engleski

DFT study of C–H bond activation in 4, 4'-bis(N, N-dimethylamino)azobenzene by palladium(II) acetate

An important class of catalytic reactions are palladium-mediated processes for which the C–H bond activation, i.e. cyclopalladation, is the key step. Among palladium catalysts, trimeric palladium(II) acetate is the most common. Widely-accepted mechanism for the C–H bond activation by [Pd(OAc)2]3 involves the C–H bond activation by a Lewis-acidic metal via agostic interaction with the exiting proton and simultaneous acceptance of this proton by a basic ligand via an intramolecular hydrogen bond. Reaction is initiated by opening of the trimer [Pd(OAc)2]3 by either the substrate or an additive, and this process yields a trimeric, dimeric or even monomeric acetate species. Similar to the chloride precursors, intermediate complex should be formed by coordination of the substrate to [Pd(OAc)2]3 before any C–H bond cleavage takes place. Herein, we present a computational study of activation of two C–H bonds in a symmetric azobenzene substrate, 4, 4'-bis(N, N-dimethylamino)azobenzene, and its monocyclopalladated complex yielding mono- and dicyclopalladated products, respectively.

DFT calculations ; C-H bond activation ; palladium ; azobenzene

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