73Ge NMR Spectral Investigations of Singly Bonded Oligogermanes
Monika L. Amadoruge§, Claude H. Yoder†, Julia Hope Conneywerdy‡, Katie Heroux, Arnold L. Rheingold and Charles S. Weinert*§
Organometallics, 2009, 28 (10), pp 3067–3073
Abstract:The synthesis of the two digermanes Bus3GeGePh3 and PhMe2GeGePh3, as well as the branched tetragermane PhGe(GeBun3)3, was achieved using the hydrogermolysis reaction. These species were fully characterized by NMR (1H, 13C) spectroscopy and elemental analysis, and the crystal structure of PhMe2GeGePh3 was determined. These three species, along with 11 other oligogermanes, were also characterized by 73Ge NMR spectroscopy. Chemical shifts of the 73Ge NMR resonances for these oligogermanes have been correlated with the substitution pattern at germanium and also with the number of germanium−germanium bonds at the individual Ge centers. Germanium centers having only one attached germanium atom result in resonances appearing in the range δ −30 to −65 ppm, while those having two or three bonded germanium atoms exhibit resonances in the respective ranges δ −100 to −120 and δ −195 to −210 ppm. Chemical shifts of resonances for germanium centers bearing phenyl substituents appear upfield from those having alkyl substituents.