Encapsulation of H4PVMo11O40 (1-vanado-11-molybdophosphoric acid) inside silica provided a single-site long-lived pervanadyl cation (VO2+) for oxidation reactions. Protective silica residues allowed vanadium to sit in the secondary Keggin structure without being reduced, contrasting the classical situation for H4PVMo11O40 supported on silica. The vanadium of this Keggin molecule is frivolous, tending to exit the primary structure, with one-electron reduction, even during efflorescence under ambient conditions. Hydrated crystals circumvented this problem, allowing high resolution V-51 MAS NMR conditions and the first quadrupolar and chemical shift anisotropy interaction parameters for this intact Keggin.
Parker, W.O., Cavani, F. (2015). Stable pervanadyl cation encapsulated in silica: Frivolous vanadium in the H4PVMo11O40 Keggin. JOURNAL OF PHYSICAL CHEMISTRY. C, 119(42), 24003-24015 [10.1021/acs.jpcc.5b08039].
Stable pervanadyl cation encapsulated in silica: Frivolous vanadium in the H4PVMo11O40 Keggin
CAVANI, FABRIZIO
2015
Abstract
Encapsulation of H4PVMo11O40 (1-vanado-11-molybdophosphoric acid) inside silica provided a single-site long-lived pervanadyl cation (VO2+) for oxidation reactions. Protective silica residues allowed vanadium to sit in the secondary Keggin structure without being reduced, contrasting the classical situation for H4PVMo11O40 supported on silica. The vanadium of this Keggin molecule is frivolous, tending to exit the primary structure, with one-electron reduction, even during efflorescence under ambient conditions. Hydrated crystals circumvented this problem, allowing high resolution V-51 MAS NMR conditions and the first quadrupolar and chemical shift anisotropy interaction parameters for this intact Keggin.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
