Oxo-bridged (haloarylimido)[tris(3,5-dimethylpyrazolyl)borato]- molybdenum(V) complexes: Crystal structures of geometric isomers of [MoTp*(O)Cl](µ-O)[MoTp*(Cl)(?NC6H 4Br)]

Abstract

The reaction between [MoTp*(O)Cl2], [Tp* = hydrotris(3,5-dimetylpyrazol-1-yl)borate] and 4-bromoaniline in refluxing toluene gave geometric isomers of [MoTp*(O)Cl](μ-O)[MoTp*(Cl) (≡NC6H4Br)] (1a, cis; 1b, trans), but a similar reaction between [MoTp*(O)Cl2] and 4-chloroaniline yielded only one product, [MoTp*(O)Cl](μ-O)[MoTp*(Cl)(≡NC 6H4Cl)] (2) as a red crystalline solid. The new compounds were characterized by microanalytical data, mass, IR and 1H NMR spectroscopy. The X-ray structure analysis of 1a and 1b revealed that the complexes are geometric isomers, the two chloro ligands being cis in 1a and trans in 1b. Both compounds have Mo-O-Mo linkages and nearly linear arylimido moieties.