Novel metal-organic frameworks with specific topology formed through noncovalent Br•••Br interactions in the solid state

Two coordination polymers [Ag(bib)]NO3.H2O (1) and [Ag(bib)]ClO4 (2) with one-dimensional (1D) chain structure were synthesized by reactions of ditopic ligand containing imidazole donors, namely, 1-bromo-3,5-bis(imidazol-1-ylmethyl)benzene (bib), with corresponding silver salts. While the bib ligand reacted with ditopic diacetato-zinc(II) acceptors, M2L2-type metallocyclic ring-like complex [Zn-2(bib)(2)(OAc)(4)].2H(2)O (OAc = acetate anion) (3) was obtained, which was further connected by Br...Br interactions to lead to the formation of 1D pseudo-polyrotaxane. When ligand bib reacted with Zn(NO3)(2).6H(2)O and Mn(NO3)(2), two complexes [Zn(bib)(2)(H2O)(2)](NO3)(2).2H(2)O (4) and [Mn(bib)(2)(H2O)(2)](NO3)(2).2H(2)O (5) with 2D network structure were obtained in which the metal atoms had octahedral coordination geometry. The structures of these coordination complexes were determined by X-ray crystallography, and the results revealed that the coordination geometry of metal atoms have a great impact on the structure of the supramolecular architectures. Furthermore, the nitrate anions located in the voids between the 2D cationic layers in 4 can be exchanged by nitrite anions, which means that complex 4 with 2D network structure has anion exchange properties.