Nitrile carbon centers, nucleophilic reactions

Carbon-centered radicals are nucleophilic or electrophilic species, depending upon the substituents at the radical center. Electron-donating substituents like alkyl or alkoxy groups increase the nucleophilicity - of the radicals whereas electron-withdrawing groups (EWG) like ester or nitrile groups increase their electrophilic nature . In nucleophilic radical reactions SOMO LUMO interaction dominates whereas electrophilic radical reactions are controlled by SOMO-HOMO interactions. 

The presence of the electron-withdrawing nitrile group in acrylonitrile leads to polarization (6+CH2=CH-C=N6-) that promotes nucleophilic attack at the methylene carbon atom. The coordination of acrylonitrile to a metal center through the nitrile group results in enhanced polarization and further promotes reactions with nucleophilic reagents. For example, acetylacetonate ion reacts with the acrylonitrile complex, [Co(NH3)5NsCCH=CH2] , in aqueous solution at pH = 9, Eq. 1.28 62... 

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