page_title: Ruthenium
section_title: Homogeneous catalysis
hierarchical_section_title: Ruthenium / Applications / Catalysis / Homogeneous catalysis
context_page_description: Ruthenium is a chemical element with the symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals. Russian-born scientist of Baltic-German ancestry Karl Ernst Claus discovered the element in 1844 at Kazan State University and named ruthenium in honor of Ruthenia. Ruthenium is usually found as a minor component of platinum ores; the annual production has risen from about 19 tonnes in 2009 to some 35.5 tonnes in 2017. Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinum alloys and as a chemistry catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks. Ruthenium is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are also found in pentlandite extracted from Sudbury, Ontario and in pyroxenite deposits in South Africa.
context_section_description: Solutions containing ruthenium trichloride are highly active for olefin metathesis. Such catalysts are used commercially for the production of polynorbornene for example. Well defined ruthenium carbene and alkylidene complexes show comparable reactivity and provide mechanistic insights into the industrial processes. The Grubbs' catalysts for example have been employed in the preparation of drugs and advanced materials.
  Ruthenium complexes are highly active catalysts for transfer hydrogenations (sometimes referred to as "borrowing hydrogen" reactions). This process is employed for the enantioselective hydrogenation of ketones, aldehydes, and imines. This reaction exploits using chiral ruthenium complexes introduced by Ryoji Noyori. For example, (cymene)Ru(S,S-TsDPEN) catalyzes the hydrogenation of benzil into (R,R)-hydrobenzoin. In this reaction, formate and water/alcohol serve as the source of H₂:
  A Nobel Prize in Chemistry was awarded in 2001 to Ryōji Noyori for contributions to the field of asymmetric hydrogenation.
  In 2012, Masaaki Kitano and associates, working with an organic ruthenium catalyst, demonstrated ammonia synthesis using a stable electride as an electron donor and reversible hydrogen store. Small-scale, intermittent production of ammonia, for local agricultural use, may be a viable substitute for electrical grid attachment as a sink for power generated by wind turbines in isolated rural installations.
caption: [RuCl(S,S-TsDPEN)(cymene)]-catalysed (R,R)-hydrobenzoin synthesis (yield 100%, ee >99%)