Mehrkernige Oxo-Vanadium- und Oxo-Molybdän-Komplexe mit dem Dianion der Quadratsäure als Brückenligand. Strukturen von [C(NH2)3]4[V2O2F4(C4O4)2]·4H2O, [nBu4N]4[V3O3F4(C4O4)3]·2H2O, [Et4N]3[Mo3O8F(C4O4)2], [Et4N]4[Mo4O10F6(C4O4)] und [ Et4N]3[Mo2O3Cl3(C4O4)2] / Polynuclear Complexes of Oxo-Vanadium and Oxo-Molybdenum with the Dianion of Squaric Acid as Bridging Ligand. Crystal Structures of [C(NH2)3]4[V2O2F4(C4O4)2]·4H2O, [nBu4N]4[V3O3F4(C4O4)3]·2H2O, [Et4N]3[Mo3O8F(C4O4)2], [Et4N]4[Mo4O10F6(C4O4)] and [ Et4N]3[Mo2O3Cl3(C4O4)2

Abstract

Abstract Aqueous or methanolic solutions containing vanadium(IV), molybdenum(V) and molyb-denum(VI) oxo species and fluoride ions react with squaric acid to give the oligonuclear complexes [C(NH2)3]4[V2O2F4(C4O4)2]·4H2O (1), Cs4[V3O3F4(C4O4)3]·5H2O (2a), [nBu4N]4[V3O3F4(C4O4)3]·2H2O (2b), [Et4N]4[Mo4O10F6(C4O4)] (3a), [Et4N]4[Mo4O10Cl6(C4O4)] (3b), [Et4N]3[Mo3O8F(C4O4)2] (4) and [Et4N]3[Mo2O3Cl3(C4O4)2] (5). The structures of compounds 1, 2a, 2b, 3a, 4 and 5 have been determined by single crystal X-ray diffraction. The [V2O2F4(C4O4)2]4- ion in 1 consists of the planar V2O2F4 core with the vanadium sites bridged by two ,μ-1,2-squarato ligands. The unique cone-shaped [V3O3F4(C4O4)3]4- ion in 2a and 2b contains a central defect and severely distorted V3F4 cubane unit. Each vanadium atom bears a terminal oxo ligand; pairs of vanadium atoms are bridged by μ-1,2-squarato ligands. The [Mo4O10F6(C4O4)]4- ion in 3a consists of a squarate ion, which is coordinated to four metal centers. Pairs of metal atoms are bridged by μ(O)μ(F)-bridges. Two terminal oxo ligands and one terminal fluoro ligand complete the metal coordination. Oxo and fluoro ligands are partly disordered. The structure of the [Mo3O8F(C4O4)2]3- ion in 4 is related to the structure of [V3O3F4(C4O4)3]4- It consists of a defect Mo3(O3F) cubane unit. Two pairs of molybdenum atoms are bridged by μ-1,2-squarato ligands. Terminal oxo and dioxo groups complete the molybdenum coordination. The [Mo2O3Cl3(C4O4)2]3- ion in 5 exhibits a unique structure with a planar OClMo(μ-O)(μ-Cl)MoOCl core and a cis, cis-orientation of the oxygen ligands. Two, μ-1,2-squarato ligands bridge the molybdenum centers above and below the Mo2O3Cl3 plane.