Electronic Structure and Spectra of Oxovanadium Silicate

Published

January 11, 1999

Author(s)

Morris Krauss

Abstract

The electronic structure and spectroscopy of the oxovanadium catalytic center on a silica surface is modeled with the molecule OV(OSIH₃)3. Excited electronic states are examined at optimized geometries for the ground singlet and triplet states. For both the singlet and triplet states, the lowest energy transitions are calculated to be from orbitals on the terminal vanadyl oxygen to d-orbitals in the metal. This result is consistent with most interpretations of the electronic spectra but does not support a recent view that lowest energy triplet is obtained by promotion of an orbital localized on the basal oxygens. Large shifts in the vanadyl bond length are calculated for the singlet and triplet excited states which are consistent with earlier calculations and the observed vibrational modes in the emission spectrum. The charge density in the Vanadyl bond is comparable with that in, OV(Osi(OH)e)e, and the excitation energies shift by less than 3 nm from those in the compound, OV(OSiH₃)₂(OSiH₂(OH)). The vibrational frequencies of the model compounds are scaled relative to known values for the vanadyl stretching frequency to provide additional support for the emission electronic transition.

Citation

Journal of Molecular Structure-Theochem

Volume

458

Issue

1-2

Pub Type

Journals

Keywords

assignment, electronic spectra, excited state, MCSCF, oscillator strength

Citation

Krauss, M. (1999), Electronic Structure and Spectra of Oxovanadium Silicate, Journal of Molecular Structure-Theochem (Accessed December 26, 2024)