Matrix-Isolation and Quantum-Chemical Analysis of the C Conformer of XeF, XeOF, and Their Acetonitrile Adducts.

A joint experimental-computational study of the molecular structure and vibrational spectra of the XeF molecule is reported. The vibrational frequencies, intensities, and in particular the isotopic frequency shifts of the vibrational spectra for XeF and XeF isotopologues recorded in the neon matrix agree very well with those obtained from relativistic coupled-cluster calculations for XeF in the C structure, thereby strongly supporting the observation of the C conformer of the XeF molecule in the neon matrix. A C transition state connecting the C and O local minima is located computationally. The calculated barrier of 220 cm between the C minima and the transition state corroborates the experimental observation of the C conformer and the absence of the O conformer in solid noble gas matrices. For comparison matrix-isolation spectra have also been recorded and analyzed for the XeOF and the XeOF isotopologues. The matrix-isolation complexation shifts obtained for the XeF·NCCH relative to those of free matrix isolated XeF and CHCN are in good agreement with those reported for crystalline XeF·NCCH.