Cobalt(II) complexes with trimethylphosphine oxide and trimethylphosphine sulphide

Abstract

The preparation of new tertiary phosphine sulphide and arsine sulphide complexes of cobalt(II) is reported and comparative spectral and magnetic data presented for Me₃PO and Me₃PS tetrahedral complexes of the types [CoL₄](ClO₄)₂ and CoL₂X₂(X = Cl, Br, and I). The results demonstrate the high metal-ligand covalency which is produced by thioxo-ligands. Electronic spectra for complexes with Me₃PO, Me₃PS, and related ligands are compared. A conspicuous feature of the spectra of [CoL₄]²⁺ complexes with oxo-ligands is that phosphine oxides produce an identical ν₃ band profile while arsine oxides produce a different, characteristic profile. By contrast, phosphine and arsine sulphides do not produce marked differences in the splitting of electronic bands.