Effect of distal metal species on lewis basicity of a μ3-oxo ligand in a doubly oxo-bridged (μ3-O)[Rh(cod)]3(μ4-O)M core

Abstract

The Lewis basicity of a μ₃-oxo ligand for (μ₃-O)[Rh(cod)]₃(μ₄-O)M (cod = 1,5-cyclooctadiene) complexes was controllable by metal species on the μ₄-oxo ligand locating at the opposite site of the μ₃-oxo ligand. Coordination of the μ₃-oxo ligand of [(μ₃-O){Rh(cod)}₃(μ₄-O){Au(PPh₃)}][BF₄] (1) to [Au(PPh₃)]⁺ indicated sufficient Lewis basicity of the μ₃-oxo ligand in 1 to form [{(Ph₃P)Au}(μ₃-O){Rh(cod)}₃(μ₄-O){Au(PPh₃)}][BF₄] (2). In contrast, the addition of Li⁺ to 1 induced elimination of the originally coordinated [Au(PPh₃)]⁺ due to the weak Lewis basicity of the μ₃-oxo ligand for (μ₃-O){Rh(cod)}₃(μ₄-O)Li(THF)₃, in which a pentanuclear species, [{(Ph₃P)Au}(μ₃-O){Rh(cod)}₃(μ₄-O){Li(THF)₃}][BF₄] (3), was assumed to be generated in situ before the dissociation of [Au(PPh₃)]⁺.