title: The structural and stereogenic properties of pentaerythritoxy-bridged cyclotriphosphazene derivatives: spiro-spiro, spiro-ansa and ansa-ansa isomers.
abstract: Reactions of pentaerythritol with hexachlorocyclotriphosphazene, N3P3Cl6, and gem-disubstituted cyclotriphosphazene derivatives, N3P3Cl4R2 [R = Ph, NHBu(t) or (OCH2CF2CF2CH2O)0.5] gave a series of pentaerythritol-bridged derivatives linked spiro-spiro, spiro-ansa and ansa-ansa. The structures and stereogenic properties of the products were characterised by X-ray crystallography and 31P NMR spectroscopy on addition of the chiral solvating agent, (S)-(+)-2,2,2-trifluoro-1-(9-anthryl)ethanol. Molecules with spiro-spiro and spiro-ansa bridged gem-disubstituted cyclophosphazenes [R = Ph, NHBu(t) or (OCH2CF2CF2CH2O)0.5] are found to be chiral and exist as racemates. Molecules with ansa-ansa bridged cyclophosphazenes [R = Cl or (OCH2CF2CF2CH2O)0.5] have been characterised for the first time and are shown to have meso configurations. Analysis of crystal structure data shows that the six-membered chair form of the spiro rings and the eight-membered boat-chair form of the ansa rings in the bridged compounds are similar to analogous spiro and ansa exocyclic ring conformations of 1,3-propanedioxy-derivatives of cyclophosphazenes.
authors.affiliation: Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BG, UK.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Coles
authors.forename: David B
authors.initials: DB
authors.lastname: Davies
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Eaton
authors.forename: Michael B
authors.initials: MB
authors.lastname: Hursthouse
authors.forename: Adem
authors.initials: A
authors.lastname: Kiliç
authors.forename: Robert A
authors.initials: RA
authors.lastname: Shaw
authors.forename: Aylin
authors.initials: A
authors.lastname: Uslu