Bis‐Ruthena(III)cycles [Ru(C∩N)2(N∩N)]PF6 as Low‐Potential Mediators for PQQ Alcohol Dehydrogenase (C∩N = 2‐phenylpyridinato or 4‐(2‐tolyl)pyridinato, N∩N = bpy or phen)

Abstract

AbstractBis‐cyclometalated analogs of tris(2,2′‐bipyridine)ruthenium(II), namely [RuIII(C∩N)2(N∩N)]PF6 complexes 3, are prepared in 52–57 % yield from the mono‐cyclometalated N,N‐dimethylbenzylamine (dmbaH) derivatives [RuII(dmba)(N∩N)(MeCN)2]PF6 (N∩N = bpy or phen) and mercurated 2‐phenylpyridinato‐ or 4‐(2‐tolyl)pyridinato (C∩N) species Hg(C∩N)Cl. Two new bis‐ruthenacycles studied by X‐ray crystallography revealed a C1 symmetry, with the C and N atoms of different C∩N ligands trans to the nitrogen atoms of the N∩N ligand. The reduction potential of the RuII/III feature of 3 is as low as ca.–0.2 V (vs. SCE in MeCN). Complexes 3 display a unique mediating ability in moving electrons from the reduced active site of PQQ‐dependent alcohol dehydrogenase (PQQ‐ADH) to an electrode with 1,2‐propanediol as a substrate at a working potential of +0.1 V. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)