Structural, spectroscopic and electrochemical consequences of displacing the co-ordinated thioethers from a copper(I) N2S2 complex

Abstract

The effect of detaching the two co-ordinated thioethers from the copper(I) N₂S₂ complex N,N′-bis{[2-(phenylmethylthio)phenyl]methylene}ethane-1,2-diaminecopper(I) perchlorate, [CuL]ClO₄, has been investigated. This has been achieved by treating this complex with a second mole of the same ligand such that Cu^I becomes co-ordinated to two ligands, each by way of its diimine moiety. The resulting orange coloured complex, [CuL₂]ClO₄, is air-stable in the solid state. Results from X-ray crystal structure analysis indicate that the cation has approximately tetrahedral stereochemistry with a CuN₂–CuN₂ dihedral angle of 90.7(4)°, Cu–N bond lengths all 2.05(1)Å and intrachelate N–Cu–N angles of 83.9(4) and 85.0(4)°. Results from cyclic voltammetry indicate quasi-reversibility of the Cu^I↔ Cu^II electron-transfer process, and a standard reduction potential of 0.23 ± 0.02 V vs. saturated calomel electrode. Chemical decomposition of the copper(II) species is also apparent, which is consistent with its high reactivity when direct synthesis was attempted.