Potassium and Magnesium Complexes of the (Iminophosphoranyl)(selenophosphoranyl)methanide Ligand [CH(PPh 2 Se)(PPh 2 NSiMe 3 )] –

Abstract

The Se,N ligand CH2(PPh2Se)(PPh2NSiMe3) (1e) was prepared in excellent yield by treatment of [CH2(PPh2)(PPh2NSiMe3)] with selenium in hot toluene. Reactions of 1e with a small excess of KH or with Mg[N(SiMe3)2] in a 2:1 molar ratio in boiling THF or toluene produced [K{CH(PPh2Se)(PPh2NSiMe3)}]2 (K3e) or Mg{CH(PPh2Se)(PPh2NSiMe3)}2 [Mg(3e)2], respectively. Compounds 1e, (K3e)2, and Mg(3e)2 were characterized by multinuclear (1H, 13C, 29Si, 31P, 77Se) NMR spectroscopy, and their X-ray structures were determined. In the solid state the N,Se-coordinated potassium salt forms a centrosymmetric dimer via weak K···Se interactions [3.269(1) A]; the K+ ions also engage in intramolecular (η3 and η6) interactions with neighboring phenyl groups. The homoleptic magnesium complex Mg(3e)2 is monomeric and exhibits a Se,C,N-bonding mode [Mg–C 2.480(5) and 2.442(5) A].