title: Hydrogen-bond and solvent dynamics in transition metal complexes: a combined simulation and NMR-investigation.
abstract: Self-assembling ligands through complementary hydrogen-bonding in the coordination sphere of a transition metal provides catalysts with unique properties for carbon-carbon and carbon-heteroatom formation. Their most distinguishing chemical bonding pattern is a double-hydrogen-bonded motif, which determines much of the chemical functionality. Here, we discuss the possibility of double proton transfer (DPT) along this motif using computational and experimental methods. The infrared and NMR spectral signatures for the double-hydrogen-bonded motif are analyzed. Atomistic simulations and experiments suggest that the dynamics of the catalyst is surprisingly complex and displays at least three different dynamical regimes which can be distinguished with NMR spectroscopy and analyzed from computation. The two hydrogen bonds are kept intact and in rapid tautomeric exchange down to 125 K, which provides an estimate of 5 kcal/mol for the barrier for DPT. This is confirmed by the simulations which predict 5.8 kcal/mol for double proton transfer. A mechanistic interpretation is provided and the distribution of the solvent shell surrounding the catalyst is characterized from extensive simulations.
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland.
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
authors.forename: Daniel
authors.initials: D
authors.lastname: Häussinger
authors.forename: Urs
authors.initials: U
authors.lastname: Gellrich
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Seiche
authors.forename: Bernhard
authors.initials: B
authors.lastname: Breit
authors.forename: Markus
authors.initials: M
authors.lastname: Meuwly
mesh_terms: D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D009942:Organometallic Compounds / Q000737:chemistry*; D011522:Protons; D012997:Solvents / Q000737:chemistry; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D011522:Protons; D012997:Solvents; D028561:Transition Elements