The heterobimetallic complexes [Y][M(N)R 2 (µ-O) 2 CrO 2 ] (where Y is either N(n-Bu) 4 + or PPh 4 + ; M is either Ru or Os; and R is an alkyl or aryl ligand) catalyze the selective oxidation of alcohols with molecular oxygen. The rate of the reaction is higher with a ruthenium-containing complex than with an analogous osmiumcontaining catalyst. The rate decreases with steric bulk in either the catalyst or substrate. Single-crystal X-ray diffraction studies of [N(n-Bu) show the chromate group coordinated to each nitrido(dialkyl)metal center through two oxo ligands. The oxidation of benzyl alcohol by [N(n-Bu) 4 ][Os(N)(CH 2 SiMe 3 ) 2 (µ-O) 2 CrO 2 ] was examinined in detail. It is first order in alcohol and substrate, and, when oxygen partial pressure is low, the rate depends directly on the O 2 partial pressure. A mechanism in which alcohol coordinates to the osmium center and is oxidized by β-hydrogen elimination is consistent with the data. [N(n-Bu) 4 ][Os(N)(CH 2 SiMe 3 ) 2 (µ-O) 2 CrO 2 ] catalyzes the oxidation of dppe with O 2 through a different pathway.

Anionic nitridoruthenium(VI) alkyl complexes [Ru(N)Me4]™ and [Ru(N)(CH2SiMe3)4]" have been prepared by the alkylation of [Ru(N)(OSiMe3)4]~w ith AlMe3 or with Mg(CH2SiMe3)2, respectively. The structure of one of these, [N-n-Bu4] [Ru(N)Me4], was determined by single-crystal X-ray diffraction: o = 9.359 (3) A, f> = 18.368 (4) A, c = 15.193 (5) A; V = 2519 (1) A34; Z = 4; ß = 105.31 (2)°; Pcalcd = 1.101 g/cm3, monoclinic space group P21/n. Mixed alkyl-chloro complexes, [Ru(N)R4_zClz]™ (R = CH2SiMe3, x = 1-2; R = Me, x = 1-3), result from the reaction of HCl(g) with the alkyl complexes. The gold(I) chloro complex Au(PPh3)Cl reacts in a manner analogous to HC1 and converts [Ru(N)Me4]™ to [Ru(N)ClMe3]' with formation of Au(PPh3)Me. In contrast to the related osmium complexes, both Lewis acid adducts of the ruthenium nitrides and (alkylimido)tetraalkylruthenium complexes are thermally unstable.

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The imido ligand in [(η 5 -C 5 H 5 )Os(NCH 3 )(CH 2 SiMe 3 ) 2 ][SO 3 CF 3 ] reacts with basic and nucleophilic molecules. Triphenylphosphine, pyridine, and water act as bases and deprotonate the methylimido ligand forming the first osmium(IV) methyleneamido complex, (η 5 -C 5 H 5 )Os(NdCH 2 )(CH 2 SiMe 3 ) 2 . The reaction is reversible, and treatment of (η 5 -C 5 H 5 )-Os(NdCH 2 )(CH 2 SiMe 3 ) 2 with HBF 4 produces [(η 5 -C 5 H 5 )Os(NCH 3 )(CH 2 SiMe 3 ) 2 ][BF 4 ]. Triphenylphosphine also abstracts the imido ligand to form MeNdPPh 3 . The imido complex reacts with ethylene to produce an olefin complex, [(η 5 -C 5 H 5 )Os(NHCH 2 )(CH 2 CH 2 ) 2 ][SO 3 -CF 3 ]. Under pressures of ethylene, products resulting from imide transfer to the olefin are obtained.

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