Abstract: | Zinc complexes supported by tertiary 1,3,5‐triazapenta‐1,3‐dienate ligand (L1) and N ‐benzoyl‐N′ ‐arylbenzamidinate aryl =2,6‐diisopropylphenyl (L2), phenyl (L3)] ligands have been synthesized and characterized. The reaction of L1H with ZnEt2 affords a mononuclear zinc complex L1ZnEt] ( 1 ) in good yield. Tetra nuclear zinc complex (L1)2Zn4O(OAc)4] ( 2 ) is prepared by treating L1H with one equivalent of Zn(OAc)2 in toluene. Further, dinuclear zinc complexes L2ZnEt]2 ( 3 ) and L3ZnEt]2 ( 4 ) are obtained in good yields from L2H and L3H with ZnEt2 in toluene respectively. The complexes 1–4 have been characterized by 1H/13C NMR spectroscopy and single crystal X‐ray diffraction studies. All of the complexes have been explored for their catalytic activity toward the ring‐opening polymerization (ROP) of ε ‐caprolactone. It has been found that complex 1 is an active catalyst for the polymerization of ε ‐caprolactone in presence of a cocatalyst benzyl alcohol (BnOH). While complex 2 is as active as 1 there is no need for a cocatalyst for the polymerization to proceed. Dinuclear zinc complexes 3 and 4 show very high activity for the ROP of ε ‐caprolactone (CL) and rac ‐lactide (LA) without requiring a cocatalyst. The resultant polymers are found to have very high molecular weight (M n = 296 X 103 g mol?1) and relatively narrow polydispersity index compared to 1 and 2 . |