Bridged cyclophosphazenes resulting from deprotonation reactions of cyclotriphophazenes bearing a P–NH group

Abstract

Cyclotriphosphazene derivatives containing a P–NHR group in the side-chain react in the presence of a strong base to form stable intermolecular bridged products. Reaction of sodium hydride with mono-spiro cyclophosphazene derivatives having a P–NH group, N₃P₃Cl₄[O(CH₂)₃NH], (1a) or N₃P₃Cl₄[CH₃N(CH₂)₃NH], (1b) leads to formation of bis-cyclophosphazenes bridged with an eight-membered cyclophosphazene ring in an ansa arrangement (2a, 2b) whereas reaction of sodium hydride with mono-amino cyclophosphazene derivatives [N₃P₃Cl₅(NHR), R = n-hexyl, 3a; i-Pr, 3b; Ph, 3c] give bis-cyclophosphazenes bridged with a four-membered cyclophosphazane ring in a spiro arrangement (4a–c). In the latter reaction P–O–P bridged compounds (5a–c) were also obtained as a result of hydrolysis reactions associated with the amount of moisture in the solvent tetrahydrofuran. In addition, it was found that reaction of a mixture of cyclotriphosphazene with either mono spiro compound, (1a) or (1b), in the presence of sodium hydride lead to formation of the first examples of asymmetrically-bridged cyclophosphazenes (6a–b).