Anion-controlled structural motif in one-dimensional coordination networks via cooperative weak noncovalent interactions

Abstract

The self-assembly of an exoditopic N-donor ligand (3-py-3-py) with HgX₂ (X = Cl, Br, I) was investigated. X-ray structure analysis shows that all the compounds have an infinite one-dimensional structure and the Hg(II) ions are in a distorted trigonal pyramidal N₂HgX₂ geometry. Our results indicate that the coordinated anion can control the structural motif of the resulting one-dimensional coordination polymers through cooperative weak noncovalent interactions. In the case of [Hg₂(μ-3-py-3-py)₂Cl₄]_n (1) and [Hg₂(μ-3-py-3-py)₂Br₄]_n (2), the 1D zigzag chains are constructed as a consequence of cooperative noncovalent interactions, such as hydrogen bonds, halogen⋯π and π–π interactions. However, for [Hg(μ-3-py-3-py)I₂]_n (3), the coordinated iodide ion tunes the folding of the 1D structure into a helical array by bifurcated C–H⋯I–Hg hydrogen bonds and π–π interactions in a cooperative manner.