Tin(iv) and lead(iv) complexes with a tetradentate redox-active ligand

Abstract

The coordination chemistry of a tetradentate redox-active ligand, glyoxal-bis(2-hydroxy-3,5-di-tert-butylanil) (H₂L), was investigated with the diorganotin(IV) and diphenyllead(IV) moieties. Complexes R₂SnL (R = Me (1), Et (2), ^tBu (3), Ph (4)) and Ph₂PbL (5) have been prepared and characterized. The molecular structures of compounds 1, 3 and 5 have been determined by single crystal X-ray diffraction. The diamagnetic octahedral complexes bear a tetradentate O,N,N,O redox-active ligand with a nearly planar core. Complexes 1–5 demonstrate solvatochromism in solution. The CV of complexes 1–5 reveals four one-electron redox processes. The spin density distribution in the chemically generated cations and anions of 1–5 was studied by X-band EPR spectroscopy. The experimental data agree well with the results of DFT calculations of electronic structures for 1, its pyridine adduct 1·Py, cation 1⁺ and anion 1⁻−−.