title: Gas-Phase Ion-Molecule Reactions of Copper Hydride Anions [CuH2]-and [Cu2H3].
abstract: Gas-phase reactivity of the copper hydride anions [CuH2]-and [Cu2H3]-toward a range of neutral reagents has been examined via multistage mass spectrometry experiments in a linear ion trap mass spectrometer in conjunction with isotope labeling studies and Density Functional Theory (DFT) calculations. [CuH2]-is more reactive than [Cu2H3]-, consistent with DFT calculations, which show it has a higher energy HOMO. Experimentally, [CuH2]-was found to react with CS2via hydride transfer to give thioformate (HCS2-) in competition with the formation of the organometallic [CuCS2]-ion via liberation of hydrogen; CO2via insertion to produce [HCuO2CH]-; methyl iodide and allyl iodide to give I-and [CuHI]-; and 2,2,2-trifluoroethanol and 1-butanethiol via protonation to give hydrogen and the product anions [CuH(OCH2CF3)]-and [CuH(SBu)]-. In contrast, the weaker acid methanol was found to be unreactive. DFT calculations reveal that the differences in reactivity between CS2and CO2are due to the lower lying π* orbital of the former, which allows it to accept electron density from the Cu center to form the initial three-membered ring complex intermediate, [H2Cu(η2-CS2)]-. In contrast, CO2undergoes the barrierless side-on hydride transfer promoted by the high electronegativity of the oxygen atoms. Side-on SN2 mechanisms for reactions of [CuH2]-with methyl iodide and allyl iodide are favored on the basis of DFT calculations. Finally, the DFT calculated barriers for protonation of [CuH2]-by methanol, 2,2,2-trifluoroethanol, and 1-butanethiol correlate with their gas-phase acidities, suggesting that reactivity is mainly controlled by the acidity of the substrate.
authors.affiliation: School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne , 30 Flemington Road, Parkville, Victoria 3010, Australia.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Zavras
authors.affiliation: Department of Chemistry, Faculty of Science, Central Tehran Branch, Islamic Azad University , Shahrak Gharb, Tehran, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Ghari
authors.affiliation: The School of Physical Sciences, University of Tasmania , Private Bag 75, Hobart, Tasmania 7001, Australia.|Department of Chemistry, Faculty of Science, Central Tehran Branch, Islamic Azad University , Shahrak Gharb, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Ariafard
authors.affiliation: The School of Physical Sciences, University of Tasmania , Private Bag 75, Hobart, Tasmania 7001, Australia.
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Canty
authors.affiliation: School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne , 30 Flemington Road, Parkville, Victoria 3010, Australia.
authors.forename: Richard A J
authors.identifier: http://orcid.org/0000-0002-8044-0502
authors.initials: RA
authors.lastname: O'Hair