Hydrothermal synthesis and characterization of (N(C2H5)4)4[VMo12V2O44

Abstract

AbstractThe hydrothermal reaction of a mixture of Na2MoO4·2H2O, V2O5, pyromellitic acid (1,2,4,5‐C6H2(COOH)4), (C2H5)4NCl and 0,1 M H2SO4 for 88 h at 180°C gives blue needle‐like crystals of [VIV2O2(H2O)2 (C6H2(COO)4)] in 20% yield (based on V) and dark blue prismatic crystals of the title compound, mixed‐valance (N(C2H5)4)4[VMo12V2O44], 1, in 12% yield (based on Mo). 1 was investigated by means of elemental analysis, thermogravimetry, Fourier Transform Infrared Spectroscopy and Single Crystal X‐ray Diffraction Methods. Crystal data for the compound: monoclinic space group P21/c (No:14), a=13.7815(12) b=13.0271(9) c= 21.189(2) Å, β= 113.909(7)°, Z=2. Although [XM14O42]‐n (X=P, Si, Ge, V and M=Mo and/or V) cores have been previously determined, this is the first time that [VMo12V2O44]‐4 core is synthesized and characterized. The structural difference between 1 and these HPOMs is the coordinational geometry of the central metal atoms. The central vanadium in 1 has an octahedral coordination geometry, whereas in literature, the central V, P, Si and Ge atoms in [V15O42]‐9 / [SiM8V6O42]‐4 / [PM8V6O42]‐5 / [GeM8V6O42]‐4 have tetrahedral coordinational geometry. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)