Synthesis and catalytic application of monometallic molybdenum(IV) nitrile complexes

The novel molybdenum(IV) compound [MoO(NCMe)5][B(C6F5)4]2 (1a) has been prepared by air oxidation of [Mo(CO)3(NCMe)3] in the presence of [H(OEt2)2][B(C6F5)4] at room temperature. The [MoO(NCMe)5]2+ cation shows a distorted octahedral configuration with two different acetonitrile-metal bond lengths due to a trans effect of the oxo-ligand. The trans-acetonitrile ligand is easily abstracted under oil pump vacuum to form [MoO(NCMe)4][B(C6F5)4]2 (1b). The complex [MoO(NCPh)4][B(C6F5)4]2 (2) is formed by substitution of acetonitrile ligands of 1a with benzonitrile molecules. The Mo(IV) complexes can be applied in the homopolymerization of isobutene at 30 °C leading to high yields and moderate molecular weights.