VAPOR-PHASE VIBRATIONAL-SPECTRA FOR RE2O7 AND THE INFRARED-SPECTRUM OF GASEOUS HREO4 - MOLECULAR SHAPES OF MN2O7, TC2O7, AND RE2O7

The Raman and infrared spectra of gas phase Re2O7 are reported. The ex perimental vibrational spectra of molecular Tc2O7 and Re2O7 are compar ed with calculated spectra. The results of these studies agree with a nonlinear M-O-M bridge for Tc2O7 and Re2O7. For infrared intensity cal culations, the point charge approximation is used, while for the Raman calculations a combination of bond and atom polarizabilities is adopt ed. Pure Re2O7 was prepared from rhenium wire, but attempts to prepare it from rhenium powder and oxygen always led to infrared spectra show ing serious contamination from a species containing an -OH linkage. De tailed experiments identified this molecule as HReO4, a unique transit ion metal analogue of the perhalic acids, and a partial infrared spect rum of this molecule is reported.