L-EDGE STUDIES ON MOLYBDENUM

The L(II)- and L(III)-edge XANES features of the 4d transition metals and mono- and dinuclear molybdenum complexes of differing oxidation state and coordination geometry have been recorded on a synchrotron radiation source using a Ge(111) monochromator. The L(III) edge white line areas of the metal foils show a decrease in area with increasing 4d occupancy, with the exception of a peak at molybdenum, a result that is hard to explain. No relationship between the white line areas and the oxidation state and coordination charge could be obtained for the molybdenum complexes; indeed differing L(III)/L(II) edge branching ratios for these complexes demonstrate that no common correlation can be expected for these two edges. Second derivatives of the L(III)-edge XANES features show that for octahedral complexes a splitting of ca. 3 eV, due to the 4d t2g-e(g) separation, can be observed. This can provide additional information to K-edge EXAFS data for the coordination geometry at a 4d transition-metal center.