Manganese(II) complexes containing the phenyl diphenylphosphinate ligand and their reactivity with SO2; the first crystallographically characterised complex containing a phosphinate ligand

Abstract

Complexes of manganese(II) with the rarely studied phenyl diphenylphosphinate ligand have been synthesised. Their isolation is solvent dependent: the bis(ligand) complexes, [Mn{OPPh₂(OPh)}₂X₂](X = Cl, Br, I or NCS), are readily isolated, but the tetrakis derivatives are only isolated for X = I or NCS. The complex [Mn{OPPh₂(OPh)}₄I₂] co-ordinates two molecules of sulfur dioxide and one of these is readily displaced. In marked contrast to the isostructural OPPh₃ derivative, [Mn{OPPh₂(OPh)}₄(NCS)₂] shows no tendency to bind SO₂. The X-ray crystal structure of [Mn{OPPh₂(OPh)}₄(NCS)₂]·C₆H₅Me has been determined. The Mn–O–P angle is 167.5(0.5)°, much increased over the analogous OPPh₃ complex (147.5°); this difference is attributed to enhanced sp character of the oxygen donor atom in the phosphinate complex.