Phosphorus–nitrogen compounds. Part 73. Dispiromono and dispirobicyclotetraphosphazene derivatives: syntheses, and spectroscopic, crystallographic and thermal studies

Abstract

Reactions of octachlorocyclotetraphosphazene (OCCP), N₄P₄Cl₈ (1), with two equimolar amounts of N-ethyl-N′-(4-fluorobenzyl)-1,2-diaminoethane (L1) gave the trans-monocyclic-(2) and cis-monocyclic-(3) bis(ethyl-4-fluorobenzylspiro)cyclotetraphosphazenes. The obtained trans-monocyclic-bis-(2) reacted separately with excess n-propyl and iso-propylamines to afford the monocyclic (4c and 4d) and bicyclic (5b and 5c) cyclotetraphosphazenes, respectively. The reactions of trans-monocyclic-bis-(2) with n-propylamine in 1 : 1/1 : 2 mole ratios were also investigated to elucidate the formation pathways of bicyclophosphazenes. Trichloro-n-propylamino-(4a), dichloro-bis(n-propylamino)-(4b) and monochloro-2-trans-6-bis(4-fluorobenzylspiro)bicyclo-(5a) tetraphosphazenes were formed. Thus, it was determined how many Cl atoms in the tetramer ring of 2 were replaced by amines and a route to the formation of the bicyclic product was proposed. Moreover, the reaction of cis-monocyclic-bis (3) was carried out only with excess n-propylamine. Monocyclo-(6a) and bicyclo-(7a) cyclotetraphosphazenes were obtained. Spectroscopic, crystallographic (2 and 4c) and thermal characterization of the new phosphazenes was performed.