Stability, atomic charges, bond order analysis, and the directionality of lone‐electron pairs on nitriles and isocyanides

The carbon atoms in :CN and the nitrogen atoms in CN: are always the global electrostatic minima in the whole molecules of nitriles and isocyanides. The global molecular electrostatic potential minima (Vmin) values and the electrostatic potential isosurfaces higher than Vmin by 10 kcal/mol were investigated and visualized based on the optimized geometrical structures at B3LYP‐D3(BJ)/def2‐QZVP level for a series of nitriles and isocyanides with the selected 21 functional groups. The relative stability between RCN: and :CNR was quantified with isomerization energies and bond dissociation enthalpies by single‐point energy (SPE) calculations at B2PLYP‐D3(BJ)/cc‐pVTZ level. The bond dissociation enthalpies of RCN: were evaluated, and the standard molar enthalpies of formation for RCN: and R· were also calculated to estimate the bond dissociation enthalpies. The theoretical results show that the directionality of the lone pairs influences electrostatic distribution. The population analyses in terms of Hirshfeld and ADCH atomic charges and bond‐order analyses via Laplacian and fuzzy bond orders were also discussed in detail.