Synthesis of Chiral <i> C ₂ </i> ‐Symmetric Bimetallic Zinc Complexes of Amido‐Oxazolinates and Their Application in Copolymerization of CO ₂ and Cyclohexene Oxide

Abstract

Abstract A family of new chiral C 2 symmetric amido‐oxazolinate ligands H 2 L ( 1 a‐1 d ) that are bridged by three different linkers based on m ‐phenylenediamine, 4‐(4’‐aminobenzyl)benzenamine, and 1,8‐diaminoanthracene have been synthesized in high yields (85‐90 %). Treatment of ligands ( 1 a‐1 d ) with two equiv. of Zn[N(SiMe 3 ) 2 ] 2 in dry toluene generated a series of heteroleptic dizinc complexes (L)[ZnN(SiMe 3 ) 2 ] 2 ( 2 a ‐ 2 d ) and reaction of 1 b with one equiv. of Zn[N(SiMe 3 ) 2 ] 2 leads to formation of a homoleptic binuclear zinc complex (L) 2 Zn 2 ( 3 b ) in good yield. Complexes 2 a ‐ 2 d were found to be effective catalysts for asymmetric alternating copolymerization of CO 2 and cyclohexene oxide (CHO). The catalyst 2 a is more active towards polycarbonate formation (78 % carbonate linkages), while the catalyst 2 d generates highly isotactic poly(cyclohexene carbonate) (86 % of m ‐centered tetrads).