Three new coordination polymers have been obtained using bis(4-pyridyl)mercury (py 2 Hg) as a spacer: [Cu(Hmea) 2 (py 2 Hg)](ClO 4 ) 2 ·2(py 2 Hg) 1; [Cu 2 (pa) 2 (py 2 Hg)(ClO 4 ) 2 ] 0.5(py 2 Hg)·H 2 O 2, and [Cu 2 (pa) 2 (py 2 Hg) 2 ](BF 4 ) 2 3 (Hmea = monoethanolamine; Hpa = propanolamine).Compounds 1 and 2 are linear coordination polymers with mononuclear and binuclear alkoxobridged nodes, respectively. Compound 3 features a 3-D network with cadmium sulfate topology. The ability of py 2 Hg to generate supramolecular solid-state architectures is illustrated by three systems resulted from co-crystallization processes: (4,4'-dihydroxybiphenyl)·(py 2 Hg) 4;(pyrogallol)·(py 2 Hg) 5; (phloroglucinol)·2(py 2 Hg) 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 in a twostep reaction, starting from 4-iodopyridine and using i PrMgCl·LiCl and HgCl 2 .The spacers with pyridyl groups connected by aliphatic chains can show various conformations (for example, antiperiplanar and gauche for the case of 1,2-bis(4-pyridyl)ethane), which play a crucial role in imposing a certain topology of the coordination polymers. 7 Apart from their ability to connect two metal ions, these molecules can act as monodentate ligands or can be found uncoordinated, as guests, in the crystal. The nitrogen atom from the uncoordinated pyridyl moiety acts in such cases as a hydrogen bond acceptor. 8 The pyridyl rings can be involved in π−π stacking interactions which also sustain the supramolecular solid state architectures. 9Most of the spacers employed in constructing coordination polymers are organic molecules. Several inorganic anions (e. g. azide, 10 thiocyanate, 11 dicyanamide 12 ) are also good linkers. The organometallic compounds containing functional groups that can coordinate to another metal ion have been also used as ligands in classical (Wernerian) coordination chemistry and crystal engineering, but to a lesser extent in comparison with organic molecules. 13 Few organometallic species with ligands containing pyridyl groups were reported as tectons for homo-or heterometallic coordination compounds. 13u-13x We recently enlarged the library of exo-bidentate ligands with 1,3-bis(4-pyridyl)azulene, which has an interesting potential in crystal engineering. 14 Herein we present our first results on another bis(4-pyridyl) derivative, bis(4-pyridyl)mercury (py 2 Hg), and its ability to generate coordination polymers, as well crystals resulting from co-crystallization processes. Although organomercurials represent already a quite large class of compounds, their use in crystal engineering was less explored. 15 A new synthetic method for bis(4-pyridyl)mercury was developed.
Results and DiscussionThe synthesis of bis(4-pyridyl)mercury was first reported by Partyka and Gray in 2009, with a yield of 12%. 16 Their procedure, that is general for homoleptic diarylmercurial...
