Exploiting the (–C–H···C–) Interaction to Design Cage-Functionalized Organic Superbases and Hyperbases: A Computational Study

Abstract

A set of carbon center-based P-ylidesubstituting bases have been exploited computationally with pentacyclo­[5.4.0.02,6.03,10.05.9]­undecane (PCU) and pentacyclo [6.4.0.02,7.03,11.06,10] dodecane (PCD) scaffolds using the B3LYP-D3/6-311+G­(d,p) level of theory. The proton affinities calculated in the gas phase are in the range of superbases and hyperbases. The Atomsin-Molecules and Natural Bond Orbital calculations reveal that the –C–H···C– interaction plays a substantial role in improving the basicity, and tuning the –C–H···C– interaction can enhance the basicity of such systems. The free activation energy for proton exchange for PCD and PCU scaffolds substituted with P-ylide is substantially low. The computed results reveal the strength and nature of such – C–H···C– interactions compared to the –N–H···N– hydrogen bonds. The isodesmic reactions suggest that the superbasicity achieved using these frameworks arises from a combination of several factors, such as the ring strain of the bases in their unprotonated form, steric repulsion, and the intramolecular –C–H···C– interaction.

Three novel mononuclear 4‐vinylpyridine‐based Fe(III) complexes displaying various spin‐crossover behaviour

“…The complex cations and counter anions in 1 are connected by C 21 -H 21 ⋯C 33 (green dotted line), even the À CÀ H•••CÀ hydrogen bonds are often considered weaker than typical hydrogen bonds and have received less attention. [46] Two complex cations [Fe(salten)( 4…”