Hydrothermal synthesis and characterization of mixed-valence hexatungstates: crystal structures of [(C2H5)(4)N](3)[(WW5O19)-W-V-O-VI]center dot 0.5H(2)O and [H3N(CH2)(2)NH3](2)[(WW5O19)-W-V-O-VI]center dot[H2N(CH2)(2)NH2]Cl center dot 8H(2)O

摘要

The hydrothermal reaction of a mixture of Na2WO4. 2H(2)O, MoO3, Mo, Et4NCl, and H2O at 160 degrees C gives bluish-purple crystals of [(C2H5)(4)N](3)[(WW5O19)-W-V-O-VI]. 0.5H(2)O (1) in 60% yield. Under analogous reaction conditions, a mixture of Na2WO4. 2H(2)O, V, H2N(CH2)(2)NH2. 2HCl, and H2O yields brown crystals of [H3N(CH2)(2)NH3](2) [(WW5O19)-W-V-O-VI].[H2N(CH2)(2)NH2]Cl . 8H(2)O (2). 1 and 2 are the first one-electron reduced mixed valence hexatungstates to be crystallized and fully characterized. The crystal structures of 1 and 2 consist of discrete [W6O19](3-) anions, cations, and water molecules of crystallization. Crystal data. 1: Orthorhombic space group Pbcn (No. 60), a = 19.063 (4), b = 22.257 (5), c = 19.631 (4) Angstrom, V= 8329 (3) Angstrom(3), Z = 8. A total of 6617 reflections (2 theta(max) = 45 degrees) were collected, of which 4434 unique reflections with F-o > 4 sigma (F-o) were used for structural elucidation. The structure was solved by direct methods and least-squares refinement converged at R = 0.0834. 2: Monoclinic, space group C2/m (No. 12), a = 15.7339 (10), b = 11.4970 (9), c = 9.0934 (5) Angstrom, beta = 100.855 (4)degrees, V= 1615.5(2) Angstrom(3), Z = 2, A total of 2473 reflections (2 theta(max) = 30 degrees) were collected. The structure was solved by direct methods and least-squares refinement converged at R = 0.0600. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 51]