Light-induced electron-transfer reactions involving the tris(2,2'-bipyridine)ruthenium dication and related complexes. I. The bis(2,2'-bipyridine)(diethyl 2,2'-bipyridine-4,4'-dicarboxylate)ruthenium dication

Abstract

Irradiation of the bis(2,2'-bipyridine)(diethyl 2,2'-bipyridine-4,4'- dicarboxylate)ruthenium(II) dication (2c) in water, in the presence of ethylenediaminetetraacetic acid, methyl viologen and a platinum catalyst, produces hydrogen at about one-tenth the rate observed with Ru(bpy)32+. This decrease is ascribed to electron withdrawal by the ester group in (2c) and to bimolecular quenching of photo-excited (2c) by water (rate constant 9.3 × 104 1. mol-1 s-1), which follows (in ethanol) Stern-Volmer kinetics (KSV 9.5 x 10-2 1. mol-1).