How acid can become a dihydrogen complex in water? A DFT study
Ortuño, Manuel A. (Universidade de Santiago de Compostela. Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares)
Lledós, Agustí (Lledós i Falcó) (Universitat Autònoma de Barcelona. Departament de Química)

Data:	2021
Resum:	To accurate know the acidity of a dihydrogen molecule coordinated to a transition metal ion in water medium is an issue of interest in many areas, from electrochemistry to enzymes and catalysis. However, experimental determination of this magnitude is challenging, and very few values have been reported. In this article we describe a computational protocol, based on DFT calculations and employing a discrete-continuum solvent representation, to estimate pK of transition metal dihydrogen complexes. In this approach the number of solvent molecules explicitly included in the calculations is determined by the convergence with the solvation Gibbs energy of the proton in the solvent. The approach has been initially validated with experimental data in tetrahydrofuran (THF) solvent. Using (THF) clusters a mean absolute deviation from experiments of only 1. 4 pK unit is achieved. In water the convergence is reached with (HO) clusters. Using them in a discrete-continuum model, the pK of twelve dihydrogen complexes experimentally characterized in water have been computed. pK values span a wide range, from 23 to -4, illustrating how coordination to a transition metal modifies the dihydrogen acidity. Decomposition of the ∆G of the acid-base equilibrium in two contributions, one intrinsic to the complex and another one accounting for solvent effects enables a deeper analysis of the dihydrogen acidities.
Ajuts:	Ministerio de Ciencia e Innovación PID-2020-116861GB-I00
Nota:	Altres Ajuts: Xunta de Galicia Programa Investigador Distinguido ED431H 2020/21, Acreditación Centro singular de investigación de Galicia 2019-2022, ED431G 2019/03
Nota:	Altres ajuts: acords transformatius de la UAB
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Dihydrogen complexes ; Pka ; Water solvent ; DFT calculations ; Discrete-continuum solvation methods
Publicat a:	Journal of Organometallic Chemistry, Vol. 949 (September 2021) , art. 121957, ISSN 0022-328X

DOI: 10.1016/j.jorganchem.2021.121957

10 p, 1.7 MB

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