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

The Ge(II) halide complexes [GeX2(L-L)] (L-L =o-C 6H4(PPh2)2, o-C6H 4(PMe2)2, Me2P(CH2) 2PMe2; X = Cl, Br, I. L-L = Et2P(CH 2)2PEt2; X = Cl or Br. L-L = o-C 6H4(AsMe2)2; X = Br or I) and [GeCI(L-L)][GeCl3] (L-L = c-C6H4(AsMe 2)2) have been prepared and characterized by IR, 1H and 31P(1H) NMR spectroscopy, and microanalyses. The crystal structures of [GeX2{o-C6H 4(PPh2)2}] (X = Cl, Br, I) reveal discrete mononuclear units with a very asymmetric bidentate o-C6H 4(PPh2)2 ligand and a bent GeX2 unit. Those of [GeX2{o-C6H4(PMe 2)2}] show symmetrically coordinated dlphosphlne with loosely associated dimer arrangements, formed through long Ge - X bridges between adjacent monomer units. [GeX2{R2P(CH 2)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 dlphosphine chelating and approximately linear GeX2 units. [Gel2{c-C 6H4(AsMe2)2}] involves significant interinolecular Ge - I interactions, giving rise to a zigzag polymer chain. Finally, the structure of [GeCl{o-C6H4(AsMe 2)2}][GeCI3] 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. © 2009 American Chemical Society.