Ag-catalyzed azide alkyne cycloaddition: a DFT approach

In this study, the mechanism of AgAAC reaction has been studied by quantum mechanical calculations to gain insights into this promising reaction and the first successful application of a Ag catalyst alone in AAC. Elucidating the reaction mechanism will enable more control over the synthesis and help to obtain tailor made products in good yields without copper. The feasibility of the experimentally proposed reaction mechanism was investigated by modelling the profound intermediates and the transition state structures connecting them. The DFT calculations with the wB97XD functional with MWB28 effective core potential and 6-31+G* basis set combination herein show that once the silver acetylide structure forms, triazole synthesis via the experimentally proposed cycloaddition is a facile reaction in terms of energetics. The number of metal atoms involved in a click reaction is one of the main questions considered in mechanistic studies. In AgAAC reaction, comparison of mononuclear and binuclear paths shows that the barrier for binuclear cases is lower than that of mononuclear cases.