Coexistence of planar tetramer and cyclic octamer water clusters in a polymer: Synthesis, DFT study and magnetism

A new complex of {[Co2(bib)2(fum)(HCOO)2(H2O)2]·10H2O}n (1) (bib = 4,4’4′-bis(2-methylimidazol-1-ylmethyl)biphenyl and fum = succinate) has been synthesized and characterized. Single crystal X-ray analysis shows that 1 is a 1D chain. Interestingly, 1n 1, two different (H2O)8 and (H2O)4 water clusters are formed by free water molecules, which are further extend into a big (H2O)10 cluster through the coordinative water molecules. The most stable conformation of bib has been analyzed by B3LYP calculation, which reveals that anti-configuration are relatively more stable than trans-conformation. In addition, the magnetic behavior of 1 shows antiferromagnetic exchange between Co magnetic centers. The results indicate that the host environment may play an important role in the formation and stabilization of the water clusters.