title: Homoleptic aminophenolates of Zn, Mg and Ca. Synthesis, structure, DFT studies and polymerization activity in ROP of lactides.
abstract: The reaction of MgBu2, ZnEt2 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.
authors.affiliation: Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland. jolanta.ejfler@chem.uni.wroc.pl.
authors.forename: Jakub
authors.initials: J
authors.lastname: Wojtaszak
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Mierzwicki
authors.forename: Sławomir
authors.initials: S
authors.lastname: Szafert
authors.forename: Nurbey
authors.initials: N
authors.lastname: Gulia
authors.forename: Jolanta
authors.initials: J
authors.lastname: Ejfler
mesh_terms: D002118:Calcium / Q000737:chemistry; D060326:Chemistry Techniques, Synthetic; D018360:Crystallography, X-Ray; D004146:Dioxanes / Q000737:chemistry*; D008024:Ligands; D008274:Magnesium / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D058105:Polymerization; D011789:Quantum Theory; D015032:Zinc / Q000737:chemistry
chemical_list: D004146:Dioxanes; D008024:Ligands; D009942:Organometallic Compounds; D010636:Phenols; C091880:dilactide; D008274:Magnesium; D015032:Zinc; D002118:Calcium