Hydrogen-Bonded Quartz-type Network of Diprotonated Tetrakis(4-pyridyl)methane Dications

The crystal structures of the perchlorate, tetrafluoroborate, chloride, and p-toluenesulfonate salts of the diprotonated tetrakis(4-pyridyl)methane (Py4C) dication, [(Py4C)center dot 2H](2+)center dot(CIO4-)(2)center dot(CH3CN) (1), [(Py4C)(2+)center dot(BF4-)(2)center dot(CH3CN) (2), [(Py4C)center dot 2H](2+)center dot 2Cl(-) (3), and [(Py4C)center dot 2H](2+)center dot 2(TsO-) (4), respectively, have been determined by X-ray analysis. Dication [(Py4C)center dot 2H](2+) constructs a three-dimensional polycationic network though the formation of intermolecular N-H center dot center dot center dot N hydrogen bonds between pyridinium ions and pyridines in 1 and 2, respectively, that is characterized by a 3-fold interpenetrated quartz-type network structure. In contrast, no network structure is observed in 3 and 4, as each pyridinium ion forms a hydrogen bond with a counterion. The network structure of the l(Py4C)center dot 2H](2+) dication described here is not only an aesthetically pleasing form but is expected to possess interesting dielectric and thermal properties.