Calculation of transition metal compounds using an extension of the CNDO formalism. IV. CNDO-CI-calculations on tetracarbonylnickel and pentacarbonyliron; electronic spectra and photochemical implications

CI-calcns. based on an extended CNDO formalism, were used to analyze the low lying excited states of Ni(CO)4 and Fe(CO)5. At. d -> s and d -> p excitations are important in the low energy region. Inspection of the d. matrixes of excited states indicates that these transitions are responsible for the photochem. activity of metal carbonyls. The influence of double excited configurations is reduced with respect to that for org. compds