Seven-coordinated tantalum trichloride complex containing substituted pyrrolyl ligand: Synthesis and characterization of [NC₄H₃(CH₂NMe₂)-2]₂ TaCl₃

bis[2-(Dimethylaminomethyl)pyrrolyl]tantalum chloride (1) was prepared by treatment of the TaCl₅ with 2 equiv. of [2-(dimethylaminomethyl)pyrrolyl]lithium. The solid state structure of 1 shows the seven-coordinated tantalum atom, with a geometry corresponding to a pentagonal bipyramidal structure, in which two chlorine atoms occupy the axial position with the angle of 174.8(2)°. Furthermore, variable-temperature ¹H NMR spectra infer the fluxionality of the two chelating pyrrolyl ligands with an estimated energy barrier of 13.8 kcal mol^-1. Compound 1 shows no catalytic activity toward ethylene polymerization even activated with MAO.