title: Polyoxoanions Derived from [gamma-SiO(4)W(10)O(32)](8-)-Containing Oxo-Centered Dinuclear Chromium(III) Carboxylato Complexes: Synthesis and Single-Crystal Structural Determination of [gamma-SiO(4)W(10)O(32)(OH)Cr(2)(OOCCH(3))(2)(OH(2))(2)](5-).
abstract: The previously unknown heteropolyoxometalates [gamma-SiO(4)W(10)O(32)(OH)Cr(2)(OOCR)(2)(OH(2))(2)](5-) (R = H, CH(3)) have been prepared by the reaction of [gamma-SiO(4)W(10)O(32)](8-) with [Cr(OH(2))(6)](3+) in formate or acetate buffer solution. Isolation of these new Cr(III)-substituted polyoxometalates was accomplished both as Cs(+) salts and as the Bu(4)N(+) salt for the acetate-containing anion. The compounds were characterized by elemental analysis, UV/vis, IR, and ESR spectroscopy, and cyclic voltammetry. The single-crystal X-ray structural analysis of (Bu(4)N)(3)H(2)[gamma-SiO(4)W(10)O(32)(OH)Cr(2)(OOCCH(3))(2)(OH(2))(2)].3H(2)O [P2(1)2(1)2(1); a = 17.608(12), b = 20.992(13), c = 24.464(11) Å; Z = 4; R = 0.057 for 6549 observed independent reflections] reveals that the two corner-linked CrO(6) octahedra are additionally bridged by two acetate groups, demonstrating the relationship to the well-studied oxo-centered trinuclear carboxylato complexes of Cr(III).
authors.affiliation: Institut für Chemie der Humboldt-Universität zu Berlin, Hessische Strasse 1/2, 10115 Berlin, Germany, Fachbereich Chemie der Freien Universität, Fabeckstrasse 34-36, 14195 Berlin, Germany, and Department of Chemistry, Georgetown University, Washington, D.C. 20057.
authors.forename: Knut
authors.initials: K
authors.lastname: Wassermann
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Lunk
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Palm
authors.forename: Joachim
authors.initials: J
authors.lastname: Fuchs
authors.forename: Norbert
authors.initials: N
authors.lastname: Steinfeldt
authors.forename: Reinhard
authors.initials: R
authors.lastname: Stösser
authors.forename: Michael T.
authors.initials: MT
authors.lastname: Pope