Phosphine derivatives of the 4-methylquinoline triosmium cluster [(μ-H)Os3(CO)10{μ-1,2-η2-C9H5(CH3)N}]:: crystal structures of two isomeric compounds [(μ-H)Os3(CO)9{μ-1,2-η2-C9H5(CH3)N}(PPh3)] and [(μ-H)Os3(CO)9{μ-1,2-η2-C9H5(CH3)N}{P(OMe)3}]

The 4-methylquinoline triosmium cluster [(mu-H)Os-3(CO)(10){mu-1,2-eta(2)-C9H5(CH3)N}] 9 reacts with PPh3 at 110 degrees C to give the mono and bis-substituted products [(mu-H)Os-3(CO)(9){mu-1,2-eta(2)-C9H5(CH3)N}(PPh3)] 10 and [(mu-H)Os-3(CO)(8){mu-1,2-eta(2)-C9H5(CH3)N}(PPh3)(2)] 11, respectively. Similarly the reaction of 9 with P(OMe)(3) gives [(mu-H)Os-3(CO)(9){mu-1,2-eta(2)-C9H5(CH3)N}{P(OMe)(3)}] 14 and [(mu-H)Os-3(CO)(8){mu-1,2-eta(2)-C9H5(CH3)N}{P(OMe)(3)}(2)] 15. Compound 10 exists as a mixture of three isomers in solution with the major (60%) having the PPh3 ligand on the rear osmium atom and the hydride, which initially bridged the same edge as the 4-methylquinoline ligand, migrating to the carbon bound osmium and the phosphine bearing osmium edge. In contrast compound 14, in which the P(OMe)(3) resides on the unbridged osmium atom and the hydride bridges the same edge as the 4-methylquinoline ligand, exists as two isomers in solution. The structures of 10 and 14 have been ascertained by X-ray crystal structure determination. Compound 11 exists as four isomers in solution and 15 as two isomers. (C) 1998 Elsevier Science S.A. All rights reserved.