Ru(II)(bpy)₃-Cob(II)yrinat – ein binuklearer Photoredox-Photokatalysator. Synthese und Anwendung in der organischen Chemie

Abstract

The synthesis of the binuclear 'Ru^II-Co^II' complex (5a) is described. Its two subunits consist of derivatives of Ru^II(bpy)₃⁺⁺ and cob(II)yrinate. 5a undergoes 7 one-electron redox processes in the potential range +1.5 to–1.8 V (vs. SCE). Luminescence from the Ru^II(bpy)₃-subunit is effectively reduced, however, the quenching mechanism has not been elucidated. Upon visible light irradiation and in presence of triethanolamine (TEOA), the formation of 'Ru^II-Co^I' is observed. Using TEOA as an electron donor, the catalyst consumes formally two quanta of visible light to promote the endergonic reduction of an aliphatic alkyl halide. 5a has been used as a 'photoredox-photocatalyst' in the radical-type cyclisation of methyl 1-(3-bromopropyl)-4-oxocyclohexa-2,5-diene-1-carboxylate (8) to the corresponding indene derivative (9).