title: Characterization of reactive sites in supported catalysts by 51V/15N rotational echo double resonance NMR spectroscopy: formation of phenylimido groups at surface-bound oxovanadium sites.
abstract: Silica-supported oxovanadium groups were reacted in a gas-solid reaction with aniline at 175 degrees C. The reaction was clean as monitored in situ by UV-vis spectroscopy and resulted in the elimination of water as the principal product of the reaction and the disappearance of the terminal V=O stretch in the Raman spectrum. 15N MAS solid-state NMR spectroscopy showed only a single nitrogen-containing species on the surface. Proton-dephased 15N NMR showed only weak attenuation of its intensity, indicating that there are no protons directly bonded to the nitrogen. The formation of a vanadium-imido covalent bond was characterized by 51V/15N rotational echo double resonance NMR spectroscopy where the quadrupolar 51V nucleus was monitored and the spin-1/2 15N nucleus was dephased.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32310, USA.
authors.forename: Carole
authors.initials: C
authors.lastname: Brown
authors.forename: Randall
authors.initials: R
authors.lastname: Achey
authors.forename: Riqiang
authors.initials: R
authors.lastname: Fu
authors.forename: Thomas
authors.initials: T
authors.lastname: Gedris
authors.forename: A E
authors.initials: AE
authors.lastname: Stiegman
mesh_terms: D002384:Catalysis; D007094:Imides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009587:Nitrogen Isotopes; D013499:Surface Properties; D017968:Vanadium Compounds / Q000737:chemistry*
chemical_list: D007094:Imides; D009587:Nitrogen Isotopes; D017968:Vanadium Compounds