Competition between the stabilizing effects of saturated alkyl substituents and pi bonds on complexes of silver ion (Ag+) with alkenes

The coordination of Ag+ ions to alkenes is of both theoretical and practical interest. While much attention has been paid to how the nature of the C=C π bond affects the coordinative process, little attention has been directed toward the effect of saturated side chains on complex stabilization despite experimental evidence suggesting its importance. Calculations employing the M06‐2X DFT functional have revealed that saturated chains can exhibit as powerful a stabilizing effect on Ag+/alkene complex formation as increased alkyl substitution about the C=C bond. Natural bond orbital (NBO) analysis confirms the mechanism of stabilization to be that of agostic interactions of properly‐oriented CH σ‐bonds in the saturated chain with the Ag+ ion. Analysis by the extended transition state energy decomposition approach with the natural orbital for chemical valence method (ETS‐NOCV) and the reduced density gradient (RDG) model were used to better characterize the nature of the interaction as a near equivalent combination of electrostatic and orbital interactions.