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.