Syntheses, Structures, and Electronic Properties of the Branched Oligogermanes (Ph<sub>3</sub>Ge)<sub>3</sub>GeH and (Ph<sub>3</sub>Ge)<sub>3</sub>GeX (X = Cl, Br, I)
journal contribution
posted on 2011-03-14, 00:00 authored by Christian R. Samanamu, Monika L. Amadoruge, Claude H. Yoder, James A. Golen, Curtis E. Moore, Arnold L. Rheingold, Nicholas F. Materer, Charles S. WeinertThe branched oligogermanium hydride (Ph<sub>3</sub>Ge)<sub>3</sub>GeH was synthesized via a hydrogermolysis reaction from GeH<sub>4</sub> and Ph<sub>3</sub>GeNMe<sub>2</sub> and was converted to the halide series of compounds (Ph<sub>3</sub>Ge)<sub>3</sub>GeX (X = Cl, Br, I) upon reaction with [Ph<sub>3</sub>C][PF<sub>6</sub>] in CH<sub>2</sub>X<sub>2</sub> solvent (X = Cl, Br, I). These species were fully characterized by NMR (<sup>1</sup>H and <sup>13</sup>C) and UV/visible spectroscopy, cyclic voltammetry, and elemental analysis. In addition, (Ph<sub>3</sub>Ge)<sub>3</sub>GeH was analyzed by <sup>73</sup>Ge NMR spectroscopy and exhibits two resonances at δ −56 and −311 ppm. A Ge−H coupling constant of 191 Hz was observed in the proton-coupled <sup>73</sup>Ge NMR spectrum of (Ph<sub>3</sub>Ge)<sub>3</sub>GeH. The X-ray crystal structures of (Ph<sub>3</sub>Ge)<sub>3</sub>GeH and (Ph<sub>3</sub>Ge)<sub>3</sub>GeX (X = Cl, Br, I) were obtained and represent the first examples of branched oligogermane hydrides or halides to be characterized in this fashion. The Ge−Ge bond distances in (Ph<sub>3</sub>Ge)<sub>3</sub>GeH are short (average value 2.4310(5) Å), while those in the halide compounds (Ph<sub>3</sub>Ge)<sub>3</sub>GeX are similar to one another and range from 2.4626(7) to 2.4699(5) Å. The UV/visible and cyclic voltammetry data for these species have been correlated with DFT computations, and excellent agreement was found between the experimental and theoretical data.
