Models for copper-proteins: Structure and properties of dimeric copper(I) and (II) complexes of a tetraamino-tetrathioether ligand

Abstract

Reaction of the binucleating ligand 6,6′-bis(5′-amino-3, ′4′-benzo-2′-thiapentyl)-1,11-diamino-2, 3:9, 10-dibenzo-4,8-dithiaundecane (H 4L) with copper(II) salts in dried methanol (MeOH) results in the isolation of the mixtures of copper(I) and (II) complexes with Cl − and ClO 4 − counterions. The major products were the copper(I) complexes obtained pure after recrystallization from DMSO-MeOH. The ligands lose four protons from the amine functions to form copper(I) complexes of the general formula (Cu 2L)X 2, where X = Cl −, ClO 4 −. The complexes were oxidized to (Cu 4L)X 4 with hydrogen peroxide in DMF. Cu(NO 3) 2, on the other hand, gave [Cu 2(H 4L)(NO 4) 2](NO 3) 2. The structure consists of two copper(I) and copper(II) atoms, each of which is coordinated through two thioether and two primary amine atoms. The two copper sites are linked through a saturated spiro carbon atom. The copper complexes were characterized by elemental analyses, molar conductivities, magnetic moments, and spectra (UV-Vis, IR).