr,(CO)3(dmpm),, fast 0 Hydracarbons, conversions, a 230 transfer, u 37 dehydrogenation, catalyst synergism, a 43 macromolecular chelates 185 hydrogenolysis, a 229 [~WH3),Hlol(C1Od1,a 100 synthesis, a 161 Iridium Oxide, IrO,-PAN/Ti anodes, properties, a 226 Hydroconversion, n-heptane, on Pt, Re, SIROFs, on wires, planes, morphdogy, a 100 Pt-Re/NaM catalysts, a 229 Iron, impurity in Pt cathodes, a 37 Hydroformylation, I-hexene, a 46 ISFET, Pt-PtO,pH microsensor, a 165 alkene, a 45 Isocyanate, catalytic production, a 42, 43, 106 allyl alcohol, a 107 movement on Pd/SiO, , a 43 polybutadiene, a 232 Isomerisation, allylbenzene, a 46 Hydrogen, absorption, in Pd-Gd, a 155 n-butane, a 228 adsorption with CO, a 45, 229 n-pentane, a 229 chemisorption, a 106, 162 ITS-90, a 235 detector, a 159 electrooxidation, on Pt modified copolymer Johnson Matthey, Brussels autocatalyst plant 71 electrode, a 156 “Platinum 1990” 141 evolution, electrode porosity effect, a 225 from Pd/glassy C microdeposits, a 225 Kerr Rotation Spectra, a 165 for CO, reduction, a 107 KharPseh Reactions, on RuCI,[PE-PPh2I1, (I 45 for hydrocarbon synthesis, a 161 formation from alkanes, a 39 Lanthanum, a 162 from bacteria, permeation, a 157 hrWriting, a 109, 110 HER, on pure Pt cathodes, in KOH, a 37 Lead, contamination of autocatalysts 16, 97 H/D exchange reactions, benzene on Pt, u 224 Luminescence, Pd(II) porphyrins, for O2 detection 181 in-Pd-rare earth alloy system 81 in [Ru(bpy),@P~-d~)~-~l’+,a 103 MeOH synthesis, on Pdsupport, a 43 GSorbose, oxidauon, a 230 photoevolution, a 38. 102, 103, 158 production, from Rh complexes, a 227 Magnetism, a 165 via NdNaH, a 108 behaviour of F’tMnSblCuMnSb films, a 98 solubility in PdaAg,, a 222 CoIPd.-- --. a-- 99 sorption, effects on PdC, a 230 in thin films, a 234 storage, on metal hydrides 142 perpendicular magnetic anisotropy, in Hydrogen Fluoride, impregnated Rh/Al,O,, a 44 magneto-oplical thin films, a 48, 99

Platinum Metals Rev., 1990,34, (4) 253 Page Oxidation (contd.) Page Magneto-optics 48, 76, 99, 165, 234 MeOH, HCOOH, on WC, a 226 Manganese, contamination of autocatalysts 16, 97 MeOH, HCOOH, HI, a 156 Medical, blood activating factor inhibitors, a 232 methane, a 228 book review 15 methylnaphthalene, a 232 conference 207 olefins, Wacker process, a 44 Cu determination in urine, a 104 organochlorines 180 Ir oxide neural electrodes 154 styrene, a 107 physiological 0, detection 181 Oxygen, atom, transfer by Ir carbonate complex, a 37 Pt anti-cancer drugs, review, a 166 detection, in physiological media 181 surgical implants 97 electroreductions, a 101, 102 Medical, a 48, 110, 166, 235 evolution on Rh oxide films, a 157 Membranes, Pd, Pt, reactions, a 47, 225 exchange on Pt electrodes, in YSZ cell, a 101 GMenthol, production 184 reduction, at Pt-polypyrrole electrodes, a 157 Mercury, determination, a 104 in PEM cell, a 47 Methanation, C02,a 44 Oxygenates, synthesis, a 106 Methane, catalytic oxidation, NEMCA effect 122 Oxypalladation, alkenes, a 162 ignition at C,H, boundary on Pt, a 41 oxidation, a 160, 228 Palladium, carbonyl clusters, in NaY zeolites, a 43 polymerisation, a 108 carbonyl phosphine clusters, synthesis, a 224 production from CO, reduction, a 227 cathodes, in cold fusion studies, a 225 reforming by CO,, a 230 CePdIn, specific heat, a 222 Methanol, see Alcohols, methyl clusters, growth, reduction, in zeolite Y, a 99 Methyl Esters, a 161, 163 coatings on metal hydrides 142 Methyl Methacrylate, polymerisation, a 45 D in, electrical resistivity, a 222 Methylcydopentane, hydrogenolysis, a 162 foil, H permeation from bacteria, a 157 Methylnaphthalenes, oxidation, reforming, a 44, 232 in alcohol sensor 130 Methylnaphthaquinone, formation, a 232 in bifunctional membrane reactor, a I65 Microelectronics, a 108, 109, 110 in butane, pH detectors, a 159 Mineralogy, 5th Int. Platinum Sym. 214 in contacts, a 109, 234 Morphology, porous Pt electrodes, a 38 in corrosion prevention, review 204 Pt particle, in reforming catalysts, a 228 in diodes, a 109 Pt-Hf oxides, a 36 in doped SnO ,, for CO detection, a 40 in electroless Cu deposition, a 110 Naphtha, aromatisation, a 160 in Fe-24Cr, Fe-rlOCr, a 99, 101, 155, 223 NEMCA 122 in flame composition detector, a 40 Neopentane, conversion, a 162 in Ir filmlglassy C electrode, a 38 for Pd/AI,O, characterisation, a 42 in magneto-optical thin films, a 48, 76, 99, 165 Neutrons, thermal detection system, a 225 in ohmic contacts, a 109, 166, 234, 235 Neutron-Capture Therapy, cancer treatment, a 48 in thermocouples, a 159 Nitrogen Oxides, NO, adsorption on Pt-Rh(IOO), a 98 LiPdH., superconductor, a 166 catalytic reduction by CO, a 105 membrane, cyclohexane dehydrogenation, a 47 C2H, to C,H, conversion, a 161 microprecipitateslglassy C, properties, a 225 isocyanate formation, a 106 Pd thin films/Ta, CO adsorption, a 222 reactions on Rh, a 100 PdCH,, IMPdCH,,Pd'lCHI, ESR, a 222 Nitrogen Oxides, adsorption on polycrystalline Pt, a 98 Pd( 100)-S, CO adsorption, a 99 Non-Faradaic Modification of Catalytic Activity 122 Pd-H system 81 Pd-polymer/C electrodes, a I57 Olefins, oxidation, Wacker Process, a 44 Pt-Ti compounds, enthalpies of formation, a 36 Organic Industrial Waste, destruction 10, 180 Pd/Co, magneto-optics 48, 76, 99, 165, 234 Osmium, electroless deposition 70 Pdln-GaSb, Schottky contacts, a 234 Osmium Alloys, 0s-Rh-W, thermionic emission 191 Pd+, in TiO, films, electrocatalysis, a 102 Osmium Complexes, in polynuclear films, a 158 plating baths, a 159, 166, 229 macromolecular chelates 185 sols, a 39, loo Oxidation, alkanes, a 41 Te0,-Pd thin films, optical recording media, a 166 ammonia, industrial plant 62 Palladium Alloys, Pd-Ag, H solubility in, a 222 benzene, a 43 pulse-plating, a 40 cyclohexane, in fuel cell, a 108 Pd-Au, reactivity with superconductors, a 234 benzyl alcohol, a 226 Pd-Cu, gauzes, in NH, oxidation plant, a 47 by phase transfer catalysis 2 Pd-Gd, H, absorption in, a 155 CO, by Pd(II) catalyst, a 45 Pd-Ni-P, mechanical alloying, a 223 CO, propane, xylene, propene, a 160 Pd-Ni-P glass, structural relaxation, a 155 cyclic, of superalloys, a 164 Pd-Rare Earths-H, miscibility gap 81 cyclohexanol, a 107 Pd-Te, phase relations 223 ethane, on Pt wire, a 228 Pd-Ti, phase studies, a 223 ethylene, in a fuel cell, a 233 Pd-U-Si, phases, a 36 ethylene, on modified Pt, a 42 Pd-W-Cr-Mo, oxidation resistance 204 Fe-24Cr. prevention by Pd, a 223 Palladium Complexes, effect on Ag halide HCOOH, on Pt(100)+Bi, a 224 photography, a 36 high temperature, IrAI, a 156 K,PdH,, a 156 Pt-Cu, a 155 macromolecular chelates 185 Pt-Hf, a 36 organopalladium studies 72 resistance, of Pd-W-Cr-Mo, a 204 Pd porphyrins, for physiological 0 , detection 18 1 L-sorbose, on Pd-Bi/D3520 adsorbing resin, a 230 tris(hydroxymethy1)phosphine 74 MeOH, electrode deactivation, a 225 [Pd(CNMe),l.+, photoreduction, a 158 on Pt-In-Pb,Au foil electrodes, a 156 Palladium Silicides, in high energy physics, a 227

Platinum Metals Rev., 1990, 34, (4) 254 Palladium Silicides (conrd.) Page Platinum (conrd.) Page Pd,Si formation, a 155 thin films, a 36, 98, 164, 166 thin films/Si(m), growth, a 156 wire, in high temperature NMR probe, a 235 Palladium Tritide, He release from, a 156 (2xI)Pt(llO), C,H4 adsorption, a 98 Paraffin, aromatisation, a 41 “Platinum 1990’’ 141 Pentane, reactions, a 229 Platinum Alloys, Cr-Pt-P, corrosion resistant 84 Phase Changes, Pd-Ni-P, glass transition, a 223 Pt4Cu. oxidation, a 155 Pd-Te system, a 223 Pt-Fe, ion beam mixed, a 157 Pd-Ti, a 223 Pt-Hf oxides, morphology, a 36 Pd-U-Si, a 36 Pt-Rh(100). NO, NO + H adsorption, a 98 Phase Diagrams, Fe-Rh-S, a 223 Pt-Ru, anodes, for MeOH oxidation, a 225 Phase Transfer Catalysis 2 ZGS-Pt, a 233 Phenol, production, a 43, 108 Platinum Complexes, anti-cancer, a 110, 166, 235 Phenyl, coupling, in triphenylantimony, a 23 1 macromolecular chelates 185 Phosphine Metal Complexes, for catalysis 74 Pt salts, history 215 Phosphorescence, in Pd(II) porphyrins, for 0, tris(hydroxymethy1)phosphine 74 detection 181 (qs-MeCp)PtMe,, for Pt deposition, a 98 Phosphoric Acid Fuel Cells, electrodes in, a 47 IF’t(NH 1)j OHI(CIO4) 3. u 100 Phosphorus, contamination of autocatalysts 16, 97 Platinum Metals, conference 207 Phot~talysis,u 3840, 102-103, 158-159, 226-227 macromolecular chelates 185 Photoelectrochemid Cells, a 39 stainless steel alloys 85, 144, 154

Photoeraohv. effect of Pd. Zn ions on AeI halides. a 36 Platinum SiliciQs, a 155, 165 Photohsis, i‘ 226 in Schottky diodes, a 109 Plating Baths, Pd, a 159, 166, 229 PtSi, reaction with Cu, a 222 Pt, a 229 Poisoning, Pd/AI,O,, on styrene hydrogenation, a 161 Ru, a 166 Pollution Control, aqueous sulphide, a 158 Platinum, 5th Int. Sym. 214 autocatalyst contamination 16, 97 additions to aluminide coatings, a 164 hy autocatalysts 206 anti-cancer drugs, a 15, 166 furnace gas purification catalyst, a 229 as a-Si:H diode substrate, a 109 new autocatalyst plant 71 carbonyl phosphine clusters, synthesis, a 224 organic waste destruction 10, 180 clustersllines of Cu film, a 108 Polybutadiene, hydroformylation, a 232 coatings for gas turbines 24 Polymer Gels, a 164 compounds, AI,Pt, amorphisation, a 155 Polymerisations, methyl methacrylate, CePtIn, specific heat, a 222 C2H4, CH4, a 45, 106, 108 PtAs, , fim formation, a 222 Polymers, from Pt macromolecular chelates 185 PtGa,, CVD, a 103 Powders, Bi,Ru,O,, formation, a 223 Pt,Si formation at Si/h interface, a 99 Pd-Ni-P, glass transition, a 223 CoNiPt films, a 98 Presulphidisation, effects on Ru catalysts, a 106 CVD, for laser writing, a 109 Promoters, alkali nitrates to Pd, Ru catalysts, a 230, 231 effects on photmtalysts, a 38, 39 La, for Pd catalysts, a 162 electrodes, a 37, 38, 40, 104, 224, 225 CeO,, VO,, MgO, effects on RuK, a 106 Faraday Lecture 14 Propane, hydrogenolysis, a 229 Fe hydroxide layers/Pt, redox processes, a 157 Propyne, CO, addition, a 106 films, discontinuous, on photoanodes, a 47 Pumping, O’+ onto Pt, a 42 in coal gasification plant 35 Pyridine, in catalyst poisoning, a 161 on n-Si photoanodes, a 226 Pyrone, formation, a 106 high temperature plating, a 159 in corrosion prevention, review 204 Quinolines, Isoquinolines, hydrogenation, a 46 in diodes, a 109 in electrical contacts, a 234 Reactors, Pd membrane, a 165 in fuel cells, a 47, 80, 108, 233 Recording Materials 48, 76, 98, 99, 108, 109 in glass industry, a 233 Red List, toxic chemicals 10 in humidity sensor, a 104 Reduction, by phase transfer catalysis 2 in ohmic contacts, a 109 CO,, by Ru complex, a 107, 227 in pH microsensor, a 165 C,H4, electrode morphology, a 225 in photocatalysis, a 38, 39, 102, 103 Pd in Y-zeolite, a 99 in SnO,.l, CO sensitive, a 104 Rh(III) chloride, a 221 in SO, sensor, a 159 Reforming, I-methylnaphthalene, catalyst coking, a 44 in TEM for imaging molecules, a 104 methane, a 230 lining in furnace, a 104 n-heptane, a 228 0 electroreactions on, a 101 Resistance Thermometers, a 110, 166, 235 plating bath, for stainless steel, a 229 Resistors, RuO, effect, a 100 polycrystalline, NO, NO, adsorption, a 98 Reviews, cathodically modified alloys 204 PtMnSb, for crystal growth, a 233 Japanese catalyst technology 184 hMnSb/CuMnSh films, anomalous Pd-catalysed cycloisomerisation, a I62 magnetisation, a 98 Pt anti-cancer drug action, a 166 Pt(l00) + Bi, adsorption studies, a 224 Rhenium, effect on Pt catalysts, a 42 Pt( 11 I) surface, STM, a 155 Rhodium, CO adsorption on, a 223 Pt + Ru, MeOH oxidation, a 225 electrode porosity, a 225 Pt-A1 thin films, thermal stability, a 222 in diodes, a 109 Pt-H bond, addition to C=C bond, a 100 in surgical implants 97 Pt-Sic system, a 155 NO reactions, a 100 Pt/Co, magneto-optics 48, 76, 165, 234 Rh-Fe-S phase diagram, a 223 recovery in NH, oxidation plant, a 47 Rh,O,, for CO, reduction, a 225 resistance thermometers, a 235 ultrafine particle dispersions, a 227

Platinum Metals Rev., 1990, 34, (4) 255 Page Structure (conrd.) Page Rhodium Alloys, Pt-Rh(100). NO, NO + H Pt-Hf oxides, a 36 adsorption, a 98 Styrene, reactions, a 107, 161 ternary and complex, mechanical pmperties 192 Sulphur, catalyst resistance, catalyst effects, a 44, 228 Rhodium Chloride, photoreduction, a 227 Superalloys, protective coatings 24, 164 Rhodium Complexes, formation with azo Superconductors, LiPdH,, a 166 compounds, a 36 reactivity with Pd alloys, a 234 macromolecular chelates 185 Surface Science, Pt catalyst, a 41, 42 NMe,lRh(ox)(CO),l, preparation, anisotropy, a 101 Synerpism, in Pd-Tclsupport catalysts, a 43 RhH,(FPh,),L+, photophysics, chemistry, a 227 Synthesis Gas, for ethylene glycol formation, a 163 rrm-Rh(PMe,), (CO)Cl, photochemical for hydrocarbon synthesis, a 161 dehydrogenation, a 227 production, a 42 (q'-CsH ,)Rh(CO) ,, photochemistry, a 227 reaction with small Rh particles, a 106 [RhCl,(nicH+)Il(PF,),, bacterial activity, a 48 IRh(NH3) JHzOI(CIO,), v a 100 Tellurium, TeO, +Pd, optical recording media, a 48 [Rh,C(CO) ,,(Au, (PPh ,),}I, preparation, Temperature Measurement, a 110, 159, 166. 235 structure, a 100 Temperature We, 13.8033 K - 961.78"C. a 166 Ruthenium, Bi-Ru-0 powder formation. a 223 Tetramethylbutane, hydrogenolysis, a I 62 carbonyl compounds, a 224 Thermocouples, for thermopile, a I59 colloids, for CO,reduction, a 227 Pt-Pt(Rh), in NMR detector, a 235 electroless deposition, a 166 Thermopile, a I59 in capacitors, a 166 Thick Films, Pdly-Fe,O,, for butane sensor, a 159 P~,RU~O~,~,for 0 reduction electrodes, a 164 Rh oxide, hydrous, for 0,evolution, a 157 Ru+, in TiO, films, electrocatalysis, a 102 Ru polypyrrole, electrode modifiers, a 226 Ruthenium Alloys, Fe-Cr-Ru, passivation, a 102 Thin Films, conference 207 Ru-Cr, corrosion in H,SO,, a 158 CoNiPt, a 98 Ruthenium Complexes, cis-Ru(bipy) ,CI for DNA FeO, PdO, in Fe-40Cr-Pd, n 99 pbe, a 105 FeTbCo, + Pt, Zr, magneto-optics. a 48 in polynuclear films on electrodes, a 158 in Pt resistance thermometers, in high magnetic macromolecular chelates 185 fields. a 166

R~(~PY)3 + 9 ECL, a 39 Ir oxide, morphology, a 110 in H20photoreduction, a 39 Ir/GaAs, a 223 (~L-H),Ru,~,-CX)(CO),, eliminations, a 224 0s 70 IRu(bpy),NOOHI'+, reactions, a 226 Pd/Co, multilayers, magneto-optics, a 99, 234 IRu(bpy)&py-d,), -.I2 +,luminescence, a 103 Pt/Co, magneto-optics 76, 99, 165 IRu(Mebpy),Bz)ln+, photo roperties, a 39 Pt/Co, PtMnSb. perpendicular magnetic lRuu(bpy),(bpy-cycly)NiR I+, a 156 anisotropy. a 48 [RulO(OOCCHl),L, , electrode modifiers, a 226 PdlCu, on thermopile, a 159 Ruthenium Oxides, RuO,, for CO, reduction, a 225 PdllnP, n 166 standard Gibbs energy of formation, a 233 Pd/Ta(llO), CO adsorption, a 222 solubility, in F'b borosilicate glass+Al,O,, a100 Pd,Si/Si(III), observations, a 156 RuO,.xH,O, thermal studies, a 36 polypyrrole/Pt/glass, a 164 RuO,/Ni, cathode in chloralkali cell, a 38 Pt, by CVD, a 36. 98 Pt, on photoanodes, a 47 Schottky Barrier Diodg, a 109, 165 PtGa,, CVD, a 103 Schottky Contacts, Pdln-GaSb, properties, a 234 PtMnSblCuMnSb, anomalous magnetisation, a 98 Semieonduetors, ISFET, a 165 Pt-AI, thermal stability, a 222 MESFETs, a 234 Pt-C, ultrathin, for TEM imaging, a 104 P-PtSb,, a 233 Pt-SnO, -,, CO sensitive, a 104 sensors, see Detectors Pt/Co, multilayers, magneto-optics, a 234 Silver, electrodeposition, Pd/Co, ultrathin, on C-IOs(bipy)2(PVP),,ClICI,a 227 for magneto-optics, a 48, 76, 165 SIROFs, morphology, a 100, 110 WFe-24Cr. PtIFeCr-Y, high temperature SMSI, on Pd/SiP, , a 230 oxidation, a 164 Solar Cells, electrodes, a 38 WSi, Pt,Si formation, a 99 sdpr Energy, conversion, storage, a 102, 108 Ru polypyrrole, electrode modifiers, a 226 Solid State Fusion, 136, 225 SIROFs, morphology, a 100 see also Cold Fusion TeO, +Pd, optical recording media, a 48 Sols, for Ru/SiO, catalyst preparation, a 45 Te0,-Pd, crystallisation speeds, a 166 Ni-Pd, for photoreduction of H,O, n 39 TiO, + Pd+, Ru+, electrocatalytic activity, a 102 organopalladium, a 100 Thiophene, in catalyst poisoning, a 161 Pt, Pd, Rh, Ru colloids/ion-exchange resin, a 41 Transistors, ISFET, MESFETs, a 165, 234 sol-gel glass, with W, (I 103 Triglycerides, Dlabelled, a 163 Specific Heat, CePdln, CePtIn, low temperature, a 222 Tris@ydroxymethyl)phphine, metal complexes 74 Sputtering, a 48, 98, 99, 100. 101, 105 Tritium, a 101 Standard Gibbs Energies of Formation, a 233 electrochemical production, a 225 Steel, Fe-24Cr, Pd, Mo, V additions, a 223 Fe-40Cr-0.2Pd. acid effect on, a 101 Vinylacetylene, hyrogenation, a 43 Fe-40Cr-Pd. a 99, 101, 155 Vinylations 2, 232 Fe-40Cr-Ru. passivation, a 102 Vinylidene Carbonate, cyclic, formation. a 232 stainless, cathodic modification 154,204 coated with Pd, Pt, a 229 Wacker Process, a 44, 162 corrosion behaviour, a 164 Water, photosplitting, a 38-40, 103, 226 with FGM additions 85, 144, 155 Water Gas Shifl Readion, a 46, 107 Structure, micro-, Pt electrodes in solid electrolyte, a37 Pt( 111) surface. a 155 ZCSPlatinum Alloys, a 233

Platinum Metals Rev., 1990, 34, (4) 256