Hydrothermal synthesis and characterization of (N(C 2 H 5 ) 4 ) 4 [VMo 12 V 2 O 44 ]

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