Diazine based ligand supported Co II3 and Co II4 coordination complexes: role of anions

Abstract

We report the synthesis and characterisation of a family of three Co^II₄ and two Co^II₃ complexes from a symmetrical diazine ligand, H₂hyda = N,N-bis(3-methoxy salicylidene)hydrazine. The metallic skeletons of all complexes reveal a nearly linear arrangement of Co^II centers. The present results highlight the profound influence of anions on the structural outcome of a complex. Furthermore, distortion imposed by the twisted nature of the diazine-based ligand depends on the use of associated anions which results in triple helical Co^II₄ and double helical Co^II₃ entities. The Co^II ions in complexes 1–3 are antiferromagnetically coupled leading to an S = 0 ground state. In contrast, complexes 4 and 5 exhibit a magnetic ground state, but exhibit different behaviours at low temperatures due to differences in crystal packing and hence intermolecular interactions.