Imidazolium 1,3‐Benzazaphospholide Ion Pairs with Strong C–H···N Hydrogen Bonds – Synthesis, Structures, and Reactivity

Abstract

AbstractThe treatment of 2‐phenyl‐1H‐1,3‐benzazaphosphole (H[2‐ph‐bp], 1) with free 1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene (IMes, 2) and 1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIMes, 3) afforded two imidazolium 1,3‐benzazaphospholides, [1,3‐bis(2,4,6‐trimethylphenyl)imidazolium 2‐phenyl‐1,3‐benzazaphospholide [(IMesH)+(2‐ph‐bp)–, 4] and 1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazolium 2‐phenyl‐1,3‐benzazaphospholide [(SIMesH)+(2‐ph‐bp)–, 5], which further reacted with carbodiimide to give 2‐(N,N′‐diisopropylcarbamimidoyl)‐1,3‐bis(2,4,6‐trimethylphenyl)imidazolium 2‐phenyl‐1,3‐benzazaphospholide (6) and 2‐(N,N′‐diisopropylcarbamimidoyl)‐1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazolium 2‐phenyl‐1,3‐benzazaphospholide (7), respectively. These compounds were characterized by multinuclear (1H, 13C{1H}, and 31P{1H}) NMR and IR spectroscopy, and X‐ray diffraction analysis. The structures feature ion pair conformation in the solid state with strong charge‐assisted C–H···N or N–H···N interaction.