title: The free-energy barrier to hydride transfer across a dipalladium complex.
abstract: We use density-functional theory molecular dynamics (DFT-MD) simulations to determine the hydride transfer coordinate between palladium centres of the crystallographically observed terminal hydride locations, Pd-Pd-H, originally postulated for the solution dynamics of the complex bis-NHC dipalladium hydride [{(MesIm)2CH2}2Pd2H][PF6], and then calculate the free-energy along this coordinate. We estimate the transfer barrier-height to be about 20 kcal mol(-1) with a hydride transfer rate in the order of seconds at room temperature. We validate our DFT-MD modelling using inelastic neutron scattering which reveals anharmonicity of the hydride environment that is so pronounced that there is complete failure of the harmonic model for the hydride ligand. The simulations are extended to high temperature to bring the H-transfer to a rate that is accessible to the simulation technique.
authors: School of Physical Sciences (Chemistry), University of Tasmania, Private Bag 75, Hobart, Tasmania 7001, Australia. E-mail: Michael.Gardiner@utas.edu.au.
authors: C R
authors: CR
authors: Vanston
authors: G J
authors: GJ
authors: Kearley
authors: A J
authors: AJ
authors: Edwards
authors: T A
authors: TA
authors: Darwish
authors: N R
authors: NR
authors: de Souza
authors: A J
authors: AJ
authors: Ramirez-Cuesta
authors: M G
authors: MG
authors: Gardiner
mesh_terms: D004735:Energy Transfer; D006859:Hydrogen / Q000737:chemistry*; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D010165:Palladium / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D010165:Palladium; D006859:Hydrogen