Effect of chain length on the formation of intramolecular and intermolecular products: Reaction of diols with cyclotriphosphazene

The reactions of cyclotriphosphazene, N(3)P(3)Cl(6) (1), in a 1:1.2 stoichiometry with the sodium derivative of seven diols [ethane- (2a), 1,3-propane- (2b), 1,4-butane- (2c), 1,5-pentane- (2d.), 1,6-hexane- (2e), 1,8-octane- (2f) and 1,10-decane- (2g) diol] in THF solution at room temperature have been used to investigate the effect of chain length on the formation of reaction products. Although no new products were found for the reaction of 1 with diols 2a-c compared to those in the literature using other bases and solution conditions, the reactions of 1 with the diols 2d-g gave six different types of products, whose structures have been characterized by elemental analysis, mass spectrometry, I H and (31)P NMR spectroscopy; ansa compounds N(3)P(3)Cl(4)[O(CH(2))(n)O], (5d-5g): single-bridged compounds N(3)P(3)Cl(5)[O(CH(2))(n)O]N(3)P(3)Cl(5) (6d-6f); double-bridged compounds N(3)P(3)Cl(4)[O(CH(2))(n)O](2)N(3)P(3)Cl(4) (7d-7g, syn and anti) and triple-bridged compounds, N(3)P(3)Cl(3)[O(CH(2))(n)O](3)N(3)P(3)Cl(3) (8d-f). Where suitable single crystals were obtained, X-ray crystallographic studies confirmed the structures of two ansa compounds (5d and 5f), one single-bridged compound (6e), and five double-bridged compounds (meso-anti for 7d, 7e, 7f and meso-syn for 7d and 7f). (31)P NMR measurements of the reaction mixtures were used to quantify the formation of products for the reactions 1 with all the diols, 2a-g; it is found that, with increasing chain length of the diol, there is a decrease in the products formed by intramolecular reactions (spiro and ansa derivatives) and a concomitant increase in the amounts of products formed by intermolecular reactions (single-, double- and triple-bridged derivatives) of cyclophosphazene. (C) 2010 Elsevier Ltd. All rights reserved.