Coordination of the nido-carboranyldiphosphine ligand to ruthenium(II):: the first example of the tricoordinating capacity of the 7,8-(PPh2)2-7,8-C2B9H10 moiety

Reaction of [RuH(AcO)(PPh3)(3)] and [NMe4][7,8-(PPh2)(2)-7,8-C2B9H10] in methanol yields [RuH(7,8(PPh2)(2)-7,8-C2B9H10)(PPh3)(2)] (1). The reaction of [RuCl2(PPh3)(3)] and [NMe4]17,8-(PPh2)(2)-7,8-C2B9H10] in a 1: 1 or 1: 2 ratio in methanol yields [RuX(7,8-(PPh2)(2)-7,8-C2B9H10)(PPh3)(2)] (X = Cl, H) (2). NMR spectroscopic analyses of 1 and 2 indicate that the centers have an octahedral geometry and the carborane acts as a tricoordinating ligand to ruthenium(II) by means of P-Ru, B(11)-H-->Ru and B(2)-H-->Ru agostic bonds. A chloride or hydride and two PPh3 ligands complete the coordination sphere of the metal. The formation of two B-H--> Ru agostic bonds rather than a second P-Ru bond appears to be due to steric factors. Reaction of [NMe4][7,8-(PPh2)(2)-7,8-C2B9H10] with [RuCl2(PMePh2)(4)] in ratios of 1: 1 and 2: 1 in methanol yields complexes [Ru(7,8-(PPh2)(2)-7,8-C2B9H11)(2)] (3) and [RuH(7,8(PPh2)(2)-7,8-C2B9H11)(2)] (4) respectively, which incorporate two nido-carboranylphosphine ligands. Copyright (C) 2003 John Wiley Sons, Ltd.