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Ensemble Effects of Explicit Solvation on Allylic Oxidation
preprintsubmitted on 19.01.2021, 20:32 and posted on 22.01.2021, 07:21 by Hung Le, Mariano Guagliardo, Anne Gorden, Aurora Clark
Umbrella-sampling density functional theory molecular dynamics (DFT-MD) has been employed to study the full catalytic cycle of the allylic oxidation of cyclohexene
using a Cu(II) (E)-6-amino-7-((2-hydroxybenzylidene)amino)quinoxalin-2-ol complex in acetonitrile, which creates the desired cyclohexenone and H 2 O as products. In comparison to prior study using gas-phase DFT, a significant solvent effect is observed on the rate determining allylic H-atom abstraction step (which has a free energy barrier of 12.1 ± 0.2 kcal/mol). During the cycle, the explicit solvation and ensemble sampling of solvent configurations reveals an important dehydrogenation and re-hydrogenation step of the -NH 2 ligand that is essential to catalyst recovery. This work illustrates the importance of ensemble solvent configurational sampling to reveal the breadth of processes that underpin the full catalytic cycle.