The vibrations of bridging carbonyl groups as more sensitive indicators of molecular geometry than terminal carbonyl groups in transition metal carbonyl cluster compounds

The ν(CO) spectra of a series of transition metal cluster compounds are compared with their structures. Despite considerable structural differences, the spectra in the terminal region are surprisingly invariant. Rather more variation is shown in the bridging region spectra; it proves possible to understand these variations in terms of a qualitative model. A generalisation concerning bridging region spectra is presented.