Hydrothermal Synthesis and Characterization of (N 5)4)4VMO12V2O 44

Abstract

The hydrothermal reaction of a mixture of Na<inf>2</inf>MoO <inf>4</inf>·2H<inf>2</inf>O, V<inf>2</inf>O<inf>5</inf>, pyromellitic acid (1,2,4,5-C<inf>6</inf>H<inf>2</inf>(COOH)<inf>4</inf>), (C <inf>2</inf>H<inf>5</inf>)<inf>4</inf>NCl and 0,1 M H<inf>2</inf>SO<inf>4</inf> for 88 h at 180°C gives blue needle-like crystals of [VIV <inf>2</inf>O<inf>2</inf>(H<inf>2</inf>O)<inf>2</inf> (C<inf>6</inf>H <inf>2</inf>(COO)<inf>4</inf>)] in 20% yield (based on V) and dark blue prismatic crystals of the title compound, mixed-valance (N(C<inf>2</inf>H <inf>5</inf>)<inf>4</inf>)<inf>4</inf>VMo<inf>12</inf>V<inf>2</inf>O <inf>44</inf>], 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 P2<inf>1</inf>/c (No:14), a=13.7815(12) b=13.0271(9) c= 21.189(2) Å, β= 113.909(7)°, Z=2. Although [XM<inf>14</inf>O <inf>42</inf>]-n (X=P, Si, Ge, V and M=Mo and/or V) cores have been previously determined, this is the first time that [VMo<inf>12</inf>V <inf>2</inf>O<inf>44</inf>]-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 [V<inf>15</inf>O<inf>42</inf>]-9 / [SiM<inf>8</inf>V <inf>6</inf>O<inf>42</inf>]-4 / [PM<inf>8</inf>V<inf>6</inf>O <inf>42</inf>]-5 / [GeM<inf>8</inf>V<inf>6</inf>O<inf>42</inf>] -4 have tetrahedral coordinational geometry. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.