title: Effect of Noncovalent Interactions on Vibronic Transitions: An Experimental and Theoretical Study of the C2H⋅⋅⋅CO2Complex.
abstract: We report on the experimental and theoretical infrared spectrum of the C2H⋅⋅⋅CO2complex. This complex was prepared by UV photolysis of propiolic acid (HC3OOH) in argon and krypton matrices. The experimental bands of C2H in the C2H⋅⋅⋅CO2complex are blue-shifted from those of the C2H monomer. The calculations on the C2H⋅⋅⋅CO2structures were performed at the RMP2/aug-cc-pVTZ level. The relative stability of the complex structures was evaluated by using the RCCSD(T)/aug-cc-pVQZ level. To simulate the spectrum of the C2H⋅⋅⋅CO2complex, we developed the theoretical approach used earlier for the C2H monomer. Based on the calculations, the main experimental bands of the C2H⋅⋅⋅CO2complex are assigned to the most stable parallel structure. Almost all the strong bands predicted by theory (with intensities >30 km mol-1) are observed in the experiment. To our knowledge, it is the first study of the effect of noncovalent interactions on vibronic transitions and the first report on an intermolecular complex of the C2H radical.
authors.affiliation: Department of Chemistry, University of Helsinki, P. O. Box 55, FI-00014, Helsinki, Finland.|Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia.
authors.forename: Sergey V
authors.identifier: http://orcid.org/0000-0001-8662-580X
authors.initials: SV
authors.lastname: Ryazantsev
authors.affiliation: Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna, Viale, Risorgimento 4, 40136, Bologna, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Tarroni
authors.affiliation: Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia.
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Feldman
authors.affiliation: Department of Chemistry, University of Helsinki, P. O. Box 55, FI-00014, Helsinki, Finland.
authors.forename: Leonid
authors.identifier: http://orcid.org/0000-0002-1146-5212
authors.initials: L
authors.lastname: Khriachtchev
keywords: IR spectroscopy; matrix isolation; noncovalent interaction; radicals; vibronic transition