Chemistry of Coordinatively Unsaturated Bis(thiolato)ruthenium(II) Complexes (η⁶-arene)Ru(SAr)₂[SAr = 2,6-Dimethylbenzenethiolate, 2,4,6-Triisopropylbenzenethiolate; (SAr)₂= 1,2-Benzenedithiolate; Arene = Benzene,p-Cymene, Hexamethylbenzene]

Mononuclear 16-electron arene−ruthenium(II)−thiolate complexes of the general formula (η 6 -arene)Ru(SAr) 2 ( 2, Ar = 2,6-C 6 H 3 Me 2 = Xyl; 3, Ar = 2,4,6-C 6 H 2 (CHMe 2 ) 3; arene = C 6 H 6 ( a ), arene = p -MeC 6 H 4 (CHMe 2 ) = p -cymene ( b ), arene = C 6 Me 6 ( c )) have been prepared by treatment of [(η 6 -arene)RuCl 2 ] 2 ( 1 ) with the corresponding sodium arenethiolate in methanol. Reaction of 2b with disodium of 1,2-benzenedithiolate (=S 2 C 6 H 4 ) led to a mixture of monomer and dimer complexes (η 6 - p -cymene)Ru(S 2 C 6 H 4 ) ( 4b ) and [(η 6 - p -cymene)Ru(S 2 C 6 H 4 )] 2 ( 5b ) in solution. A complex (η 6 -C 6 Me 6 )Ru(S 2 C 6 H 4 ) ( 4c ) was predominantly monomeric, revealed by a crystal structure analysis of 4c . All these monomeric complexes show intense blue color of the LMCT band due to the donation from the filled S(pπ) orbital to the empty Ru(dπ*) orbital, which stabilizes coordinatively unsaturated ruthenium(II). The structures of these complexes are characterized by NMR and mass spectra and elemental analysis in addition to the X-ray crystal structure determinations of 2a, b, 3c, and 4c, indicating the two-legged piano stool geometry. The newly prepared 16-electron complexes react with π-accepting molecules such as isocyanide, carbon monoxide, and trialkylphosphine. Treatment of 2b with an excess of tert -butyl isocyanide resulted in the release of the p -cymene ligand to give trans -Ru(SXyl) 2 (CN t Bu) 4 ( 8 ). Similarly, reaction of 5b with an excess of tert -butyl isocyanide afforded cis -Ru(S 2 C 6 H 4 )(CN t Bu) 4 ( 10 ), while reaction of 5b with 6 equiv of tert -butyl isocyanide gave a binuclear complex [Ru(S 2 C 6 H 4 )(CN t Bu) 3 ] 2 ( 11 ). In the case of more strongly coordinating C 6 Me 6 derivatives 2c and 4c, one molecule of tert -butyl isocyanide can coordinate to the ruthenium atom, resulting in the formation of (η 6 -C 6 Me 6 )Ru(SXyl) 2 (CN t Bu) ( 9c ) and (η 6 -C 6 Me 6 )Ru(S 2 C 6 H 4 )(CN t Bu) ( 12c ), respectively. Reactions of 5b and 4c with an excess of triethylphosphine afforded (η 6 - p -cymene)Ru(S 2 C 6 H 4 )(PEt 3 ) ( 13b ) and (η 6 -C 6 Me 6 )Ru(S 2 C 6 H 4 )(PEt 3 ) ( 13c ), respectively. In the carbonylation, 2b gave a binuclear carbonyl complex (CO) 3 Ru(μ-SXyl) 3 Ru(CO) 2 (SXyl) ( 14 ), while the carbonylation of the C 6 Me 6 complex 2c afforded (η 6 -C 6 Me 6 )Ru(SXyl) 2 (CO) ( 15 ). Versatile reactivity of 16-electron ruthenium(II) thiolate complexes is thus demonstrated.