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Home , Platinum group, William Odling

DOI: 10.1595/147106708X297486 The and the

By W. P. Griffith Department of , Imperial College, SW7 2AZ, U.K.; E-mail: [email protected]

The year 2007 marked the centenary of the death of (1834–1907). This article discusses how he and some of his predecessors accommodated the platinum group metals (pgms) in the Periodic Table, and it considers the placing of their three transuranic congeners: (108Hs), (109Mt) and (110Ds). Over twenty-five years ago McDonald and Hunt (1) wrote an excellent account of the pgms in their periodic context. This account is indebted to that work. The present article introduces new perspectives and shows some of the relevant tables. There are good books on the history of the Periodic Table, e.g. (2, 3) and other texts (4, 5) which provide a fuller picture than it is possible to give here.

Discovery and Early Classification and in 1802 and 1804 (6) and of the Platinum Group Metals Smithson Tennant’s (1761–1815) isolation of iridi- Antoine-Laurent Lavoisier (1743–1794) in 1789 um and in 1804 (7, 8). was the defined the element as being “the last point that last to be isolated, by Karl Karlovich Klaus analysis can reach”, and it was largely this clear state- (1796–1864) in 1844 (9–11). Thus, five of the six ment which brought about the discovery of 51 new were known by 1804, and the sixth by 1844, in good elements in the nineteenth century alone. John time for the development of the Periodic Table. Dalton’s (1766–1844) recognition in 1803 of the The pgms are now known to fall into two hori- atom as being the ultimate constituent of an element, zontal groups: Ru-Rh-Pd and Os-Ir-Pt, but we with its own unique weight, was crucial. Stanislao benefit from some 200 years of hindsight in this Cannizzaro (1826–1910), at the celebrated Karlsruhe observation. Johann Döbereiner (1780–1849) noted Congress (1860), published a paper recognising the similarities in the chemical behaviour of ‘triads’ of true significance of Avogadro’s molecular hypothesis elements, in which the equivalent weight of the mid- and thereby clarified the difference between atomic dle element lay roughly halfway between those of the and molecular weights. From then, reasonably accu- other two. In 1829, when Professor of Chemistry at rate atomic weights of known elements became Jena, he used his equivalent weights for these metals readily available and greatly helped the construction (based on oxygen = 100) to demonstrate that Pt-Ir- of useful Periodic Tables. Atomic (or elemental) Os and Pd-‘pluran’-Rh ‘triads’ existed (12). ‘Pluran’ weights were useful but were not a sine qua non for had been reported together with two other ‘new’ ele- table construction. A number of tables were pro- ments in 1827 by Gottfried Osann (1796–1866). It duced with incorrect values, or, as Mendeleev later may possibly have contained some ruthenium, but noted, inconsistencies in published atomic weights Berzelius was unable to confirm the novelty of these became apparent from these tables. We have the three elements, and Osannn subsequently withdrew benefit of hindsight and know that atomic numbers his claim (13). are crucial factors for periodicity. In 1853 John Hall Gladstone (1827–1902), then Platinum is a of antiquity, but the other five a chemist at St. Thomas’s Hospital, London, noted pgms were isolated in the nineteenth century. The that the Rh-Ru-Pd triad was related to that of bicentenaries of four were marked in this Journal: Pt-Ir-Os, while the ‘atomic weights’ (sic) of the latter ’s (1766–1828) discovery of triad were roughly twice those of the former (14). In

Platinum Metals Rev., 2008, 52, (2), 114–119 114 1857 William Odling (1829–1921), then teaching early form of the atomic number (e.g. H = 1, Li = 2 chemistry at Guy’s Hospital, London, noted the etc.) (22). Although the pgms featured in Newlands’s great similarity of Pd, Pt and Ru, that the ‘atomic tables they were often out of place. William Odling weight’ (sic) of Pt (98.6) was about twice that of Pd (born, like Newlands, in Southwark, London), (53.2), and that Pt, Ir and Os were chemically similar whose pgm triads we have noted above (15), pro- (15). The stage was now set for a periodic classifica- duced in 1864 a table of 61 elements in which the six tion of these and indeed all the elements then pgms were grouped together (Ro is rhodium). He known. was the first to arrange them in a reasonably logical way in a Periodic Table (Figure 2) (23). The Development of Periodic The stage was now set for two giants of periodic- Classifications ity, Lothar Meyer and, above all, Dmitri Mendeleev. In 1862 Alexandre-Emile Béguyer de In 1868 Julius Lothar Meyer (1830–1895), Professor Chancourtois (1820–1886), Professor at the École of Chemistry at Tübingen arranged 52 elements in des Mines, Paris, devised a ‘vis tellurique’ (telluric an unpublished table with Ru & Pt, Rh & Ir, Pd & screw) (16), a helix on a vertical cylinder on which Os side-by-side. His slightly later table, published in symbols of the elements were placed at heights pro- 1870 (24), places the pgms correctly, but a number portional to their atomic weights. Although some of other elements lie in a sequence different from pgms appeared on it (Rh and Pd on one incline and that of modern tables: Ir and Pt on another), no relationships between Mn = 54.8 Ru = 103.5 Os = 198.6? them are discernible. Fe = 55.9 Rh = 104.1 Ir = 196.7 Karl Karlovich Klaus, then professor of chem- Co = Ni = 58.6 Pd = 106.2 Pt = 196.7 istry at the University of Kazan (now in Tatarstan), had discovered Ru in 1844 (9–11) and knew more On 6th March, 1869, Dmitri Mendeleev about the pgms than anyone else. In 1860 (1834–1907) produced his first table (25, 26). he arranged the three most abundant ones in a Mendeleev was born in Tobolsk, Siberia, the last of Principal series (Haupt Reihe), and beneath them fourteen children. His father became blind when placed a Secondary series (Neben Reihe), noting Dmitri was sixteen, and his indomitable mother, also the chemical similarities of each vertical pair determined that he should be well educated, hitch- (17–19) (Figure 1 (18)). hiked with him on the 1400 mile journey to the Klaus’s table shows the correct vertical pairs, but University at Moscow. Here he was refused admit- not in the now accepted sequence. The pgms were tance because he was Siberian; they travelled a not set in the context of other elements. In 1864 the further 400 miles to St. Petersburg. There in 1850 analytical chemist John Alexander Raina Newlands Mendeleev got a job as a trainee teacher; his mother (1837–1898) proposed the first of his tables, arrang- died from exhaustion in the same year. In 1866, after ing the known 61 elements in order of ascending a spell of study in Germany (he had attended the atomic weights (20, 21). In his subsequent ‘law of 1860 Karlsruhe Congress) and France, Mendeleev octaves’ he noted that the chemical properties of became Professor of Chemistry at the University of some elements were repeated after each series of St. Petersburg. seven, and assigned ordinal numbers to elements in Mendeleev’s interest in periodicity may well have the sequence of their ascending atomic weights: an dated from the Karlsruhe Congress and been

Fig. 1 Klaus’s arrangement of the platinum group metals of 1864 (18)

Platinum Metals Rev., 2008, 52, (2) 115 Fig. 2 William Odling’s table of elements from 1864 (23)

cemented by a textbook on inorganic chemistry, part partly brought about by his astonishingly accurate of which he finished in 1868. More than any of his predictions of the properties of the then unknown predecessors in the field of periodicity, he had a scandium (shown as ‘–- = 44’ in Figure 3), gallium remarkable knowledge of the chemistry of the ele- ‘–- = 68’ and germanium ‘–- = 72’. Mendeleev’s pre- ments. His first published version placed the pgms dictions also led to the subsequent discovery of other together but with unusual pairings (25, 26): elements including francium, radium, technetium, Rh 104.4 Pt 197.4 rhenium and polonium. Other factors such as the Ru 104.4 Ir 198 successful accommodation or placement of the ele- ments were also important, a topic well discussed in Pd 106.6 Os 199 a recent book (3). The version normally regarded as Mendeleev’s It is apparent from Mendeleev’s tables that for definitive table appeared in 1871, first printed in a him (and others) the pgms, some of the transition Russian journal (27) and then reprinted in Annalen in metals, and then known posed the same year (Figure 3) (28). By then Mendeleev a problem; here we concentrate on the pgms. He had seen Lothar Meyer’s paper and almost certainly noted their very similar properties and that there knew of Newlands’s and Odling’s work, but his table were very small differences between the atomic represents a major advance in classification of the weights of Ru-Rh-Pd and between those of Os-Ir- elements, for the first time placing the pgms in their Pt (28). He knew that only Ru and Os demonstrated modern sequence and in context. The dashes under octavalency in Group VIII (‘RO4’; R denotes an ele- the Ru-Rh-Pd-Ag listing under Group VIII misled ment), but includes Rh, Pd, Ir and Pt in Group some later workers to think that missing elements VIII. Mendeleev also placed , and , were being denoted (13). Acceptance of his table was and the , and in

Platinum Metals Rev., 2008, 52, (2) 116 Fig. 3 Mendeleev's Periodic Table of 1871 (28)

Group VIII; he additionally accommodated the appropriately placed in the fourth row of the tran- coinage metals in Group I. His problems with all his sition metals (using 6d orbitals), or were members Group VIII elements continued to trouble him: as of a -like series, the ‘actinides’, using 5f late as 1879 he published two papers in Chemical orbitals. The latter view prevailed (33), and now all News which tried to address this difficulty (29, 30). the actinides ( to lawrencium inclusive) are In the first paper he split Groups I–VII into left- known. Indeed, elements up to and including 118 hand ‘even’ and right-hand ‘odd’ blocks, with are now established, with the exception of element Group VIII in the centre, Cu, Ag and Au being 117 (34). These elements are recognised by the accommodated in both VIII and the ‘odd’ I–VII International Union of Pure and Applied (29). In the second paper he ruefully refers to Chemistry (IUPAC), although only those up to 111 Group VIII as ‘special’ and ‘independent’ (30). have ‘official’ names (Figure 4) (35); see also (36). Mendeleev published some thirty Periodic Mendeleev’s table (28) omits most of the lan- Tables and left another thirty unpublished (3), but thanides and actinides and, of course, the noble the 1871 one (Figure 3) (28) is his most successful: gases which were not known when he made up his it is the definitive Periodic Table of the nineteenth table. However, some 140 years earlier, his version century and the basis of all later ones. As late as had essentially contained the kernel of our modern 1988, the leading inorganic textbook “Advanced Periodic Tables. Inorganic Chemistry”, by Cotton and Wilkinson Recent chemical work on a few very short-lived (fifth edition) (31) shows Group VIII as containing atoms of each element strongly suggests that ele- the nine elements Fe, Co, Ni and the pgms (Cu, Ag ments 104 to 111 are members of a fourth and Au are designated as Group IB). It was only in series involving 6d orbitals. Thus the sixth edition of 1999 that the modern form 104rutherfordium, 105dubnium, 106seaborgium and (Figure 4), in which the pgm vertical pairs are in 107bohrium have properties analogous to those of Groups 8, 9 and 10, was used (32). hafnium (Group 4), tantalum (Group 5), tungsten (Group 6) and rhenium (Group 7) respectively. The Transuranic Congeners of the The next three elements were all made in the Platinum Group Metals linear accelerator in the city of Darmstadt, Hessen, The story now moves forward to the Second Germany. Hassium was first made in 1984, and World War, when there was discussion as to named from the Latin ‘Hassias’ for the state of whether uranium, neptunium and plutonium were Hessen. Meitnerium was first made in 1982, and

Platinum Metals Rev., 2008, 52, (2) 117 Fig. 4 The current Periodic Table (35) based on IUPAC recommendations named after (1878–1968), the dis- more difficult to study chemically, since distinc- coverer of protactinium in 1917. Darmstadtium tive volatile Ir and Pt compounds are rare and was first made in 1994, and named after difficult to synthesise on a very small scale, unlike

Darmstadt. For any meaningful chemistry to be HsO4, although the fluorides IrF6 and PtF6 are carried out on a given element, at least four atoms volatile above 60ºC. It seems likely, however, that are necessary, of half-life (t½) > 1 second, and a these three elements are congeners of Os, Ir and production rate of at least one atom per week is Pt, particularly since it has recently been shown required. The nuclear reactions producing the ele- that the unnamed (at the time of writing) element ments should give only single products. For these 112 is itself volatile. This suggests that it is a con- three elements the most useful nuclear reactions gener of mercury (39), as would be expected if are (Equations (i)–(iii)): elements 104–111 inclusive form a fourth transi-

248 26 269, 270 1 tion metal series. 96Cm + 12Mg → 108Hs + 5 or 4 0n (i)

209 58 266 1 83Bi + 26Fe → 109Mt + 0n (ii)

208 64 271 1 Conclusions 82Pb + 28Ni → 110Ds + 0n (iii) The story of the Periodic Table is convoluted, 269 270 Of these, Hs and Hs have t½ = 14 and 23 s and this article has concentrated on the pgms. It 266 –3 271 respectively; Mt has t½ = 6 × 10 s and Dt has is clear that they represented a challenge to the –2 t½ = 6 × 10 s, so at present chemistry can only be makers of the tables, but the problem was finally carried out on hassium. It is clearly a congener of resolved by Mendeleev some 140 years ago (28). Os: using just seven atoms it was found to form a The three man-made congeners of these ele- volatile tetroxide (37) which in alkaline NaOH ments, hassium, meitnerium and darmstadtium, gives a species which is probably cis- are likely to have chemistries similar to those of

Na2[HsO4(OH)2] (38). For studies on meitnerium osmium, and platinum. At the time of and darmstadtium to be made, longer-lived iso- writing it has been possible to demonstrate this topes are essential – they would also be much only for hassium.

Platinum Metals Rev., 2008, 52, (2) 118 Acknowledgements Darmstadt, Germany) and Dr Simon Cotton I am grateful to Professor Christoph Düllmann (Uppingham School, Rutland, U.K.) for their advice (Gesellschaft für Schwerionenforschung mbH, on aspects of transuranium chemistry.

References 1 D. McDonald and L. B. Hunt, “A History of 28 D. Mendelejeff, Ann. Chem. Pharm. (Leipzig), Platinum and its Allied Metals”, Johnson Matthey, Supplementband VIII, 1871, 133 London, 1982, p. 333 29 D. Mendeleef, Chem. News, 1879, 40, 231 2 J. W. van Spronsen, “The Periodic System of 30 D. Mendeleef, Chem. News, 1879, 40, 267 Chemical Elements: A History of the First Hundred 31 F. A. Cotton and G. Wilkinson, “Advanced Years”, Elsevier, Amsterdam, 1969 Inorganic Chemistry: A Comprehensive Text”, 5th 3 E. R. Scerri, “The Periodic Table: Its Story and Its Edn., John Wiley & Sons, Chichester, U.K., 1988 Significance”, Oxford University Press, New York, 32 F. A. Cotton, G. Wilkinson, C. A. Murillo and M. U.S.A., 2007 Bochmann, “Advanced Inorganic Chemistry”, 6th 4 M. E. Weeks and H. M. Leicester, “Discovery of the Edn., John Wiley & Sons, Chichester, U.K., 1999 Elements”, 7th Edn., Journal of Chemical 33 G. T. Seaborg, Chem. Eng. News, 10th December, Education, Easton, Pennsylvania, U.S.A., 1968 1945, 23, (23), 2190 5 W. H. Brock, “The Fontana History of Chemistry”, 34 S. Cotton, “Lanthanide and Chemistry”, Fontana Press, London, 1992 John Wiley & Sons, Chichester, U.K., 2006 6 W. P. Griffith, Platinum Metals Rev., 2003, 47, (4), 175 35 Periodic Table, World Wide Web version prepared 7 W. P. Griffith, Platinum Metals Rev., 2004, 48, (4), 182 by G. P. Moss, London, U.K., 2007: 8 M. Usselman, in “The 1702 Chair of Chemistry at http://www.chem.qmul.ac.uk/iupac/AtWt/table. Cambridge”, eds. M. D. Archer and C. D. Haley, html Cambridge University Press, Cambridge, U.K., 2005, 36 IUPAC Periodic Table of the Elements, 2007: Chapter 5, p.113 http://www.iupac.org/reports/periodic_table/ind 9 C. Claus, Ann. Phys. Chem. (Poggendorff), 1845, 64, 192 ex.html 10 C. Claus, Phil. Mag. (London), 1845, 27, 230 37 Ch. E. Düllmann, W. Brüchle, R. Dressler, K. Eberhardt, B. Eichler, R. Eichler, H. W. Gäggeler, T. 11 V. N. Pitchkov, Platinum Metals Rev., 1996, 40, (4), N. Ginter, F. Glaus, K. E. Gregorich, D. C. 181 Hoffman, E. Jäger, D. T. Jost, U. W. Kirbach, D. M. 12 J. W. Döbereiner, Ann. Phys. Chem. (Poggendorff), 1829, Lee, H. Nitsche, J. B. Patin, V. Pershina, D. Piguet, 15, 301 Z. Qin, M. Schädel, B. Schausten, E. Schimpf, H.-J. 13 W. P. Griffith, Chem. Brit., 1968, 4, (10), 430 Schött, S. Soverna, R. Sudowe, P. Thörle, S. N. 14 J. H. Gladstone, Phil. Mag., 1853, 5, (4), 313 Timokhin, N. Trautmann, A. Türler, A. Vahle, G. Wirth, A. B. Yakushev and P. M. Zielinski, Nature, 15 W. Odling, Phil. Mag., 1857, 13, (4), 480 2002, 418, (6900), 859 16 A. B. de Chancourtois, Compt. Rend. Acad. Sci., 1862, 38 A. von Zweidorf, R. Angert, W. Brüchle, S. Bürger, 54, 757, 840 and 967 K. Eberhardt, R. Eichler, H. Hummrich, E. Jäger, 17 C. Claus, J. Prakt. Chem., 1860, 79, (1), 28 H.-O. Kling, J. V. Kratz, B. Kuczewski, G. 18 C. Claus, J. Prakt. Chem., 1860, 80, (1), 282 Langrock, M. Mendel, U. Rieth, M. Schädel, B. 19 C. Claus, Chem. News, 1861, 3, 194 and 297 Schausten, E. Schimpf, P. Thörle, N. Trautmann, K. Tsukada, N. Wiehl and G. Wirth, Radiochim. Acta, 20 J. A. R. Newlands, Chem. News, 1863, 7, 70 2004, 92, (12), 855 21 J. A. R. Newlands, Chem. News, 1864, 10, 59 and 94 39 R. Eichler, N. V. Aksenov, A. V. Belozerov, G. A. 22 J. A. R. Newlands, Chem. News, 1865, 12, 83 and 94 Bozhikov, V. I. Chepigin, S. N. Dmitriev, R. 23 W. Odling, Quarterly J. Sci., 1864, 1, 642 Dressler, H. W. Gäggeler, V. A. Gorshkov, F. 24 L. Meyer, Ann. Chem. Pharm. (Leipzig), Supplementband Haenssler, M. G. Itkis, A. Laube, V. Ya. Lebedev, O. VII, 1870, 354 N. Malyshev, Yu. Ts. Oganessian, O. V. Petrushkin, D. Piguet, P. Rasmussen, S. V. Shishkin, A. V. 25 D. Mendeleev, Zhur. Russ. Khim. Obshch., 1869, 1, 60 Shutov, A. I. Svirikhin, E. E. Tereshatov, G. K. 26 D. Mendelejeff, Z. Chem., 1869, 12, 405 Vostokin, M. Wegrzecki and A. V. Yeremin, Nature, 27 D. Mendeleev, Zhur. Russ. Khim. Obshch., 1871, 3, 25 2007, 447, (7140), 72

The Author Bill Griffith is an Emeritus Professor of Chemistry at Imperial College, London. He has much experience with the platinum group metals, particularly ruthenium and osmium. He has published over 260 research papers, many describing complexes of these metals as catalysts for specific organic oxidations. He has written seven books on the platinum metals, and is currently writing another on oxidation by ruthenium complexes. He is the Secretary of the Historical Group of the Royal Society of Chemistry.

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