Zinc complexes chelated by bifunctional ketiminate ligands: Structure, reactivity and possible applications in initiation of ROP and copolymerization of epoxides with carbon dioxide

•Homo- and heteroleptic zinc complexes were prepared.•Monoanionic potentially terdenate ketiminate ligands were used.•Reactivity studies of heteroleptic ethyl zinc complex with alcohols and amines was performed.•Heteroleptic ethyl zinc complex was screened in as a catalyst in various co/polymerization reactions.

Bifunctional ketiminate zinc complexes were synthesized via alkyl or LiCl elimination route from appropriate zinc species (ZnCl2 or ZnEt2) and methoxyaryl substituted monoanionic ketimine {[2- or 3- or 4-(MeO)C6H4]}N(H)C(Me)=CHC(Me)=O. Homo- or heteroleptic complexes were prepared and characterized by the help of multinuclear NMR spectroscopy techniques. One of the heteroleptic ethyl substituted zinc complexes - {κ2-N,O-[(2-MeO)C6H4NC(Me)–CHC(Me)–O]ZnEt}2 was selected for further reactivity experiments with alcohols and amines. Molecular structures of some products were determined by X-Ray diffraction methods showing di- or trinuclear arrangement in solid state caused by the presence of intramolecular zinc–oxygen or zinc–nitrogen bridges. {κ2-N,O-[(2-MeO)C6H4NC(Me)–CHC(Me)–O]ZnEt}2 was also screened for of its catalytic activity in co/polymerization reactions (ROP: trimethylene carbonate, ɛ-caprolactone, l-lactide; copolymerization of epoxides with CO2).

Graphical abstractHomo- and heteroleptic zinc complexes containing monoanionic methoxyaryl substituted ketiminate ligands were synthesized and characterized. Selected complex was studied for further reactivity with alcohols and amines and also screened as co-initiator of various co/polymerization reactions.Figure optionsDownload full-size imageDownload as PowerPoint slide