Synthesis of Heterometallic Rare Earth(III)–Cobalt(II) Complexes and Their Application in Alternating Copolymerization of Cyclohexene Oxide and Carbon Dioxide

Abstract

Comprehensive Summary Four heterometallic rare earth(III)‐cobalt(II) complexes (rare earth = Y (1), Sm (2), Nd (3), La (4)) stabilized by an o‐phenylenediamine‐bridged tris(phenolato) ligand (L) have been synthesized and characterized. In these tetranuclear complexes, one polydentate L coordinates to one rare earth(III) ion, and one cobalt(II) ion, respectively, while two rare earth ions are bridged by four acetate groups. These complexes were applied in the copolymerization of cyclohexene oxide and CO2, which showed good activity (TON up to 440) and high poly(cyclohexene carbonate) selectivity (>99%). Kinetic studies determined the equation as rate = k[CHO]1[CO2]0[initiator]1, which proves a first‐order dependence on initiator concentrations and implies a synergistic mechanism with rare earth and cobalt ions cooperating in epoxide ring‐opening and chain propagation.

Random Terpolymer of Carbon Dioxide, Butadiene and Epoxides: Synthesis, Functionalization and Degradability

“…Epoxides are the ideal co‐monomers due to the high ring‐strain, and the alternating copolymerization of CO 2 with epoxides has been extensively studied, producing degradable polycarbonates (Scheme 1). [ 6‐12 ] However, the preparation of functional polycarbonates remains challenging. [ 13‐15 ]…”

Bio-based, random terpolymers with defined functionality based on poly(limonene carbonate-ran-menth-1-ene carbonate)

“…Cyclohexene oxide could be obtained as a waste product in the self-metathesis of plant oils, but the brittleness of PCHC makes it impractical for industrial applications. 3,5,6 Another excellent example for a bio- and non-food-based polymer is poly(limonene carbonate) (PLimC). PLimC is based on R -(+)-limonene, which is extracted from orange peel and subsequently oxidized to trans -limonene oxide (LimO) and copolymerized with CO 2 using a β-diiminate zinc catalyst.…”