Studies of phosphazenes. Part 25. Synthesis, nuclear magnetic resonance spectroscopy, and mode of formation of (aziridino)(triphenylphosphazenyl)cyclotriphosphazenes. X-Ray crystal structure and enzyme-inhibiting activity of N3P3(NPPh3)(NC2H4)5

Abstract

Aziridino (HNC₂H₄) reacts with the triphenylphosphazenyl derivative N₃P₃(NPPh₃)Cl₅(1) to yield the compounds N₃P₃(NPPh₃)(NC₂H₄)_nCl_{5 –n}[n= 1–5; (3)–(9)], the structures of which are elucidated by ¹H and ³¹P n.m.r. spectroscopy. The fluoro-analogue, N₃P₃(NPPh₃)F₅(2), is unreactive even under drastic conditions. The chlorine replacement pattern and the associated mechanistic aspects are discussed. The X-ray crystal structure analysis of N₃P₃(NPPh₃)(NC₂H₄)₅(9) shows a novel conformation of the –NPPh₃ substituent in which one of the phenyl groups lies in a plane nearly perpendicular and in close proximity to the –NC₂H₄ group at the P(NPPh₃)(NC₂H₄) site. The n.m.r. [¹H, ¹³C, and ³¹P] parameters of (9) are discussed in relation to its structure. The enzyme-inhibiting activity of (9) is compared with that of N₃P₃(NC₂H₄)₆.