The Dicopper( II ) Complex of the Novel Asymmetric Dinucleating Ligand Hpy3asym as a Structural Model of Catechol Oxidase

The new asymmetric dinucleating ligand 2‐{[bis(2‐pyridinylmethyl)amino]methyl}‐4‐methyl‐6‐{[(2‐pyridinylmethyl)amino]methyl}phenol (Hpy3asym) has been designed in order to model the type‐3 active site of the copper proteins. This phenol‐based “end‐off” compartmental ligand has one tridentate and one didentate arm attached to the 2‐ and 6‐positions of the phenolic ring, respectively. A dinuclear copper( II ) nitrate complex with this ligand [Cu 2 (py3asym)(H 2 O) 1.5 (NO 3 ) 2 ]NO 3 has been obtained and structurally characterized. In this complex both copper ions have a distorted octahedral geometry and are endogenously bridged by the phenolic oxygen atom of the deprotonated ligand. The complex shows a donor‐atom asymmetry that consists of an N 3 O 3 donor set for the Cu1 ion and an N 2 O 4 donor set for the Cu2 ion. The electrochemical, magnetic behavior and spectral properties of the complex are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)