Structural and functional models for the dinuclear copper active site in catechol oxidases - Synthesis, X-ray crystal structures, magnetic and spectroscopic properties of mu-methoxo-bridged dinuclear copper(II) complexes with N-substituted sulfonamid

摘要

Two new mu-methoxo-bridged dinuclear copper(II) complexes with a N-substituted sulfonamide, [Cu(mu-OMe)(L)(NH3)](2) (1) and [Cu(mu-OMe)(L)(DMSO)](2) (2) [HL, N-2-(4-methylbenzothiazole)benzenesulfonamide], have been prepared and characterized by single-crystal X-ray difraction analyses. Compound 1 crystallizes in the monoclinic space group C-2/C with a=22.0678(18), b=7.9134(7), c=21.1186(18)Angstrom, beta=113.788(4)degrees and Z=8. Compound 2 crystallizes in the monoclinic space group C-2/C with a=18.0900(10), b=9.5720(10), c=24.2620(10) Angstrom, beta=98.7120(10)degrees and Z=8. In both complexes the copper atoms have square-planar environments bridged by two oxygen atoms from methoxide groups. Magnetic susceptibility measurements indicate a very strong antiferromagnetic coupling between the copper(II) ions in both complexes (2J < -1000 cm(-1)). Electronic Paramagnetic Resonance (EPR) spectra of the two complexes both in solid and in solution are silent. C-13 NMR spectra of the complexes in solid state have been studied. The complexes have been evaluated as model systems for the catechol oxidase enzyme using 3,5-di-tert-butylcatechol as the test substrate. Complex 2 is slightly more active than complex 1. (C) 2003 Elsevier Inc. All rights reserved. [References: 42]