Zavras, AthanasiosGhari, HosseinAriafard, AlirezaCanty, Allan J.O'Hair, Richard A.J.2025-12-162025-12-160020-1669PubMed:28186779ORCID:/0000-0003-2383-6380/work/163628649https://hdl.handle.net/1885/733795611Gas-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 CS2 via hydride transfer to give thioformate (HCS2-) in competition with the formation of the organometallic [CuCS2]- ion via liberation of hydrogen; CO2 via 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 CS2 and CO2 are due to the lower lying ∗ 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(2-CS2)]-. In contrast, CO2 undergoes 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.We thank Dr. George Khairallah for useful discussions regarding the mass spectrometry experiments and the Australian Research Council for financial support DP150101388 (to R.A.J.O. and A.J.C.). We gratefully acknowledge the generous allocation of computing time from the University of Tasmania and the National Computing Infrastructure. We thank the reviewers for their helpful insights.13enPublisher Copyright: © 2017 American Chemical Society.2017-03-0610.1021/acs.inorgchem.6b0214585014530957