Comparison of the Catalytic Activity of Mono- and Multinuclear Ga Complexes in the ROCOP of Epoxides and Cyclic Anhydrides

Ghosh S., Glöckler E., Wölper C., Linders J., Janoszka N., Gröschel A.H., Schulz S.

Abstract

Tetranuclear Schiff-base complexes L1–32Ga4(t-Bu)8 1–3 are highly active and selective (>99 %) catalyst in the alternating ring-opening copolymerization (ROCOP) of epoxides and anhydrides, yielding polyesters with high molecular weights (Mn) and narrow dispersity (Đ). The thermal properties (Tg) of the resulting polyester range from 18 °C to 124 °C and increase with increasing steric bulk or rigidity along the polymer backbone. Comparative studies using structurally related complexes L4Ga(t-Bu)2 4, [L5GaR2]2 (R=t-Bu 5, R=Me 6) and L6Ga(t-Bu)2 7 proved that the Ga2O2 core of catalyst 1 is the catalytically active species.