Organically Functionalized Mixed-Valent Polyoxo-30-molybdate Wheel and Neutral Tetramolybdenum(V) Oxo Cluster
Anusree Sundar, Saurav Bhattacharya, Juliane Oberstein, Xiang Ma, Bassem S. Bassil, Talha Nisar, Dereje H. Taffa, Michael Wark, V. Wagner, Ulrich Kortz
Abstract
The first organofunctionalized mixed-valent polyoxo-30-molybdate wheel, [MoVI18MoV12O84{AsO2(CH3)2}18]18– (Mo30), was synthesized in aqueous, mildly acidic conditions, and upon further acidification, the neutral tetramolybdenum(V) oxo cluster [MoV4O8{AsO2(CH3)2}4] (Mo4) was obtained. Single-crystal X-ray diffraction (XRD) revealed that Mo30 comprises 18 MoVI and 12 MoV ions arranged in a cyclic fashion with alternating {MoV2} and {MoVI3} groups, which are capped by 18 dimethylarsinate ligands, resulting in a novel polyoxo-30-molybdate wheel with a central cavity of ∼1.5 nm. On the other hand, Mo4 has a distorted-cubic structure, with the corners of the cube being occupied by alternating MoV ions and oxo ligands. The compounds were characterized in solution by 1H and 13C NMR and UV–vis spectroscopy and in the solid state by X-ray photoelectron spectroscopy and powder XRD. Mo30 represents a novel type of polyanionic cycle with manyfold possibilities regarding host–guest chemistry.