5-Phenyl-3-(2-phosphono-eth-yl)-1,2,3-triazol-1-ium chloride

The new triazole-functionalized phospho-nic acid 5-phenyl-3-(2-phosphono-eth-yl)-1,2,3-triazol-1-ium chloride, C H N O P ·Cl (PTEPHCl), was synthesized by the 'click' reaction of the alkyl azide diethyl-(2-azido-eth-yl)phospho-nate with phenyl-acetyl-ene to give the dieth-yl[2-(4-phenyl-1 -1,2,3-triazol-1-yl)eth-yl]phospho-nate ester, which was then hydrolyzed under acidic conditions (HCl) to give the 'free' phospho-nic acid. The use of HCl for the hydrolysis caused protonation of the triazole ring, rendering the compound cationic, charged-balanced by a Cl anion. There are extensive hydrogen-bonding inter-actions in the structure of PTEPHCl, involving the phospho-nic acid (-PO H ) group, the triazolium ring and the Cl anion.