A computational study of multicomponent orbital interactions during the cyclization of silyl, germyl, and stannyl radicals onto C-N and C-O multiple bonds

Abstract

(Chemical Equation Presented) BHandHLYP/6-311G** and BHandHLYP/DZP computations of the potential surface of Si-, Ge-, and Sn-radical cyclizations onto the imine double bond reveal that these reactions proceed through simultaneous SOMO → π*, LPN → SOMO, and LPN → σ* interactions. Such multicomponent orbital interactions are responsible for the regioselectivity in these radical cyclizations, where the nucleophilic radical unexpectedly attacks the more electron-rich end of the π system. Less nucleophilic heteroatoms, for example, the nitrogen atom in nitriles or the oxygen atom in carbonyl compounds, show reduced LP interactions with the radical center in the respective transition states, so th..