Studies in cyclophosphazenes. Part 8. The equilibria between isomeric non-geminal aminochlorocyclotriphosphazenes

Abstract

The cis and trans isomers of three pairs of non-geminal chloro (dimethylamino) cyclotriphosphazenes N₃P₃Cl_6–n(NMe₂)_n with n= 2, 3, or 4 have been allowed to equilibrate in two solvents at several temperatures using dimethylamine hydrochloride as catalyst, and then the isomer ratios were determined using gas chromatographic analysis. Values of ΔH and ΔS for the equilibria have been evaluated. As solvent effects appear to exceed inter-substituent interactions, no conclusions on the planarity of the cyclotriphosphazene ring can be drawn from the results. Consideration of the relative rates of the isomerization reactions of compounds with different degrees of substitution reveals differences in their mechanisms and supports the operation of certain mechanisms proposed earlier.