Syntheses and crystal structures of four silver(I) complexes based on 2-(4-pyridyl)benzimidazole

Four new silver(I) complexes constructed with 2-(4-pyridyl)benzimidazole, namely, [Ag(PyBIm) · H2O] · NO3 (1), [Ag(PyBIm) · H2O] · ClO4 (2), [Ag2(PyBIm)2] · (SiF6) · 2H2O (3) and [Ag(PyBIm) · (HBDC)] (4) (PyBIm = 2-(4-pyridyl)benzimidazole, BDC = 1,3-benzenedicarboxylate) have been synthesized and characterized by X-ray crystallography. All the silver(I) atoms in complexes 1–4 are bridged by the different PyBIm ligands via NPy and NBIm into one-dimensional “zigzag” chains. The anions do not coordinate to the silver(I) atoms and only act as counter ions in complexes 1–3. Due to the anions, different hydrogen bonding systems are found in those three compounds, resulting in the different crystal packing. Through hydrogen bonding interactions, the structures of complexes 1–3 display a double layer, a three-dimensional framework and a novel double chain, respectively. In complex 4, the HBDC− anions act not only as a counter ion but also as bridging ligands, which lead the “zigzag” [Ag2(PyBIm)2]∞ chain into a two-dimensional undulating sheet. The sheets are connected through hydrogen-bonding as well as π–π interactions into a three-dimensional framework. The thermal stabilities of the four complexes and anion exchange properties of complexes 2 and 3 were also studied.

Four silver (I) coordination polymers were prepared by the reactions of PyBIm and various silver(I) salts under different conditions. The results show that the anions play important roles in the coordination sphere of the silver(I) atoms as well as the crystal packing of the coordination polymers.Figure optionsDownload as PowerPoint slide