Basicity Enhancement by Multiple Intramolecular Hydrogen Bonding in Organic Superbase <i>N</i>,<i>N</i>′,<i>N</i>″,<i>N</i>‴-Tetrakis(3-(dimethylamino)propyl)triaminophosphazene

Abstract

With the synthesis of N,N′,N″,N‴-tetrakis(3-(dimethylamino)propyl)triaminophosphazene (TDMPP, 1), we present the first phosphazene superbase with enhanced basicity through the effect of multiple intramolecular hydrogen bonding (IHB). Due to intramolecular solvation of four NH protons, the proton affinity is even higher than that of second-order phosphazene (dma)P2-tBu. X-ray structural proof, NMR titration experiments, and computational investigations provide a more detailed quantitative description of the IHB influence on the superbasicity of 1 in solid-state, solution, and the gas-phase.