Knowledge Bank

The infrared spectrum from $2.5\mu -15\mu$ and the visible and ultraviolet spectra from $2100A-7000A$ were obtained for dicobaltoctacarbonyl. The presence of a carbonyl frequency at $1858cm-1$ in the infrared spectrum and the peak at 2800A in the ultraviolet spectrum indicate the presence of bridged carbonyls in the molecule. Four feasible structures with bridging carbonyl groups were proposed and critically examined. It was concluded that the most probable structure was that of two trigonal bipyramids joined at an edge.