Synthesis and Characterization of Binuclear Oxo-Vanadium Complexes of Carbon Oxoanion Ligands. Crystal Structures of the Binuclear Vanadium(IV) Complex (NH4)[V2O2(OH)(C4O4)2(H2O)3]·H2O, of the Mixed-Valence Vanadium(V)/Vanadium(IV)-Squarate Species [(n-C4H9)4N][V2O3(C4O4)2(H2O)3]·3H2O and [(C4H9)4N]4[V4O6(C4O4)5(H2O)4]·6H2O, and of the Binuclear Vanadium(IV)-Oxalate Species [V2O2Cl2(C2O4)(CH3OH)4]·2Ph4Cl

M. Ishaque Khan, Yuan Da Chang, Qin Chen, Jose Salta, Young Sook Lee, Charles J. O'Connor, Jon Zubieta

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Abstract

Under reducing conditions, aqueous vanadium-oxo solutions react with squaric acid to give the binuclear V(IV) species NH4[V2O2(OH)(C4O4(H2O)3]·H2 (1·H2O). In the absence of reducing agents and upon addition of (C4H9N)4NBr, vanadate solutions react with squaric acid to give the binuclear mixed-valence species [(C4H9)4N]-[V2O3(C4O4)2(H2O)3]·3H2O (2·3H2O). The structure of the anion [V2O3(C4O4)2(H2O)3]2- consists of the {V2O3-(μ-H2O)}3+ core with the vanadium sites bridged additionally by two μ-1,2-squarate ligands and with an aquo ligand on each vanadium center completing the coordination. From the filtrate are isolated 2·3H2O and dark brown crystals of [(C4H9)4N]4[V4O6(C4O4)5(H2O)4]·6H2O (3·6H2O) after 2 weeks of standing at room temperature. The tetranuclear mixed-valence V(IV)/V(V) species 3·6H2O exhibits a structure consisting of two binuclear (V2O3-(C4O4)(H2O)2]0 units bridged by a (μ-1,3) squarate group. The structure thus exhibits both μ-1,2- and μ-1,3-squarate ligands. While analogous oxalate derivatives were not isolated from reactions in aqueous solvent, the binuclear V(IV) species [V2O2Cl2(C2O4)(CH3OH)4]·2Ph4PCl (4·2Ph4PCl) was prepared by the reaction of a suitable binuclear V(IV) precursor with oxalic acid in methanol. The structural core of the neutral [V2O2Cl2(C2O4)(CH3-OH)4] consists of a planar {V2O2Cl2(C2O4)} unit; the methanol ligands occupy positions normal to this moiety. Crystal data: 1·H2O. monoclinic. P21/n, a = 11.554(2) Å, b = 6.568(1) Å, c = 13.436(3) Å, β = 108.76(3)°, V = 965.5(5) Å3. Z = 4. Dclac = 1.638 g cm-3, 867 reflections, R = 0.0763; 2·3H2O, triclinic. P1, a = 11.628(2) Å. b = 14.990(3) Å, c = 10.746(2) Å, α = 108.49(3)°, β = 99.02(3)°, γ = 98.13(3)°, V = 1717.5(9) Å3, Z = 2, Dclac = 1.399 g cm-3, 2741 reflections, R = 0.0597; 3·6H2O, triclinic, P1, a = 16.670(3) Å, b = 18.440(4) Å, c = 20.151(4) Å. α = 65.96(2)°, β = 69.14(3)°, γ = 80.10(3)°, V = 5284(3) Å3, Z = 2, Dcalc = 1.261 g cm-3, 2858 reflections. R = 0.0832; 4·2Ph4PCl. monoclinic. P21/C, a = 10.906(2) Å, b = 14.724(3) Å, c = 17.574(3) Å, β = 94.93(2)°, Dcalc = 1.387 g cm-3, 1397 reflections, R = 0.0688.

Original languageEnglish (US)
Pages (from-to)6340-6350
Number of pages11
JournalInorganic Chemistry
Volume33
Issue number26
DOIs
StatePublished - Dec 1 1994

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Fingerprint Dive into the research topics of 'Synthesis and Characterization of Binuclear Oxo-Vanadium Complexes of Carbon Oxoanion Ligands. Crystal Structures of the Binuclear Vanadium(IV) Complex (NH<sub>4</sub>)[V<sub>2</sub>O<sub>2</sub>(OH)(C<sub>4</sub>O<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>3</sub>]·H<sub>2</sub>O, of the Mixed-Valence Vanadium(V)/Vanadium(IV)-Squarate Species [(n-C<sub>4</sub>H<sub>9</sub>)<sub>4</sub>N][V<sub>2</sub>O<sub>3</sub>(C<sub>4</sub>O<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>3</sub>]·3H<sub>2</sub>O and [(C<sub>4</sub>H<sub>9</sub>)<sub>4</sub>N]<sub>4</sub>[V<sub>4</sub>O<sub>6</sub>(C<sub>4</sub>O<sub>4</sub>)<sub>5</sub>(H<sub>2</sub>O)<sub>4</sub>]·6H<sub>2</sub>O, and of the Binuclear Vanadium(IV)-Oxalate Species [V<sub>2</sub>O<sub>2</sub>Cl<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)(CH<sub>3</sub>O<sub>H</sub>)<sub>4</sub>]·2Ph<sub>4</sub>Cl'. Together they form a unique fingerprint.

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