The reaction of Zn(OAc)(2) with 3-ferrocenylpyrazol-1-ylmethylenepyridine (L1), 3-ferroceny1-5-methylpyrazol-1-ylmethylenepyridine (L2), 3-ferrocenylpyrazol-1-ylethylamine (L3) and 3-ferroceny15-pyrazol-1-ylethylamine (IA) afford the corresponding zinc complexes [Zn(CH3COO)(2)(L1)] (1), [Zn(CH3COO)(2)(L2)] (2), [Zn(CH3COO)(2)(L3)] (3), and [Zn(CH3COO)(2)(I4)] (4). These zinc complexes behave as catalysts or initiators for the ring opening polymerization of E-caprolactone, depending on the nature of the ligands, to produce polymers that are capped with cem-dihydroxy, hydroxyl or ferrocenylpyrazolylethylamino end groups. Complexes 1 and 2 were found to act as catalysts when the [CL]/[C] ratios were varied from 100 to 800 to produce PCL with ci,w-dihydroxy and nearly the same molecular weight. Complexes 3 and 4 on the other hand act as initiators to produce a mixture of PCL that have polymers with ferrocenylpyrazolylethylamino and a hydroxyl as end groups as the major component of the mixture and minor species with ovo-dihydroxy end group. (C) 2015 Elsevier B.V. All rights reserved.