Heterodinuclear Mg(II)M(II) (M = Cr, Mn, Fe, Co, Ni, Cu and Zn) complexes for the ring opening copolymerization of carbon dioxide/epoxide and anhydride/epoxide

Journal article

The catalysed ring opening copolymerization (ROCOP) of carbon dioxide or anhydrides with epoxides are controlled polymerizations that access useful polycarbonates and polyesters. Here, a series of heterodinuclear Mg(II)M(II) complexes reveal the most effective metal combinations. They combine first row transition metals (Cr(II) to Zn(II)), with Mg(II); all complexes are coordinated by the same macrocyclic ancillary ligand and two acetates. The complex syntheses, characterization and polymerization data, for both carbon dioxide/cyclohexene oxide (CHO) and endo-norbornene anhydride (NA)/cyclohexene oxide, are reported. The fastest catalyst for both polymerizations is Mg(II)Co(II) showing propagation rate constants ( k p ) of 34.7 mM -1 s -1 (CO 2 ) and 75.3 mM -1 s -1 (NA) (100 °C). The Mg(II)Fe(II) catalyst shows equivalently high rates for CO 2 /CHO ROCOP ( k p = 34.7 mM -1 s -1 ) and may have preferable metallic abundance, cost and low toxicity. Polymerization kinetics analyses show that the two lead catalysts have second order rate laws, with zeroth order dependencies in CO 2 or anhydride and first order in both catalyst and epoxide concentrations. Compared to the Mg(II)Mg(II) complex, nearly all the transition metal heterodinuclear complexes show synergic rate enhancements whilst maintaining high selectivity and polymerization control. These findings are relevant to the future design and optimization of copolymerization catalysts and should stimulate broader investigations of synergic heterodinuclear main group/transition metal catalysts.

Authors: Reis, NV; Deacy, AC; Rosetto, G; Durr, C; Williams, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Chemistry – A European Journal
• Volume: 28
• Issue: 14
• Article number: e202104198
• Publication date: 2022-02-17
• Acceptance date: 2022-01-17
• DOI: 10.1002/chem.202104198
• EISSN: 1521-3765
• ISSN: 0947-6539
• Language: English
• Keywords: FFR