The deoxygenation of the mixed-metal polyoxoanion [(C4H9)4N]3NbW5O 19 with benzoyl chloride in dichloromethane forms quantitatively the condensed polyoxanion [(C4H9)4N]4(NbW5O 18)2O, in which two polyoxoanion fragments are linked together by a Nb-O-Nb oxo bridge. The product is characterized by a strong IR band at 692 cm-1 assigned to a Nb-O-Nb stretch and a broad single 93Nb NMR resonance at 975 ppm. Partial hydrolysis of [(C4H9)4N]4(NbW5O 18)2O to NbW5O19O3- in wet acetonitrile was observed by IR and 17O NMR spectroscopy. The reaction of [(C4H9)4N]4(NbW5O 18)2O with a variety of alcohols and phenol forms alkoxide-derivatized polyoxoanions [(C4H9)4N]2Nb(OR)W5O 18 (R = methyl, ethyl, isopropyl, cholesteryl, phenyl). The similarity of the IR spectra of these deriviatives suggests that functionalization occurs at the terminal NbO oxygen. A crystallographic study of [(C4H9)4N]4(NbW5O 18)2O revealed a crystallographically imposed linear Nb-O-Nb oxo bridge (Nb-Obridge = 1.887(3) Å) and a structure in which the terminal tungsten-oxo bonds on the adjoining polyoxoanion fragments are eclipsed. Crystal data: orthorhombic, Cmca; Z = 4, a = 15.817(2) Å, b = 17.870(2) Å, c = 35.058(2) Å; V = 9928.0(10) Å3; R = 5.52%.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry