A study of bridging and terminal carbonyl groups in transition metal complexes by x-ray photoelectron spectroscopy

The oxygen 1s x-ray photoelectron spectra of gaseous CH/sub 3/COMn(CO)/sub 5/, (..pi..-C/sub 5/H/sub 5/Fe(CO)/sub 2/)/sub 2/, and Co/sub 4/(CO)/sub 12/ can be readily resolved into separate peaks due to bridging and terminal carbonyl groups. From the spectra of CH/sub 3/COMn(CO)/sub 5/ and Co/sub 4/(CO)/sub 12/, it was concluded that the O ls binding energy of a bridging carbonyl group is lower than that of a terminal carbonyl group. This result is consistent with recent structural assignments of O ls spectra of carbon monoxide adsorbed on metal surfaces. The O ls spectrum of CH/sub 3/COMn(CO)/sub 5/ can be resolved into three peaks; the two peaks due to the acetyl group are at lower binding energies than the peak due to the five terminal CO groups.