Reactions of hydroxylamido-(O,N) complexes of vanadium(V) and of molybdenum(VI) with oxalic acid. Crystal structure of (Et2NHOH)2[Mo2O4(Et2NO)2(C2O4)2]: a .mu.-dioxo complex containing two pentagonal-bipyramidal molybdenum(VI) ions

Abstract

The reaction of [0(V0(R2N0)2)2] (R = ethyl, benzyl) with oxalic acid in ethanol yields colorless neutral complexes of vanadium(V) containing a bridging u4-oxalato ligand: [(V0(R2N0)2)2(C204)]. The reaction of MoG2(Et2NO)2 (Et = ethyl) in ethanol with oxalic acid yields pale yellow crystals of (Et2HNOH)2[Mo204(Et2NO)2(C204)2], This complex has been characterized by a single-crystal X-ray diffraction study. The complex crystallizes in the monoclinic space group P2,/c (Cl*-No. 14) with a = 11.593 (3) A, b = 12.120 (3) A, c = 12.045 (3) A, ß = 102.75 (2)°, V= 1650 A1 23, and Pcaicd = L587 g cm"3 for Z = 2 and mol wt 788.5. Diffraction data were collected on a Syntex R3 diffractometer using 9-26 scan and Mo Ka radiation, and the structure was solved by conventional methods, resulting in a final R factor of 0.051 for 2314 independent reflections. The structure consists of Ar,7V-diethylhydroxylammonium cations and of binuclear dianions, [Mo204(Et2NO)2(C204)2]2 567", upon which a center of symmetry is imposed crystallographically. the Mo(VI) ions are in a distorted pentagonal-bipyramidal environment containing an , -coordinated TV.A-diethylhydroxylamido ligand, a bidentate oxalate anion, and a terminal and two bridging oxo ligands. The two terminal oxo ligands are in a trans position with respect to each other. The structure of the dianion may be regarded as two pentagonal bipyramids sharing an equatorial edge.

Vanadium(V) Hydroxylamido Complexes: Solid State and Solution Properties1

“…Consequently, the much greater bond length change in hydroxylamido groups probably indicates larger charge transfer from ligand to metal in metal hydroxylamido complexes than in the related peroxo complexes. Corresponding structural changes have also been observed in other metal hydroxylamido complexes. ,− Thus, we predict solution characterization of vanadium hydroxylamido complexes will demonstrate a larger charge transfer from ligand to metal than peroxo complexes.…”

Redetermination of μ-oxido-bis[bis(N,N-diethylhydroxylaminato)oxidovanadium(V)]

“…The two vanadium atoms are six-coordinate within a considerably distorted octahedral coordination geometry defined by two deprotonated N,O-bidentate diethylhydroxylamine groups, an terminal and a bridging oxide ligand. In order to compare the difference of the previous determination and our work, some important bond length and bond angles are listed in Table 1. A structurally similar dimethylhydroxamidovanadium(V) complex was previously prepared in a nonaqueous solvent system (Paul et al, 1997;Wieghardt et al, 1981).…”

“…For the pharmacological activities of vanadium complexes, see: Posner et al (1994); Zhou et al (2000); Huyer et al (1997); Nxumalo et al (1998). For related hydroxylamide complexes, see: Zhang et al (2009Zhang et al ( , 2010; Paul et al (1997); Wieghardt et al (1981). For van der Waals radii, see: Bondi (1964).…”

Structural characterization of α-amino acid complexes of molybdates: a spectroscopic and DFT study

“…Mo 2 (µ-O) 2 ), 21,22 however Mo−O ligand stretching vibrations may also contribute. 17(g), 22,23 The carboxylate group − − − − The wavenumber difference between the anti-symmetric and the symmetric stretching vibration of a carboxylate ligand (∆ν a−s ) has proven to be a useful parameter in order to discriminate between monodentate, chelating and bridging-bidentate coordination modes. 24 More specifically, the separation between carboxylate stretching wavenumbers relative to a reference ionic carboxylate compound; hence ∆ν rel a−s = ∆ν a−s (metal complex)− ∆ν a−s (ionic reference).…”