Spectroscopic studies on matrix-isolated metal carbonyls. Part I. Use of C18O enrichment to obtain characteristic frequency and intensity patterns

Abstract

This paper is concerned with a general method of characterising simple binary carbonyls produced under matrix isolation conditions, where i.r. spectroscopy is often the only means of detection. I.r. band frequency and intensity patterns are calculated for a number of isotopically mixed carbonyls, and in particular, it is shown that if one were to use a mixture of C¹⁶O and C¹⁸O in the metal-atom synthesis of these compounds, then the species MCO, M(CO)₂, M(CO)₃(D_3h), M(CO)₄(D_4h or T_d), and M(CO)₆(O_h) would each give rise to a characteristic frequency and intensity pattern. These patterns not only reveal the stoicheiometry and symmetry of the species, but also yield the appropriate Cotton–Kraihanzel force constants. The calculations are displayed as line spectra and cover a wide range of force constants.