Vibrational spectra of matrix-isolated rhenium trifluoride dioxide and rhenium fluoride trioxide: the molecular shape of ReF3O2
Abstract
The vibrational spectrum of monomeric ReF3O2 isolated in inert-gas matrices has been studied using i.r. and Raman techniques. From a total of six possible structural models based on trigonal-bipyramidal or square-pyramidal geometries, only one structure [a trigonal bipyramid with equatorial oxygen atoms (C2v symmetry)] satisfies the observed spectra in terms of selection rules and relative band intensities. A new synthesis of ReF3O2 has been utilised in the preparatron of isotopically enriched 18O material, the spectra of which confirm that ReF3O2 contains two equivalent oxygen atoms. This C2v structure is thus analogous to that proposed for ClF3O2. The vibrational spectrum of ReFO3 produced as a by-product during these studies is also discussed in detail.