Halogenated β‐diketiminato magnesium complexes: Preparation, characterization, and catalysis for ring‐opening polymerization of aliphatic lactones

Abstract

The halogenated β‐diketiminato magnesium butyl complexes LXMgBu(THF) (X = Cl (1), Br (2)) and allyl complexes LXMg(allyl)(THF) (X = Cl (3), Br (4)) (LCl = ((2,6‐Cl2C6H3)N═C(Me)CH═C(Me)N(2,6‐Cl2C6H3)), LBr = ((2,6‐Br2C6H3)N═C(Me)CH═C(Me)N(2,6‐Br2C6H3)) were prepared and characterized. The treatment of butyl complex 2 with (S)‐1‐phenylethanol gave the corresponding alkoxide complex [LBrMgOCHMePh]2 (5), the dimeric structure of which was confirmed by single‐crystal x‐ray diffraction. When bulky diphenylmethanol was employed to react with Complex 2, THF‐ligated monomeric complex LBrMgOCHPh2(THF) (6) was afforded. The catalytic performances of these magnesium complexes for ring‐opening polymerization of ε‐caprolactone (ε‐CL), δ‐valerolactone (δ‐VL), and γ‐butyrolactone (γ‐BL) were evaluated.