Structural characterization of [M,C,2H]+ products formed by reaction of 5d metal cations Pt+ and Ir+ with ethylene oxide and Ta+ with methane using messenger spectroscopy

• Published in: Journal of molecular spectroscopy Vol. 378; p. 111472
• Main Authors: Bakker, Joost M., Owen, Cameron J., Nooteboom, Sjoerd W., Lushchikova, Olga V., Armentrout, P.B.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-04-2021
• Subjects: Action spectroscopy; CH bond activation; Infrared multiple photon dissociation; Potential energy surfaces; Potential energy surfaces; CH bond activation; Infrared multiple photon dissociation; Action spectroscopy
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1016/j.jms.2021.111472

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•IR spectroscopic characterization of [M,C,2H]+ (M = Pt,Ir,Ta) dehydrogenation products of ethylene oxide and methane.•Comparison of direct IRMPD and messenger spectroscopy to assess influence of Ar on product structure.•Activation of ethylene oxide by M = Pt+ and Ir+ leads to the same [M,C,2H]+ product as for methane.
Structural characterization of gas-phase [M,C,2H]+ (M = Ta, Ir, Pt), formed by reacting laser ablation formed M+ with ethylene oxide (c-C2H4O) or methane under multiple collision conditions, is achieved using infrared multiple-photon dissociation (IR-MPD) spectroscopy with the intracavity free-electron laser FELICE. After product formation, part of the product distribution is complexed with Ar, allowing for simultaneous recording of IR-MPD spectra of both bare [M,C,2H]+, which dissociates via dehydrogenation, and [M,C,2H]+∙Ar, which loses Ar. Comparison of the spectra with density functional theory (DFT) calculations allows for an internally consistent assignment of the spectra to the Ta+CH2 (3A′′) distorted carbene, Pt+CH2 (2A1) carbene, and to the HIr+CH (1A′) carbyne-hydride. Evidence for a symmetric Ta+CH2∙Ar (3B2) complex is also obtained. For Pt and Ir, these structures match those found in previous work when these species were formed by reaction of M+ with methane, CH4 and CD4. Under the current conditions, no clear signs of the previously observed Ir+CH2 (3A2) carbene product were found, consistent with its higher energy, especially after Ar complexation. Potential energy surfaces for the reactions of Pt+ and Ir+ with c-C2H4O are also computed.