Efficient Production of Poly(Cyclohexene Carbonate) via ROCOP of Cyclohexene Oxide and CO₂ Mediated by NNO-Scorpionate Zinc Complexes

• Main Authors: Sonia Sobrino, Marta Navarro, Juan Fernández-Baeza, Luis F. Sánchez-Barba, Agustín Lara-Sánchez, Andrés Garcés, José A. Castro-Osma, Ana M. Rodríguez
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Polymers
• Subjects: scorpionate zinc complexes; ring-opening copolymerization (ROCOP); CO₂ fixation; poly(cyclohexene carbonate) production
• Online Access: https://www.mdpi.com/2073-4360/12/9/2148

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 <b>2</b>, <b>4</b> and <b>6</b> 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 °C, 10 bar of CO₂ pressure and 1 mol % of loading, the dinuclear thioaryloxide [Zn(bpzaepe)₂{Zn(SAr)₂}] (<b>4</b>) 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 polycarbonate materials with narrow dispersity values.