Structural Characteristics of Molecular Metal Clusters

The binding energy of 2.7 eV for the 0 2p electrons is unusually small compared to NaaO (4.2 eV) (70) or transition metal oxides (4-lOeV) (71). Indeed, it is the smallest known value which has to be interpreted as due to the comparably weak electrostatic field of positive charges acting on the 0 " ion in the suboxides. The very narrow structure of the 0 2p band is unusual, too. A band width of 5 eV is reported e.g. for NbO. (73) The narrow 0 2p band is characteristic of crystalline as well as amorphous suboxides. Obviously, it is the well-defined atomic environment and the isolation of the nearly gas-like 0 ions in the quasi-molecular clusters, which is responsible for the narrow 0 2p band in the suboxides, as this band is significantly broadened with the oxide CS2O itself. 

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