Anions of 1,3,5‐Benzenetricarboxylic and Heptanedioic Acids Serving as Bridges between Dimolybdenum(V) Metal–Metal Bonded Units: Preparation and Structural Characterization of Dinuclear and Tetranuclear Complexes

Abstract

Abstract(PyH)5[MoOCl4(H2O)]3Cl2 and (PyH)[MoOBr4] reacted with the anions of 1,3,5‐benzenetricarboxylic acid (btcH3) and heptanedioic acid (hdaH2) to afford a series of novel carboxylato complexes based on the {Mo2O4}2+ structural core: (PyH)4[Mo2O4Cl4(μ2‐btcH2)]Cl (1), (PyH)4[Mo2O4Br4(μ2‐btcH2)]Br (2), [(Mo2O4Py3)2(μ3‐btcH)2]·6Py (3), (PyH)6[(Mo2O4Cl4)2(μ4‐hda)]·2CH3CN (4), and (PyH)10[(Mo2O4Cl4)2(μ4‐hda)][MoOCl5]Cl2 (5) {Py = pyridine, C5H5N; PyH+ = pyridinium cation, C5H5NH+; btcH2– = (HOOC)2C6H3COO–; btcH2– = (HOOC)C6H3(COO)22– and hda2– = –OOC(CH2)5COO–}. A pair of isostructral compounds 1 and 2 contains dinuclear anions [Mo2O4X4(μ2‐btcH2)]3– (X = Cl, Br) in which the btcH2– ligand is bonded to the {Mo2O4}2+ core via one carboxylate group in a syn‐syn bidentate bridging manner. In 3, two btcH2– ligands link two {Mo2O4}2+ cores into a loop‐like structure. Each btcH2– ligand is coordinated via two carboxylate groups, with one in the syn‐syn bidentate bridging manner and with another in a monodentate manner. The linkage of two dinuclear subunits was also realized in [(Mo2O4Cl4)2(μ4‐hda)]6–, the anion in 4 and 5, where both carboxylate groups of the hda2– ligand bind in the syn‐syn bidentate‐bridging manner to {Mo2O4}2+ cores. The title compounds were characterized by X‐ray crystallography and infrared spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)