Cyanphosphorverbindungen. IX. Cyanidabbau von weißem Phosphor zu Dicyanphosphiden und die Dicyanphosphid‐Struktur

Abstract

Genügend starke anionische Nucleophile X− bauen weißen Phosphor unter mehr oder weniger weitgehender Disproportionierung ab. Mit Kronenether‐Alkali‐, Ammonium‐ oder Phosphoniumcyaniden, X− = CN−, entsteht dabei selektiv das entsprechende Dicyanphosphid, P(CN)2−, und ein Polyphosphid, bevorzugt P15−. [18] Krone‐6‐KP(CN)2 entsteht auch bei der Umsetzung von P(CN)3 mit KF und Kronenether. Im Kristall dieses Salzes sind die am Phosphor (um 95°) gewinkelten Dicyanphosphid‐Anionen mit beiden Stickstoffenden an je ein Kation koordiniert. Der PC‐Abstand ist (mit durch‐schnittlich 168 pm) so kurz wie in Phosphaalkenen. δ13C und JPC von P(CN)2− ordnen sich gut in einen für Cyanphosphorverbindungen allgemein geltenden Zusammenhang mit der Ladungsdichte am Phosphor ein.

Synthesis of Heavy Dicyanamide Homologues from Air‐Stable Precursors

“…In most cases, the separated dppe byproduct may be recycled for later use—for example in the preparation of [dppeP] + —simply by evaporating all volatiles from the diethyl ether filtrate in vacuo. The spectroscopic properties of [PPh 4 ][DCP] agree well with earlier reports of sodium‐ and potassium‐crown ether DCP salts; a singlet at −192.7 ppm in the 31 P{ 1 H} NMR spectrum and a doublet centered at 132.2 ppm in the 13 C{ 1 H} NMR spectrum (| 1 J CP |=106 Hz) corresponding to the DCP anion are apparent alongside the typical signals expected for the PPh 4 cation. The FT‐IR spectrum of the isolated solid features two bands in the CN region at 2088 cm −1 and 2111 cm −1 , corresponding to the CN asymmetric (B 2 ) and symmetric (A 1 ) stretching modes, respectively.…”

“…The packing structure is shown in Figure alongside the structure of one of the DCP anions. Compared to the previously reported sodium‐ and potassium‐[18]crown‐6 salts of DCP, the P−C bond lengths of the anions found in [PPh 4 ][DCP] are slightly longer (ranging from 1.802(10) Å to 1.755(6) Å), whereas the C‐P‐C angles (92.7(3)° on average) are slightly smaller . These changes are likely attributable to the absence of alkali metal cations to which the nitriles of DCP are coordinated in the former salts.…”

“…Surprisingly, and in stark contrast to its lighter homologue, very little chemistry involving the dicyanophosphide (DCP) anion has been pursued in the forty years since its initial isolation . Schmidpeter published preparative routes to DCP salts involving either the reduction of tricyanophosphine (P(CN) 3 ) or “more conveniently” through the nucleophilic disproportionation of white phosphorus (P 4 ) by cyanide in refluxing acetonitrile (MeCN) . Both cases require toxic and pyrophoric starting materials which are volatile and thus pose significant exposure risk.…”

Molecules that we made: An essay on phosphorus chemistry

“…‫מ‬ P(CN) 2 We found two preparative routes based in essence on the reduction of phosphorus tricyanide [121,122] and on the disproportionation of white phosphorus [123,124].…”

Dispersion-corrected energy barriers for silylene addition to white phosphorus, a density functional investigation into substituent effects

“…Experimental studies in the 1980s [7][8][9] reveal that the degradation process is strongly dependent on a diverse set of conditions: the choice of the nucleophile, the ratio of the nucleophile with respect to P 4 , etc. A more clear-cut understanding of these reactions comes from the systematic investigation into metal fragments involved in white phosphorus degradation [10][11][12], as well as, more recently, by reactions with carbenes [13,14] and, in one report, on silylene addition to white phosphorus [15].…”