Synthesis and Structural Characterization of Singly,Doubly, and Triply Bridged Derivatives of Hexachlorocyclotriphosphazene with Bis(2-hydroxyethyl) Ether and 2,2-dimethylpropane-1,3-diol

Abstract

The reactions of hexachlorocyclotriphosphazene, N₃P₃Cl₆ (1), with 2,2-dimethylpropane-1,3-diol (2), and bis(2-hydroxyethyl) ether (3) have been previously reported. Although both reactions gave the expected spiro, ansa, and bridged type products, open-chain and triply bridged derivatives from both systems and singly bridged derivatives from 2,2-dimethylpropane-1,3-diol (2) were not isolated, and doubly bridged compounds were only detected in trace amounts in both systems. However, in a subsequent reinvestigation in tetrahydrofuran (THF) solution, the reaction of 1 with the diols 2 and 3 gave the open chain compounds N₃P₃Cl₅[O(CH₂)₂CMe₂OH] (4) and N₃P₃Cl₅[(OCH₂CH₂)₂OH] (5), the singly bridged compound N₃P₃Cl₅[(OCH₂)₂-CMe₂]N₃P₃Cl₅ (6), the doubly bridged compounds N₃P₃Cl₄[(OCH₂)₂CMe₂]₂N₃P₃Cl₄ (8) and N₃P₃Cl₄[(OCH₂CH₂)₂O]₂N₃P₃Cl₄ (9), and the triply bridged compounds N₃P₃Cl₃[(OCH₂)₂-CMe₂]₃N₃P₃Cl₃ (10) and N₃P₃Cl₃[(OCH₂CH₂)₂O]₃N₃P₃Cl₃ (11).

The doubly bridged derivatives were also isolated in better yields relative to earlier reports. The substituted cyclotriphosphazenes have been characterized by elemental analysis, mass spectrometry, as well as by ¹H, ³¹P, and ¹³C NMR spectroscopy. It is found that with variation of the solvent there is a decrease in the product formed by intramolecular reactions (spiro and ansa derivatives) and a concomitant increase in the amount of products formed by intermolecular reactions (singly, doubly, and triply bridged derivatives) of cyclophosphazene.