Vibrational spectroscopic and force field studies of organorhenium(VII) trioxides-I. Methyltrioxorhenium(VII), ethyltrioxorhenium(VII) and (n-propyl)trioxorhenium(VII)

The infrared absorption spectra of the alkyltrioxorhenium(VII) compounds, methyl-, ethyl-, and (n-propyl)trioxorhenium(VII) have been recorded and analyzed. The Raman spectrum could be obtained for the methyl compound, for which the IR and Raman spectra of a perdeuterated sample (CD₃ReO₃) were also examined. Full vibrational assignment is proposed for all three molecules. The band assignments were based on comparison with the spectra of similar molecules (e.g. alkylmercury halides) and supported or improved by normal coordinate analysis. For the CH₃ReO₃, a hybrid orbital force field (HOFF) was used while for C₂H₅ReO₃ and (n-CH₃H₇)ReO₃ a common simplified valence force field was obtained from an overlay calculation. The influence of size and conformation of the alkyl group on the vibrations of the ReO₃ moiety is discussed.