Effcient production of poly(cyclohexene carbonate) via ROCOP of cyclohexene oxide and CO2 mediated by NNO-Scorpionate zinc complexes

Abstract

New mono- and dinuclear chiral alkoxide/thioalkoxide NNO-scorpinate zinc complexes were easily synthesized in very high yields, and characterized by spectroscopic methods. X-ray diffraction analysis unambiguously confirmed the different nuclearity of the new complexes as well as the variety of coordination modes of the scorpionate ligands. Scorpionate zinc complexes 2, 4 and 6 were assessed as catalysts for polycarbonate production from epoxide and carbon dioxide with no need for a co-catalyst or activator under mild conditions. Interestingly, at 70 ffiC, 10 bar of CO2 pressure and 1 mol % of loading, the dinuclear thioaryloxide [Zn(bpzaepe)2(Zn(SAr)2)] (4) behaves as an efficient and selective one-component initiator for the synthesis of poly(cyclohexene carbonate) via ring-opening copolymerization of cyclohexene oxide (CHO) and CO2, affording polycarbonatematerials with narrow dispersity values.