Homoleptic aminophenolates of Zn, Mg and Ca. Synthesis, structure, DFT studies and polymerization activity in ROP of lactidesElectronic supplementary information (ESI) available: Additional tables and figures of DFT calculations. CCDC 962645 and 969646. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3dt52868e

• Main Authors: Wojtaszak, Jakub, Mierzwicki, Krzysztof, Szafert, S awomir, Gulia, Nurbey, Ejfler, Jolanta
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c3dt52868e

The reaction of MgBu 2 , ZnEt 2 or Ca(O i Pr) 2 with 2 eq. of three-coordinating N -[methyl(2-hydroxy-3,5-dimethylphenyl)]- N -methyl- N -methyl-1,3-oxolaneamine (mpoa-H) or N -[methyl(2-hydroxy-3,5-di- tert -butylphenyl)]- N -methyl- N -methyl-1,3-oxolaneamine (tbpoa-H) gave neutral, monomeric [Mg(mpoa) 2 ], [Zn(mpoa) 2 ], [Zn(tbpoa) 2 ], and [Ca(tbpoa) 2 ] as white powders in 58-90% yields. The resulting aminophenolates were characterized in solution by NMR showing, in the case of [Zn(tbpoa) 2 ], interesting dynamics. [Zn(tbpoa) 2 ] and [Ca(tbpoa) 2 ] were characterized by X-ray crystallography to show the Zn atom to be pseudo-octahedrally coordinated and the Ca atom in six-coordination mode. The new homoleptic complexes were tested in the polymerization of lactide with an external alcohol to reveal stable behaviour (during the polymerization process) only in the case of [Zn(tbpoa) 2 ]. The high activity of the catalyst was correlated with a ligand flexibility that was further supported by theoretical studies. A series of new homoleptic Zn, Mg and Ca aminophenolates were obtained and characterized. The compounds showed interesting differences in molecular dynamics in solution which greatly influenced their activities in ROP of lactides.