title: Competitive solvent-molecule interactions govern primary processes of diphenylcarbene in solvent mixtures.
abstract: Photochemical reactions in solution often proceed via competing reaction pathways comprising intermediates that capture a solvent molecule. A disclosure of the underlying reaction mechanisms is challenging due to the rapid nature of these processes and the intricate identification of how many solvent molecules are involved. Here combining broadband femtosecond transient absorption and quantum mechanics/molecular mechanics simulations, we show for one of the most reactive species, diphenylcarbene, that the decision-maker is not the nearest solvent molecule but its neighbour. The hydrogen bonding dynamics determine which reaction channels are accessible in binary solvent mixtures at room temperature. In-depth analysis of the amount of nascent intermediates corroborates the importance of a hydrogen-bonded complex with a protic solvent molecule, in striking analogy to complexes found at cryogenic temperatures. Our results show that adjacent solvent molecules take the role of key abettors rather than bystanders for the fate of the reactive intermediate.
authors.affiliation: Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Knorr
authors.affiliation: Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors.forename: Pandian
authors.initials: P
authors.lastname: Sokkar
authors.affiliation: Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schott
authors.affiliation: Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Paolo
authors.initials: P
authors.lastname: Costa
authors.affiliation: Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Thiel
authors.affiliation: Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Sander
authors.affiliation: Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors.forename: Elsa
authors.initials: E
authors.lastname: Sanchez-Garcia
authors.affiliation: Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Nuernberger