title: A soluble phosphorus-centered Keggin polyoxoniobate with bicapping vanadyl groups.
abstract: A water-soluble tetramethylammonium (TMA) salt of a novel Keggin-type polyoxoniobate has been isolated as TMA9[PV2Nb12O42]·19H2O (1). This species contains a central phosphorus site and two capping vanadyl sites. Previously only a single example of a phosphorus-containing polyoxoniobate, [(PO2)3PNb9O34](15-), was known, which is a lacunary Keggin ion decorated with three PO2 units. However, that cluster was isolated as an insoluble structure consisting of chains linked by sodium counterions. In contrast, the [PV2Nb12O42](9-) cluster in 1 is stable over a wide pH range, as evident by (31)P and (51)V NMR, UV/Vis spectroscopy, and ESI-MS spectrometry. The ease of substitution of phosphate into the central tetrahedral position suggests that other oxoanions can be similarly substituted, promising a richer set of structures in this class.
authors: Department of Chemistry, University of California, Davis, One Shields Ave., Davis, CA 95616, USA.
authors: Jung-Ho
authors: JH
authors: Son
authors: C André
authors: CA
authors: Ohlin
authors: Rene L
authors: RL
authors: Johnson
authors: Ping
authors: P
authors: Yu
authors: William H
authors: WH
authors: Casey
mesh_terms: D006863:Hydrogen-Ion Concentration; D007477:Ions; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009556:Niobium / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D014638:Vanadates / Q000737:chemistry*
chemical_list: D007477:Ions; D009556:Niobium; D010758:Phosphorus; D014638:Vanadates