Synthesis and characterisation of fifteen-electron dihalo(carbonyl)tungsten(iii) complexes, Tp*WX2(CO) (X = Br, I)

Abstract

The oxidation of Tp*WIII(NCMe)(CO) [Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate] by iodine in refluxing acetonitrile produces paramagnetic Tp*WIIII2(CO), withμeff= 1.70μBandν(CO) = 1881 cm−1. The analogous bromo complex, Tp*WIIIBr2(CO) (μeff= 1.72μB,ν(CO) = 1905 cm−1), is produced by the oxidative decarbonylation of Tp*WI(CO)3with bromoacetonitrile in refluxing tetrahydrofuran. The crystal structures of both complexes reveal mononuclear, six-coordinate, distorted octahedral metal complexes bearing facial Tp* and mutuallycishalide and carbonyl ligands. The structures, magnetic moments and spectroscopic data (including isotropically shifted NMR spectra) are consistent with a low-spin, doub..