Studies of phosphazenes. Part 17. Reaction of hexachlorocyclotriphosphazatriene with n-methylethanolamine: X-ray crystal structure of a dispirocyclotriphosphazatriene, N<SUB>3</SUB>P<SUB>3</SUB>(NMeCH<SUB>2</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>Cl<SUB>2</SUB>

Hexachlorocyclotriphosphazatriene, N<SUB>3</SUB>P<SUB>3</SUB>Cl<SUB>6</SUB>, reacts with N-methylethanolamine to give the spirocyclic derivatives, N<SUB>3</SUB>P<SUB>3</SUB>(NMeCH<SUB>2</SUB>CH<SUB>2</SUB>O)nCl<SUB>6 - 2n</SUB>(n= 1-3), whose structures have been elucidated by 1H and 31P n.m.r. spectroscopy. The structure of the dispiro compound, N<SUB>3</SUB>P<SUB>3</SUB>(NMeCH<SUB>2</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>Cl<SUB>2</SUB>, has been determined by X-ray crystallography; the exocyclic nitrogen atoms are in a cis configuration and the phosphazene and the two spiro rings are planar. The observed chlorine replacement pattern is discussed briefly. Variations in the <SUB>31</SUB>P chemical shifts of spirocyclic phosphorus nuclei with the size of the spiro ring are correlated with differences in structural features