The University of Southampton
University of Southampton Institutional Repository

Chiral configurations of cyclophosphazenes

Davies, D. B., Clayton, T. A., Eaton, R. E., Shaw, R. A., Egan, A., Hursthouse, M. B., Sykara, G. D., Porwolik-Czomperlik, I. and Siwy, M. K. (2000) Chiral configurations of cyclophosphazenes Journal of the American Chemical Society, 122, (50), pp. 12447-12457. (doi:10.1021/ja0028469).

Record type: Article

Abstract

Tetracoordinated phosphorus atoms in derivatives of cyclophosphazenes are pentavalent and are potentially chiral. Chirality does not seem to have been investigated nor discussed for any literature examples of crystal structures of those cyclophosphazene compounds which are expected to be chiral. In cyclotriphosphazatriene compounds with ansa-substituted macrocyclic rings the two phosphorus atoms attached to the macrocycle are chiral, although the cis-ansa cyclotriphosphazatriene-macrocycle 1 is the meso form. Reaction of 1 with the di-secondary amine, piperazine, provides a convenient way to investigate the chiral configurational properties of cyclophosphazene compounds. It is found by X-ray crystallography that there are two configurational isomers (one meso and one racemate) of the singly bridged di(cyclophosphazene-macrocyclic) piperazine derivative 6i, and that there are two configurational isomers (both meso) of the doubly bridged di(cyclophosphazene-macrocyclic) piperazine derivative 8i; in 8i one meso form has a center of symmetry and the other a plane of symmetry. The chiral configurational properties of each stage of the reaction scheme for formation of 6i and 8i from 1 have been confirmed by P-31 NMR spectroscopy and the results are consistent with inversion of configuration at phosphorus at each step of the reaction of >P(OR)Cl groups with HNR'R" to form >P(OR)(NR'R") derivatives: viz. reaction of 1 with piperazine gives the monosubstituted compound 4i, which exists as a racemate with the macrocyclic ring in the trans-configuration; reaction of compound 4i with 1 gives the two configurational forms (meso and racemate) of the singly bridged derivative 6i with the macrocyclic rings in the trans-trans configuration; reaction of 6i with piperazine gives the monosubstituted singly bridged derivative 7i. which exists as two racemic mixtures with the macrocyclic rings in cis-trans configurations; and intramolecular condensation of 7i gives the two configurational forms of the doubly bridged derivative 8i with each of the macrocyclic rings in the cis-cis configuration. In this work the configurational properties of derivatives of cyclotriphosphazatriene rings with two (one N3P3 unit) or four (two N3P3 units) chiral centers have been rationalized. It is found that the chiral structures of cyclotriphosphazatriene derivatives may be represented by 2D molecular diagrams, as long as the Fischer rules for chiral carbon compounds are followed for phosphorus compounds.

Full text not available from this repository.

More information

Published date: 20 December 2000
Keywords: phosphorus-nitrogen-compounds, substitution-reactions, derivatives, spectra

Identifiers

Local EPrints ID: 19059
URI: http://eprints.soton.ac.uk/id/eprint/19059
ISSN: 0002-7863
PURE UUID: 8495e211-78dc-40e1-abe7-033d31c3be7e

Catalogue record

Date deposited: 20 Dec 2005
Last modified: 17 Jul 2017 16:33

Export record

Altmetrics

Contributors

Author: D. B. Davies
Author: T. A. Clayton
Author: R. E. Eaton
Author: R. A. Shaw
Author: A. Egan
Author: M. B. Hursthouse
Author: G. D. Sykara
Author: I. Porwolik-Czomperlik
Author: M. K. Siwy

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×