Structure-Activity Relationships for s-Block Metal/Co(III) Heterodinuclear Catalysts in Cyclohexene Oxide Ring-Opening Copolymerizations.

In homogeneous catalysis, uncovering structure-activity relationships remains very rare but invaluable to understand and rationally improve performances. Here, generalizable structure-activity relationships apply to a series of heterodinuclear polymerization catalysts featuring Co(III) and s-block metals M(I/II) (M= Na(I), K(I), Ca(II), Sr(II), Ba(II)). These are shown to apply to polycarbonate production by the ring-opening copolymerizations (ROCOP) of cyclohexene oxide (CHO) and carbon dioxide (CO2), conducted at high (20 bar) and low (1 bar) CO2 pressures, and to polyester production by copolymerization of cyclohexene oxide and phthalic anhydride (PA).

Understanding the Effect of M(III) Choice in Heterodinuclear Polymerization Catalysts.

The ring-opening copolymerization (ROCOP) of epoxides with CO or anhydrides is a promising strategy to produce sustainable polycarbonates and polyesters. Currently, most catalysts are reliant on scarce and expensive cobalt as the active center, while more abundant aluminum and iron catalysts often suffer from lower activities. Here, two novel heterodinuclear catalysts, featuring abundant Al(III), Fe(III), and K(I) active centers, are synthesized, and their performance in the polymerization of four different monomer combinations is compared to that of their Co(III) analogue.

Synergic Catalysis: the Importance of Intermetallic Separation in Co(III)K(I) Catalysts for Ring Opening Copolymerizations.

Dinuclear polymerization catalysts can show high activity and control. Understanding how to design for synergy between the metals is important to improving catalytic performances. Three heterodinuclear Co(III)K(I) catalysts, featuring very similar coordination chemistries, are prepared with different intermetallic separations.

Quantifying CO Insertion Equilibria for Low-Pressure Propene Oxide and Carbon Dioxide Ring Opening Copolymerization Catalysts.

While outstanding catalysts are known for the ring-opening copolymerization (ROCOP) of CO and propene oxide (PO), few are reported at low CO pressure. Here, a new series of Co(III)M(I) heterodinuclear catalysts are compared. The Co(III)K(I) complex shows the best activity (TOF = 1728 h) and selectivity (>90% polymer, >99% CO) and is highly effective at low pressures (<10 bar).