Non-oxo 5-coordinate and 6-coordinate vanadium(IV) complexes with their precursor [LVIII(CH3OH)](0), where L = a trianionic aminetris(phenolate)-[N,O,O,O] donor ligand: a magnetostructural and EPR study

Ligating properties of a tripodal, potentially tetradentate aminetris(phenol) ligand, tris(2-hydroxy-3,5-di-tert-butylbenzyl) amine, H3L, containing [N,O,O,O] donor atoms toward the vanadium ions in +III and IV oxidation states have been studied. The structures of complexes 1 [LVIII(CH3OH)](0), 2[LVIV(OCH3)](0) and 3[LVIV(acac)](0) were determined by X-ray diffraction methods as having five-coordinate V(III), 1, five-coordinate non-oxo-vanadium(IV), 2, and six-coordinate non-oxo-vanadium(IV) 3, respectively. Compounds 1-3 were also studied with electrochemical methods, variable-temperature (2-295 K) magnetic susceptibility measurements and X-band electron paramagnetic resonance (EPR) spectroscopy. The electrochemical results of 2 and 3 suggest metal-centered oxidation, i.e. the generation of a V-V-phenolate species. EPR investigations indicate a (d(xy))(1) ground state showing a considerable increase in the in-plane p-bonding, as is expected for a phenolate ligand.