Hydrogenation and dehydrogenation reactions of the phenalenyl radical/1H-phenalene system at low temperatures

• Published in: Chemical physics letters Vol. 743; p. 137183
• Main Authors: Schneiker, Anita, Csonka, István Pál, Tarczay, György
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 16-03-2020
• Subjects: Astrochemistry; Interstellar H2 formation; Matrix isolation; Photochemistry; Polyaromatic hydrocarbons; Matrix isolation; Astrochemistry; Polyaromatic hydrocarbons; Interstellar H2 formation; Photochemistry
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2020.137183

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•IR spectrum of 1H-phenalene was recorded in Ar and Kr matrices.•Phenalenyl radical was generated by laser UV photolysis from H-phenalene.•Phenalenyl radical recombines with an H atom upon warming up the Xe matrix.•Computations indicate that H abstraction reaction from 1H-phenalene is also feasible.•The investigated molecules are effective catalysts in interstellar H2 formation.
Phenalenyl radical was generated in situ in inert matrices by laser UV photolysis of 1H-phenalene, and was identified by recording laser induced fluorescence and IR spectra. Theoretical computations predict that the H atom addition to phenalenyl radical is barrierless, while the H atom abstraction from 1H-phenalene has only a small barrier. Upon annealing the Xe matrix after the photolysis, the radical and the H atom recombine, while H atom abstraction from 1H-phenalene is a possible explanation for additional spectral changes. These results show that the phenalenyl radical/1H-phenalene system can be a very effective catalyst in the formation of interstellar H2.