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Research article2007Peer reviewed

Isolation and single crystal study of [Nb-2(mu-OMe)(2)((OPr)-Pr-i)(8)]. Can alcohol interchange provide the homoleptic niobium isopropoxide?

Nunes GG, Seisenbaeva GA, Kessler VG


Niobium isopropoxide, Nb((OPr)-Pr-i)(5), is an attractive precursor of simple and complex niobium oxides in sol-gel technology. This compound cannot, unfortunately, be obtained by alcohol interchange starting from linear chain homologues such as Nb(OMe)(5) or Nb(OEt)(5). The equilibrium in the latter reaction favours formation of mixed-ligand complexes, [Nb-2(OR)(2)((OPr)-Pr-i)(8)], R = Me, Et. In particular, [Nb-2(OMe)(2)(OPri)(8)] (1) has been isolated in high yield from repeated treatment of Nb-2(OMe)(10) with excess of isopropanol. The X-ray single crystal study reveals a dinuclear structure containing a pair of edge-sharing octahedra with methoxide ligands in the bridging position. Infrared (IR) and mass spectroscopy (MS) studies confirmed the incomplete ligand substitution. The H-1-NMR spectra suggest equilibrium between different molecular forms in solution. Solvothermal interaction of 1 with La chips in toluene/isopropanol media results in formation of a mixture of LaNb2((OPr)-Pr-i)(13) and La2Nb4(mu(4)-O)(4)(OH)(2)(mu-(OPr)-Pr-i)(8)((OPr)-Pr-i)(8) (2)


Niobium alkoxides; Alcohol interchange; Sol–Gel; Precursors; Lanthanum; Solvothermal synthesis

Published in

Journal of Sol-Gel Science and Technology
2007, Volume: 43, number: 1, pages: 105-109
Publisher: SPRINGER