Controlled hydrolysis of hexachlorocyclotriphosphazene and related, sulphur-containing ring systems

Studies of phosphazenes. Part 22. High-field nuclear magnetic resonance investigation of novel isomeric oxophosphazadienes

“…The compounds N,P,(NPPh,)Cl, (1) and gem-N,P,(NPPh,)-(NMe,)Cl, (5) were prepared by methods reported previously. *-' Methanol was distilled over CaO and methyl cyanide over P,O,; both were preserved over molecular sieves before use.…”

The mechanism of a phosphazene–phosphazane rearrangement

“…24 This effect is more pronounced in low dielectric effect solvents such as toluene which is used in this study. The intimate ion pair intermediate consists of the well-known 7,8 oxyphosphazene anion and a dioxolane(dioxoenium) cation which is stabilized by allylic resonance of the positive charge. This type of carbocation has been observed in other systems 25 and is known to exist in acidic media.…”

“…The simplest system in the cyclophosphazenes is in the degradative hydrolysis of hexachlorocyclotriphosphazene, N 3 P 3 Cl 6 (1) (Scheme 1), where the rearrangement of the hydroxyphosphazene (2) eventually leads to trimetaphosphinic acid, [NHP(O)OH] 3 (3). 2,[7][8][9] Semi empirical calculations confirm the energetically favorable nature of the hydrolysis rearrangement and suggest a proton stabilized by both the oxygen and nitrogen centers in the intermediate. 10 The hydrolytic rearrangement has also been studied by solid state NMR and the results reproduced by ab initio methods.…”

“…13 The rearrangement occurs in the larger per methoxy substituted cyclophosphazenes,[NP(OMe) 2 ] n up to the hexamer. 13,14 The rearrangement of mixed substituent trimers such as 2,2-N 3 P 3 R 2 (OMe) 4 (6) leads to six membered rings with both phosphazene and phosphazane bonds (7). 14,15 Certain of these have been examined by X-ray crystallography and the relative orientations of the phosphoryl and methoxy groups was established.…”