Synthesis and Crystal Structure of the First Tetraaminophosphonium Salt P(NH₂)₄I

Abstract

Unprecedented in chemistry, the acid-base pair H 8 PN 4 "7 PN 4~ enables structural comparison over a range of eight succes sive dissociation steps: According to the results of the X-ray struc ture analysis, 161 P(NH 2 ) 4 and I" ions form a CsCl-analogous arrangement in the solid. The P-N bond length (160.7(2) pm) ( Fig. 1) represents the shortest P-NH 2 bond distance reported to date. The valence sum for the phosphorus center (5.56), calculatThe characteristic building blocks in phosphorus(v) nitrides are PN 4 tetrahedra. Linkage of these structural elements through common corners allows access to a large number of condensa tion degrees. This is reminiscent of the varied structural chem istry of the silicates and phosphates.111 One of the extremes in the series of differently condensed phosphorus nitrides is the ionic compound Li 7 PN 4 , which comprises "isolated" PN] -ions. 121Due to its extremely high formal charge, no indications for the existence of this anion in solution have yet been found; there fore, Li 7 PN 4 is accessible only by solid-state reaction of the corresponding binary nitrides. Thus, the certainly high synthetic potential of isolated PN 4 groups in solution for the formation of well-defined Ρ-Ν solid compounds has remained unexplored.The salt Li 7 PN 4 is derived from the hypothetical acid H 7 PN 4 , which is suspected to be an unstable monophosphazene interme diate during ammonolysis of PC1 5 . 131 However, due to its high basicity and tendency to undergo condensation reactions it has not yet proven possible to isolate imidophosphoric acid triamide, H 7 PN 4 . With P(NH 2 ) 4 I (C) we report the first successful synthesis and structural proof of a tetraaminophosphonium salt, which can be regarded as a hydroiodide of H 7 PN 4 . The synthesis followed the modification of a procedure 141 that starts from phosphorothionic triamide (A).t51 Methylation of the sul phur atom in A with methyl iodide and careful subsequent am monolysis of Β readily yields the desired product C. As the last reaction step is a heterogeneous solid-liquid reaction, C is ob tained as a sparingly-soluble, fine-crystalline powder. The crys tal growth of tetraaminophosphonium iodide was severely ham pered by the fact that C is insoluble in most solvents and that, due to its reactivity, it easily undergoes hydrolysis and conden sation reactions. In the past methanol had been suggested as a solvent for C. However, according to our investigations pro longed exposure of C to methanol leads to the formation of tetramethylammonium iodide [Eq. (a)]. Sufficiently large single crystals of C were obtained by crystallization from dry acetonitrile employing a temperature gradient between 70 °C and room temperature. Obviously, tetraaminophosphonium iodide is sufficiently soluble at the higher temperature. ed from the four Ρ-Ν bonds according to O'Keeffe et al., (7] is indicative of significant polar bonding or multiple bonds between the phosphorus and nitrogen atoms. The electrostatic repulsion between the nitrogen atoms in PN 4 " (...

Phosphorus Nitride P3N5: Synthesis, Spectroscopic, and Electron Microscopic Investigations

“…From the P· · ·P-distance (295 ppm) a P−N−P-bonding angle of 124° is calculated which is comparable to those found in other ternary phosphorus nitrides . There are at least five distinguishable, magnetic different phosphorus atoms ( 31 P MAS NMR) with a chemical shift at higher field (about −50 ppm) compared to non-cross-linked compounds with tetrahedrally coordinated phosphorus, e.g., P(NH 2 ) 4 I: σ = 14.2 ppm. , Investigations on the 15 N nucleus show two signal groups with a ratio of 3:2. In contrast to the oxygen atom (maximum coordination number in silicates and phosphates: CN = 2) nitrogen atoms may form one, two, or three covalent bonds to phosphorus.…”

Nontypical Luminescence Properties and Structural Relation of Ba3P5N10X:Eu2+ (X = Cl, I): Nitridophosphate Halides with Zeolite-like Structure

“…Ba 3 P 5 N 10 X (X = Cl, I) compounds were synthesized using a modified Walker-type multianvil apparatus by the reaction of stoichiometric amounts of Ba­(N 3 ) 2 , P 3 N 5 , and the respective barium halide (Sigma-Aldrich, 99.999% trace metals basis) according to eq . Alternatively, the synthesis of both compounds can be carried out starting from other halide precursors, such as P­(NH 2 ) 4 X (X = Cl, I) , or NH 4 X (X = Cl, I) according to eqs and . For luminescence investigations small amounts of the respective europium halide EuX 2 (X = Cl, Strem Chemicals, 99.9% trace metals basis; X = I, Sigma-Aldrich, 99.9% trace metal basis) were added as dopand.…”

Phosphor(V)-nitrid α-P3N5: Synthese ausgehend von Tetraaminophosphoniumiodid und Kristallstrukturaufklärung mittels Synchrotron-Pulver-Röntgenbeugung

“…Ûber die Reindarstellung, Charakterisierung und Strukturaufkla È rung von Tetraaminophosphoniumiodid wurde bereits von uns berichtet [10,11]. Die Darstellung erfolgte ausgehend von SP(NH 2 ) 3 [12].…”