title: Facile Ru-H2 heterolytic activation and intramolecular proton transfer assisted by basic N-centers in the ligands.
abstract: The use of the phosphine PPh2py instead of PPh3 in complexes of the type [Cp*RuH(P)2] enormously alters the kinetic control of the proton-transfer reactions over this compound and its chemical behavior. The reaction at low temperature of [Cp*RuH(PPh2py)2], 2, with HBF4 gives as products the classical dihydride trans-[Cp*RuH2(PPh2py)2](BF4), 3 (1 equiv of HBF4) or the dihydrogen-bonded complex [Cp*RuHH(PPh2pyH)(PPh2py)](BF4)2, 4 (2 equiv of HBF4). These complexes exhibit very accessible intramolecular processes of proton transfer, and finally, a slow release of H2 takes place at room temperature. Derivatives 2 and 3 are active catalysts for the deuterium labeling of H2 using methanol-d4 as an isotopic source. This demonstrates that the release of hydrogen is reversible, that the heterolytic activation of H2 is an easy process, and that acid species participate in the intramolecular proton-transfer processes. These observations are supported by reaction-coordinate calculations at the DFT/B3LYP level that show the existence of a low-energy reaction path that easily transforms the classical trans dihydride complex into the nonclassical cis dihydrogen compound in a reversible way, through the involvement of hydrogen- and dihydrogen-bonded intermediates and the essential participation of the pyridine centers. The different energy minima of this reaction profile are very accessible through low-energy transition states, all of which have been located.
authors.affiliation: Departamento de Química Inorgánica, Orgánica y Bioquímica, IRICA, Departamento de Química Física, Universidad de Castilla-La Mancha, Avda. C. J. Cela 10, 13071 Ciudad Real, Spain. Felix.Jalon@uclm.es
authors.forename: Félix A
authors.initials: FA
authors.lastname: Jalón
authors.forename: Blanca R
authors.initials: BR
authors.lastname: Manzano
authors.forename: Agustín
authors.initials: A
authors.lastname: Caballero
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Carrión
authors.forename: Lucía
authors.initials: L
authors.lastname: Santos
authors.forename: Gustavo
authors.initials: G
authors.lastname: Espino
authors.forename: Miquel
authors.initials: M
authors.lastname: Moreno