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Abstract
The reaction of the δ3-cyclotriphosphazanene, (EtNPCl)3 with 2-bromo or 2-nitro phenol in the presence of diazabicyclooctane yields a cis-trans isomeric mixture of [EtNP(OC6H4X-2)]3 (X=Br or NO2) from which the cis-[EtNP(OC6H4Br-2)]3 or trans-[EtNP(OC6H4NO2-2)]3 is isolated in a pure state by fractional crystallisation. The two compounds have been characterised by elemental analysis and NMR (31P, 13C, and 1H) spectroscopic data. Variable temperature (303–363 K) 31P NMR studies on cis-[EtNP(Oc6H4Br-2)]3 indicate its slow conversion to the trans-analogue with increasing temperature. The structure of cis-[EtNP(OC6H4Br-2)]3 and the previously known trans-[EtNP(OC6H3Me2-2,6)]3 have been determined by single crystal X-ray analysis. The six-membered P3N3 ring adopts a chair and a twist conformation in cis-[EtNP(OC6H4Br-2)]3 and trans- [EtNP(OC6H3Me2-2,6)]3 respectively. The structural features are compared with those observed for other δ3-cyclotriphosphazas.
