Compounds N-(1H-benzimidazol-2-ylmethyl)aniline (L1), N-(1H-benzimidazol-2-ylmethyl)-2-bromoaniline (L2), and N-(1H-benzimidazol-2-ylmethyl)-2-aminothiophenol (L3) react with ZnII and CuII carboxylates to form complexes Zn2(L1)2(OBn)4 (1), Zn2(L2)2(OBn)4 (2), Zn2(L3)2(OBn)4 (3), Cu2(L2)2(OBn)4 (4), Zn(L1)2(OAc)2 (5), Zn(L2)2(OAc)2 (6) and Cu2(L1)2(OAc)4 (7). Structures of 2, 4 and 6 revealed that L1-L3 are monodentate, binding through the imidazolyl N-atom. The X-band EPR spectrum of 4 in the solid state is consistent with an antiferromagnetically-coupled (singlet) ground state and a low-lying EPR-active triplet excited state characterised by two main transitions. In dimethyl sulfoxide (DMSO) solution, a single resonance confirmed the retention of the dinuclear paddlewheel core. Complexes 1-7 formed active catalysts towards ring-opening polymerisation of -caprolactone. The polymerisation reactions follow first-order kinetics with respect to the monomer and occur through a coordination-insertion pathway. PUBLICATION ABSTRACT