Bis(4-pyridyl)mercury – a new linear tecton in crystal engineering: coordination polymers and co-crystallization processes†
Three new coordination polymers have been obtained using bis(4-pyridyl)mercury (py2Hg) as a spacer: [Cu(Hmea)2(py2Hg)](ClO4)2·2(py2Hg) (1), [Cu2(pa)2(py2Hg)(ClO4)2]·0.5(py2Hg)·H2O (2), and [Cu2(pa)2(py2Hg)2](BF4)2 (3) (Hmea = monoethanolamine; Hpa = propanolamine). Compounds 1 and 2 are linear coordination polymers with mononuclear and binuclear alkoxo-bridged nodes, respectively. Compound 3 features a 3-D network with a cadmium sulfate topology. The ability of py2Hg to generate supramolecular solid-state architectures is illustrated by three systems obtained from co-crystallization processes: (4,4′-dihydroxybiphenyl)·(py2Hg) (4), (pyrogallol)·(py2Hg) (5), and (phloroglucinol)·2(py2Hg) (6). The convolution of various supramolecular interactions (Hg⋯N, Hg⋯O, π⋯Hg, and π–π) in sustaining the architecture of the crystals is analyzed. A new synthetic method for bis(4-pyridyl)mercury was developed. It consists of a two-step reaction, starting from 4-iodopyridine and using iPrMgCl·LiCl and HgCl2.