Solid state structures of dinuclear and trinuclear tungsten and molybdenum complexes with single metal–metal bonds

•Analogous di- and trinuclear W and Mo complexes with oxalate were prepared.•In all, metal ions (M) are linked by single MM bonds with ca. 2.5 Å lengths.•trans-(PyH)2[WV2O4(η2-C2O4)2(Py)2] contains a rare {WV2O4}2+ core.•[MIV3O4(η2-C2O4)3(R-Py)3]2− ions contain a triangular {MIV3O4}4+ core.•Metric parameters of the homologous {MIV3O4}4+ cores are very similar.

A series of high-valent tungsten and molybdenum complexes with oxalate was synthesized solvothermally. Oxidation of K3[WIII2Cl9] resulted in trans-(PyH)2[WV2O4(η2-C2O4)2(Py)2] (1) (Py = pyridine; PyH+ = pyridinium cation) and (PyH)2[WIV3O4(η2-C2O4)3(Py)3]·Py (2). Compound 1 consists of a rare singly metal–metal bonded {WV2O4}2+ core, whereas 2 contains a triangular {WIV3O4}4+ core with each tungsten ion forming two single WW bonds. Reduction of {(C4H9)4N}[WOCl4(H2O)] (C4H9)4N+ = tert-butylammonium cation) in the presence of potassium ions afforded another trinuclear product, K(PyH)[WIV3O4(η2-C2O4)3(Py)3] (3). Following analogous procedures with molybdenum(V) starting material, (PyH)[MoVOBr4], and 4-methylpyridine as the reaction medium resulted in (4-MePyH)(H3O)[MoIV3O4(η2-C2O4)3(4-MePy)3]·H2O (4) (4-MePy = 4-methylpyridine; 4-MePyH+ = 4-methylpyridinium cation) and (MeNC6H7)(H3O)[MoIV3O4(η2-C2O4)3(4-MePy)3]·1/2(4-MePy) (5) (MeNC6H7+ = N-methylated 4-methylpyridine). Compounds 4 and 5 contain trinuclear [MoIV3O4(η2-C2O4)3(4-MePy)3]2− ions which possess a central triangular {MoIV3O4}4+ core with each molybdenum ion forming two single MoMo bonds. The solid state structures of all compounds were determined by X-ray structure analysis. Metric parameters of the {WV2O4}2+ and {WIV3O4}4+ cores were compared with their molybdenum homologues.

Graphical abstractA [WIV3O4(η2-C2O4)3(Py)3]2− cluster ion.Figure optionsDownload full-size imageDownload as PowerPoint slide