Molecular structures, acid-base properties, electron affinities, and reactivities of transition metal oxide clusters

PHYS 613

Shenggang Li, sli@bama.ua.edu and David A. Dixon, dadixon@bama.ua.edu. Department of Chemistry, The University of Alabama, Shelby Hall, Box 870336, Tuscaloosa, AL 35487-0336
Transition metal oxides (TMOs) have been widely applied as catalysts due to their versatile acid-base and redox properties. Although widely studied, detailed electronic structure information and the role it plays on cluster reactivities are often lacking. Using density functional theory (DFT) and coupled cluster (CCSD(T)) methods, we carried out detailed studies on the (MO3)n (M = Cr, Mo, W; n = 1-6) clusters and their reactivities towards small molecules such as water and methanol. For MO3 and M2O6, the electron affinities were calculated at the CCSD(T)/CBS level, and compared with results from photoelectron spectroscopy. A large number of exchange-correlation functionals were benchmarked for calculating their electron affinities, and the B88-P86 and PW91-PW91 functionals were found to yield the best results. Studies on the reactions of these clusters with methanol provided detailed mechanism for the transformation of methanol to formaldehyde using these clusters as catalysts.