title: Different behavior of nitrenes and carbenes on photolysis and thermolysis: formation of azirine, ylidic cumulene, and cyclic ketenimine and the rearrangement of 6-phenanthridylcarbene to 9-phenanthrylnitrene.
abstract: Flash vacuum thermolysis (FVT) of 9-azidophenanthrene 8, 6-(5-tetrazolyl)phenanthridine 18, and [1,2,3]triazolo[1,5-f]phenanthridine 19 yields 9-cyanofluorene 12 as the principal product and 4-cyanofluorene as a minor product. In all cases, when the product is condensed at or below 77 K, the seven-membered ring ketenimine 24 is detectable by IR spectroscopy (1932 cm(-1)) up to 200 K. Photolysis of Ar matrix isolated 8 at lambda = 308 or 313 nm generates at first the azirine 26, rapidly followed by the ylidic cumulene 27. The latter reverts to azirine 26 at lambda > 405 nm, and the azirine reverts to the ylidic cumulene at 313 nm. Nitrene 9 is observed by ESR spectroscopy following FVT of either azide 8, tetrazole 18, or triazole 19 with Ar matrix isolation of the products. Nitrene 9 and carbene 21 are observed by ESR spectroscopy in the Ar matrix photolyses of azide 8 and triazole 19, respectively.
authors.affiliation: Chemistry Building, School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Kvaskoff
authors.forename: Pawel
authors.initials: P
authors.lastname: Bednarek
authors.forename: Lisa
authors.initials: L
authors.lastname: George
authors.forename: Sreekumar
authors.initials: S
authors.lastname: Pankajakshan
authors.forename: Curt
authors.initials: C
authors.lastname: Wentrup
mesh_terms: D001389:Azirines / Q000138:chemical synthesis*; D004578:Electron Spin Resonance Spectroscopy; D005030:Ethylenes / Q000138:chemical synthesis*; D006358:Hot Temperature; D006838:Hydrocarbons / Q000737:chemistry; D007097:Imines / Q000138:chemical synthesis / Q000737:chemistry*; D007659:Ketones / Q000138:chemical synthesis*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D010617:Phenanthridines / Q000138:chemical synthesis / Q000737:chemistry*; D010782:Photolysis; D013053:Spectrophotometry; D013816:Thermodynamics
chemical_list: D001389:Azirines; D005030:Ethylenes; D006838:Hydrocarbons; D007097:Imines; D007659:Ketones; D010617:Phenanthridines; C030011:carbene; C017621:phenylnitrene; C008223:ketene; D008697:Methane