Synthesis and structural characterization of mono- and dinuclear Mo(V)-oxo-complexes containing bis(3,5-dimethylpyrazol-1-yl)acetate anion as ligand

Reactions of bis(3,5-dimethylpyrazol-1-yl)acetic acid (Hbdmpza) with (pyH)5[MoOCl4(H2O)]3Cl2, and (pyH)[MoOBr4] in acetonitrile at elevated temperatures result in obtaining two new compounds, [MoOX2(bdmpza)]∙yCH3CN (X=Cl y = 0 (1), X=Br, y = 1 (2)), respectively. The treatment of mononuclear 1 and 2 in acetonitrile/water solution gives dinuclear [Mo2O4(bdmpza)2]∙2H2O (3). The complexes were analyzed by elemental analysis UV–Vis and IR spectroscopy. The κ3-N,N,O coordination of Mo atoms by bdmpza was proven by the single-crystal X-ray structure. In all compounds the Mo(V) centers are six-coordinated; in 3 the Mo atoms in cis-{Mo2O4}2+ core are bridged by two O atoms.