Direct observation of catalytically active species in reaction solution by X-ray absorption spectroscopy (XAS)

Abstract

Solution V, Nb K-edge XANES (X-ray absorption near edge structure) analysis of molecular catalysis, high oxidation state vanadium(V), niobium(V) complexes containing both imido ligands (possessing metal-nitrogen double bond, NR) and mono anionic ancillary donor ligands (L) of type, M(NR)(L)X2 (X = Cl, Me), which catalyze ethylene dimerization/polymerization in the presence of Al cocatalysts, has been explored. The analysis method is highly useful to obtain the direct information of the active species (oxidation state, basic framework around the centered metal) in solution (in situ), and should thus become a powerful tool for better understanding the catalysis mechanism, basic coordination and organometallic chemistry.