MULTIPLE BONDS BETWEEN TRANSITION-METALS AND MAIN-GROUP ELEMENTS .18.VIBRATIONAL SPECTROSCOPIC AND FORCE-FIELD STUDIES OF ORGANORHENIUM(VII), ETHYLTRIOXORHENIUM(VII) AND (N-PROPYL)TRIOXORHENIUM(VII)

The infrared absorption spectra of the alkyltrioxorhenium(VII) compoun ds, methyl-, ethyl-, and (n-propyl)trioxorhenium(VII) have been record ed and analyzed. The Raman spectrum could be obtained for the methyl c ompound, 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.