SYNTHFSIS OF ORGANOTUNGSTEN COMPOUNDS
A Thesis submitted by
A. I= GALYER, B.Sc., M.Sc.,
for the Degree of Doctor of Philosophy
of the University of London.
Royal College of Science, Imperial College of Science and Technology, London, SW7 2AY.
July, 1976. 2
ABSTRACT
Hexamethyltungsten has been synthesized by the reaction of tungsten hexachloride with trimethylaluminium in iso-pentane, This method replaces the earlier, unsatisfactory route, from tungsten hexachloride in diethylether. The salts, dilithium octamethyltungstate, are described as are the products of the reaction of hexamethyltungsten and trimethylsilylmethyllithium
followed by treatment with acid. The improved synthesis has allowed
multigram amounts of pure WMe6 to be prepared and a more detailed
analysis of some of its physical properties has proved possible.
Efforts to synthesize and then alkylate tungsten(IV) phosphine
complexes and tungsten(VI) phenoxychlorides are also described.
A computer programme for simulating mass spectral multiplets
is presented. 3
ACKNOWLEDGEMENTS
I would like to express gratitude to Professor G. Wilkinson, F.R.S., for his helpful advice and supervision during this work. Thanks also to the members of the department for all their help. I would also particularly like to thank Dr. D. R. Lloyd of Birmingham University for the photoelectron spectra and Dr. J.A. Connor of Manchester
University for the thermochemical measurements.
I acknowledge the donors of the Petroleum Research Fund of the
American Chemical Society for support. CONTEES
Page:
ABSTRACT 2
ACKNOWLEDGEMENTS 3
CONTENTS 4
ABBREVIATIONS 6
INTRODUCTION
(a) Transition Metal Methyls 7 (b) The Alkylation of Metal Salts with Alkylaluminium Compounds 12
RESULTS 15 (a) Reaction of Tungsten Hexachloride with
Methylli thium 15 (b) Reaction of Tungsten Hexachloride with
Trimethylaluminium 16 (c) Reaction of Trimethylaluminium with Other Transition
Metal Compounds 19
(d) Reactions of Hexamethyltungsten 19
(e) Physical Properties of Hexamethyltungsten 22 (f) Reactions of the Lithium Salts of Octamethyl- and
Mixed Methyltrimethylsilylmethyltangstate(VI) 25
(g) Tungsten(VI) phenol Compounds 26
(h) Tungsten(IV) phosphine Chloride Complexes 27
(1) Dimethylzinc and Pentamethyltantalum 28
EXPERIMENTAL 30
(a) Synthesis and Reactions of Hexamethyltungsten 32
(b) Reactions of Dilithiumoctarnethyltungstate 38 (c) Reaction of the Salt from Hexamethyltungsten and
Trimethylsilylmethyllithium 39 (d) Reactions of Trialkylaluminium Compounds with Other
Transition Metal Salts 41 (e) Preparation and Reactions of Some Tungsten(IV)
Chloride Tertiary Phosphine Complexes 45 5
Page:
(f) Synthesis and Reactions of cis-Dichloro- tetraphenoxytungsten 48 (g) MoC25 + PhOH 50 (h) WCA6 + 2-t-butylphenol 50 (i) WCA6 + PhSH 51 (j) WC/6 + Catechol 51 (k) WC2 6 + Hexachlorophene 51 (1) WCL6 + 2-isopropylphenol 52 (m) wae6 + 2,2'-biphenol 52 (n) WC26 + 2-allylphenol 52 (o) WCA6 + 2-naphthol 53 (p) Tungsten Hexaphenoxide 54 (q) Synthesis and Reactions of tris(2-methyl- phenoxy)tungsterrcrichloride 56 DISCUSSION 61 APPENDIX - Listing of and Input Information for Program PEAKS for Simulating Isotopic Multiplet Patterns 78 REFERENCES 85 6
ABBREVIATIONS
THE - tetrahydrofuran
DME - 1,2-dimethoxyethane
Me - methyl
Et20 - diethylether
TMEDA - N,N,NI ,N1 -tetramethylethylenediamfme
diphos - 1,2-bis(diphenylphosphino)ethane
dipy - 2,21-dipyridyl en - ethylenediamine
Et - ethyl Ph - phenyl
By - butyl
py - pyridine 7
INTRODUCTION
(a) Transition Metal Methyls
In recent years quite a large number of transition metal
n,salts Li MMe or complexes MMe permethyls, as binary alkyls MMe m n n (donor ligand) have been reported:
Ti V Cr Mn Fe Co Ni Cu
Zr Nb Mo Tc Ru Rh Pd Ag
Hf Ta W Re Os Ir Pt Au
U
The salts are stabilized by coordinated solvent e.g.,
Li4Mo2Me8.(THF)4 1 or some other donating ligand e.g., Li2UMe6(TMEDA)72 and some have been oiserved only in solution e.g., Li2PtMe6 3. In
the complexes, cf the neutral permethyls, the donor ligand is
usually a phosphine or aromatic heterocyclic amine. Of the donor-free
binary alkyls MMen, only those of the metals Ti, Ta, W, Re and Cu
are known and reasonably well characterized. These species vary
widely in thermal stability (all ara extremely reactive to o 4 atmospheric oxygen) from TiMe4 which decomposes above - 70 to
WMe6 which, when very pure, can be kept at room temperature for
5 and (MnMe2) 6 whilst being thermally short periods. (CuMe)n n more stable, explode when dry at room temperature. These two are
polymers and it is unlikely that they have been prepared pure and
purity would almost certainly enhance stability.
The deep green solutions obtained on treating TiCL3 in THE or
DME with ethereal LiMe at - 50° are thought to contain TiMe3 but
these decompose above - 20° and isolation of an alkyl has not
proved possible 6' 7. Pure TiMe4 (from TiCZ4 and LiMe) decomposes 8
o 0 6 above - 70 but the etherate distills unchanged at 0 . Some of the complexes TiMe4.Lni of which there are many, are stable at room 8 temperature e.g., TiMe4.py2 and TiMe4.Me2PC2H4PMe2 9. The salt
LiTiMe5.(dioxane)2 is stable at 0° and is a 1: 1 electrolyte in 10 THE . In ether TiMe4 decomposes to a species (n = 1.7-3.1) TiMe4-n and methane. This lower alkyl decomposes at 200° to titanium 11 carbide . A red etherate of ZrMe4 is obtained from ether-toluene mixtures of ZrCL4 and LiMe. This liquid product distills at - 30° but decomposes above - 15° and nothing is known about its chemistry.
A bright yellow salt, Li2ZrMe6, is formed with excess LiMe and is o 12 stable at 0 for several hours .
An ethereal solution of NbMe5 (from Me2NbC/3 and three equivalents of LiMe) decomposes at - 50° but addition of Me2PC2H4PMe2 precipitates NbMe5.L which is stable at room temperature. With excess
LiMe a solution probably containing Li2NbMe7, is obtained, and is stable at 0° for a few hours. Analogous reactions with Me3TaCL2 produce much more stable species and it is possible to isolate pure volatile solid TaMe5 which also forms a more stable Me2PC2H4PMe2 adduct. The solution obtained from excess LiMe and Me3TaC/2 is o o 13 stable to at least 35 whereas TaMe5 decomposes rapidly above 0 Reaction of CrC22 with 4 molar equivalents of LiMe in ether yields the chromium(II) salt [Li2CrMe4.(Et20)2 ]2 which decomposes at 128-135° under argon 14. The crystal structure of the Try' 15 analogue: [Li2CrMe4.(THF)2 I has been published . There is a brief report on the reaction of CrMe3 with diphenylacetylene to give
1,2,3,4-tetraphenylcyclopentadiene but no details of the synthesis 16 or other properties of this alkyl are given . Similarly brief notes reporting the syntheses of CrMe3 and CrMe2 from LiMe in THE 6 and CrCL3 and CrC/2 respectively have never been substantiated . An 9 orange Cr(III) salt; Li3CrMe6, is formed from CrC/3 and 6 molar equivalents of LiMe in ether, addition of dioxane precipitates a blood-red dioxanate 14. The Cr(IV) binary alkyl is prepared by 17 reaction of LiMe and (t-Bu0)4 Cr in petrol and the maroon volatile oily product decomposes at - 600 18 •
MoC/3.3THF or Mo2(000CH3)4 react with excess LiMe in THE or ether respectively to give the extremely reactive pyrophoric salts 1, 19 of Mo(II),Li4[M02Mes](solvent)4 . The deep red compound is stable to 25° (etherate) or 100° (tetrahydrofuranate) and the 1 crystal structure of the latter has been determined . The synthesis and some reactions of WMe6 (from WC/6 and LiMe) have been 20 published .
(MnMe2)n is a bright yellow explosive polymer prepared from
MnI2 and LiMe in ether. The products always contain ca. 10% I which is apparently impossible to remove. The salt LiMnMe3 is prepared o 6 21 from MnMe2 and LiMe and is stable to ca. 100 and not explosive '
The red salt Li2MnMe4.(TMEDA)2 is prepared from MnCi2 and LiMe in ether followed by TMEDA 2, the compound decomposes at 150°.
Reaction of Re0C/3.(PP113)2 with LiMe in ether produces volatile magneta Re0Me4 22. This very stable alkyl reacts with
A/Me3 to give ReMe6, a volatile green crystalline solid which is stable at 25° for short periods, and with NO to produce yellow crystalline cis-Re02Me3, a Re(VII) alkyl `-.
Ei2FeMe4, prepared from FeC/3 and LiMe in ether, forms a dark-red etherate and a light-yellow dioxanate, both of which o decompose above 0 and are of uncertain composition 24.
Me2Fe(PPh3)3 is prepared from Fe(acac)3 , PPh3 and Me 3A/ 25 and
Me2Fe(diphos)2 similarly except that Me2A2OEt is used 26. The latter compound forms orange crystals that are stable to 130° and on 10 thermal decomposition CH4, C2116 and C2M4 are formed (mole ratio
75 : 20 : 5) and a carbenoid intermediate in this process is 26 postulated .
Brief notes on the synthesis of Me2Ru(PPh3)4 , from the corresponding dichloride and Me3AL, have been published 27.
Co(acac)3 reacts with R2A/0Et (R = Me, Et), in the presence of a donor ligand, to yield Et20o(dipy)2 28 or MeCo(PPh3)3 29, the former decomposing at 50° to give ethane and ethylene (2: 1).
Li2CoMe4.(TMEDA)2 is prepared from CoC/2 and LiMe as a blue solid unstable at room temperature 2. MeRh(Pa3)3 is prepared from the 31 corresponding chloride 30 or bromide and methyl-Grignard reagent in ether. The complex melts at 120° with decomposition. A note reporting the synthesis of this alkyl from the chloride and Me3k/ has appeared 27 MeIr(PPh3)3 , from the chloride and LiMe, forms red crystals, stable in ethereal solution at 0° for a few hours, but in the solid state ortho-metallating very rapidly at much lower temperatures 32.
Trimethylaluminium and nickel(II) salts form reaction mixtures which decompose above - 100° depositing metallic nickel 33. Additj.on of PhPMe2 allows the formation of Me2Ni(PhPMe2)2 which is stable to
60° 34. Similarly trans-Me2Ni(P(cyclohexy1)02 is prepared as a colourless solid, stable to room temperature but very light sensitive, turning pink as methane and ethane are evolved. It reacts further with trimethylaluminium and nitrogen to form [((cyclohexy1)3P)2 Nia2 N2 35. 36 Me2Ni(dipy)2 is prepared from Ni(acac)2 , Me2A/OEt and dipy . cis-Me2Nidiphos, from the dichloride ard LiMe, is a yellow solid, stable in air for up to 30 min. and decomposing at 130° 37
Similarly prepared is Me2Ni(PMe3)2 which forms yellow needles and takes up excess phosphine to form the red 5-coordinate Me2Ni(Me3)3 11
38 complex . The salt Li2NiMe4.(TEF)2 is prepared from nickel(II)halide
salts and excess LiMe and is yellow, diamagnetic and decomposes ° 39 at 130 . A series of Pd(II) dimethyls stabilized by various donor ligands have been prepared from the corresponding dichlorides and MeMgBr, or better LiMe 4°. A number of Pt(II) dimethyls and
Pt(IV) tetramethyls, stabilized by tertiary phosphines and arsines, have been prepared from the corresponding chlorides and LiMe. These are all very stable and the tetramethyls on pyrolysis yield the 41 corresponding dimethyl and ethane . Various other cis-Me2PtL2 compounds (L = donor ligand) have been prepared from 7-(C8H8)PtMe2 and the donor ligand 42. Solutions containing Li2PtMe6 have recently been reported 3.
The explosive yellow polymer (CuMe) is prepared from Cu' and n one equivalent of methyllithium in ether 43 or from Cu(acac)2 and Me2ALOEt 44. Excess LiMe dissolves the polymer to yield solutions ° 43 of LiCuMe2 which are stable at 0 and are widely used in organic chemistry as a methylating agent 45. In the presence of a donor ligand Me2ALOEt reduces and alkylates Cu(acac)2 to give MeOu(PPh3)3 -
.solvent 46. Whilst there is nothing in the literature on silver methyls the chemistry of methyl- and trimethylgold has been much investigated. Solutions of AuMe, can be prepared from AuBr3 and ° 47 LiMe but these decompose above - 65 Addition of ethylenediamine precipitates en(AuMe3)2 and PPh3 yields PPh3AuMe3 which on thermal decomposition at 1200 gives ethane and no methane or ethylene.
Heating the PPh3 complex in xylene gives ethane and MeAuPPh3 48 49 which can also be made from C2AuPPh3 and LiMe and itself decomposes to ethane, metallic gold and triphenylphosphine 50.
MeAuPP115 reacts with LiMe to LiMe2AuPPh3, which is stable only in ethereal solvents and reacts with methylbromide or iodide to give 12
51 Me..;AuPPh3 + LOC . The details of the mechanisms of many reactions of gold methyl comple\es have been published 52. Recently the preparation and isolation of complexes of the quite stable Au(I) and
Au(III) methyl salts, LiAuMe2 and LiAuMe4 have been reported 53.
(b) The Alkylation of Metal Salts with Alkylaluminium Compounds
Alkylaluminium compounds have been extensively used in the synthesis of alkyl derivatives of non-transition metals:
BeC22 + Et 2A2 = EtBeC2 + Et2A/C/ 54
Zn(0Ac)2 + 2Me3A/ = Me2Zn + 2Me2A/OAc 55
B203 + excess Et 3A2 2C/ 3 = Et 3B 56
2PbS + /4Me3AA = Me4Pb + Pb + 2(Me2A/)2 S 57
KBF4 + Et 3A.2 = Et 3B + KA/F4 58
These examples illustrate the variety of starting materials that can be used (in general compounds of Groups II to V are those most readily alkylated), the degree of alkylation obtained and the number
of alkyl groups transferred from the aluminium to the metal. In all
of these reactions it is necessary to heat the reaction mixtures
strongly in order to distil out the volatile product alkyl and so
displace the equilibrium that is invariably set up. In some cases
the reaction will not go to completion unless a complexing agent is
added to bind the aluminium by-product e.g., the reactions
4R 3A.2 + 3SnC/4 = 3R4Sn + 4A/C/3
(R = Et, n-Bu, i-Bu and n-Octyl) are carried out with excess Et20 59 or (n-Bu)2 0 to effectively remove the ANC/3 from the equilibrium . 13
Alternatively NaCA or KCA may be used to form salts of the type
NaALC/4 when the reaction mixtur,, is heated.
In general the reaction of alkylaluminium compounds with transition metal salts does not lead to simple alkylation, but reduction is more usual with the final product quite likely not containing a metal-
-carbon bond e.g.,
Ni(acac + Me 3A.2 = Ni + CH4 + C2H6 33
Ni(acac)2 + Et3AA + C8H8 = Ni(n-C8H8)2 60
61 Rh(acac)3 + Et3A2 + PPh3 = HRh(PFh3)4
WC/ 6 + Et 3A2 + CO = W(C0)6 62
In these, and the many other similar reactions, there is evidence for metal-carbon bonds in the intermediate structures, but in the absence of ligands known to stabilize metal-alkyl species decomposition proceeds by homolytic cleavage, coupling, or by the beta-elimination mechanism 33, 63.
For the earlier transition metals the chemistry of metal salt-alkylaluminium compounds is enormous, if not that well understood. The number of catalytic mixtures that have been produced from Ti, Cr and V halides and alkylaluminium's is very large and whilst it is certain that in many cases these catalysts contain species with a metal-carbon bond, very few have been isolated and characterized, and confusion and conjecture abounds in the literature as to the nature of these mixtures.
Although there is a reasonable number of per-methyls of the transition metals of the Fe, Co and Ni triads which have been prepared from methylaluminium compounds in admixture with a donor ligand, the only donor free per-methyl, apart from WMe6, synthesised 14 with these reagents, is ReMe6 from Re0Me4 and Me 3A2 23
This thesis describes some reactions of organo-tungsten compounds, some attempts to extend the Me3A2 reaction to other metal salts but
emphasis will be on the improved synthesis of WMe6 and the synthesis of the lithium salts of this alkyl. 15
RESULTS
(a) Reaction of Tungsten Hexachioride with Methyllithium
Initial attempts to repeat the synthetic method developed by
Shortland 20:
WCA6 + 3LiMe WMe6 + products resulted in a series of failures. Apparently after 2 molar equivalents of LiMe have been added the mixture should become green, changing to deep-red on adding the 3rd. equivalent, if the synthesis is to be a success. This green solution was found by E.S.R. to contain
W(V) 20 and it seems reasonable that an oxidising agent may be required at this stage if WMe6 is to be formed. Dry diethylether poured directly from a winchester and used as the solvent, dramatically increased the yields of WMe6. Attempts to add known amounts of oxygen by addition of a little benzene, in which oxygen is very soluble, or by use of dibenzoylperoxide were unsuccessful.
The scaling-up of the reaction was not practicable because of the difficulty of controlling the reaction at its various stages, particularly as regards to temperature.
Dimethylether was tried as a possible alternative solvent in view of its favourable boiling point (- 26°) (it is not easy to separate WMe6 and Et20 as they have similar volatilities at - 10°), but this ether reacted with WC26 extrctiely rapidly giving, what was by now the familiar, "tungsten blue" species which reacted no further. By using di-n-butylether it was thought possible that
WMe6 could be sublimed as it was formed. This yielded a small amount of a red oil, very rich in n-Bu200
Attempts were also made to remove the solvent at the various 16 stages of the reaction, in order to establish the intermediates, however evaporation in vacuo and at low temperatures resulted in much decomposition. Addition of dioxane to the green solution obtained after the addition of 2 molar equivalents of LiMe to a solution of WC26 in Et20 (oxygen-free) yielded a colourless unidentifiable solid insoluble in 06116, Et20, CC24 and dioxane.
Eventually these attempts were abandoned in favour of the more reliable Me3A2 method.
(b) Reaction of Tungsten Hexachloride with Trimethylaluminium
w016 + 6Me 3A2 = WMe6 + 6me 2A1c1
6Me2AiC2 6NMe3 = 6Me2A2C2.NMe3
This reaction is best carried out in iso-pentane (BMR. 27°), because of the high volatility of WMe6 and of the low solubility of Me2ALC2.NMe3 at - 78°. A suspension of Wae6 in iso-pentane at - 70° is treated dropwise with 6 molar equivalents of Me3AI and the mixture allowed to warm, with vigorous mechanical stirring, to Oc. As only one methyl group is transferred the problem now becomes one of removing the large amount of stable Me2A1C/ by-product. Treatment of the petroleum solutions with finely. powdered Na2SO4.10H20 is only successful on a small scale and neutral
A1203,wi1en stirred with the reaction mixture at 0°,hydrolyses the WMe6 as well as presumably removing the Me2A/CL, A2203 preheated in yaw() at 160P to remove free water and oxygen neither hydrolyses the WMe6 nor removes the aluminium alkyl. Liquid water has no effect on WMe6 as long as the water-petroleum mixtures are heterogeneous. Addition of water to a solution of WMe6 and
Me2A/C2 containing NMe 3results in an immediate loss of colour and 17 the deposition of white crystals. It is thought that Me3N.9H20 is formed and this being reasonably soluble in petroleum produces a homogeneous H2O-We system. The use of liquid water to remove the aluminium alkyl by-product is restricted to very small scale applications because of the large amounts needed to solubilize the hydrolysis products acid the difficulty in keeping lots of water cold enough to avoid thermal decomposition of the hexamethyl. Aqueous solutions of oxalate, formate, fluoroborate and tartrate are also impracticable for much the same reasons.
Of the amine complexes of Me2AACA,the o-phenanthroline, quinoline and N,Ng -dimethylpiperazine adducts appear to be the least soluble however they all suffer from the disadvantage that heavy solid clods of precipitate are formed, making stirring and further reaction very difficult. o-Phenanthroline is expensive for large scale use and normally needs to be dehydrated before use, and like quinoline it is rather insoluble in iso-pentane. The
N,Ng -dimethylpiperazine adduct forms a precipitate that is exceptionally difficult to work with, and much of the WMe6 containing petroleum is entrapped on attempted filtration. The major disadvantage of these amines is that if an excess is added that excess is virtually impossible to separate from the WMe6 after filtration. Trimethylamine is a gas (B.P. 4°), cheap, easy to dry and forms a very stable, if rather soluble, Me2A2O2 adduct.
The best method is to pour an excess of dry liquid NMe3 into the stirred reaction mixture at - 70°, allow the mixture to warm to
0°, re-cool to - 78° and filter. Drying of the amine is necessary, not because of obvious hydrolysis of the hexamethyl, but because the precipitate is much easier to filter when made with dry liquid. 18
The reaction between the aluminium alkyl and the amine is very exothermic and good cooling and stirring are a must. A large jacketed frit capable of containing the entire reaction mixture
(up to 600 ml) is used to keep the whole at - 73° whilst filtration proceeds. As NMe3 is very soluble in iso-pentane, the excess is removed from the filtrate at - 15° in vacuo and the solvent which co-distills is replaced by fresh petroleum if desired. In a further experiment an excess of Mea was added, together with the
NMe3, in the hope that the reaction 64:
Me2A/a + Mea, + NMe 3 = Me2ALCL2.+NMe4 would produce a less soluble adduct, however no apparent reaction occurred.
After the removal of the aluminium the petroleum solutions can be stored at - 25° for up to 7-8 days before a fine precipitate of W metal powder forms. At - 40° the solutions are almost indefinitely stable but freqUent opening of the flask to remove samples for reactioAs soon produces yellow W03 from the reaction with small amounts of oxygen. The petroleum solutions can be carefully evaporated to dryness and the Wee, sublimed onto a probe and then washed into sample tubes for analysis. Alternately larger volumes can be concentrated and cooled to - 100° to precipitate very dark-
-red crystals of the hexamethyl. Because of the extreme solubility of the alkyl this method is very inefficient and, due to the potentially explosive nature of the solid, not without hazard.
During this work we have had several serious explosions when even 65 small amounts of the solid hexamethyl were being handled . Special care must be taken when the solid is being sublimed or when samples are being cooled or warmed in vacuo for spectral analysis. For 19 most purposes petroleum solutions may be used for chemical reactions and if the exact concentration is required a spectrophotometric method for determining tungsten can be used.
(c) Reaction of Trimethylaluminium with Other Transition Metal
Compounds
In attempts to extend the use of Me5A/ to the synthesis of other transition metal methyls a variety of other metal salts were used, but without much success. Mo0C/4, MoC25, WOCL4, WO(OMe)4,
UC26, TaC/5, Ta 05 and K2TaF7 were reduced to the metals, in some cases even at - 70°C. WF6 gave an immediate deep-red colouration but only very unstable partially alkylated species were formed. WC/6 was completely reduced by Et3A2 and only partially alkylated by (Me5SiCH2)5 A/.Et20. Other workers at
Imperial College have found that Re0C24, Reae5, Re207, 0604, Me3PtI,
K2PtC26, MnC/2 and Mn(acac)2 also fail to yield any alkylated products. No reaction was observed between WF6 and. Me4Sn under reflux.
(d) Reactions of Hexamethyltungsten
(i) Methyllithium
Addition of an ethereal solution of LiMe (excess) to a solution of WMe6 in iso-pentane/Et20 at - 20° produces an immediate orange-red colouration. All the solvent is removed in vacuo to leave a mass of light grey solid containing yellow octamethyltungstate(VI).
Extraction of this residue with iso-pentane followed by filtration yields an intense yellow solution which is stable at 00.
Concentration and cooling to - 78° precipitates bright-yellow 2 crystals of the etherate of [WMe8] : 20
WMe6 + 2MeLi + nEt20 = Li2WMe5.nEt20
which exhibit, in the 1 H N.M.R. spectrum (06116), a series of peaks
between 8.3 and 9.11 T. Attempting to dry these crystals in vacuo
yields the yellow unsolvated Li2WMe8 which is insoluble in petroleum
and benzene but redissolves in donating solvents. The powder is
completely non-volatile decomposing at 80-85°/0.01 mm. In air it initially turned red before decomposing to a light coloured mass.
Addition of 1,4-dioxane to a petroleum solution of Li2WMe8.nEt20
precipitates the orange-red bis-dioxanate Li2WMe8.(C411802)2, which is totally insoluble in petroleum, CHG/5, dioxane, 06116 and Et20
but soluble in pyridine. The powder is thermally very stable but
is somewhat light sensitive and on hydrolysis with water in a gas
burette 7.8 moles of CH,, are produced.
Iso-pentane solutions of Li2WMe8.nEt20 also react with
1,2-dimethoxyethane to precipitate red Ii2WMe8.(C4H1 002)5 which is
soluble in warm 06H6 and C6H5Me but rapidly forms an oil if these
solvents contain the slightest trace of water. The oils will
sometimes crystallize on washing with anhydrous ether. The
IH N.M.R. of this salt, in benzene, showed resonances due to 2 - 1, 2-dim ethoxyethane (6.60, 6.75 T) and [Wes) (8.3 T) with the required peak areas.
Precipitates are also formed on treating Iii2WMe5onEt20 in iso-pentane with THF, o-phenanthroline, dipyridyl,
N,N,N2 ,N1-tetramethylethylenediamine and N,W -dimethylpiperazine
but the stoichiometry of these products has not been established.
There is no apparent reaction when Me3N, Ph3P or Me2PPh are added
to Li2WNes.nEt20,,
An attempt was made to prepare the salt IiWMe7 by the addition 21 of 1 molar equivalent of MeLi to WMe6 in Et20 followed by evaporation and cooling. The orange product formed initially 2 rapidly turned to yellow [WMe8] when work-up was attempted.
(ii) Trimethylsilylmethyllithium
Addition at - 10° of a slight excess of Me3SiCH2Li in hexane to WMe6 in iso-pentane together with a slight excess of
1,2-dimethoxyethane forms an immediate precipitate of orange
LiWe5(CH2 SiMe3). (C4111003)3 which is pumped dry at 0°.
In the 1 H N.M.R. in pyridine this compound shows resonances due to W-Me (8.3 T), 1,2-dimethoxyethane (6.60, 6.75 T) and a series of peaks near 10.0 T.
Reaction at - 10° of a large excess of a petroleum solution of Me3SiCH2Li with WMe 6 in iso-pentane followed by stirring at - 10° for an hour produces a fine pale precipitate of Meld. (+ ve Li flame test, insoluble petrol, soluble Et20 and IH N.M.R. doublet at
11.2 T). The filtrate on evaporation leaves an orange precipitate of
LiWMe(CH2SiMe which reacts with CF3COOH to produce a mixture 3)n of methyl-trimethylsilylmethyltungsten alkyls.
(iii) Other Organo-lithium Compounds
Ethereal solutions of PhLi and WMe6 reacted to precipitate on evaporation a sluggy dark oil which is slightly soluble in petrol. Repeated extraction of this oil with petroleum, combination of the extracts and addition of 1,2-dimethoxyethane gives an immediate precipitate of a dark brown intractable glug.
PhC E CLi similarly produces dark insoluble unidentifiable tars. n-Buii in hexane reacts with WMe6 in iso-pentane at - 70° to give a yellow powder. Addition of 1,2-dimethoxyethane at - 40° precipitates 22 a thermally unstable red tar. A similar red tar is produced from
WMe6, EtLI and 1, 2-dimethoxyethane.
(iv) Miscellaneous Reagents
WMe6 is unaffected by liquid water and petroleum solutions are quite stable when stirred with water. The solid hexamethyl reacts explosively with atmospheric oxygen and great care must be exercised when handling the solid especially during sublimations in vacuo. WMe6 reacts with excess BF 3, FS03Me ('magic methyl' ), H2
+ 1,5,9-cyclododecatriene, NaAAH2(OCH2CH20Me)2 , (C6F03 SiH, and
LiA2114 to give fine black sludgesof W metal at reaction temperatures ranging from - 50° (LiA2114) to 20° ((C6F5)3 SiH). With SO2 in GH2C12 at 10° a fine, brown and very insoluble precipitate is formed and this unidentified polymer has a strong sulphurous odour and possibly contains sulphur bridging. A solution of WMe6 when treated with Ph3P or Me2PPh does not visibly react nor does any product precipitate on concentration and cooling, however the solutions are stable at room temperature for many weeks under nitrogen.
Similarly fluorene stabilizes WMe6 solutions but no reaction product has been isolated. Cyclopentadiene reacts to form a very dark, petrol soluble, very pyrophoric volatile red tar which has also not been isolated. Ph 3B does not react with WMe6 to give a methyl-phenyl exchange product but instead, after stirring the reaction mixture at 10° for 3 hours, filtering and evaporating, very pure
WMe6 is obtained. These solid samples are stable at room temperature for about an hour and can be kept at - 25° for weeks.
(e) Physical Properties of Hexamethyl tungsten
WMe6 forms dark-red very volatile crystals which, when very pure, 23 are stable at room temperature for short periods and can be stored at - 25°. In general the solid product isolated directly from the WC4/Me3AL/Me3N reaction sequence decomposes on attempted o storage above - . Solutions it iso-pentane can be kept for about a week at - 25° before decomposition is apparent.
The 60 MHz IH N.M.R. spectrum in CC23F and at - 20° shows a singlet at 8.2 T with 2 J(183w-1H) = 3 Hz. This singlet is unchanged at - 100°C. The 1H decoupled 25.16 MHz 13 C N.M.R. spectrum (Fig. 1) in
C7D8 and at - 50° shows a sharp singlet at 83.6 ppm downfield from
TMS with J(i 83 W-13 C) = 43.2 Hz. The IH coupled 13 C N.M,R. spectrum, under the same conditions, showed a quartet with 1 J(15c_1/0 = 124.8 Hz.
In the mass spectrum (ionization energy 70 eV, source temperature
24° and pressure 4 x 10 8 mm Hg) WMe6 gave a multiplet, with the + (m / correct isotopic ratios, about 184WMe5 /e = 259). Also present was the multiplet at mie = 184 corresponding to 184 W+. Between these two was a forest of peaks from which the 184wme+ (n = 4 -1) multiplets could not be distinguished. On lowering the ionization energy to
15 eV (,source 40°C) and increasing the pressure of alkyl to -7 2 x 10 mm Hg the multiplet corresponding to the parent ion
184wm e4-6 appeared at mie = 274. The intensity of this multiplet, + compared to the WMe5 peaks, was extremely low and it could only be observed with relatively large concentrations of WMe6 in the spectrometer. Between the WMe6 and WMe+5 multiplets no peaks were observed but a multiplet, not containing tungsten, appeared at mie = 281, 282, 283, 284 with the first of these being the most intense. The species giving rise to this multiplet has not been identified. I ll I 1 I■ii‘i 3000 2000 1000
1500 1000 500 0)—H±
600 400 200 Hz
300 200 100
150 100 zHN 60 40
30 20 D
15 10
W-GH
o • 0 Solvent
1 I 1 r 1 I t 1 I 1 r I Ir 1 PPM il l 1 I 1 1 I I I I . I 11 11-7-11. 1 I 11 1 I i I l 1 1 1 1 .1i 25
(f) Reactions of the Lithium Salts of Octamethyl- and Mixed
Methyltrimethylsilylmethyltungstate(VI) 2- Solutions of [WM08] do not react with dry hydrogen, + Ph3C BF4, 1-hexene, Me4P+C2 or butadiene. Addition of oxygenated solvents cause the immediate appearance of an intense red colour and in air the dry solids quickly turn red before decomposing to a white residue.
Two equivalents of dry acetic acid when added to a suspension of 2 - the [WMe8] .1,2-dimethoxyethane adduct in iso-pentane produces methane (2 equivalents), a precipitate of lithium acetate and a deep-red solution. On filtration, evaporation and sublimation of the red oily residue, WMe6 contaminated with 1,2-dimethoyyethane is isolated. A suspension of unsolvated Li2WMe8, in iso-pentane, similarly reacts with two equivalents of CF3C00H to give petroleum solutions of very pure WMe6 and provides a rather convenient way of preparing small amounts of the pure hexamethyl. Four equivalents of
CH3COOH similarly yields CH4, a precipitate of CH3C00Li and, after
filtration and evaporation, a red oily residue. This residua is thenually more stable than WMe6, lithium free, and is non-volatile.
Its IH N.M.R. spectrum in CC/3F shows two singlets at 8.2 T
(W-CH3) and 7.94 T (H30-C) in the ratio 6: 2. The N.M.R. spectrum
of a sample which had been stirred in iso-pentane with cellulose
powder was identical to that above. No 1 H N.M.R. evidence for a
hydroxyl proton has been found and the samples are two unstable for
I.R. analysis but the species is apparently WMe 4(CH3COOH)2 . o . Li2WMe8 complexes react at - 15 in GH2CL2 with
trimethyloxonium hexafluorophosphate:
Li 2WMe8 + 2Me30PF6 = 2LiPF6 + WHe 6 + 2Me0Me + 2C2H6
An iso-pentane solution of WMe6 when treated with a known 26 large excess of Me3SiCH2Li in hexane and then reacted with an equivalent amount of CF3C00H goes deep red-brown and liberates methane (and possibly TMS). On evaporation of the filtered mixture a red-brown oily residue is left which is quite volatile and have complex 1 H N.M.R. spectra in the regions 8.3 - 8.4 T
(W-CH3), ca. 10.0 T (Si-Me) and 9.2 T (W-CH2?). Peak integration does not yield consistent ratios W-CH3 : W-CH2 : Si-CH3 and so mixtures are presumed. The mass spectra of these oils are further evidence for mixtures in that many of the species ranging from
(Me3SiCH2)3 WMe+3 (m/e = 490) through (Me3SiCH2)2 WMe+1, (m/e = 418) and Me3SiCH2WM4 (m/e = 346) to 183 W+ (m/e = 184) can be identified with high concentration of sample and low ionization
energies.
(g) Tungsten(VI) phenol Compound;;
A series of W(VI) phenolic compounds were prepared in order
to investigate their suitability as starting materials for
alkylation reactions. In particular it was hoped that the phenolic residues would remain and the halides would be substituted
e.g.:
W(OPh)4 C/1 + MeLi = W(OPh)4Me2 2LiCS
68 W(OPh)6 is easily prepared from phenol and tungstenoxytetrachloride 69 or tungsten hexachioride and forms red crystals quite stable in air, very soluble in organic solvents and apparently an ideal
substitute for air and water sensitive WC/6 which needs to be
sublimed before use. Unfortunately W(OPh)6 is very unreactive to
most reagents and gave no recognizable products on reaction with
MeLi or Me3A/. 27
cis-W(OPh)4C/2 70 is prepared from WC°6 and PhCH 69 in CCI4, the reported synthesis from WOC24 and phenol in isc-octane 68 gave only a large proportion of an insoluble, phenolic powder. WCA 6 and 4 molar equivalents of PhOT/ or Me3Si0Ph yielded only black tarry masses from which no W(OPh)4 CL2 could be extracted. This compound reacted with Me2NCS2Na.2H20, catechol and 2,21 -biphenol but the products have defied identification. There was no reaction with
Me2NCS2TA in refluxing benzene, With MeLi (2 molar equivalents) reaction occurred in ether at - 50° but the orange product decomposed below 0° to a black tarry mass.
With 2-methylphenol, WC/6 forms W(0C,X7)3 C/3 which does not react by substitution or adduct formation with a wide variety of reagents and with MeLi or Me3SiCH2Li forms species which decompose above - 40°. With Me2PPh W(0C7H7)3 0/3-Me2PPh has been isolated and characterized. 69 2-Naphthol reacts to form W(0C10EAC/2 which reacts with
NaALH2(OCH2CH20Me)2 or LiAAH4 to give, as the only isolable product,
2-naphthol. 2-tert-Butylphenol reacts with WCA6 to give
W(0C101113)3 C/3 but catechol, hexachlorophene, 2-iso-propylphenol,
2-allylphenol. 2,2'-biphenol, bis-(2-naphtholyl)methane, thiophenol and the Schiff base from salicylaidehyde and 1,2-diaminopropane all give oils, tars or the starting materials.
(h) Tungsten(IV)phosphine Chloride Complexes
A method was developed for the synthesis of complexes of the type WC/4(PR3)2 which involves the reaction of WC/6 and excess phosphine in benzene. By this method the complexes can be synthesised in high yield very easily. 28
wcz 6 + 3PR 3 = WCZ „ ( PR 3 )2 + R 3Pc,e 2
R = Ph yield = 87%
= p-CH3C6H4 yield = 81%
R = Me2PPh yield = 93%
The latter phosphine yields the complex WC24(PMe2Ph)3 .12C6H6 which loses benzene and the third phosphine ligand in vacuo. The phosphines
(n-C4H9)3P, PhP(OEt)2 and P(OEt)3 all yielded oils under similar reaction conditions.
The complexes with triarylphosphine ligands are totally insoluble in hydrocarbons and diethylether and so reaction with Meld at lo;. temperatures is not possible. At room temperature and above reduction occurs due to the decomposition of the product as it is formed. WC24(PMe2Ph)3 .12C6H6 is more soluble in ether and benzene and with Meld this complex, in Et20, reacts at below - 20° to give solutions unstable above - 20° which reek strongly of Me2PPh.
No- product has been characterized from these reaction mixtures.
The same complex reacts in refluxing benzene with NaA2-12(OCH2CH20Me)2 to give dark oils which show no evidence for hydride formation. A mixture of WC26, Me2PPh (6 molar equivalents), NaA2H2(OCH2CH20Me)2 in hydrogen saturated benzene precipitates a yellow powder, totally insoluble in organic solvents with no sign of W-H in the infrared and which does react when treated with aqueous HC2.
(i) Dimethyizinc and Pentamethyltantalum
During the course of this work Schrock's note on the synthesis 13 of TaMe5 appeared and because of the desirability of comparing
WMe6 and TaMe5 in their physical properties, especially bond 29
strength and photoelectron spectroscopic studies, the synthesis of
TaMe5 was developed. The reactions involved are:
2TaC25 + 3Me 2Zn = 2Me3TaC22 F 3ZnC22 73
Me3TaC22 + 2MeLi = TaMe5 + 2LiC2 13
This requires Me2Zn for which the published methods of synthesis are 74 not very satisfactory, viz.Zn + Me2Hg , Zn-Cu + CH3I 75, 76 ZnC22 + MeMgBr and ZnC22 + Me3A2 77. The last method is the most convenient of these but suffers from the disadvantage of having to dry and handle ZnC22. Zinc acetate is very easily rendered anhydrous by boiling the commercial hydrated salt with acetic anhydride or from 78 zinc nitrate and acetic anhydride . The reaction
Zn(OCOCH3)2 + 2Me2A2 = Me 2Zn + 2Me2A2000CH3 in decalin at 1000 gives dimethylzinc in 88% yield.
The synthesis of TaMe5 was carried out as outlined by Schrock 13 but with careful evaporation and cooling green crystals of T:aMe5
(yield 60-70%) rather than the reported oil, could be obtained.
This compound, like WMe6, reacts very violently with atmospheric oxygen and extreme caution should be exercised in its use. 30
EXPERIMENTAL
All operations were performed in an inert atmosphere (nitrogen or argon) using conventional vacuum, Schlenk tube and glove box techniques. Iso-pentane was stirred with conc. H2SO4 to remove olefins and then refluxed in a still over LiA/H4. All other
solvents were dried and de-oxygenated before use. Tungsten hexachloride was sublimed, in vacuo at ca. 180° before use;
trimethylaluminium (Ethyl Corporation) was used as received; Meld
solutions (ca. 1 molar) were prepared from lithium chips and gaseous
Meae, in diethylether under argon, and were filtered before use.
Microanalyses were by the microanalytical laboratories at Imperial
College and A. Bernhardt, Mjhlheim. Lithium and tungsten were
determined by plasma emission spectrometry by Mr. J. Goulter,
Imperial College. The n.m.r. spectra were recorded on Perkin-Elmer
R12 (1 H) and Varian XL-100 (13 C, Fourier transform) spectrometers
both fitted with variable temperature probes. For the 13 C
measurements B14 sockets were blown onto 10 mm n.m.r. tubes to
facilitate the transfer of cold solutions of the alkyls into the
tubes. Mass spectra were recorded using AEI-MS9 instruments at
Imperial College and Queen Mary College. In both cases the solid
alkyls were sublimed into break-seal tubes and then these were blown
onto glass tubes with the metal fittings required for attachment to
the spectrometer, the samples were then sublimed directly into the
source chamber.
The procedures for the handling of Me3Ai were essentially
similar to those recently described 79. Volumes up to 20-30 ml
could be readily transferred by 50 ml syringe and for larger volumes
a pressure equalized dropping funnel was used The extreme 31 reactivity of Me3AZ renders these operations not without hazard, in particular most stopcock greases are rapidly attacked and a grease ("Fluorolube"), stable to volatile metal fluorides, was used as it seemed to be less prone to corrosion than most. This same grease or Teflon cone and socket seals were used on ground-glass joints on the reaction vessels but for storing Me3AL Schlenk.-like tubes with "Rotaflow" taps and Teflon seated ball and socket joints were required. In syringing Me3A2 a few drops invariably fall flaming from the needle and it is essential that any acetone-0O2 bath cooling the reaction vessel is saturated with solid lumps of CO2 to avoid fires.
Solid WMe6 reacts eIplosively with atmospheric oxygen and must always be handled in small quantities and with care, especially during sublimations when several serious detonations have occurred.
The substance may also detonate in vacuo and care must be taken when samples are being warmed or cooled in vacuo for spectroscopic study or analysis. The detonations have been quite violent, even small amounts (< 500 mg) have Shattered the apparatus and caused deep cuts to the hands and gram amounts have destroyed a sublimation apparatus and ignited the acetone from the shattered cooling bath. It is safer to use powdered CO2 for cooling during sublimations. 3?
(a) Synthesis and Reactions of Hexamethyltungsten
(i) Synthesis
WC/6 + 6Me3A/ = WMe6 + 6Me2A/C/
6Me2A/C/ + 6NMe 3 = 6Me2A/C/.NMe3
To a cooled (- 700), stirred suspension of WC/6 in iso-pentane
(10 ml/gm WC/6) is added, via syringe or dropping funnel, six molar equivalents of Me 3A2 over 10-15 min. Stirring is maintained whilst the reaction mixture is allowed to warm slowly to room temperature.
After about 10-15 min. at ca. 20°C the very dark-red fuming mixture is retooled to - 70°C and an excess of (ca. 1.2 ml/ml Me3A/) liquid NMe3 (dried by passage through a 30 x 5 cm column of 4A mol- ecular sieves) is carefully added. The reaction of the NMe3 with
Me2A/C2 is very exothermic and the liquid should be slowly pourer: from a Schlenk tube with vigorous stirring and good cooling. A rather heavy light-brown slurry is formed and after stirring for a few minutes to ensure complete reaction the whole mixture is poured into a large jacketed frit which has been carefully dried, purged with nitrogen or argon and cooled to - 70°. The bulky precipitate of Me2ALC2.NMe3 is removed at this temperature but, as the solid adduct is rather soluble in iso-pentane, washing is not very effective
to remove the entrapped WMe6. The excess amine is removed by
concentrating the deep red-orange filtrate at - 10° in vacuo; retooling to - 70° and filtration removes more alkyl-amine adduct.
Analysis of the final solution indicates the yield of WMe6 to be
60-746, the losses are mainly due to entrainment in the solid by-
-product. The solution can be carefully evaporated to dryness and
the solid residue sublimed on to a probe at - 10°C. Due to the
similar volatilities of the solvent and product some WMe6 will 33 accumulate in the cold trap of the vacuum line and so nitrogen, rather than air, should be admitted to the line on completion of the operation. The solutions of WMes in iso-pentane may be determined by 66,80 the following method • 1 ml of a WMe6/petroleum solution is added to 10 ml of 0.880 aqueous ammonia and heated on a steam bath for
10 min. Water (50 ml) is added to give a clear solution of
(NH4)2 W04 and this solution is made up to 1 litre in a volumetric flask.
To 15 ml of this solution is added 10 ml conc. H2SO4 and after mixing and cooling, 20 ml conc. 1102 and 5 ml. 2 M SnCL2 in conc. He/ are added and the solution heated at 100° for 5 min. After cooling the solution is treated with 10 ml of 20% KSCN (aqueous), diluted to
100 ml with H2O and read at 400 mp. A reagent blank is also prepared as well as a standard (in this work a standard solution containing
0.1988 g, Na2W04.2H20/litre was used, 10 ml being taken and treated as above).
(ii) Reaction with Methyllithium
WMe6 + 2MeLi = Li2WMe8
A solution of WMe6 in iso-pentane is evaporated to a small volume at - 20° and the petroleum replaced with diethylether. To this solution is added an excess of ethereal MeLi and the resulting orange-red solution evaporated to dryness at - 10° leaving a yellow mass. Iso-pentane is added and the mixture vigorously stirred and then filtered leaving a pale grey residue of MeLi and a bright yellow filtrate. Concentration and cooling to - 78° yields crystals of the etherate Li2WMe8.nEt20. On drying in vacuo the ether is lost and a yellow powder, insoluble in non-donating solvents, is left.
Addition of 1,4-dioxane to a solution of the etherate in 34
petroleum causes the immediate precipitation of the orange-red
bis-dioxonate which is also totally insoluble in CHCA 3 and dioxane
but soluble in pyridine.
[Found: CH4 (by hydrolysis End collection in a gas burette)
7.8 moles; 0,"31_2 ._; Li, 2.9; W, 38. %. C16H 401,1 04W requires
CH4, 8 moles; 0, 12.9; Li, 2.8; W, 37.2%].
1,2-dimethoxyethane when added to the etherate in petroleum
precipitates a deep red powder, the tris-1,2-dimethoxyethanate,
[Found: C, 41.1; H, 8.6; W, 29.2%. C20H54Li206W requires C, 40.8;
H, 9.2; W, 31.2%].
(iii) Reaction with Trimethylsilylmethyllithium
WMe6 + (11+1)Me- 3SiCH - 216 - - LiVIMp- -6- n(CH 2 -3) n+i + nMeLi
1. A petroleum solution of WMe6 containing a slight excess of
1,2-dimethoxyethane is treated at - 10° with a slight excess of
Me3SiCH2Li (0.9 M solution in hexane). An immediate precipitate of
the bright orange salt is formed and is removed by filtration,
washed with iso-pentane (2 x 25 ml) and pumped dry at 0°. [Found:
Li, 1.03 + 0.02; W, 26.9 + 0.9%; Li/W = 1.01; LiMe6(CH2SiMe3)-
.(04Hi 002)3 requires Li, 1.09; W, 28.8%; Li/W = 1.00].
2. To a petroleum solution of WMe6 is added at - 10° a large
excess of Me 3SiCH2Li in hexane. The mixture is stirred for about
an hour at this temperature and then filtered through a fine frit.
The light coloured solid thus removed was washed with petrol and
dried. This product exhibited a very strong lithium flame on ignition
end when dissolved in diethylether showed, in the 1 H n.m.r. at room
temperature, a doublet at T 11.2 and is thus MeLi. No identifiable
solid could be isolated from the filtrate. 7r
(iv) Reaction with Phenyllithium
A solution of WMe6 in diethylether reacts with an ethereal solution
of PhEi at - 10°, to yield on evaporation a dark oil which is
slightly soluble in iso-pentane. Repeated extraction with i:so-pentane,
combination of the extracts and addition of 1,2-dimethoxyethane
precipitated a dark brown glug thermally quite stable but quite
insoluble in non-reacting solvents.
(v) Reaction with Ethyllithium
To WMe6 in iso-pentane (20 ml) is added diethylether (50 ml) and
the solution is cooled to - 50°. An excess of EtIi in isc-pentane
(0.2 molar) is added resulting in a deep yellow solution. Addition of
a slight excess of 1,2-dimethoxyethane precipitates a thermally
unstable red tar which cannot be induced to crystallize.
(vi) Reaction \Tith n-Butyllithium o To WMe6 in iso-pentane is added, at - 80 , an excess of n-BuLi
in hexane (2.67 molar). After stirring whilst the solution warmed
to ca. - 40° a slight excess of 1,2-dimethoxyethane was added
producing a red tar which is thermally unstable above about - 10°.
(vii) Reaction with Borontrifluoride
Gaseous BF3 when bubbled through a solution of WMe6 in iso-
-pentane at - 30° causes the precipitation of a dark oil which is
slightly soluble in petrol. Dissolution of this residue in toluene
at 0° followed by filtration and evaporation yields an intractable
black solid. (viii) Reaction with Triphenyl- and Dimethylphenylphosphine To a solution of WMe6 in iso-pentane (10 ml) is added a solution of PPh3 (2 g, excess) in CH2C,e2 (10 ml). On evaporation to ca. 10 ml and cooling to - 60° only PPh3 precipitates and the solutions are
stable at room temperature for weeks. Me2PPh behal;es similarly, with no stable adduct isolable and WMe6 stabilized at room temperature for long periods.
(ix) Reaction with Methylfluorosulphonate Methyl'
To WMe6 in iso-pentane (10 ml) is added FS03110 (0.5 ml, excess) at - 60° and the solution is allowed to slowly warm to + 10° at
which temperature a unidentifiable brown tar is deposited.
(x) Reaction with Sulphur Dioxide
To a solution of WMe6 in CH2CL2 at - 70° is added an excess of
dry liquid S02. On stirring to 20° a fine brown precipitate is
deposited from a colourless liquor. This powder is air stable and
totally insoluble in organic solvents and shows in the infrared
strong very broad absorptions at 850, 1630 and 3800 an-1.
(xi) Reaction with 1,5,9-Cyclododecatriene and Hydrogen To WMe6 (0.25 g, 0.92 mmol) in iso-pentane (35 ml) containing
1,5,9-cclododecatriene (0.3 g, 1.84 mmol) is added at - 70° dry o hydrogen. Flow is continued whilst the mixture warms slowly to - 10
at which temperature a fine black sludge of tungsten metal forms
leaving a colourless organic phase.
(xii) Reaction with Lithium Aluminium Hydride
To WMe6 in diethylether (50 ml) is added at - 70°, 1 molar 3?
equivalent of LiA/H4 with vigorous stirring. On warming slowly to
- 50° a fine black sludge of tungsten metal is deposited.
(xiii) Reaction with Sodiumdihydridobis(2-methoxyethoxy)-
aluminate 'Pedal'
To a solution of WMe6 in iso-pentane (10 ml) is added an excess of NaA2H2(0GH2CH20Me)2 (0.5 ml) in benzene. At - 20° the solution is colourless and fine black precipitate of tungsten metal has formed.
(xiv) Reaction with Tris-(pentafluorophenyl)silane
A solution of (C6F5)3 SiH (2 g) in diethylether (70 ml) is added at 0° to WMe6 in iso-pentane (25 ml). After stirring at this temperature for some hours then at 20° for a period longer the solution has deposited a black precipitate of tungsten metal.
(xv) Reaction with Triphenylboron
A solution of WMe6 in iso-pentane (25 ml) is stirred with an excess of Ph3B for some hours at 0°. There is no apparent reaction and no Me3B is evolved (a slow stream of argon passed over the solution and through a pyridine wash bottle) and on evaporation a volatile red solid is obtained. After sublimation the 1 H N.M.R. of this product shows a singlet 'r 8.3 (WMe6) and no evidence of Ph-.
This solid is stable, under argon, for weeks at - 25°C. 38
(b) Reactions of Dilithiumoctamethyltunp;state
(i) Reaction with Acetic Acid
1. Li2WNE3 2MeCOOH = 2McCOOLi 2CH4 + WMe6 To a suspension of Ii2WMe8.(C4H1002)3 (1.5 g, 2.4 mmol) in iso-pentane (25 ml) at 20° is added dry acetic acid (0.28 ml, 4.8 mmol). Methane is vigorously evolved and the solid dissolves to give a red solution and a pale precipitate of MeCOOLi. After filtration and evaporation the red oily residue is sublimed at - 10° onto a probe and identified by 1 H N.M.R. as WMe6 (T 8.3) contaminated with 1,2-dimethoxyethane (T 6.60, 6.75).
2. Li 2WMe5 + 4MeCOOH = 2MeCOOLi + 20114 + WMe6.(MeCOOH)2 A suspension of Li2WMe8.(C4H1002)3 treated with 4 molar equivalents of acetic reacts similarly to the above. After filtration of the mixture and evaporation to a small volume cellulose powder (2 g) is added and the suspension stirred for
15 min at 0°. Filtration and evaporation leaves a red oil which does not sublime, or brystallize at - 1:0°. In CCL3F at 0° the IH
N.M.R. shows a singlet at T 8.2 (WMc,6) and a singlet at T 7.94 (CH3COOH) in the ratio 3 : 1 with only traces of 1,2-dimethoxyethane.
(ii) Reaction with Trimethyloxonium Hexafluorophosphate
Li 2WMe8 + 2Me30PF6 = 2LiPF6 + 2Me20 + 2C2H6 + WMe6
To Li2WMe8.(04H1 002)3 g) in CH20e2 (50 ml) is added at room temperature Me3O+PF-6 (0.61 g) and the mixture is stirred for 1 hr.
The dark mixture is stored at - 15° overnight, filtered and evaporated to dryness. Extraction with iso-pentane gives a red solution which on evaporation yields WMe6 N.M.R. singlet T 8.3). 39
(c) Reaction of the Salt from Hexamethyltunrsten and Trimethylsilyl-
methyllithium
(i) With T:i.fluoroacetic Acid
To a solution of WMe6 in isopentane at - 30° is added an excess of 0.93 molar Me3SiCH2Li in hexane producing a fine pale yellow precipitate. The mixture is stirred at - 30° for 1 hour, filtered at - 70°, the residue washed with isopentane (2 x 5 ml) at room temperature and then dried in a stream of argon. To this solid, suspended in isopentane, is added CF3COOH (1 molar equivalent based on Me3Si0H2Li added) whilst stirring at 0°. An immediate red colouration is produced and some methane is evolved. After 3 hours stirring at this temperature, the mixture is filtered to remove a light residue (+ ve Li flame test) and the filtrate is evaporated to an oil (- ve Li flame test). This red-brown oil, dissolved in
CCL3F showed in the I H N.M.R. peaks due to W-CH3 and Me3SiCH2-W
(T 8.3-8.4; T 9.2 and T 10.0) but with varying integration ratios.
The mass spectrum showed, at 20 eV and with high concentrations of sample, peaks ranging from (Me3SiCH2)3 WMe+3 (m/e = 490) through
(Me3Si01-12)2 WMei, (m/e = 418) and Me SiCH2WM4 (m/e = 346) to
(m/e = 184).
(ii) With Acetic Acid Then N,N,NI ,NI-Tetramethvlethylenediamine
and n-butvllithium
To WMe6 in isopentane (20 ml) is added diethylether (180 ml) and
Me3Si0H2Li (15 ml of a 0.93 molar solution in hexane) after stirring at near room temperature for 1 hr. NeCC,OH (0.8 mis) is added. When gas evolution ceases the milky orange-brown mixture is filtered at
- 20° and Me2NCH2CH2NMe2 (6 ml) is added to the red-brown filtrate.
No precipitate Is produced and n-BuLi (10 ml of a 2.67 molar 40
solution in hexane) is added giving a yellow brown solution which is o concentrated at - 20 to 100 ml and kept at - 250 overnight. No
product precipitates and the solution is evaporated to a brown tar which is insoluble in isonentane but soluble in diethylether.
This tar can not be freed of petrol, ether or amine and so shows very unsatisfactory 1 11 N.N.R. spectra, contains Li, is non-volatile and can not be crystallized. 41
(d) Reactions of Trialkylaluminium Compounds with Other Transition
Metal Salts
(i) WO(OMe)4 and Me3A2
To WOC/4 (5.5 g) is added Me3SiOMe (10 ml, excess) and the almost colourless mixture is refluxed 15 min and the excess ether and
Me3SiC/ removed in vacuo. Iso-pentane (30 ml) is added to the residue followed by 6 molar equivalents of Me3A/ causing immediate production of a deep-red colouration. After stirring at 0°C for
1 hr the solvent is removed and the residue sublimed. Only traces of a volatile red species, highly contaminated with aluminium alkyl are obtained.
(ii) Mo0C/4 and Me3AL
To Mo0C/4 (2.6 g) suspended in petroleum (60 ml, 30-40) is added. at - 70°C, Me3A/ (5.8 ml, 6 molar equivalents). Immedfately
Mo metal powder is precipitated from a colourless supernatent liquid.
(iii) WC/6 andEt3A/
To WC/6 (1.4 g) in iso-pentane (50 ml) is added Et3A2 (3 ml,
6 molar equivalents) at - 70°C. At ca. - 25°C the OC/6 dissolves to a green-brown solution which, with continued stirring, deposits
W metal powder.
(iv) WC/6 and (Me3SiCH2)3 A2.Et20
To WC/6 (2.1 g) in iso-pentane (80 ml) at - 70°C is added
(Me3SiCH2)3 ALEt20 (12 ml, 6 molar equivalents) with vigorous
stirring. At - 55°C a brown precipitate is formed and is redissolved by - 10°C to form a deep brown solution. Stirring is continued (1 hr Lt2
10°C, overnight - 25°C) and Me3N added to try to precipitate the
alkylaiuminiumchloridc. No solids separate and evaporation leaves
a deep-green oily mass which does not sublime and cannot be
chromatographed on cellulose.
(v) UC/6 and Me 3A2
To UC/6 (3 g) in iso-pentane (40 ml) at - 70°C is added Me3A/
(4 ml, 6 molar equivalents) causing an immediate precipitation of
fine U metal powder from the colourless supernatant liquor.
(vi) WOCA4 and Me3A/
To WOC/4 in iso-pentane at - 70°C is added Me3A/ (6 molar
equivalents) and the mixture stirred as the temperature slowly rises.
By 0°C the very dark mixture has deposited an appreciable precipitate
of fine W metal and no volatiles can be sublimed from the organic
phase.
(vii.) W(OPh)6 and Me 3A2
To W(OPh)6 in iso-pentane is added Me3A2 (6 molar equivalents)
at 25°C and the mixture stirred for 2 days. No reaction is apparent
and only minute traces of volatile species are found in the
evaporated solvent phase.
(viii) WF6 and Me 3A/
1. WF6 (3 g, 0.01 mol) in iso-pentane (20 ml) is added to Me3A/
(1.95 ml, 0.02 mol) in iso-pentane (50 ml) at - 70°. Immediately a
deep red colouration appears with evolution of heat. The solution is
stirred to 0° and the solvent removed in vacuo. From the dark
semi-solid mass only traces of a volatile red species could be 43 obtained.
2. To WF6 (19.8 g, 0.07 mol) in iso-pentane (100 ml) and cooled to - 70° is added over 1 hr. Me3A2 (38 ml, 0.4 mol). The dark red solution is warmed slowly to 0° and the volatiles removed in vacuo. The red distillate is treated with excess Me3N at - 50° and some solid removed at - 20°C. Evaporation and sublimation of the distillate yields an unstable (> - 30°) red oil which contains much aluminium.
3. To WF6 (4.5 g. 0.015 mol) in iso-pentane (50 ml) is added dry finely powdered KF (5.25 g, 0.09 mol) and the mixture cooled to
- 70°. Me3A2 (8.7 ml, 0.09 mol) in iso-pentane (40 ml) is added slowly. The dark red mixture is filtered at 0° and the filtrate evaporated in vacuo. The red oil obtained is very unstable above
- 20° and contains ca. 180 ppm AA.
(ix) TaC25 and Me3AL
1. To TaC25 (4.4 g, 0.012 mol) cooled to - 70° is added Me3A2 (5.9 ml, 0.06 mol) to give an immediate black tarry mass. Near
room temperature a violent exothermic reaction commenced and much
gas was evolved. Nothing volatile could be extracted from the
residue.
2. To TaCL5 (3.7 g, 0.01 mol) in 30-40 petroleum (50 ml) was
added Me3AL (5 ml, 0.05 mol) over 1/2 hr. at - 70°. After standing for a time at - 25° the very dark mixture had deposited a fine black precipitate from a pale green solution. Nothing volatile could be
obtained from the organic phase and the black precipitate was
amorphous to X-rays and contained 5.26° C and 1.85% H. (x) K2TaF7 and Me3A2
K2TaF7 is prepared from Ta205, HF and KF: To Ta203 (50.g,
0.113 mol) in a Pt dish is added. 40% HF (300 ml) and the mixture boiled for 2-3 hr. As the HF evaporated more is added (100 ml) and then KF (26 g, 0.45 mol) in H2O (75 ml) stirred in. The mixture is boiled vigorously whilst more HF (100 ml) is added. After 1/2 hr the contents are allowed to cool overnight. The HF is poured off and the remaining solid washed by decantation with EtOH (2 x 250 ml).
The white solid is washed onto a filter with a further 250 ml of Et0H and dried in vacuo at 25°, yield of white crystals 80 g (93%). The product is identified by T.R. by comparison with an authentic sample.
1. To K2TaF7 (1 g, 2 mmol) suspended in 30-40 petroleum
(25 ml) is added Me3A2 (1.25 ml, 12.7 mmol) at - 70°. Filtration, at - 25°, of the dark mixture yields ca. 1 g of a solid with an I.R. spectrum very similar to K2TaF7. The filtrate fumes and shows all the characteristics of Me3A2 in petroleum.
2. To K2TaF7 (7.1 g, 18 mmol) in decalin (30 ml) is added
Me3A2 (9 ml, 90 mmol) with stirring. The mixture darkens rapidly and was heated quickly to 110° whereupon a small amount of pale yellow-green liquid distills leaving a black residue. The green liquid contains (analysis by 1H N.M.R.) Me3A2 (10.65 'r) and a methyltantalum species (ca. 8.6 T).
(xi) Ta205 and Me3A2
Ta205 on heating with Me3A2 to 100°C is completely reduced with no reaction being apparent at any lower temperature. 45
(e) Preparation and. Reactions of Some Tungsten(IV) Chloride Tertiary
Phosphine Complexes
(i)Preparation of bis(triphenylphosphine)tun stentetrachloride
WC/6 + 5PPh3 = WC/4(PPh3)2 + Ph3PC22
To WCL6 (12.6 g, 0.0318 mol) in C6H6 (150 ml) is added PPh3
(25 g, 0.095 mol) in C6H6 (100 ml). Reaction occurs immediately and the mixture is refluxed and stirred far 4 hr. The yellow-orange solid is removed by filtration and washed with a little acetone.
Yield 23.3 g (80); Found: C, 49.03, 50.06; and H, 4.03, 3.72%. C361130C/4P2W requires C, 50.80, and H, 3.53%.
(ii)Preparation of bis(tri(p-tolyl)phosphine)tun stentetrachloride
WCA 6 + 4 (p-Me06H4)3 P = WU, (0711 7)3
To WCL6 (3.6 g, 0.0091 mol) in refluxing C6E6 (100 ml) is added tri(p-tolyl)phosphine (12 g, 0.0394 mol) and the refluxing continued for 2 hr. After stirring at 25° overnight the orange- -yellow solid is removed by filtration and washed with Me2C0 (40 ml) to leave a pale yellow product. The dry solid is air stable indefinitely but the solutions decompose slowly in air. Yield 7 g (81%); Found: 0, 53.86; H, 4.76; CL, 16.37 and P, 6.16%.
04042C/ 4P2W requires: C, 53.98; H, 4.54; CL, 15.17 and P, 6.65%.
(iii)Preparation of tris(dimethylphenylphosphine)tungsten- tetrachloride
WCL6 + i+Ne2PPh = WC/4(Me2PPh)3 + Me2(Ph)PCL2
To WC26 (6.2 g, 0.0156 mol) in C6H6 (100 ml) is added Me2PPh 46
(8 ml, 0.0625 mol) and the solution refluxed for 10 hr. After
cooling the deep red mixture is filtered leaving a pale solid 81 identified as Me2(Ph)PC22, M.P. 173° (CHC23), Lit. M.P. 174-6 .
The filtrate is evaporated to a red solid which was washed with
petrol and dried. Yield 10.9 g, 93%. This product displays all the 82 characteristics of the compound (Me2PPh)3 WC/4. 1/2 C6H6 but as the
third Me2PPh ligand is readily lost on attempted drying satisfactory
analyses are not obtainable. Attempted reaction of WCL6 with 4 molar
equivalents of (n-Bu)3 P, in benzene, produces a deep yellow solution
which gives a green oil on evaporation, from which no pure or
crystalline product can be obtained.
(iv) WC24(Me2PPh)3.1/2 C6H6 + NaA/H2(0C21140Me)2
To W(Me2PPh)3 C/4.1,2 C6H6 (4.5 g) in C6H6 (50 ml) is added,
dropwise, excess FraH2A/(0C2H40Me)2 (10 ml). With the first few drops
a little gas is evolved but none thereafter. After some hours
refluxing the solution has not changed appreciably in colour. After
cooling and treating with H2O to remove excess reducing agent
nothing but dark oils can be isolated from the organic layer. These
oils show no evidence (n.m.r., i.r.) for hydride formation. The
reaction of WC/6, Me2PPh, NaH2AE0C2H40Me)2 (1 : 6: excess) in H2
saturated C6H6 yields a yellow solid insoluble in EtOH, C6H6, THF,
PhMe, Me200. It gives no reaction with dil. HOZ and shows no
evidence of hydride formation (n.m.r., i.r.).
(v) WOL4(Me2PPh)3.12C6H6 + Meld
The reaction of W(Me2PPh)3 C24.%C6H6 with MeLi in Et20 at - 70°
(molar ratios 1:4, 1: 6 or 1: excess) In each case yields unstable
solutions (above - 20°) which reek strongly of Me2PPh and on 47
evaporation the residues obtained are involatile (mole ratio 1:4) and generally unstable. The problems are compounded by the fact that reproducible results are not obtained, over 6-8 experiments; however
various colour changes are observed and 'del is generally
precipitated. Attempts to "trap" the products formed initially at
ca. - 50° by the addition of CS2 yields only brown tar.
W(PPh3)2 Ci4 is much too insoluble in any suitable solvent to react with MeLi in Et20. 48
(f) Synthesis and Reactions of cis-Dichlorotetraphenoxytungsten
Synthesis: (i) WOC24 + 4PhOH
cis-WC/2(0Ph),, is reported to be synthesized from WOC24 and PhOH 83 in iso-octane , however this procedure was found to yield a large proportion of an orange-red powder with strong odour of phenol.
(ii) WC26 + 41120Ph
T20Ph is prepared from PhOH and T/OEt in Et20. To WC/6 (9.6 g,
24 mmol) in C6H6 (300 ml) is added T/OPh (29 g, 98 mmol) and the
mixture is stirred overnight and filtered. Concentration of the
filtrate, addition of Meal and cooling to - 25° resulted in the precipitation of an unidentifiable black tarry mass.
(iii)WC2 6 + PhOSiMe3
FhOSiMe3 is prepared in 62% yield from PhOH, Me3SiC2 and PhNEtz
in C6H6 84. To WC26 in CS2 or CC24 is added 4 molar equivaltmts of the silylether. Even at low temperatures (< - 30°) a large
proportion of insoluble black tar is rapidly precipitated and only
small amounts of the desired product can be extracted.
(iv) WC2 6 , 4Ph0H
W016 + 4PhOH = WC22(0Ph)f, 4HC2 85 The tetraphenoxide is best prepared from WC26 and PhOH in CC24 .
Yield: 60%, M.P. 136°, (Dit.85 M.P. 136°). Found: C, 46,56, 46.18;
H, 3.76, 3.36; C2, 11.09, 11.32%. C241120C2204W requires: C, 45.95; H, 3.22; 02, 11.32%. 49
Reactions:
(i) MeLi
To cis-WC22(0Ph)4 (1.2 g, 2 mmol) in Et20 (50 ml), and cooled to - 70°, is added a solution of Meld (4.5 mmol) in Et20. At
- 50° the clear red-brown solution separates into two layers, one light orange and the other orange-brown. By 0° the mixture consists of a pale green precipitate and a rapidly darkening liquor which deposits a dark tarry mass.
(ii) Me2NCS2T2
To cis-WC/2(0Ph)4 (2.1 g, 3.4 mmol) in C6H6 (100 ml) is added
Ne2NCS2T2 (2.2 g, 6.8 mmol) and the mixture is refluxed for some hours. The starting materials are recovered unchanged.
(iii) Me2NCS2Na.2H20
To cis-WC/2(0Ph)4 (6.27 g, 10 mmol) in C6H6 (100 ml) is added
Me2NCS2Na.2H20 (3.78 g, 20 mmol) in Meal (150 ml). On refluxing the red-brown solution changes bright red and after cooling overnight the NaC/ is removed and the filtrate evaporated to a small volume.
Addition of 30-40 petrol precipitates an oil and a small amount of a red solid both of which defy identification.
(iv) Squaric Acid
110 0
110 --- 0
cis-WC22W(OPh)6 and C411204 are refluxed (1: 1 mole ratio) for many hours in C6H6 and the starting materials are recovered unchanged. 50
(v) 2_,29 -Biphenol
To cis-WC/2(0Ph)4 (12.5 g, 20 mmol) in C6H6 (120 ml) is added
2,2t-biphenol (3.7 g, 20 mmol) and the solution refluxed until HCL evolution ceases. After filtration only black tars can be obtained from the residue precipitated by Me0H.
(vi) Catechol
To cis-WC/2(0Ph),, (12.5 g, 20 mmol) in C6H6 (100 ml) is added catechol (2.2 g, 20 mmol) and the solution refluxed until HCL evolution ceases (4 hr.). After cooling, filtration and evaporation to dryness the residue is extracted with hot benzene. Addition of
MeCH to the extracts produces a small amount of black powder, this and the residues being unidentifiable.
(g) MOC/5 + PhOH
86 An attempt to repeat the reported synthesis of Mo(OPh)3 Cte 2 yields a product which can not be recrystallized or dried in vacuo due to tar formation. An analysis of washed material was low in C and H and high in CL.
(h) WC/6 + 2-t-butylphenol
WC/6 + 3C10H130H = WC/ 3(0010H / 3)3 + 3HCL
To WCL6 (12.5 g, 0.03 mol) suspended in CC/4 (250 ml) is added with stirring 2-t-butylphenol (19 g, 0.12 mol) in CC/4 (100 ml).
HCL is vigorously evolved for 3-4 hours whilst the mixture is refluxed. After filtering hot the volume of the filtrate is 51 reduced to 100 ml and 30-40 petroleum (200 ml) is added. Cooling to - 25° overnight produces a black solid which is removed and extracted with boiling Me0H (40) m1). On cooling black crystals form. Yield 3.2 g (10), M.P. 124°. Found: C, 48.84; H, 5.48;
CA, 14.14%. C30H39C:230314 requires : C, Ll8.82; H, 5.34; CA, 14.43%.
(i) WCL6 + PhSH
To WC/6 (4.5 g, 11 mmol) in C6H6 (50 ml) is added PhSH
(7.89, 70 mmol) and the solution refluxed until HC,2 evolution ceases. The black mixture is filtered leaving a residue insoluble in petrol, C6H6 or acetone and only tars can be obtained from the filtrate.
(j) WC/6 + Catechol
To WC/6 (8.2 g, 0.021 m) in CC/4 (150 ml) is added catechol
(4.8 g, 0.043 m) in CC24 (150 ml). After refluxing 1 hr. and stirring overnight the mixture is evaporated to dryness and
extracted with Me0H (150 ml). Only a small amount of unidentified
orange-red oil can be obtained from the solution.
(k) WC/6 + Hexachlorophene
To WCL6 (5.67 g, 0.0143 m) in. CC/4 (100 ml) is added, with stirring, hexachlorophene (17.5 g, 0.043 m) in a mixture of CC/4
(100 ml) and PhCL (200 ml). The mixture is refluxed for 7 hr. and
evaporated to dryness. The remained brown solid is recrystallized
from C611E/petrol and proved to be hexachlorophene. 52
(1) WC26 + 2-isopropylphenol
To WCA6 (5.67 g, 0.0143 m) in CC/4 (100 ml) is added
2-isopropylphenol (7.8 g, 0.0572 m) in CC/4 (100 ml). The mixture is refluxed 5 hr. and evaporated to an oil. Dissolution in C6H6 (30 m1), filtration, and addition of 40-60 petrol (150 ml) followed by cooling to - 25°C yields no crystalline product and only tars are isolated.
(m) WC26 + 2,2'-biphenol
To WC/6 (5.67 g, 0.0143 m) in CC24 (100 ml) is added 2,2'-biphenol (5.35 g, 0.0286 m) in CC24 (200 ml). Immediately HC/ begins to be evolved and solids start to precLpitate. Stirring and refluxing are continued for 3 hr. and the mixture filtered. The black residue is found to contain 5.13% CA and by thin layer chromatography to be homogeneous but is unidentifiable. The filtrate on evaporation to dryness, dissolution in benzene and addition of Me0H precipitates 5.2 g of a black solid containing 17.62% CA and also unidentifiable.
(n) WC26 2-allylphenol
To WC/6 (9.6 g, 0.0242 m) in CC/4 (150 ml) is added, dropwise,
2-allylphenol (9.8 g, 0.073 m) in CC/4 (40 ml). HC/ is evolved and the mixture is refluxed for 2 hr. and filtered hot. After
evaporation to dryness the residue is dissolved in C6H6 (50 ml), filtered, and treated with Me0H (200 ml). Only tars and oils are
obtained from the solution. 53
(o) WC26 + 2-naphthol
WC26 + 4C10H70H = WC/ 2 (0C1 a7)4 + 4HC/ To WC26 (17 g, 43 mmol) in CC24 (180 ml) is added 2-naphthol
(25 g, 172 mmol) in portions. RC/ is evolved and the mixture is refluxed 1 hr. and cooled overnight. A black powder is removed and
extracted with hot C6H6 and the extracts treated with methanol (3 volumes). 10 g (28.5%) of black powder is obtained M.P. 212°C
(Lit.85 210°). Found: C, 58.26; H, 3.49; C2, 8.31%.
C40112EpA204111 requires C, 58.06; H, 3.1+2; C2, 8.57%.
Reactions
(i) WC22(Oc10H7)4 LiA/H/,
To WC/2(0C1GH7)4 (1 g) in 50 : 50 C6H6 : Et20 (200 ml) is added,
with stirring at 25°, excess LiAiH4 in portions. Much gas is
evolved (H2) and when evolution ceases H2O (10 ml) is added dropwise. Decantation and evaporation of the organic layer yields some black
starting material and 2-naphthol. M.P. 118° (1120). Lit. M.P. 122°.
(ii) WC/2(0C10H7)4 + NaH2A2(OCH2CH20CH3)2 (Redal)
To WC22(0C10H7)4 (1 g) in C6H6 (75 ml) is added Redal,
dropwise and with stirring. Two phases form, the upper red and the
lower black and oily. After an excess is added the mixture
consists of an orange-green liquor and a little blEck solid. After
water is added the phases are separated and the organic phases are
evaporated. 2-naphthol is obtained M.P. 117° (H20). Lit. M.P. 122°. 54
(p) Tungsten Hexaphenoxide
Synthesis WC/6 + 6PhOH = W(OPh)6 + 6HC2
Tungsten hexaphenoxide was prepared from tungsten hexachloride 87 or tungsten oxotetrachloride and an excess of phenol . Molecular weight (in C6H6): found 735, calculated 742 (W(OPh)6).
Reactions (i) W(OPh)6 + triphenylphosphine
To a solution of W(OPh)6 (1 g, 0.00135 m) in C6H6 (10 ml) is added Ph 3P (0.7 g, 0.0027 m) in C6H6 (20 ml). The solution is refluxed for 51 hr, after which no reaction is apparent. The starting materials are recovered unchanged.
(ii) W(OPh)6 + dimethylphenylphosphine
To a solution of W(OPh)6 in C6H6 is added 2 molar equivalents of Me2PPh and the solution refluxed for 6 hr. No reaction is apparent and the W(OPh)6 is recovered unchanged.
(iii)W(OPh)6 + sodium hydride
To a suspension of NaH (0.192 g, 8 mmol) in 60-80 petroleum ether (150 ml) is added a solution of W(OPh)6 (1 g, 1.3 mmol) in the same solvent (100 ml). The mixture is stirred vigorously and refluxed for 3 hr. and cooled. The W(OPh)6 is recovered unchanged.
No reaction is observed when 200 mg p-toluenesulphonic acid is added, as a catalyst, to a similar mixture under similar conditions. 55
(iv) W(OPh)6 + thiophenol
To a solution of W(011)6 (1 g, 1.3 mmol) in C6116 (10 ml) is added a large excess of PhSH. The solution is refluxed for 4 hr. and the W(OPh)6 recovered unchanged.
(v) W(OPh)6 + 1.2-bis-(diphenylphosphino)ethane
A solution of W(OPh)6 (1.5 g, 0.002 m) and Ph2PCH2CH2PPh2 (1.6 g, 0.004 m) in C6H6 (50 ml) is refluxed for 4 hr. Both starting materials are recovered unchanged.
(vi) W(OPh)6 + carbon monoxide
A solution of W(OPh)6 (1 g, 1.3 mmol) in C6H6 (50 ml) is heated at 150° with CO (220 atm) overnight. No apparent absorption of CO is observed.
(vii) W(OPh)6 + pyridine
W(OPh)6 (5 g) is dissolved in pyridine (75 ml) and the solution refluxed 6 hr. No reaction is observed and the starting phenoxide is recovered unchanged.
(viii) W(OPh)6 + methyl lithium
To W(OPh)6 (3.73 g, 0.005 m) in Et20 (100 ml) is added, at
- 70°, an 0.8 molar solution of MeLi (38 ml, 0.03 m). When the addition is complete the solution is stirred and allowed to warm slowly. By 0° the solution is clear and red-brown and soon after cloudiness sets in and a fine white precipitate appears at + 5°.
After filtration at 0° the ether is removed in vacuo to leave a black viscous tar from which no volatile product can be obtained by sublimation. 56
Reaction of W(OPh)6 with MeLi in petrol results in complete reduction of the phenoxide at about room temperature. No reaction was apparent at lower temperatures. An intimate mixture of
W(CPh)6 and MeLi without solvent reacts vigorously at room temperature but no volatiles can be obtained from the black residues.
(q) Synthesis and Reactions of tris(2-methylphenoxy)tungsten-
trichloride
Synthesis:
WC26 + 3o-MeC61140H WC/3(007117)3 + 3HCL
To Wae6 (40.5 g, 0.102 m) in refluxing CC/4 (500 ml) is added dropwise 2-methylphenol (33 g, 0.306 m) in CC/4 (250 ml) at such a rate that the reaction was under- control. The mixture is refluxed until no further HC2 was evolved (2 hr.) and filtered hot. The filtrate is evaporated to an oil and dissolved iii cold C6H6 (250 ml).
After filtration Me0H (700 ml) is added and the solution left to stand overnight at - 250. The black crystallin- mass is removed and dried in air. Yield 81.5%, M.P. 111°. Found: C, 4150;
H, 3.49; C2, 17.49%. C211-121C/303W requires: C, 41.24; H, 3.47;
CA, 17.39%.
Reaction of WC/6 with 3 molar equivalents of the sodium salt of o-cresol (from the phenol and Nall in Et20) in C6H6 results in the formation of "tungsten blue", by reduction, and a black tar, from which little of the desired product can be isolated.
Reactions:
(i) WC/3(0C7H7)3 + NaBH4
To W(00711 7)3 023 (0.6 g, 1 mmol) in C6H6 (15 ml) is added NaBH4 57
(0.1 g, 2.7 mmol) in EtOH (5 ml). H2 is evolved but the solution remains black. A IH N.M.P. of a sample shows a weak multiplet at ca. 10.6 T. After stirring 2 hr. the mixture is filtered, the small residue washed with C6H6 (5 ml) and the filtrate treated with
H2O (5 ml) to decompose excess NaBH4. The two layer system is filtered, removing a black glug possibly boron containing (green flame) and leaving a pale brown benzene and a green aqueous layer.
Nothing can be isolated from either layer.
(ii) W(007117 /3 + Na/Pb
To W(OC7.H 7 C23 (0.6 g, 1 mmol) in C6H6 (25 ml) is added 10%
Na/Pb alloy (1.6 g) and the mixture is refluxed for 3 days. Only the starting materials. are recovered.
(iii) W(0C417)C23 + H2/Et3N
To W(0C7H7)3 C1,3 (0.6 g) in C6H6 (50 ml) is added Et3N (1 ml) and the solution is refluxed overnight in a H2 atmosphere. The starting material is recovered.
(iv) W(OC.47) C/3 + Me2NCS2Na.2H20
To WOC.7117)3 023 (0.6 g, 1 mmol) in C6H6 (20 ml) is added
Me2NCS2Na.2H20 (0.54 g, 3 mmol) in NeOH (30 ml). After stirring at o 45 for 12 hr. the solution is orange-zed. After evaporation to dryness the residue is extracted with C6H6 (20 ml) leaving a pale
brown solid. This solid showed a positive 02 test (AgNO3) and a negative Ph0 test (FeC23). The benzene extract on evaporation yields an unidentifiable orange oil. 58
(v) W(OC 7117)3 C/3 + Me2NCS2T.0
To W(OC711 7)3 023 (0.6 g, 1 mmol) in 06H6 (75 ml.) is added
Me2NCS2T2 (0.98 g, 3 mmol) and the mixture stirred at room temperature for 3 days. After filtration and evaporation to an oil, which smelt strongly of 2-methylphenol, a little Me0H is added and the yellow brown solid removed. This solid contained i (5.63%) and
C/ (3.20%) and is unidentifiable.
(vi) W(OC 7)3 C/3 + AgC/04 AgC204 (0.62 g, 3 mmol) and W(007H7)3 CL3 (0.6 g, 1 mmol) are dissolved in Me2C0 (30 ml) and stirred overnight. The AgC/ (0.40 g,
2.9 mmol) is removed and the dark filtrate evaporated to an unidentifiable oil.
(vii)W(00 7117)3 CL3 + PhST/
PhST1 is prepared from PhSH, NH3(aq), and T/2SO4. PhST/
(2 g, 7.3 mmol) is added to W(0C7H7)3 CZ3 (1.49 g, 2.4 mmol) in C6H6 (50 ml) and the suspension stirred overnight. The dark red mixture is stirred overnight and P.ltered to remove the TLC/.
From the filtrate only a very unstable oil can be precipitated which decomposes on attempted crystallization.
(viii)W(00 7H7)3 0/3 + Ttacac
To W(OC7H7 C/3 (2.9 g, 4.8 mmol) in C6H6 (100 ml) is added
T2acac (4.3 g, 13.7 mmol) and the suspension stirred 3 days at
25° and then refluxed for 4 hr. After filtration the filtrate contains only starting material. M.P. 114° (C6H6/Me0H). 59
(ix) W(0C7iI03 0e3 + KF
To KF (0.35 g, 6 mmol) in HO4c:Ac20 (25: 5 ffl) is added, after
12 hr. reflux, W(OC7H7). CL3 (1.2 g, 2 mmol). The solution is
stirred 3 days at room temperature and then refluxed 1 day. No reaction is observed and the starting materials are recovered.
(x) W(007H7)3 CL3 + NaALH2(0C2H40Me)2
To W(007H03 C23 in toluene (2 g, 3.3 mmol) at 90°C is added, with stirring, an excess of NaA2112(0C2H40Me)2 in C6K6. H2 is evolved and after 2 hr. the solution is bright orange. After addition of aqueous NaOH to remove excess reducing agent nothing but unidentifiable oils can be isolated from the organic layer. No evidence of hydride formation is obtained by IH N.M.R..
(xi) WOC 7H 03 CA 3 + Na/Hg + C 2114
To WOC7H7VL3(0.61 g, 1 mmol) in C6H6 (100 ml) is added, with vigorous stirring, excess 2% Na/Hg. After stirring overnight the solution has lightened in colour slightly. C2H4 is passed through for 2 hr. but only an amount of a very fine black solid, resembling W metal, can be isolated from the dark mixture.
Attempts to isolate anything from the benzene before addition of C2H4 yields only brown glugs.
If any attempt is made to reflux the trichloride with Na/Hg complete decomposition occurs. Similar results are observed when
Na/K alloy is substututed for Na/Hg.
(xii) W(0071-1 7)3 C/3 + Cr(acac)2
To W(0C71-10,,CL3 (0.i g, 0.6 mmol) in C6H6 (40 ml) is added
Cr(acac)2 (0.5 g. 1.95 mmol) with vigorous stirring. Almost 60 immediately the solution turns dark green. After stirring overnight all the solvent is removed to leave a tar which is unidentifiable and completely intractable.
(xiii) W(OC 7:H 7)3 C/3 ± Me2PPh
W(007117)3 C13 + Me2PPh = W(OC 7H 7 )3 C23.Me2PPh
To W(007H03 C23 (1.2 g, 2 mmol) in refluxing C6H6 (40 ml) is added Me2PPh (1.7 ml, 6 mmol). An immediate change in colour to orange together with the formation of orange crystals occurs. After 1 hr. the mixture is cooled and filtered to give 0.9 g (61%) of W(0071103 C23- .Me2PPh as air-stable crystals soluble in Me2CO, slightly soluble in 06116 and CHCL3 and insoluble in CC/4 and petrol. They are recrystallized from CHC23 containing a little Me2CO. Found:
C, 46.27; H, 4.36; CA, 15.46; and P, 4.88%. C29H32C23P03W requires C, 46.46; H, 4.30; CL, 14.19, and P, 4.13%.
A similar experiment, replacing Me2PPh by PPh3, yields only the two starting materials.
(xiv) W(OC7H7)3 C23 + MeLi
To W(0C7H7)3 C/3 (0.6 g, 1 mmol) in Et20 (25 ml), stirred at
- 65°, is added excess Meld in Et20. Immediately the solution changes in colour to a bright light orange which decomposes to a black glug at - 25°. If the Et20 is removed at - 70° the resulting orange product is stable to - 40°. The addition of dipyridyl to these solutions does not enhance the temperature stability.
Similar reactions using trimethylsilylmethyllithium produces solutions decomposing at similar temperatures. 61
DISCUSSION
The preparation of WMe6 from WC26 and Me3A2 is a considerable improvement on the WC/6/MeLi/Et20 synthetic method. The major problem in developing the synthesis was the removal of the
Me2A/C/ by-product. Whilst it is well known that a]kylaluminium compounds form Lewis acid-base adducts, very little information regarding their stability and, more importantly in this case, their solubility in hydrocarbons appears to have been published.
The initial attempts at reacting WF6 and W(OPh)6 were based on the assumption that the species Me2A/F and Me2A/OPh, which are dimers or trimers with boiling points of 68-700/0.5 mm 88 and 1100/0.01 mm89 respectively, would be sufficiently involatile to allow the WMe6 to be sublimed from the evaporated reaction mixtures. Because the reactions did not go to completion and the partially alkylated tungsten species tenaciously held the aluminium residue, all that was volatile also contained much aluminium. Addition of a suitable donor ligand was fruitless because the species R2A2F do not readily form Lewis acid-base complexes (Et2A2F does not form a Et20 complex and Et7A/F.NMe3 dissociates above - 200 90). The acceptor properties of Et2ALX are reported to be in the order
X = F < C2 < Br < 1 91and it was expected that Me2A/C/ would be somewhat easier to remove by complexation. A report that Mel,NF reacts very exothermically with Et3A2 in hexane:
Me411F + Et 3A2 = [Me4N] [ A/FEt3] 6k indicated that the reaction of Me4NC2 with Me2A/C/:
Me2A/C/ + Me4NC/ = [MeyN] [A/C22Me2] 62 might be possible (Me4NF is not easily prepared, requiring anhydrous
Me4NCA and HF) however Me4NC2 is totally insoluble in petroleum solvents and no reaction was apparent.
For the reasons discussed previously, the reaction of Me2A2Ct with liquid or solid tertiary amines, even though insoluble products a'e formed, gives rise to serious handling problems and any excess added is unable to be removed. The adduct Me2AMLNMe3 o 92 melts at 124 and is thermally very stable , it is quite soluble in 2-methylbutane at 0° but rather less so at - 70°. Being a gas, the excess NMe3 is readily removed from the filtrate after removal of the solid adduct, and for this reason the possibility of using the gases CO2 or SO2 was investigated. SO2 reacts rapidly with alkylaluminium compounds at - 50°, cleaving all AL-C bonds to give white polymeric solids 93 however SO2 also rapidly attacks WMe6 to give unidentifiable brown polymers. At 20° CO2 reacts with
R3AL species to give colourless involatile oils but R2ALX
(X = CL, Br) fail to react An insoluble product is formed in the reaction:
KC,2 + R2A2CA = KAIR2CL2
o but temperatures of 80-100 are required 95 and the addition of
KCA during a synthesis of WMe6 had no observable effect on the reaction.
The attemnts to extend the reaction method to other metals were all fruitless. It is noted that all the transition metal-alkyls, previously prepared from a metal salt and an alkylaluminium compound, have been complexes with a donor ligand forming a species of the form R ML . The aikylating agent-donor ligand combination must be x y chosen so that the transition metal-alkyl-donor ligand compound is 63 the one preferentially formed. As an example : nickel(II)acetylacetonate reacts with dimethyl- or diethylaluminium ethoxide in the presence of dipyridyl to form the dialkylnickeldipyTidyl complex:
Ni(acac)2 dipy + 2R2A20R = dipyNiR2 + 2RA/(acac)(0R)
Addition of RAZ (R = Pie or Et) to dipyNiR2 or a mixture of
Ni(acac)2 and dipyridyl results in decomposition and deposition of 96 metallic nickel together with formation of R3AL.dipy . Herein lies the fundamental difficulty in developing a synthesis via an alkylaluminium agent: there is such a wide variety of donor ligand-alkylating agent-transition metal salt combinations that the choice of the most probable is not easy. WMe6 being virtually coordinatively saturated, and. hence unable to form complexes with tertiary amines, is thus separable from the MaAACI, by complexation of the latter. It is unlikely that the coordinatively unsaturated molecules TaMe5, MoMe5 or UMe6 could be prepared as free uncomplexed alkyls via the method used for WMe6.
The multigram quantities of pure WMe6, regularly made available by this synthesis, have allowed a more detailed examination of some of its physical properties. The HeI and Hell photoelectron spectra 97 (Fig. 2) are so different from the HeI spectrum previously reported 98 that the authenticity of the WMe6 used in the earlier investigation must be doubted. The important conclusions to be made from the photoelectron work are that the spectra are consistent with an octahedrally symmetrical WMe6 and that there is q9. slight steric compression of the methyl groups (as in neopentane ' ;.
This steric compression is manifest in the splitting of the C-H
(12-14 eV) region of the spectra. The spectra of TaMe5 97
(Fig. 3) are consistent with a molecule with D , symmetry but the 311 64
Fig. 2. Photoelectron spectra of WMe6 using HeI (21.2 eV) and HeII
(40.8 eV) Radiation.
8 10 12 14 16
/-A C(2p)-H
He II
C(2s)-H
.fr`k.)41,1"1-1)4Mtm
—r 12 114 16 18
I.P., eV 65
Fig. 3. Photoelectron Spectra of TaMe5 using He' (21.2 eV) and Hell
(40.8 eV) Radiation.
He I
041.11014 , T 8 10 12 1.4 16
eV lower symmetry causes a smearing out in the C-H region and any
splitting due to steric crowding is impossible to determine.
That there is slight steric compression of the methyls in
WMe6 can be shown by some geometrical considerations. The
observed splitting in the C-H bonding region of the photoelectron
spectrum of neopentane is only just present in tet:carnethylsilane 99
and so it is apparent that if the methyls are closer together
than they are in TMS the steric crowding is such that splitting
is observed. The Si-C bond length in TMS is 1.888 A 100 and,
assuming the molecule is tetrahedral, the distance between the
methyl carbons-can be determined:
) 2 2 D2 = -X2 + (Y1 - y2i - Z2)
where
x i = 0, y1 = 0 and z 1 = 1.888 and
X2 = 1.883 sin 109°281 cos 120°
Y2 = 1.888 sin 109°28' sin 120°
Z2 = 1.888 cos 109°28'
therefore D = 3.08 A, and for neopentane, in which the C-C distance
is 1.54 A, D = 2.52 A. These distances are within twice the
van der Waals radius of the methyl group which is 2 A. In WMe6 tne
methyls are, by virtue of their orientation to each other in the
octahedron, more crowded for a given non-bonded C.....0 distance
than in a tetrahedral arrangement. Thus, if the methyls in WMe6
are 3.08 A apart they are more crowded than they are in TMS and, by
67
Pythagorus, the W-C distance is about 2.18 A. This tungsten-carbon
bond length is close to those M-C distances obtained by 101 102 crystallographic analysis of some alkyls ' :
WMe 4[ON(MOR-7.0]2 W-CH3 2.20 I
wcp2[cH2-3,5-me2c03]2 w-cli, 2.28 A Tamec/2[0N(me)1\60] Ta-CH3 2.25 A ELimome k(TIEn2 32 mo-CH3 2.29 A
Solutions of WMe6 were used for thermochemical measurements 103
in which the alkyl was decomposed with aqueous ammonia and the
tungsten isolated as ammonium tungstate and weighed as W03. TaMe5,
in iso-pentane, was hydrolysed with moist ether and the metal
isolated as Ta205. From the heats of hydrolysis for these two
alkyls the mean bond dissociation energies D(Ta-Me) and D(W-Me) -1 -1 were determined as 62.4 + 2 kcalmole . (261 + 6 kJ.mol ) and -1 38.1 + 2 k cal mole (159 + 1) respectively. The value for -1 W-C can be compared with the values for 151,d_F. (in WF6 121 kcalmol ) -1 and DW-C/ (in WC26 83 kcal mol ), which are much higher, but it
is quite close to fw_co in W(C0)6 which is 42.6 k.calmol . Some
corresponding values for tantalum compounds are: DTa_F (in TaF5) = 1 -1 144 k cal mol , DTa_ome (in Ta(OMe )5 ) 105 k cal mol and -1 DTa_C2 (in TaC/5) = 101 k cal mol so that TTa-Me is expected to 104 be larger than bW-Me. Comparison of these bond dissociation energies
with those of other transition metal-methyl species is difficult
due to the paucity of published data and the tendency of some authors 101
to use E, the thermochemical bond energy term, to decribe the M-C
bond strength. D is given by:
MXn(s) = M(s)+ nX(6.);l75. = .1611Vn 68 whereas E is:
i-I.MRn(g)1 hae(s) = —1MCA r , R-H n ) (g)
E(m-R E(H-CA) - E(M-C2) - E(H-R) Reaction so that apart from the thermochemical measurements, an estimation of E requires the values E(H-CL), E(M-CA) and E(H-R). Some EM-Me values are tabulated in Table 1.
Table 1
Some Mean Bond-Dissociation :Energies - 1 Bond D k cal mol Reference Li-Me 59.3 105 Zn-Me 43.8 + 2 105 Cd-Me 35.2 ± 1 105 Hg-Me 29.7 + 1 105 B-Me 89.2 105 Ai-Me 68.4 105 Ga-Me 60.2 + 2 105 Sb-Me 53.6 105 Bi-Me 33.5 105 Tr-Me 40.4 + 1.5 105 Sn-Me 54.0 + 1 105 Pb-Me 40.4 + 1 105 P-Me 67.8 105 As-Me 56.9 105 Ti-Me(Me2TiCp2) 60 + 5 106 mn-Me(memA(c0;5 ) 27.9 or 30.9 107 Re-Me(MeRe(C0)5) 53.2 + 2.5 107 W-Me(WMe6) 38.1 + 2 103 Ta-Me(TaMe5) 62.4 + 2 103 Pt-Me(Me2PtCp) 39 + 5 110 Sn-Et 46.2 + 2 105 Sn-Pr 47.1 ± 2 105 Sn-iPr 43.5 + 2.5 105 Sn-nBu 47.4 ± 2.5 105 69
It is apparent that the transition metal-to-carbon bond is not inherently weak and indicates that the observed thermal stability of many transition metal alkyls is limited by kinetic rather than thermodynamic factors. The mean bond-dissociation energies for the tin alkyls in Table 1 show that the Sn-C bond in tin-methyl compounds is stronger than if the alkyl residue is ethyl, propyl etc. and that these higher homologues have similar D parameters. It is likely that this is also true for a series cf transition metal alkyls MRn, and taking chromium as an example wide differences in thermal stability are observed (approximate thermal decomposition temperatures in parenthesis):
78o) 18, CrMe4 Cr(i-Pr)4 (200) 108
Cr(t-Bu)4 (70°) 17, Cr(CH2CMe3)4 (> 1100) 102
Cr(CH2SiMe5)4 (> 1100) Cr(l-norborny1)4102 (v. high) 109
The species with the greatest thermal stabilities are those with bulky ligands which have no P-hydrogens and also coordinatively saturate the metal. Cr(1-norborny1)4 is an example of an alkyl in which
P-elimination would violate Bredt's rule and, as the 1-norbornyl radical is not very stable, decomposition by homolytic fission is not favourable. The precise reasons for the thermal stability of a particular alkyl are not always identifiable as the possible modes of decomposition are many (in a recent review the authors 101 identify 8 possible decomposition pathways ). The relative thermal stability of TaMe5 and WMe6 compared to TiMe4, CrMe4 and
ZrMe4 probably stems from the degree of coordinative saturation and the consequent kinetic stability rather than any large differences in the strength of the metal-methyl bond. The thermal decomposition of
TiMe4, TaMe5 and WMe6 yields mainly methane, with only traces of 70
unsaturated alkenes or higher alkenes, probably via a free
radical chain reaction. in which protons are abstracted from one
methyl by another forming a carbene intermediate:
MMe = [Men-2 MI=CH,] + CH4 n
No hydrogen from the solvent is incorporeted in the liberated
methane during the thermal decomposition of TiMel, and titanium 111 carbide rather than the pure metal is deposited TaMe5 on
thermal decomposition deposits a black powder containing 5.26% C
and 1.85% H however this species was amorphous to X-rays.
There are accounts of alkylidene formation by intramolecular
Q'-hydrogen abstraction amongst tantalum and niobium neopentyls
leading to species in which the metal still retains a formal 112 oxidation state of five . The precise reasons why
attempts to prepare MR5 compounds CM = To, Nb; R = neopentyl)
results in carbene formation are as yet unknown, but the acidity of
the a-protons as well as steric considerations may well be
significant. Similar factors may be also important in the reaction
of Me5SiCH2MgX and TaCL5 or NbC1,5 and of (Me3SiCH2)2 Mg with WCA4 113, 114 to give the bridged carbynes (Me3SiCH2)4M2(CSiMe3)2
The most certain way of detecting the presence of a carbene
•or carbync in an alkyl compound is by 13 C N.M.R. and it was for
this reason that the spectra of WMe6 and the salts WM4 and
W(CH2SiMa3) were closely examined for low field resonances. x(Me)7-x For comparison purposes the 13 0 N.M.R. spectra of the trimethylsilyl-
methyl bridged carbynes were recorded and these and some other spectral
results are tabulated in Table 2. The spectrum of (Me3SiCH2)4 Ta2(CSiMe3)2 is reproduced in Figure 4. 71
Fig. 4. 25.16 MHz 1 3 C N.M„2. Spectrum of (Me 3SiCH 2 )4 Ta 2(CSiMe 3 )2 in C6D6 at 25°C 72
Table 2
Carbene or Carbene 13C Resonances in Metal Alkyl Compounds
8 (wrtTMS ) JM-C (Hz) Reference (Me 3CCH2 )3 Ta = CHCMe 3 250.1 112
Cp2Ta(Me)(CH2) 228 115
( Cp Rhaph 2 )2 188.2 42.7 116
(Me 3SiCH2 )4 W2 ( CSiMe 3 )2 354 69.0 114
(Me 3SiCH2 )4 Nb 2( CSiMe 3 )2 406 114
(Me 3SiCH2 )4 Ta 2 ( Mille ) 406 114
(C0) 5w= c(oEt) (c E cPh) 286.1 102.5 117
(CO)5 W= CPh2 357.9 92.8 118
(C0)5 W= C(011e)Me 332.9 102.5 118
(C0)5 W = C(NMe 2 )Me 253.3 92.8 118
(CO )L, BrW E CC E CPh 230.6 185.5 117
(C0)4 BrW F. CCH = C (Ph) (NMe 2) 283.9 168.5 117
(CO),, BrW F. C-CH 3 288.0 178.2 118
(CO )4 BrW E C-Ph 271.0 173.3 118
Whilst the chemical shift does not distinguish between carbenes and carbynes the recently published results on tungsten carbonyl alkylidenes show that, for a series of closely related species the
183 W-13 C coupling constant is quite different depending on the hybridization of the carbon attached to the metal 118 73
There was no evidence for alkylidene formation in any of the attempted reactions of WMe6 with some of those reagents which may + + lead to carbynes or carbynes viz.Ph3C BF4 or Me30 BF4 e.g., 115
TaCp2Me3 + Ph3C+BF4 = [TaCp2Me2]+BF4 + Ph3CMe
ETaCP2Me27+BF4 + Me 3P = CH2 = TaCp2(Me ) (CH 2)+ Me 4P BF4
This may be due to the high degree of coordinative saturation of
WMe6 so that the intermediate in the formation of the salt cannot be formed and the acidity of the methyl protons may not be sufficiently high for an intramolecular transfer.
The reasons why the most prominent ion in the mass spectrum of
WMe6 is WMe+5 are not known. The possibility of a weakening of one
W-C bond by a Jahn-Teller type of distortion has been postulated but the argument was based in part on the photoelectron spectrum of a species now known not to have been WMe6 98. The fact that
WMe6 is only observed when the exciting potential is low (ca.
20 eV) and there is high concentrations of sample in the spectrometer would point to one W-C bond being inherently weaker than the others but there is no other physical evidence for this.
As an aid in identifying the multiplets corresponding to + WMe6, WMe5 etc., in what were very complex spectra, a computer programme was written to simulate the multiplet pattern corresponding to a given fragment. This programme accepts as input the atomic number of the atoms and how many of each atom there are in the species and then calculates the multiplet pattern using the isotopic abundance and mass of each isotope. The output from the programme 74 consists of the formula of the fragment the amu number of each line together with the intensity as a absolute fraction and as a percentage of the largest peak which has been set as 100.
Finally the lineprinter output plots the peaks so that visual comparisons with the experimental spectra can be made. A listing of this programme, which is written in FORTRAN IV, is presented in the Appendix.
The programme was particularly useful in analysing the spectra of the mixed alkyl species WMe (CH2SiMe3)6_x as it was very easy to simulate multiplets of the large number of possible fragments and compare these with the experimental spectra. As examples the + simulated multiplets of (CH3SiTi2)3 WMe3 and WMe6 are presented in
Figures 5 and 6.
The most distinguishing reature of the chemical properties of WMe6 is its general unreactivity towards a wide variety of reagents. This is no doubt caused by the degree of coordination saturation in the molecule which does not allow higher coordinate intermediates to form. The relative ease at which thermal decomposition occurs is quite probably due to the free radical nature of the reaction involving hydrogen abstraction from one methyl group by another. The anionic complexes Li2WMe8.Lx are quite typical in that they are more thermally stable than the parent neutral alkyls, and they are most stable when coordinated to a donor solvent or donor ligand. The precise arrangement of the atoms in the compound must await an X-ray structural determination in particular to see if discrete WMe; units occur as these would have very crowded methyls indeed. The method of treating WM4 salts with acid to liberate the neutral alkyl is of 1 RARFrT/F8AGPE1!T PEAK ANALYSIS OF THE FRAGMENT
C H SI v. 15 42 3 or; APU AhSOLUTE FRACTION PERCENT W.R.T. LARGEST PEAK \.51 486 0.00089165 0.34437463 1-I Cf) 4R7 0.0002 115 0.11244700 0 I" 0 0 188 0.17449033 67.39522552 H 489 0.15207335 58.73384446 CD Pi 490 0.25891445 100.00000000 (-1) C1. 491 0.08557086 33.04922104 492 0.22165528 85.60781860. M H 493 0.06819852 26.45553398 494 0.0291)592 11.28765011 co frd 195 0.006)6021 2.38228822 0 " 49t, 0.00133314 0.51488459 497 0.0001 9 154 0.07397543 4(48 0.00002362 0.00912116 (1) 499 0.00000215 0.00082860 500 0.00000012 0.00004670 1-4) 0 1-1 ToTAL ERP01. IS 4 IN CALCHLATION 0.00066 fi SIMULATION OF PARENT/FRAGENT PEAK REGION
486 487 488 44.*4-4**4-****444**4, t***********i******************************44**4: 4f9 444444.4“44444*4*4444.*4“4.44**4#47t4*#**44444(*************** 490 #42 44“**4444444-4+4***#*44#4**4#4*444***44****44c*********4*****************4*4**************** 401 44**4****44444*4*“4***4*444***## 492 4************4**M44#**444*T4444***********************M****** ****4.***- 4(33 44“4$4***4*44*4******44 494, 44*44t44#4.4 495 *4 4c/6 * \„1 497 408 499 500 PARENT/E1-'AGmEN1 PEAK ANALYSIS OF THE FRAGMENT
C H 6 18 on CrN AMU ABSOLUTE FRACTION PERCENT W.R.T. LARGEST PEAK •
270 0.00125930 0.42638513 271 0.00008806 0.02981509 cl H 272 0.24626493 83.38286591 cD ci- 273 0.15154187 m 51.31158829 H (a, 274 0.29534239 100.00000000 0 775 0.02024551 6.85492897 276 X 0.26551336 89.90019226 (D 277 0.01853105 6.27544451 278 0.00054784 0.18549439 (-1- 779 0.00000886 0.00300032 hj pct. TnIAL FRHOk IN CALCOLATION Is 0.00065 fi 1-10 AMU SIULATION OF PARENT/FRAGMENT PEAK REGION
270 271 772 *4.44 4 4 4 ,4444 4. 4 4. 4 4 4 4. 4 * 44#44 4 4**********#***4 ##4***##************4.*********4* 44 +* 44 ** 773 4 4 44**-4t***4##44“***444*4*********4.*44*#**44***4.4** 274 44*44 4444****444************4,*4***4**************+*#***********,t*******-44=4*** **4-** 7Th 4 4.44*#* 27f. 4 4 4 4 4 *********4 -4 4 * 444*44 ## #44*4 44:#4.44.4444-######***4*;#####*##*****4 va########*#********** 777 44 4 444 278 279 possible general use as it is frequently much easier to isolate a salt with the same metal oxidation number than the corresponding
MMe species. The reaction of Me3SiCH2Li in hexane with petroleum n solutions of WMe6 to give mixtures of L1WMe (CH SiMe3) and a 6-x 2 x+i precipitate of MeLi is no doubt assisted by the total insolubility of methyllithium in those non-polar solvents.
The unsatisfactory results obtained in the many attempted syntheses of tungsten-halide-phenolic complexes quite possibly are due to the formation of bridged polymers or species in which the tungsten has abstracted the oxygen from the phenol to form
W=0 compounds. It is well known that WC/6 rapidly attacks oxygen containing solvents such as Et20 or THE to give cxyhalide complexes.
It is noted that all attempts to form an isolable compound with chelating phenolic groups failed and insoluble products formed.
These were probably polymers with the potentially chelating ligand preferring to bridge instead. The reactions of cis-WC22(0Ph)4 with reagents such as Meld quite likely involves attack on the rings as well as halide substitution. 78
APPENDIX
LISTING OF AND INPUT INFORMATION FOR PROGRAM PEAKS FOR
SIMULATING ISOTOPIC MULTIPLET PATTERNS 79
Input Data and Program PEPKS
Card 1 ICODE IPRNT Format A8,11
Set ICODE = TERMINAL to get reduced output suitable
for a teletype with 80 characters/line otherwise leave
blank.
Set IPRNT = 1 for list of all elements with isotopic
abundances and mass numbers otherwise leave blank.
Card 2 ATOMNO Format 4012
List of atomic numbers of all atoms in the molecule/fragment.
Card 3 SUBSCR Format 4012
List of numbers of each type of atom in the fragment in
the order corresponding to the atoms in Card 2.
Cards 2 and 3 are repeated for each fragment and the input data set is terminated by a blank card.
To generate the two simulations of WMe3(CH2SiMe3)3 and WMe
(Figures 5 and 6) the following data set was used:
Blank card
06011474
15420301
060174
061801
Blank card • • • •
80
1r-11 1,0111'11.rkf' IV v01-08 T 10 01-,1UL-7h 00:03:30 PAC,0.: 001
C 0001 1.;11.07:kS[00 ft.q 100(112),03 ),ISDTOP(13,92),PCT(1-12),STOkEf.100,1. 4: ,AT 0f-m0( 40 ),SOkSCH( 4 0),0C1, 0S(200),NArT(92),0141,40L(40), 4 PLAT(1(i0 ) ,ISOTuk(1 3,3 0 ),I50705(13,21),ISOTOT(13,18), . 1:30T00(13,23),POS(112) C. 0002 ISDTOP,ISOT[M,150TOS,ISOTOT,ISDT00,w4PCT,M1/2100 0003 8FAI.48 1Tr.:,j0O1E 0004 INTER ATomin,SUH5CO3F,G,FOPMUL,SU0I 0005 E(U1VALENCA: (ISOT(w(1,1),ISOT(J8(1,1)),(ISOTOP(1,31),ISOTOS(1,1)), ( ISOTOP( 1 ,52),Is(JTOT(1,1)),(IS0TOP(1,70),15DTOU(1,1)) C,C 0006 DATA PEAK,PKAKXX,6LANK /10*, 1H ,2H / C 0007 DATA 1.50Trik /0.009850 ,0.000150 , 11 4 0.0 .0.000001 , 10.99999 2 9 4 11 * 0,(J 0.075200 .0.921800 , 31 4 0.0 .1.000000 . 0 .0 * 0.187150 0.81)850 ,11 * 0.0 ,0.988920 ' 0.011080 , 11 0.0 4 0.996350 ,0.003650 , 11 0.0 0.997590 ,0.000374 0.002039 4 10 * 0.0 ,1000000 , 12 0.0 '0.909000 , 0.002570 0.080200 * 10 * 0.0 "1.000000 , 12 0.0 '0.780000 ,0.101100 ,0.112900 10 4 0.0 1 .000000 , 12 * 0.0 , 0.922700 ,0.0461. 00 ,0.030500 4 10 * 0.0 '1.000000 , 12 * 0.0 .0.950509 ,0.007400 , 0.041000 0.0 ,0.000160 , 8 * 0.0 , 0.754000 0.0 0.246000 10 * 0.0 ,0.003370 0.0 0.000630 0.0 ,0,996000 4 8 * 0,0 ,0.930800 ,0.000119 , 0.0691(0 ,10 * 0.0 .0.969700 , 0.0 ,0.006400 ,0.001450 ,0.020b00 ,0.000033 '0.0.00185. 4 5 * 0.0 '1.000000 ,12 * 0.0 ' 0.0i9500 ,0.077500 ,0.734500 0.055100 .0.053400 , 8 4 0.0 ,0.002400 ,0.997600 .11 * 0.0 4 0,013100 0.0 ,0.831600 ' 0.095700 ,0.023800 , 8 * 0,0 1.000000 ,12 * 0.0 ' 0.058400 0.0 ,0.916800 '0.021700 0.003100 , 0 * ' 1.000000 , 12 * 0,0 ,0,677600 0.0 0.261600 '0.012500 0.036600 0.0 0.011600 : 6 * 0.0 0.691000 0.0 ,0.309000 , 10 * 0.0 ,0.488900 , 0.0 , 0.278200 '0.041400 , 0.185400 0.0 0.006170 ,6 * 0.0 / 0008 DATA 1SOTUS /0.602000 0.0 ,0.398000 ,10 * 0.0 ,0.205500 0.0 ,0.2/3700 ,0.0/6200 ,0.367400 0.0 0.076700 6 * 0.0 ,1.000000 ,12 * 0.0 0,008700 0.0 ,0.090200 0.075800 ,0.235200 0.0 ,0.498200 ,0,091900 , 5 * 0,0 * 0.505200 0.0 0,4/4800 , 1 0 4 0,0 '0.003540 ' 0,0 0,022700 0.0 '0.115000 ,0.115500 ,0.569000 ,0.173700 * 5 4 0.0 '0.721500 0.0 ,0,278500 ,10 0.0 '0.005600 0.0 ,0.098000 '0.070200 .0.825600 ,0 * 0.0 ,1.000000 12 * 0.0 ,0.514600 0.112300 ,0.171100 0.0 0.174000 0.0 0.028000 ,6 * 0.0 '1.000000 .12 * 0.0 ,0.158600 4 0.0 ,0091200 $0.157000 ,0.155000 0.095400 .0.237500 4 0.0,0.096200 , 4 * 0.0 ,1.000000 ,12 * 0.0 ,0.054700 ,0,010400 4 0.127700 ' 0.125600 '0.171000 0.317000 .0.185600 , 6 * 0.0 4 1.000000 , 12 * 0.0 ,0009600 ,0.109700 ,0.222300 ,0.273300 • 0.267100 ' 0.118100 , 7 4 0.0 ,0.513500 ,0,486500 ,11 * 0.0 4 0.012150 ,0.008750 .0.123000 0.127500 ,0.140700 ,0.122600 4 0.286000 ' 0.075800 , 5 .1. 0.0 ,0.042300 0.957700 ,11 # 0.0 * 0.009500 0.0 O .000500 ,0.003400 '0.142400 ,0.075700 4 0.240100 ,0085800 ' 0 .319/00 , 0.0 .0.047100 , 0.0 4 0.059600 , 0.572500 u.0 ,0,427500 ,10 4 0.0 / C 81 PC-11 F01, 1Ptr; iv V010-01 THU 01-JUL-76 00:03:30 PAGE 002 i)(■0 1) 0A1A 1S1)1lii 20,00')090 , 0.0 ,0.024600 ,0.008700 ,0.046100 , 4 0.(,k9L)00 ,0.10/100 , 0.0 ,0.317900 , 0.0 ,0.344900 4 , 2 4- 0.0 ,1,000000 ,12 4 0.0 ,0.000960 , 0.0 ,0.000900 , 4 0.0 ,0.019190 ,0.264400 ,0.040800 ,0.211H00 ,0.260900 4 0.0 ,0 .101400 , 0.0 ,0.008700 ,1.000000 ,12 4 0.0 , 4 0.001010 , 0.0 ,0.000970 , 0.0 ,0.024200 ,0.065900 , 4 0.0/8100 1 0.113200 0.716600 , 4 4 0.0 .0.000890 0.999110 , 4 11 4 0.0 ,0,001930 , 0.0 ,0.002500 , 0.0 0.884800 4 , 0.0 ,0.110700 , 6 * 0.0 ,1.000000 ,12 4 0.0 0.271300 4 0.122000 ,0.238/00 ,0.083000 0.171800 , 0.0 0.057200 , 4 0, 0 ,0.066000 , 4 4 0.0 ,1.000000 .12 * 0.0 ,0.031600 I T 0.0 , 0.0 ,0.150700 ,0.112700 ,0.138400 0.074700 , 4 0.0 , 0 .200300 , 0.0 ,0.226100 , 2 4 0.0 0,477700 4 , 0.0 ,0.522300 ,10 4 0.0 0.002000 , 0.0 0.021500 4 , 0.117300 0.104/00 ,0.156800 ,0.248700 , 0.0 ,0.219000 4 , 4 4 0.0 ,1000000 .12 * 0.0 ,0,000524 , 0.0 0.000902 * , 0.0 0.022910 ,0.188800 0.255300 ,0.249700 .0.281800 , * 4 4 00 ,1.0000o0 ,12 * 0.0 ,0.001360 , 0.0 ,0.016600 , 4 0.0 ,0.344100 ,0.229400 ,0.270700 , 0.0 ,0.148800 , ,. 4 4 0.0 ,1.000000 ,12 4 0.0 / 0010 0,6 1A 1S01110 /0.001 10 0 ).0 .0.030300 0.1 4 3100 0.218200 4- 0.161300 ,0.319400 , 0.0 ,0.127300 , 4 4 0.0 ,0.974000 0.026000 ,11 4 0.0 0,001800 , 0.0 1 0.061500 ,0.183900 0.270800 ,0.137600 0.354400 , 6 4 0.0 ,0,000123 .0.999680 11 * 0.0 ,0.00130 0.0 0.264000 ,0.144000 0.306000 0.0 ,0.284000 , 6 0.0 ,0.370700 , 0.0 0.629300 4 10 4 0.0 ,0.00 010 0 0.0 ,0.015900 ,0,016400 0.1.33000 4 0,161000 0.264000 , 0.0 ,0.410000 , 4 4 0.0 0.373000 4 0.0 .0.627000 ,10 * 0,0 0.000120 , 0.0 0.007800 0.0 .0.328000 0.33/000 ,0.21000 , 0.0 0.072300 4 4 4 0,0 ,1.000000 ,12 4 0.0 ,0001460 0.0 4 ,0.100200 0.168400 0.231300 i0.131200 ,0.298000 , 0.0 ,0,068500 4 4 0.0 ,0.296000 0,0 ,0.705000 ,10 4 0.0 0.014800 0.0 ,0.236000 ,).226000 ,0,523000 , 8 4 0.0 ,1.000000 4 12 4 0.0 .Lo00oOn ,12 *0 .0 ,1.000000 ,12 * 0.0 ,1.000000 12 * 0,0 ,1000000 ,12 *0 .0 ,1.000000 ,12 * 0.0 ,1.000000 12 * 0.0 .1.000000 ,12 *0 .0 ,1.000000 ,12 * 0.0 0.000058 0.007150 , 0.0 , 0.0 ,0,992800 , 8 * 0.0 / C non DATA HW /1,3,6,9,10,12,14,16,19,20,23,14,27,28,31,32,35,36,39,40, 45,46,50,50,55,54,69,58,6 3, 6 4,69,70,75,74,79,78,85,84,89. 90,93,92,98,96,103,102,107 ,106 ,113,112,121,120,127,124, 133,130,138,136,141,112,14 7 ,14 4 ,151,151,159,156,165,162, 160,166,175,174,180 ,J 80 ,185,18 4 ,191,190,197,196,203,204, 4 209,110,210, 2 22 ,223,226,227,232,231,234,0/ C )012 0A1A /100 ,2H107',7HL1,2HIA,2HP, ,?HC ,2HN ,280 ,211F ,2HNE, 4 2H■JA,2HG12HAL,2H.91,2oP ,2HS ,2HCL,2HAH,2HK ,2HCA, 4 2880,2011,2HV ,1HCP,2HtIN,2HFK,1HC0,2HNI,2HCU,2H7A, 4 2 hGA ,2 t1 (;f::,2HA:3,2H6F.,208P.,2HKP,280'0,21ISP,2HY ,2117,R, 2HN H ,2 H mn,2HTC,2HP 0,1HPH,2HPD,7HAG,2110D,28IN,2HSt1, 2HS6,2ri1'E,281 ,2riXE,2HCS,2HBA,2HLA,2HCE,2HPR,2HND, 4 2HP M,26Sm,2h1.:. 0,20GD,20Th,2HDY,2080,2HEP,2HIM,2HYR, 2H1,0,20hF,24T8,2807 ,2HPF,21i05,2HIP,2HPT,2HAU,2HHG, 201L,1HPH,21011,2 HP0,2 HA 1 ,1H8 N,2HFP,211PA,2HAC,2H1"H, 2HPA,2H0 / -4. 11 • 44- r , .1. -1 •r 11 .r 44- .4- .1. 82 1,1'-11 F0)P1'PAN iv V01H-08 THU 01-JUL-76 00:03:30 PAGE 003 C 0013 DATA ITEkf.!. /8HUEP.%1 INAh/ 0014 PEA0(5,6i63) 1COE,IPPNT 0015 6363 FOkmAr(AH,11) 0016 (1PPNT .ED. 0) GO TO 1001 0018 wP1TE(6,666 6 ) 0019 DO 2 1 = 1,92 0020 NPITF(6,6661) N4^1E(I),1 0021 MiAiK = Mw(1) 0022 TOTADM = 0.0 0023 DO 1 J = 1,13 0024 IF (ISOTOP(J,I) .LE. 1.0E-06) CO TO 1 0026 TOTALM = TOTALM 1SOTOP(J,1) 0027 wRiv!:(6,6668) ',0 ,NAME(1),ISOTOP(J,I) 0028 1 Mv4K = MiriK + I 0029 PHITF(6,6669) TOTALM 00 30 2 CONTINUE 0031 6666 FOPmAW1 LIST' OE ISOTOPIC ABUNDANCES USED') 0032 6667 FORPAT(//' LIST FOP 1 ,A2,' ATOMIC NUMPEP = 1 ,13/) 0033 6668 F1ipHAT(1X,13,IX,A2,Fg.6/) 0034 6669 FOPMAT(' TOTAL ABUNDANCE = 1 F9.6) 0035 1001 PEAD(5,3) ATi),INOJ 0036 IF (AfomN0(1) .E.U. 0) GO TO 9999 0038 PEAD(5,3) SUPSCP 0039 3 FOPMAT(4012) 0040 N 0041 DU 25 KE = 1,40 0042 1F.(SNBSCP(KE) .LT. 1) GO TO 25 0044 SUIIKE = SUKSCR(KE) 0045 00 4 K = 1,SUPKE 0u46 N = N 1 0047 IF (N .GT. 200) GO TO 98 0049 4 NUCLDS(N) = AT(:lMN0(KP') 0050 25 CONTINUE 0051 mwPCT:1) = 1.0 0052 00 61 KAMCEL = 2,112 0053 61 NiV:PCT(KAMCE.'(j) = 0.0 0054 DO 5 JI = 1,0 0055 F = NUCLUS(J11 0056 DO h JB = 1,10.0 0057 DO 6 JC = 1,13 005P STOPEWH,JCI = ISOTOP(JC,F) miAPCT(JB) 0059 IF (STOPE(JB,3C) .LT. 0.0000001) STUHF.'(JB,JC) = 0.0 0061 6 CONTINUE 0062 DO 7 JO = 1,112 0063 7 WAPCT(J0) = u.0 0064 DO 8 KZ = 1,100 0065 DO 8 KV = 1,13 00b6 K mv,PC1(KZ + KV - 1) = MwPCT(KZ f KV - 1) + STCME(KZ,KV) 00b7 5 CONTINUE . 0068 hSlOp = 0 0069 DL; 10 KC = 1,40 0070 C = t.TCYNO(KG) 0071 IF' (C .GT. 0) CO TO 12 0073 1-0'00.11L(KG) = BLANK 0071 Go 10 10 83 or-J1 FORTRAN IV volt-08 'J rill 01-jUL-76 00:03:30 PAGE 004 0075 12 VI.11-0,0UL(KG) = NAME(G) . 0016 NSTOP = NSTOP 1 0071 10 CoNTINUE 0078 oRITE(6,111 (FORmUL(KH),KH = 1,NSTOP) 0079 11 FORMAT(1H1 I PARENf/FRAGNENT PEAK ANALYSIS OF THE FRAGMENT ///13X, 20A4) 0080 v:PITE(6,73) (SUBSCP(KH),KH = 1,NSTOP) 0081 73 FORMAT(14X,2014) 0082 MOLNC'4 = 0 0081 DO 14 KU = 1,40 0084 I = ATOmNO(KJ) 0085 IF (I .LT. 1) 1 = 93 0087 14 MOLECv4 = M7)LEC..1, + SUBSCP(KJ) MW(I) 0088 AMAX = 0.0 0089 DO 15 KK = 1,112 0090 15 AMAX = AmAX1(AmAX,M,ATCT(KK)) 0091 DO 771 L = 1,112 0092 LL = 113 - L 0093 IF (MwPCT(LL) .NE. 0.0) Gil 10 772 0095 771 CONTINUE 0096 772 KOUNT = LL 0097 10TAL = 0.0 0098 MOLECW = MIJJJNCW - 1 0099 wRITE(6,63) 0100 63 FORMAT(/' AMU ABSOLUTE FRACTION PERCENT W.R.T. LAPC +EST PEAK'/) 0101 DO 17 KK = 1,KOUNT 0102 TOTAL = TOTAL + MWPCT(KK) 0103 Mw100(KK) = MNPCT(KK) / AMAX 4 100.0 0104 MOLFCw = moLECw + 1 0105 POS(KK) = MOLEC4 0106 17 WRITE(6, 18) MOLEC1'J,0wPCT(KK),MW100(KK) 0107 18 FORMAT(110,F20.8,F23.8) 0108 19 TOTAL = 1.0 TOTAL 0109 WPITE(6,64) TOTAL 0110 64 FORMATUIX,ITOTAL ERROR IN CALCULATION IS 'F8.5/) C 0111 IF (KO(1NT .GT. 24) WRITE(6,888) 0111 88b F0NHAT(1H1) 0114' WRITE(6,92) 0115 92 FWmAT( 7X,'AMU SIMULATION OF PARENT/FRAGMENT PEAK REGION' .0116 NLIM = 100 0117 DO 31 KK = 1 , KOUNT 0118 MMM = IFIX(Mw100(KK)) 0119 IF (iCODE .NE. [TERM) GO Ti) 41 0121 mw100(KK) mvi100(KK) .0 0.6 0122 NUM = 60 0123 mMM = JF1X(m0,100(KK)) 0124 41 IF (W100(KK) - FLOAT(MmM) .GT. 0.5) MM0 = MMM t 1 0126 IF (mm!I .E0. 0) GO TO 39 0128 00 38 KZ = 0129 38 PLAT(KZ) = PEAK 0130 39 0m01 = 0M0 + 1 01 31 IF (0MM1 .GT. 100) mm01 = 100 0133 DO 40 KX = Imm1,100 0134 40 PLAT(KX) = PEAKXX 01 35 37 v,k11E(6,46) PoS(KK),(PLAr(I1,11 = 1,NLI0) 811 PT-11 F- OPFPAN IV VO1H-OH THU 01-JUL-76 00:03:30 PAGE 005 0136 FUPmA1'(110,2X,100A1) 01 37 GU TO 1001 013'; 98 w;PA`1K(6,1(101 0139 100 FOPmAT(' Too MA:Pe ATOMS') 0140 GO TO 1001 0141 9999 STOP 0142 END REFERENCES 1. F.A. Cotton, J.M. Troup, T.R. Webb, D.H. Williamson and G. Wilkinson, J. Amer. Chem. Soc., 1974, 25.., 3824. 2. R.A. Andersen, F. Carmona-Guzman, K. Mertis, E. Sigurdson and G. Wilkinson, J. Organometal. Chem., 1975, 22, C19- 3. G.W. Rice and R.S. Tobias, 170th. A.C.S. Meeting, 1975, Abstr. INOR 63. 4. H.J. Berthold and G. Groh, Z. anorg. allg. Chem., 1963, 319, 230. 5. H. Gilman, R.G. 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