title: Direct detection of a triplet vinylnitrene, 1,4-naphthoquinone-2-ylnitrene, in solution and cryogenic matrices.
abstract: The photolysis of 2-azido-1,4-naphthoquinone (1) in argon matrices at 8 K results in the corresponding triplet vinylnitrene (3)2, which was detected directly by IR spectroscopy. Vinylnitrene (3)2 is stable in argon matrices but forms 2-cyanoindane-1,3-dione (3) upon further irradiation. Similarly, the irradiation of azide 1 in 2-methyltetrahydrofuran (MTHF) matrices at 5 K resulted in the ESR spectrum of vinylnitrene (3)2, which is stable up to at least 100 K. The zero-field splitting parameters for nitrene (3)2, D/hc = 0.7292 cm(-1) and E/hc = 0.0048 cm(-1), verify that it has significant 1,3-biradical character. Vinylnitrene (3)2 (λmax ∼ 460 nm, τ = 22 μs) is also observed directly in solution at ambient temperature with laser flash photolysis of 1. Density functional theory (DFT) calculations support the characterization of vinylnitrene (3)2 and the proposed mechanism for its formation. Because vinylnitrene (3)2 is relatively stable, it has potential use as a building-block for high-spin assemblies.
authors.affiliation: †Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States.
authors.forename: Sujan K
authors.initials: SK
authors.lastname: Sarkar
authors.affiliation: ‡Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Asako
authors.initials: A
authors.lastname: Sawai
authors.affiliation: ‡Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Kousei
authors.initials: K
authors.lastname: Kanahara
authors.affiliation: §School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Curt
authors.initials: C
authors.lastname: Wentrup
authors.affiliation: ‡Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Abe
authors.affiliation: †Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States.
authors.forename: Anna D
authors.initials: AD
authors.lastname: Gudmundsdottir