Dicyano(7,7-dimethyl-2,5-di-p-tolyl-3,4-diazabicyclo[4.1.0]hepta-2,4-dien-3-ium-3-yl)methanide and (4-Benzoyl-5,5-dimethyl-2-phenyl-1-azacyclopenta-1,3-dien-1-ium-1-yl)dicyanomethanide, Two Stable Azomethine Ylides

The azomethine ylide moieties of dicyano(7,7-dimethyl-2,5-di-p-tolyl-3,4-diazabicyclo[4.1.0]hepta-2,4-diene- 3-ium-3-yl)methanide, C₂₄H₂₂N₄, and (4-benzoyl-5,5-dimethyl-2-phenyl-1-azacyclopenta-1,3-diene-1-ium-1-yl)dicyanomethanide, C₂₂H₁₇N₃O, show normal bond distances and angles in comparison with related structures reported previously. The dipolar N-C distances of 1.430 (4) and 1.401 (3) Å are appreciably shortened compared with the C-N⁺ bond lengths [1.485 (9) Å] found in N-substituted pyridinium compounds, which is consistent with previous observations. Both title compounds pack in such a way that the ylide dipoles are arranged above each other but pointing in opposite directions.

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