Synthesis and Catalytic Activity of Amido-Boratabenzene Complexes of Rare-Earth Metals and Zirconium and Chromium

Amidino-boratabenzenes represent a type of L3X ligand and can be regarded as the monoanionic analogues of the linked amido-cyclopentadienyl ligands. By employment of this type of ligand, 19 constrained-geometry complexes, including Sc­(III), Y­(III), Lu­(III), Zr­(IV), and Cr­(III) derivatives, have been successfully prepared, and some of them showed excellent catalytic activity for ethylene polymerization upon activation.