Synthetic route to vanadium(III) dichalcogenidophosphinate complexes, V(S₂PPh₂)₃ and V(Se₂PPh₂)₃: A spectroscopic and structural comparative study with analogous complexes of chromium(III), Cr(E₂PPh₂)₃ (E=S, Se)

Addition of the potassium dichalcogenidodiphenylphosphinate salts, KE₂PPh₂ (E=S, Se), to either the THF solvate of vanadium(III) chloride or unsolvated chromium(III) chloride results in rapid ligand substitution and the formation of a series of closely-related trivalent, neutral mononuclear complexes, M(E₂PPh₂)₃ (M=V, Cr; E=S, Se), isolated in modest to good yield. The metal dichalcogenidophosphinate complexes reported herein were characterized by IR, UV-vis, and ¹H NMR spectroscopies, and their solid-state molecular structures were determined by single-crystal X-ray crystallography. Importantly, the comparative analysis includes the structural and spectroscopic studies of two rare V(III) dithio- and diseleno-phosphinate VE₆ cores, as well as, two previously known CrE₆ analogues. In the solid-state the title complexes exhibit trigonal distortion from octahedral with torsion angles ranging from 43(2) to 50.3(6)° and structural parameters consistent with ligation of progressively ‘softer’ chalcogen-donors.