title: How a Thermally Unstable Metal Hydrido Complex Can Yield High Catalytic Activity Even at Elevated Temperatures.
abstract: Despite their instability in ethereal solvents, organotitanium hydride catalysts are successfully employed in catalysis at moderate to high temperatures (110 °C), even in the presence of alcohols. It is shown computationally (bond dissociation energy (BDE) analysis and energetic profile for regeneration) and experimentally (EPR studies and kinetic studies), with the specific example of hydrodefluorination (HDF), that despite the long standing belief, regeneration of Ti-H bonds from Ti-F bonds using silanes is endergonic. The resulting low concentration of Ti-H species is crucial for the catalytic stability of those systems. The resting state in the catalysis is a Ti-F species. The most promising silanes for regeneration are not the ones that have the strongest Si-F bond, but the ones that show the largest difference in Si-F and Si-H BDEs.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Via Cintia, 80126, Napoli, Italy.
authors.forename: Christian
authors.initials: C
authors.lastname: Ehm
authors.affiliation: Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstr. 34-36, 14195, Berlin, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Krüger
authors.affiliation: Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstr. 34-36, 14195, Berlin, Germany. dieter.lentz@fu-berlin.de.
authors.forename: Dieter
authors.identifier: http://orcid.org/0000-0002-0583-7024
authors.initials: D
authors.lastname: Lentz
keywords: catalyst regeneration; density functional calculations; homogeneous catalysis; hydrodefluorination; metal hydride