From Cu(i) and Cu(i)-Cu(ii) mixed-valence clusters to 2D Cu(ii) and Cu(i) coordination polymers supported by a flexible bis-tetrazole organosulfur ligand

Abstract

Three coordination compounds from the reaction of copper(ii) bromide with the flexible bis-tetrazole organosulfur ligand, 1,2-bis(1-methyl-1H-tetrazole-5-ylthio)ethane (bmtte) have been isolated and characterised. The identification of polymeric 2∞Cu2Br4(bmtte) (1), trinuclear [Cu3Br4(bmtte)2] (2) and tetranuclear [Cu2Br2(bmtte)]2 (3) compounds shows that the reaction conditions have a significant influence on the structure of the complexes formed. Moreover, two polymorphs of the 2D Cu(ii)-coordination polymer 1 have been isolated and these crystallise in the monoclinic C2/m (1m) and the triclinic P1̄ (1t) space groups. The thermal stabilities and behaviour in aqueous media of compounds 1-3 were investigated along with the reactivity of compound 2 with CuBr2 and KI. The solid-state reaction between mixed-valence compound 2 with KI or the direct reaction of CuI and bmtte under microwave irradiation allowed the preparation of the polymeric 2∞Cu4I4(bmtte)2 (4). The redox behaviour of complexes 2 and 3 was analysed by cyclic voltammetry.