Infrared laser jet spectroscopy of transition metal hexacarbonyl-rare gas dimers

Abstract

High resolution infrared absorption spectra of nine van der Waals complexes M(CO)6⋅Rg (M=Cr, Mo, W; Rg=Ar, Kr, Xe) formed in a supersonic jet expansion have been recorded near the 5 μm carbonyl stretching fundamental bands of the hexacarbonyl monomers. In each case a single red-shifted perpendicular band was observed. It is shown that the spectral results are only consistent with a C3v symmetric top structure for each dimer; no effects due to internal motions are seen in the spectra. The M–Rg separations deduced from analysing the spectra are slightly larger than the separations calculated from the van der Waals radii. Red-shifts of the band origin are partly explained by a simple vibrational dipole-induced dipole model.