Dialkylchromium complexes bearing a hydrotris(3,5-dimethylpyrazolyl)borate ligand: Synthesis and crystal structures of Tp*CrMe₂(DMAP) and Tp*Cr(Cr(CH₂Ph)₂(DMAP) (DMAP=4-dimethylaminopyridine)

The synthesis and the crystallographic characterization of two dialkylchromium complexes possessing a Tp* ligand, i.e. Tp*CrMe₂(DMAP) (4) and Tp*Cr(CH₂Ph)₂(DMAP) (5) (Tp*=hydrotris(3,5-dimethylpyrazolyl)borate; DMAP=4-dimethylaminopyridine), are described. Treatment of Tp*CrCl₂(DMAP) (3) with two equivalents of MeLi gave 4, while the complex 5 was prepared by the reaction of 3 with two equivalents of PhCH₂MgCl. These complexes were found to be thermally robust and quite stable to air and moisture. Distorted octahedral geometry around each chromium center of 4 and 5 has been determined by X-ray analysis, the chromium center being surrounded with three nitrogen atoms of the Tp* ligand at facial positions, one nitrogen atom of the DMAP ligand, and two carbon atoms. The two benzyl ligands of 5 were found to coordinate to the chromium center in η¹-fashion.