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)·2H]2+·(ClO4−)2·(CH3CN) (1), [(Py4C)·2H]2+·(BF4−)2·(CH3CN) (2), [(Py4C)·2H]2+·2Cl− (3), and [(Py4C)·2H]2+·2(TsO−) (4), respectively, have been determined by X-ray analysis. Dication [(Py4C)·2H]2+ constructs a three-dimensional polycationic network though the formation of intermolecular N−H···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 [(Py4C)·2H]2+ dication described here is not only an aesthetically pleasing form but is expected to possess interesting dielectric and thermal properties.