Highly Selective Chromium(III) Ethylene Trimerization Catalysts with [NON] and [NSN] Heteroscorpionate Ligands

Cr(III) complexes with [NON] and [NSN] heteroscorpionate ligands derived from bis(pyrazol-1-yl)methane have been prepared, which are active for ethylene trimerization to 1-hexene with high selectivity. Structural studies have established the coordination of the ether or thioether pendant group, which leads to a bicyclic metallaheterocycle flanked by pyrazoyl rings.