SYNTHESIS, CRYSTAL-STRUCTURE, AND PROPERT IES OF TETRAAMINOPHOSPHONIUM IODIDE[P(NH2)(4)]I

The title compound has been prepared starting from phosphorothionic tr iamide SP(NH2)(3) by methylation of the sulfur atom and subsequent amm onolysis reaction in dry acetonitrile and dichloromethane, respectivel y, both at room temperature. Suitable single crystals are obtained fro m an acetonitrile solution in a temperature gradient between 70 degree s C and room temperature. The crystal structure of [P(NH2)(4)]I has be en determined by single crystal X-ray methods (P4/n b m; a = 842.6(2), c = 486.7(2) pm, Z = 2). In the solid [P(NH2)(4)](+)- and I(-)ions ar e found with significant N-H...I-hydrogen bonding interactions between anions and cations (H...I: 276.4 pm). The P-N-bond length in the cati on (160.7(2) pm) represents the shortest P-NH2 bond distance reported to date indicating a significant electrostatic strengthening. The cond ensation behaviour of [P(NH2)(4)]I in solution and in the solid has be en investigated.