Diphosphine and Diarsine Complexes of Germanium(II) HalidesPreparation, Spectroscopic, and Structural Studies

The Ge(II) halide complexes [GeX2(L−L)] (L−L = o-C6H4(PPh2)2, o-C6H4(PMe2)2, Me2P(CH2)2PMe2; X = Cl, Br, I. L−L = Et2P(CH2)2PEt2; X = Cl or Br. L−L = o-C6H4(AsMe2)2; X = Br or I) and [GeCl(L−L)][GeCl3] (L−L = o-C6H4(AsMe2)2) have been prepared and characterized by IR, 1H and 31P{1H} NMR spectroscopy, and microanalyses. The crystal structures of [GeX2{o-C6H4(PPh2)2}] (X = Cl, Br, I) reveal discrete mononuclear units with a very asymmetric bidentate o-C6H4(PPh2)2 ligand and a bent GeX2 unit. Those of [GeX2{o-C6H4(PMe2)2}] show symmetrically coordinated diphosphine with loosely associated dimer arrangements, formed through long Ge···X bridges between adjacent monomer units. [GeX2{R2P(CH2)2PR2}] (R = Me; X = Cl, Br, I. R = Et; X = Cl, Br) all show discrete monomer structures with 2-fold crystallographic symmetry and based upon four-coordinate Ge, with the diphosphine chelating and approximately linear GeX2 units. [GeI2{o-C6H4(AsMe2)2}] involves significant intermolecular Ge···I interactions, giving rise to a zigzag polymer chain. Finally, the structure of [GeCl{o-C6H4(AsMe2)2}][GeCl3] shows pyramidal cations and anions both with crystallographic mirror symmetry, with the diarsine symmetrically chelating, and long Ge···Cl interactions give a loosely associated chain polymer with alternating cations and anions. Comparisons across this series of structurally diverse complexes are discussed.