Synthesis, crystal structure, and properties of tetraaminophosphonium chloride [P(NH2)(4)]Cl

[P(NH2)(4)]Cl has been prepared by ammonolysis of phosphorus pentachloride in liquid ammonia. The product was purified by reacting the byproduct, ammonium chloride. with diethylamine and removing the diethylamine hydrochloride. Suitable single crystals were obtained from an acetonitrile solution in a temperature gradient between 60 degrees C and room temperature. The crystal structure of [P(NH2)(4)]Cl has been determined by single crystal X-ray methods (Pbcn, a = 470.8(2), b = 1622.3(3), c = 756.3(2) pm, Z = 4). In the solid, [P(NH2)(4)](+) and Cl- ions are found, resembling a TlI-analogous structure. The N-H ... Cl distances indicate N-H ... Cl hydrogen bonding interactions. The distortion of the P-N sceleton of the cation and the very short P-NH2 distances (mean value: 161.2 pm) have been confirmed by ab initio calculations, which show a generalized anomeric effect of the electron pairs at nitrogen and p pi d pi bonding.