PREPARATION AND X-RAY STRUCTURE DETERMINATION OF AN ARYLTRIOXOMOLYBDENUM(VI) ANION

The reaction of dimesityldioxomolybdenum(VI) with ethylidenetriethylphosphorane in tetrahydrofuran at 0-degrees-C yields the mesityltrioxomolybdate (VI) anion, resulting from an oxygen atom transfer from one molybdenum atom to another. The molecular and crystal structure of the anion was determined by X-ray diffraction on the tetraphenylphosphonium salt. The structure was solved via standard heavy atom procedure, completed by subsequent difference Fourier method and refined to R = 0.033 using 4300 reflections. The crystal system is triclinic P1BAR with a = 10.523(3), b = 15.061(5), c = 10.248(3) angstrom, alpha = 108.90(5), beta = 97.47(5) and gamma = 102.11(5)-degrees. The molecular conformation features a single plane including the aromatic ring and one Mo = O bond; this allows the existence of an interaction between an oxygen atom and a methyl carbon.