Synthesis of a Novel Oxotungsten(VI) Complex Having a Chelating Bis(aryloxo) Ligand and Its Catalytic Behavior for Ring-Opening Metathesis Polymerization

Abstract

Abstract An oxotungsten complex coordinated with O–S–O chelating bis(aryloxo) ligand, WO{S(4-Me-6-tBuC6H2O)2}Cl2 (1), was synthesized by the reaction of WOCl4 with 2, 2′-S(4-Me-6-tBuC6H2OH)2. The structure of the complex 1 was determined by single-crystal X-ray analysis to have pseudo Cs symmetry. The catalytic behavior of 1/AlEt3 system for the ring-opening metathesis polymerization of norbornene was studied. In this catalytic system, strong dependencies of cis/trans selectivity on the catalyst concentration and on the polymerization temperature were observed. With increasing catalyst concentration and with lowering polymerization temperature, the resulting poly(norbornene)s tend to have higher cis-regularity. Oppositely, trans-rich poly(norbornene)s were produced by the polymerization under low catalyst concentration and at high polymerization temperature. We propose that these observations might come from oxotungsten–aluminum interaction.