Cyclohexene oxide/carbon dioxide copolymerization by chromium(III) amino-bis(phenolato) complexes and MALDI-TOF MS analysis of the polycarbonates

Amine-bis(phenolate) chromium(III) chloride complexes 1 center dot THF, 2 center dot THF and 1 center dot DMAP catalyze the copolymerization of cyclohexene oxide and carbon dioxide. These catalysts incorporate tetradentate amine-bis(phenolate) ligands [L1] and [L2], (where [L1] = 2-pyridyl-N,N-bis(2-methylene-4-methoxy-6-tert-butylphenolato) and [L2] = dimethylaminoethylamino-N,N-bis(2-methylene-4-methoxy-6-tert-butylphenolato)) and when combined with 4-(N,N-dimethylamino)pyridine (DMAP) or bis(triphenylphosphoranylidene)ammonium chloride or azide (PPNCl or PPNN3), yield low molecular weight polycarbonate with narrow dispersities. The structure of 1 center dot DMAP incorporates one molecule of 4-(N,N-dimethylamino)pyridine (DMAP) and can be used as a single-component catalyst precursor. Polymer end group analysis by MALDI-TOF mass spectrometry reveals possible initiation pathways.