Reactions of Ru(Cp*) Complexes with P(o-tolyl)3

Reaction of [Ru(Cp*)(CH3CN)3](PF6) with P(o-tolyl)3 affords [Ru(Cp*){(eta 6-o-tolyl)P(o-tolyl)2}](PF6) (4) in which the P-atom is not coordinated to the metal. The solid-state structure of 4 has been determined. A related reaction with P(p-tolyl)3 reveals a small quantity [Ru(Cp*){(eta 6-p-tolyl)P(o-tolyl)2}](PF6), in solution, but mostly the expected bis-phosphine complex. Reaction of the Ru(IV) dication, [Ru(Cp*)(eta 3-PhCHCHCH2)(DMF)2](PF6)2, with P(o-tolyl)3 gives a mixture of the phosphonium salt, C6H5CH=CHCH2P(o-tolyl)3 (9) and the dication [Ru(Cp*)(eta 6-C6H5CH=CHCH2P(o-tolyl)3)](PF6)2 (10). Salt 9 forms via attack of the P-atom on the allyl ligand. The latter product results from complexation of 9 via the phenyl group of the former allyl ligand. It would seem that the sterically demanding P(o-tolyl)3 ligand is not readily compatible with the Ru(Cp*) fragment, in either the +2 or +4 oxidation state. Detailed NMR studies are reported.