Premium
Highly Strained 2,3‐Bridged 2 H ‐Azirines at the Borderline of Closed‐Shell Molecules
Author(s) -
Banert Klaus,
Meier Barbara,
Penk Enrico,
Saha Biswajit,
Würthwein ErnstUlrich,
Grimme Stefan,
Rüffer Tobias,
Schaarschmidt Dieter,
Lang Heinrich
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201002474
Subject(s) - nitrene , singlet state , chemistry , ring (chemistry) , reactivity (psychology) , molecule , photochemistry , quantum chemical , crystallography , computational chemistry , excited state , catalysis , organic chemistry , physics , atomic physics , medicine , alternative medicine , pathology
Substituted 1‐azidocyclopentenes and 1‐azidocyclohexenes were photolyzed to generate 2,3‐bridged 2 H ‐azirines. In the case of bridgehead azirines with a six‐membered carbocycle, detection by NMR spectroscopic analysis was possible, whereas even kinetically stabilized bridgehead azirines with a five‐membered ring could not be characterized by low‐temperature NMR spectroscopic analysis. Thus, a recent report on the latter heterocycles was corrected. Depending on the substitution pattern, irradiation of 1‐azidocyclopentenes either led to products that can be explained on the basis of short‐lived 2,3‐bridged 2 H ‐azirines, or gave secondary products generated from triplet nitrenes. The diverse photoreactivity of 2,3‐bridged 2 H ‐azirines was also studied by quantum chemical methods (DFT, CCSD(T), CASSCF(6,6)) with respect to the singlet and triplet energy surfaces. The ring‐opening processes leading to the corresponding vinyl nitrenes were identified as key steps for the observed reactivity.