<<

CSIRO PUBLISHING Aust. J. Chem. 2019, 72, 161–163 Essay https://doi.org/10.1071/CH18622

Element 44 – Ruthenium

George Koutsantonis

Chemistry, M310, School of Molecular Sciences, The University of Western Australia, Crawley, WA 6009, Australia. Email: [email protected]

Manuscript received: 18 December 2018. Manuscript accepted: 20 December 2018. Published online: 17 January 2019.

This year has been proclaimed as the International Year of the which is relied the steady discovery of the elements and the of Chemical Elements (IYPT 2019) by the study of their properties, compounds, and chemistry. The small United Nations General Assembly. The motivation for this Swedish island of Ytterby gave the world four elements and is initiative is the relationship of chemistry to society and its role in an example of the dedicated effort that was required to identify promoting sustainable development and societal challenges in these hard-to-separate elements. ‘energy, education, agriculture and health’.[1] IYPT 2019 will The discovery of ruthenium is a little problematic in its coincide with the 150th anniversary of the formulation of the assignation. The element was named after the country of its Periodic System by Dmitry Mendeleev in 1869. It is remarkable discovery, Russia, or the Latin version , and the that we are still adding new elements to the periodic table with discoverer has been the source of some contention.[8,9] What the four newest named and added to the table in 2016. is not contentious is the source of the ore from which it was This first essay of a series to be published in the Australian identified, the area north of Ekaterinburg and west of Nizhniy Journal of Chemistry concerns this co-Editor in Chief’s favour- Tagil in the Russian Urals. The area had proved to be a bountiful ite element, ruthenium. A large proportion of my scientific source of minerals and was the centre of Russian steel output has centred on this most versatile element, clearly manufacturing during the Second World War. By the mid- initially inspired by my mentors and lately as a matter of choice. nineteenth century there were numerous mines that ScifinderÒ has over 300 000 references relating to the element led to a glut of the , so much so, that it was used as general when a chemistry search is run. currency between 1828 and 1844.[8] Ruthenium is a chemical chameleon and its position in the The main protagonists in this play were Gottfried Wilhelm periodic table, centrally located, confers upon it a mix of late and Osann (1797–1866) and Karl Karlovich Klaus (1796–1864), early properties. This fact has led to the develop- both of whom were associated in some way with the University ment of several seminal compounds in inorganic and organome- of Dorpat (later Tartu) in Estonia. Osann was provided with a tallic chemistry. In what can be considered a landmark discovery sample of Pt wastes by the Russian minister of Finance, Count in inorganic chemistry, the structure of ,[2] the very next Yegor Frantsevich Kancrin, whose remit also included the metallocene to be prepared was that of ruthenium.[3] St Petersburg Mint,[8] and was successively providing interested ’s pioneering work on electron transfer reactions scientists with samples of Pt ore to study. The size of sample that and the realisation of the role that p-backbonding plays in the Osann was provided somewhat hampered his investigations, but chemistry of ruthenium[4] have ensured the metal continues to he was able to identify the main minor components of the ore, be prominent in chemistry. Nobel laureate Robert H. Grubbs viz. Pd (0.27 %), Ir (1.30 %), Rh (0.27 %), and Os and the typical recounts his fascination with the element and its penchant for analysis for the major constituent, Pt (83.06 %).[9] He then ,[5] noting that Geoffrey Wilkinson referred to ruthenium turned to the indissoluble portion of the acid extract of the crude as ‘an element for the connoisseur’. Grubbs’ innovations in the ore. Base treatment of this residue and subsequent melting, chemistry of ruthenium-carbon multiple bonding has given us followed by the addition of water and nitric acid to the melt, gave the collection of highly active, well defined ruthenium metathesis a precipitate with an ‘unpleasant smell’[9] which, according to catalysts, leading to his sharing the 2005 Nobel prize.[6] Osann, was indicative of the presence of Os (presumably Ruthenium is often found with the other platinum OsO4!). His further research led him to conclude that he had , , , , platinum, and . discovered a new element.[9] Osann had been collaborating with Ruthenium is a hard white metal resistant to oxidation at renowned Swedish chemist, Baron Jo¨ns Jacob Berzelius, who ambient temperature, but oxidises in air at ,8008C. It is used had confirmed his observations and suggested that he had indeed in microelectronics in the manufacture of resistors and electrical come across a new element, which he named ruthenium.[9] contacts. Ruthenium is robust enough to coat the anodes Historical reassessments of the claims made by Osann suggest of electrochemical cells for production. The metal that he was perhaps a little premature in his claims[8] but he had provides efficacious catalysts for and acetic acid certainly sown the seeds that there was a new element to be production.[7] found. The great effort that was required to extract this putative It is hard to imagine a chemical life without the periodic new element is evident in the detailed steps required.[9] Modern table, so the recognition of periodicity and the construction of analysis suggests that Osann had only managed to prepare a the table is a tremendous achievement. However, it is one on crude mixture of Ir and Ru, at best.[9]

Journal compilation Ó CSIRO 2019 www.publish.csiro.au/journals/ajc 162 G. Koutsantonis

Pt ore residue

Treat NaNO3/base/distilled H2O

Sediment Solution of NaRuO4, Na2RuO4, RuO4

HNO3

Impure RuO2•nH2O Solution

Treat HCl/evaporation/distilled H2O

Sediment Ru solution: Ru(III, IV)Clx•H2O

ϩ KCI

Double salts: K2RuCl6, K3RuCl6, K4Ru2OCl10•H2O Solution

air/heat/washes H2/heat/washes Ru RuO2 (m)

Fig. 1. Extraction and purification of Ru(m) from Pt ore residue. Adapted from ref. [10].

The other player to strut and fret his hour upon the stage was In a reminder of how papers used to be written, a gentler time, Karl Karlovich Klaus who was a Dorpat local and studied at Jas Howe said of the contentious issue, ‘Claus announces the the University of Dorpat, going on to become a pharmacist discovery of a new metal, which he calls ruthenium, for the and subsequently returning to the university to take a chemistry purpose of honoring Osann, whose ruthenium had failed to degree. While there, he became acquainted with the research prove itself an element. It may be mentioned that Osann hardly that Osann was undertaking on platinum ores. Klaus moved to appreciated the compliment, for he attacked Claus with consid- the University of , first in pharmacy, but then in chemis- erable asperity, accusing him of claiming to discover what try, where he also started exploring the nature of the residues Osann himself had discovered. To an impartial critic Osann obtained after extraction of the Pt. In this endeavour he was wholly fails to make out his case. For nearly twenty years Claus greatly aided by the Russian Finance Minister who supplied him continued his work, and his greatest service was in definitely with a much larger quantity of material; most importantly, this settling the position of the six platinum metals among the material was processed ore – that is, after the extraction of elements’.[11] the Pt – clearly an advantage over Osann who had less material Before Mendeleev’s momentous work, Klaus was able to with the major constituent still present. Klaus went on to say that discern relationships amongst the elements, the residue he had obtained contained ‘in addition to 10 % of suggesting a special affinity between Ru-Rh-Pd and Os-Ir-Pt, platinum, quite a lot of iridium, osmium, some palladium and ... and in fact conceived the notion of ruthenium double salts, a a new body’.[10] Several sources characterise Klaus as being harbinger of the work of the father of coordination chemistry, ‘methodical and careful’[9] and capable of ‘careful observation Alfred Werner.[8,11] and diligence’[10] which undoubtedly served him well in the Now to return to the issue of why ruthenium is my favourite tedious procedures needed to extract the ‘new body’. element. I, and others, have been fascinated by the capacity His procedure involved the well known step, even at that of the element to stabilise reactive organic intermediates, a time, of dissolving the other platinum group metals in aqua feature that the organometallic community has pursued with regia and then working with the remanent black residue, known lepidopterological zeal. In particular, the synthesis of a to contain Os and Ir. The subsequent procedure (Fig. 1) allowed ruthenium vinylidene (Fig. 2a) shows the unique capacity that the isolation of gram quantities of the pure element. Ru has in forming ,[12] work that had been pioneered Interestingly, Klaus was a pioneer of the use of microscopes by Kolobova in the chemistry of .[13] It took and astoundingly ‘he tasted and smelt his preparations, so some 12 years more for the simplest member of the vinylidene, discovering that the ammines of ruthenium have a more caustic :CCH2, family to be captured (Fig. 2b), a task that had occupied taste than alkalis, while the taste of is acute a multitude of person years to achieve.[14a,b] The intermediacy of pepper-like’.[10] Clearly, an experimental practice that has long the p-alkyne complex was ably confirmed by a careful structural since been discontinued! and NMR study.[14c] The metal was isolated as a grey powder and Klaus claimed ‘I The element ruthenium occupies a pivotal place in named the new body, in honour of my Motherland, ruthenium. Mendeleev’s periodic table and has helped to shape the course I had every right to call it by this name because Mr Osann of inorganic/organometallic chemistry in the 174 years since its relinquished his ruthenium and the word does not yet exist in definitive discovery by K. K. Klaus. I have no doubt that the chemistry’.[10] This claim caused Osann to claim priority, but unique nature of its reactivity will continue to place it in the weight of scientific evidence fell on Klaus’ side of the ledger. the forefront of synthetic chemistry for the foreseeable future. Element 44 – Ruthenium 163

(a) ϩ Ph HC2Ph/MeOH Ru Cl Ru C C

Ph3P Ph3P H Ph P 3 Ph3P

(b) H ϩ ϩ H HC SiMe /thf Ru Cl 2 3 Ru Ru C C Ph3P H Ph3P Ph3P H Ph3P PPh3 Ph3P

Fig. 2. Ruthenium vinylidene complexes.

Conflicts of Interest [8] J. Marshall, V. R. Marshall, Rediscovery of the Elements: Ruthenium The author declares no conflicts of interest. 2009, Indianapolis, Indiana. University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT College of Arts References and Sciences. Available at: digital.library.unt.edu/ark:/67531/ metadc111238/m1/5/ (accessed 16 December 2018). [1] https://iupac.org/united-nations-proclaims-international-year-peri- [9] H. Ho¨dreja¨rv, Proc. Estonian Acad. Sci. Chem. 2004, 53, 125. odic-table-chemical-elements/ (accessed 21 December 2018). [10] V. N. Pitchkov, Platin. Met. Rev. 1996, 40, 181. [2] G. Wilkinson, J. Am. Chem. Soc. 1952, 74, 6146. doi:10.1021/ [11] J. L. Howe,Science 1900, 11,1012.doi:10.1126/SCIENCE.11.287.1012 JA01143A538 [12] M. I. Bruce, R. C. Wallis, Aust. J. Chem. 1979, 32, 1471. doi:10.1071/ [3] G. Wilkinson, J. Organomet. Chem. 1975, 100, 273. doi:10.1016/ CH9791471 S0022-328X(00)88947-0 [13] A. N. Nesmeyanov, G. G. AIeksandrov, A. B. Antonova, K. N. [4] C. Creutz, P. C. Ford, T. J. Meyer, Inorg. Chem. 2006, 45, 7059. doi:10. Anisimov, N. E. Kolobova, Yu. T. Struchkov, J. Organomet. Chem. 1021/IC060669S 1976, 110, C36. [5] http://pubs.acs.org/cen/80th/ruthenium.html (accessed 21 December [14] (a) R. M. Bullock, J. Chem. Soc. Chem. Commun. 1989, 165. 2018). doi:10.1039/C39890000165 [6] K. Wagener, M. Bell, R. Grubbs, R. Waymouth, J. Polym. Sci. A (b) M. I. Bruce, G. A. Koutsantonis, Aust. J. Chem. 1991, 44, 207. Polym. Chem. 2017, 55, 2863. doi:10.1002/POLA.28731 doi:10.1071/CH9910207 [7] http://www.rsc.org/periodic-table/element/44/ruthenium (accessed 21 (c) J. R. Lomprey, J. P. Selegue, J. Am. Chem. Soc. 1992, 114, 5518. December 2018). doi:10.1021/JA00040A005