Treatment of N,N′-bis(2,6-dimethylphenyl)formamidine (L1), N,N′-bis(2,6-diisopropylphenyl)formamidine (L2), and N,N′-dimesitylformamidine (L3) with Zn(OAc)₂·2H₂O or Cu(OAc)₂·H₂O produced the corresponding Zn(II) and Cu(II) N,N′-diarylformamidine complexes [Zn₃(L1)₂(OAc)₆] (1), [Zn₂(L2)₂(OAc)₄] (2), [Zn₂(L3)₂(OAc)₄] (3) and [Cu₂(L2)₂(OAc)₄] (4), respectively. While complex 1 is trinuclear, compounds 2–4 are dimeric in the solid state. The X-band EPR spectra of complex 4 in solid and solution states are consistent with perfect axial symmetry and confirm retention of the dinuclear paddle-wheel core in the solution state. Complexes 1–4 formed active catalysts in the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and lactides (LA). Complexes 1 and 3 exhibited higher rate constants of 0.1009 h⁻¹ and 0.0963 h⁻¹ compared to the rate constants of 0.0479 h⁻¹ and 0.0477 h⁻¹ observed for 2 and 4, respectively, in the ROP of ε-CL at 110 °C. Higher rate constants of 0.5963 h⁻¹ and 1.2962 h⁻¹ were obtained for complexes 1 and 3 in the ROP of LAs compared to those reported in the ROP of ε-CL at 110 °C. Activation parameters were determined as ΔH^‡ = 25.08 kJ mol⁻¹ and ΔS^‡ = −201.7 J K⁻¹ mol⁻¹ for the ROP of ε-CL using 3. Investigation of the kinetics of polymerization of ε-CL and LAs revealed first order dependence of the polymerization reactions on monomer concentration. Moderate molecular weight polymers of up to 21 286 g mol⁻¹ exhibiting relatively moderate molecular weight distributions and moderately heterotactic PLAs with Pr up to 0.65 were obtained.