59409-81-3Relevant academic research and scientific papers
Molecular structures of the digermanes Me2XGeGeXMe2 (X = Me, Cl, and H): An ab initio study combined with experimental investigation by raman spectroscopy and gas electron diffraction
Hoelbling, Margit,Masters, Sarah L.,Flock, Michaela,Baumgartner, Judith,Hassler, Karl,Robertson, Heather E.,Wann, Derek A.
, p. 3023 - 3033 (2008)
Ab initio calculations were carried out to investigate the potential-energy surface for internal rotation of the methylated digermanes hexamethyldigermane Me3GeGeMe3 (1), dichlorotetramethyldigermane Me 2ClGeGeClMe2 (2), and tetramethyldigermane Me 2HGeGeHMe2 (3). Different basis sets [6-31+G(d), SDD, aug-cc-pVTZ] were employed at the DFT and MP2 levels of theory to optimize structures and to calculate energies and vibrational frequencies. For 1, one minimum representing a staggered structure was located on the potential-energy surface. For 2 and 3, antiperiplanar conformations with C2 symmetry were found to be the global minima. Additionally, synclinal minima were located for 2 and 3 when certain basis sets were employed. Determination of structural parameters in the gas phase by gas electron diffraction confirmed the computed predictions for all three compounds. For 2 and 3, the ratios of antiperiplanar to synclinal conformer were detected to be 90:10 (328 K) and 72:28 (293 K), respectively, by gas electron diffraction. The experimentally determined GeGe bond lengths in 1, 2, and 3 in the gas phase are 241.4(1), 242.7(2) (averaged for antiperiplanar and synclinal), and 241.7(1) pm (equal for antiperiplanar and synclinal). Only averaged structures were observed, using Raman spectroscopy, for 2 and 3 because the wavenumber differences are small between conformers and there is only a small contribution from the second conformer in each case. For 2, the crystal structure was also determined by X-ray diffraction. An anticlinal structure (with Cl atoms eclipsing the C atoms) was found with a GeGe bond length of 242.1 pm.
