Gold(i) complexes with redox active BIAN and MIAN ligands: synthesis, structure and electrochemistry

Abstract

A series of cationic Au(I)-BIAN/MIAN complexes, namely [(PPh₃)Au(L)]OTf, where L = dpp-bian (1), dpp-mian (2), 2-Me-Ph-bian (3) and 4-Me-Ph-bian (4), has been prepared. All complexes were characterized by analytical and spectroscopic methods and their crystal structures were determined by X-ray diffraction analysis. In all structures, an asymmetric mode of coordination of the di- or monoimine ligand (one shortened Au–N bond and the second elongated Au–N(O) bond) was found, which is a consequence of the so-called antichelate effect. The analysis of the bonding in the coordination environment of gold(I) and the coordination geometry in cations 1–4 was carried out using DFT calculations. The cyclic voltammograms of 1–4 in dichloromethane featured a series of ligand-centered redox processes in the cathodic region. Preliminary bioactivity tests for complexes 1–4 and respective imine ligands have been performed.