Simple General Method of Generating Non-oxo, Non-amavadine Model Octacoordinated Vanadium(IV) Complexes of Some Tetradentate ONNO Chelating Ligands from Various Oxovanadium(IV/V) Compounds and Structural Characterization of One of Them

A simple general route of obtaining very stable octacoordinated non-oxovanadium(IV) complexes of the general formula VL<sub>2</sub> (where H<sub>2</sub>L is a tetradentate ONNO donor) is presented. Six such complexes (<b>1</b>−<b>6</b>) are adequately characterized by elemental analysis, mass spectrometry, and various spectroscopic techniques. One of these compounds (<b>1</b>) has been structurally characterized. The molecule has crystallographic 4̄ symmetry and has a dodecahedral structure existing in a tetragonal space group <i>P</i>4̄<i>n</i>2. The non-oxo character and VL<sub>2</sub> stoichiometry for all of the complexes are established from analytical and mass spectrometric data. In addition, the non-oxo character is clearly indicated by the complete absence of the strong ν<sub>V</sub><sub></sub><sub>O</sub> band in the 925−1025 cm<sup>-1</sup> region, which is a signature of all oxovanadium species. The complexes are quite stable in open air in the solid state and in solution, a phenomenon rarely observed in non-oxovanadium(IV) or bare vanadium(IV) complexes.