Redox-photosensitised reactions. Part 12. Effects of magnesium(II) ion on the [Ru(bpy)3]2+-photomediated reduction of olefins by 1-benzyl-1,4-dihydronicotinamide: metal-ion catalysis of electron transfer processes involving an NADH model

Abstract

Magnesium(II) ion catalyses the photosensitised reduction of carbon–carbon double bonds of dimethyl fumarate, derivatives of methyl cinnamate, and some other related olefins by 1-benzyl-1, 4-dihydro-nicotinamide (BNAH), which proceeds via sequential two-electron transfer initiated by the photo-excitation of [Ru(bpy)₃]²⁺(bpy = 2,2′-bipyridine). The metal ion forms a complex with BNAH in methanol as well as in 10:1 (v/v) pyridine–methanol, leading to the retardation of electron transfer from BNAH to luminescent excited-state Ru(ppy)₃²⁺. The net metal-ion effects arise from the catalysis of both the first and second one-electron reduction processes.