The Negative Ion Photoelectron Spectrum of Cyclopropane-1,2,3-Trione Radical Anion, (CO) ₃ ^•– — A Joint Experimental and Computational Study

Journal Article · Wed Sep 03 04:00:00 EDT 2014 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja505582k· OSTI ID:1168888

Chen, Bo; Hrovat, David A.; West, Robert; Deng, Shihu H. M.; Wang, Xue-Bin; Borden, Weston Thatcher

Negative Ion Photoelectron (NIPE) spectra of the radical anion of cyclopropane-1,2,3-trione, (CO)3•-, have been obtained at 20 K, using both 355 and 266 nm lasers for electron photodetachment. The spectra show broadened bands, due to the short lifetimes of both the singlet and triplet states of (CO)3. The smaller intensity of the band with the lower electron binding energy suggests that the singlet is the ground state of (CO)3. From the NIPE spectra, the electron affinity (EA) and the singlet-triplet energy gap of (CO)3 are estimated to be, respectively, EA = 3.1 ± 0.1 eV and ΔEST = -14 ± 3 kcal/mol. High-level, (U)CCSD(T)/aug-cc-pVQZ//(U)CCSD(T)/aug-cc-pVTZ, calcu-lations give EA = 3.04 eV for the 1A1´ ground state of (CO)3 and ΔEST = -13.8 kcal/mol for the energy gap between the 1A1´ and 3A2 states, in excellent agreement with values from the NIPE spectra. In addition, simulations of the vibrational structures for formation of these states of (CO)3 from the 2A2'' state of (CO)3•- provide a good fit to the shapes of broad bands in the 266 nm NIPE spectrum. The NIPE spectrum of (CO)3•- and the analysis of the spectrum by high-quality electronic structure calculations demonstrate that NIPES can not only access and provide information about transition structures, but NIPES can also access and provide information about hilltops on potential energy surfaces.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1168888
• Report Number(s): PNNL-SA-103121; KC0301020
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 35 Vol. 136; ISSN 0002-7863
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY