STUDY OF THE XANES MODELING OF MOLYBDENUM COMPOUNDS

The structural factors affecting the Mo K-edge XANES features for series of mono- and dimeric complexes have been investigated by using the one-electron multiple scattering approach of the program DLXANES utilizing ab initio phase shifts calculated from atomic charge densities. The main aspects of the experimental spectra could be reproduced, with the following generalizations. (1) Low Z backscatterers were more important contributors to the near-edge pattern (as in Li4[Mo2(Me)8].4Et2O). (2) Bond length variations of ca. 0.2 angstrom could be identified solely in the XANES region. (3) Intrashell multiple scattering pathways allowed the differentiation of coordination centers with differing bond angles at molybdenum, e.g. tetrahedral versus square planar or trigonal-bipyramidal versus square pyramidal. (4) Some evidence could be found for contributions from shells not identifiable in the EXAFS region of the spectrum (e.g. the Mo..Li shell at 2.74 angstrom in Li4-[Mo2(CH3)8].4Et2O).