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) center dot H2O] center dot NO3 (1), [Ag(PyBIm) center dot H2O]center dot ClO4 (2), [Ag-2(PyBIm)(2)] center dot (SiF6) center dot 2H(2)O (3) and [Ag(PyBIm) center dot (HBDC] (4) (PyBIm = 2-(4-pyridyl)benzimidazole, BDC = 1,3-benzenedicarboxylate) have been synthesized and characterized by X-ray crystallography. All the silver(l) atoms in complexes 1-4 are bridged by the different PyBIm ligands via N-Py and N-BIm 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" [Ag-2(PyBIm)(2)](infinity) chain into a two-dimensional undulating sheet. The sheets are connected through hydrogen-bonding as well as pi-pi 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. (c) 2006 Elsevier Ltd. All rights reserved.