Diazine based ligand supported CoII3 and CoII4 coordination complexes: role of the anions

We report the synthesis and characterisation of a family of three CoII4, two CoII3 complexes from an symmetrical diazine ligand, H2hyda = N,N−bis(3−methoxy salicylidene) hydrazine). The metallic skeletons of all complexes describe a nearly linear arrangement of CoII centers. The present results highlight the profound influence of the anions on the structural outcome of a complex. Furthermore, the distortion imposed by the twisted nature of the diazine based ligand depends on the use of associated anions which results in triple helical CoII4 and double helical CoII3 entities. The CoII ions in complexes 1−3 are antiferromagnetically coupled leading to diamagnetic ground state. In contrast, complexes 4 and 5 exhibit a magnetic ground state, but exhibit different behaviour at low temperatures due to differences in crystal packing and hence intermolecular interactions.