Dimension Increase via Hydrogen Bonding and Weak Coordination Interactions from Simple Complexes of 2-(Pyridyl)benzimidazole Ligands

Abstract

Two asymmetric ligands, 2-(3-pyridyl)benzimidazole (3-PyBim) and 2-(4-pyridyl)benzimidazole (4-PyBim) which are positional isomers and versatile to provide both coordination donors (NPy and NBim) and hydrogen bonding sites (NBim and HNBim), were utilized to synthesize a series of transition metal complexes, namely [Ag2(3-PyBim)2](X)2 (X = BF4– (1), NO3– (2), ClO4– (3), CF3SO3– (4)), [Ag(4-PyBim)](NO3)·(H2O) (5), [Cu(3-PyBim)2(H2O)2](ClO4)2 (6), [Co(3-PyBim)2(H2O)4](NO3)2·(H2O)4(7), [Cu(4-PyBim)2(Cl)2](H2O)2 (8), [Zn(4-PyBim)2(H2O)2(NO3)2] (9), and [Cu2(3-PyBim)2(OAc)4] (10). These simple complexes show diversified intermolecular interaction modes and can behave as basic structural units to be assembled into higher dimensional structures via dimension increasing. In complexes 1–4, every two Ag (I) atoms are connected by two 3-PyBim ligands to form a discrete [Ag2(PyBim)2]2+ cyclic unit, while in complex 5, Ag (I) atoms are bridged by 4-PyBim ligands into a one-dimensional “zigzag” chain. This is due to pos...