Spectra and structure of organogermanes. XIX. Microwave, infrared, and Raman spectra of ethylgermane

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Abstract
The microwave spectra of GeH3CH2CH3, GeD3CH2CH3, GeH3CH2CD3 for the three most abundant naturally occurring isotopes of germanium, 70Ge, 72Ge, and 74Ge, have been recorded in the range 18.0–40.0 GHz and the spectra have been assigned. Both R‐ and Q‐branch A‐type transitions were identified. The dipole moment components were determined from the Stark effect to be ‖μa‖=0.71±0.01, ‖μb‖=0.27±0.01, and ‖μtotal‖=0.76±0.02 D. Barriers to internal rotation of 489±10 cm−1 (1.41±0.03 kcal/mole) for the germyl top and 998±10 cm−1 (2.85±0.03 kcal/mole) for the methyl top have been determined from the analysis of the microwave splitting pattern of the coupled internal rotors of ethylgermane. Thirteen structural parameters were determined from a least squares fit of the 27 moments of inertia. Raman spectra of gaseous and solid GeH3CH2CH3, GeD3CH2CH3, and GeH3CH2CD3 were recorded. A normal coordinate calculation based on thirty internal coordinates and employing 31 internal force constants was carried out and the calculated frequencies fit the observed ones to better than 1%.