Electron-Deficient β‑Diiminato-Zinc-Ethyl Complexes: Synthesis, Structure, and Reactivity in Ring-Opening Polymerization of Lactones

A series of β-diiminato zinc­(II) complexes bearing two electron-withdrawing trifluoromethyl groups in the pentane ligand backbone were successfully isolated ((BDICF3-I)H = [CH­(CCF3N­C6H4-2,6-CH­(CH3)2)2]; (BDICF3-II)H = [CH­(CCF3N­C6H4-2,6-C2H5)2], and (BDICF3-III)H = [CH­(CCF3N­C6H4-2,6-CH3)2]). The solid-state structures illustrate differences in the ligation of the Zn atom compared to a literature known BDI-ZnEt complex. All catalysts show good activities in the ring-opening polymerization of the cyclic ester (rac)-β-butyrolactone (BL), whereas only BDICF3-II-ZnEt and BDICF3-III-ZnEt are active initiators for the polymerization of (rac)-lactide (LA).