Syntheses, crystal structures, and magnetic properties of novel copper(II) complexes with the flexible bidentate ligand 1-bromo-3,5-bis(imidazol-1-ylmethyl)benzene

Seven new metal-organic frameworks (MOFs) [Cu(bib)(2)(H2O)(2)](Cl3CCOO)(2)center dot 2MeOH center dot 2H(2)O (1), [Cu(bib)(2)]Cl-2 center dot H2O (2), [Cu(bib)(2)(SO4)(H2O)]center dot 4H(2)O (3), [Cu(bib)(SO4)(H2O)(2)] (4), [Cu(bib)(N-3)(OAc)]center dot DMF (5) (OAc = acetate), [Cu(bib)(ox)]center dot MeOH center dot 2H2O (6) (ox = oxalate), and [Cu(bib)(mal)], MeOH (7) (mal = malonate) were obtained by reactions of flexible bidentate ligand 1-bromo-3,5-bis(imidazol-1-ylmethyl)benzene (bib) with corresponding copper(II) salts. The structures of these MOFs were established by single-crystal X-ray diffraction analysis. Complexes 1 and 2 have similar one-dimensional (1D) hinged chain structure. Complex 3 has a 2D network structure with (4,4) topology. Complex 4 has M2L2 metallocyclic ring structure and the rings are further linked by the sulfate anions to form a 1D tube-like chain. Complex 5 is also a dinuclear M2L2 metallocyclic ring, which is further connected by Br center dot center dot center dot Br interactions to form 1D chain. While in the cases of complexes 6 and 7, both have 2D network structure in which the oxalate and malonate anions act as bridging ligands. The results showed that the counteranions play important roles in the construction of MOFs. In addition, the magnetic properties of complexes 6 and 7 were investigated. The results show that weak ferromagnetic interactions occurred between the copper(II) ions linked by the oxalate anions in complex 6, and there is no obvious magnetic interaction between the copper(II) ions bridged by the malonate anions in complex 7.