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

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(m-3-py-3-py)2Cl4]n (1) and [Hg2(m-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…p and p–p interactions. However, for [Hg(m-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 p–p interactions in a cooperative manner.

Coordination Polymer