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Studies of phosphazenes. Part 21. Associative and dissociative pathways in the aminolysis reactions of halogenocyclotriphosphazenes

Katti, Kattesh V and Krishnamurthy, Setharampattu S (1985) Studies of phosphazenes. Part 21. Associative and dissociative pathways in the aminolysis reactions of halogenocyclotriphosphazenes. In: Journal of the Chemical Society, Dalton Transactions: Inorganic Chemistry, 2 . 285 -289.

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Abstract

The rates of stepwise replacement of chlorine from hexachlorocyclotriphosphazene $\[(N_3P_3Cl_6\]$) by –$\[NMe_2\]$, the last chlorine atom from $\[N_3P_3(OPh)_5Cl\]$ by alkylamines, and the first fluorine atom from $\[N_3P_3F_6\]$, by –$\[NMe_2\]$, in methyl cyanide, have been determined at three temperatures. Detailed analysis of the kinetic data suggests a concerted $\[S_N\]2(P)$ mechanism for the first and second Cl substitutions. A sharp changeover from an $\[S_N\]2(P)$ to an $\[S_N\]1(P)$ mechanism occurs at the fourth substitution; the replacement of chlorine from $\[N_3P_3(OPh)_5\]Cl$ also occurs by an $\[S_N\]1(P)$ pathway. The first F substitution from $\[N_3P_3F_6\]$ by –$\[NMe_2\]$ proceeds ca. 20 times slower than the analogous reaction for $\[N_3P_3Cl_6\]$; the kinetic data for these two reactions are in accord with a two-step $\[S_N\]2(P)$ pathway. Many diverse findings reported for the aminolysis reactions of halogenocyclophosphazenes are explained in terms of the continuous spectrum of mechanisms established in the present study.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Royal Society of Chemistry.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 07 Jul 2008
Last Modified: 19 Sep 2010 04:46
URI: http://eprints.iisc.ernet.in/id/eprint/14810

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