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

The treatment of 2‐phenyl‐1 H ‐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 ( 1 H, 13 C{ 1 H}, and 31 P{ 1 H}) 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.