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

The coordination chemistry of a tetradentate redox-active ligand, glyoxal-bis(2-hydroxy-3,5-di-tert-butylanil) (H(2)L), was investigated with the diorganotin(IV) and diphenyllead(IV) moieties. Complexes R(2)SnL (R = Me (1), Et (2), (t)Bu (3), Ph (4)) and Ph(2)PbL (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(-).