posted on 2024-02-08, 13:11authored bySamuel
A. Wood, Brian J. Esselman, Samuel M. Kougias, R. Claude Woods, Robert J. McMahon
Broad-band
ultraviolet photolysis (λ > 200 nm) of (cyanomethylene)cyclopropane
(5) in an argon matrix at 20 K generates 1-cyano-2-methylenecyclopropane
(7), a previously unknown compound. This product was
initially identified by comparison of its infrared spectrum to that
predicted by an anharmonic MP2/6-311+G(2d,p) calculation. This assignment
was unambiguously confirmed by the synthesis of 1-cyano-2-methylenecyclopropane
(7) and observation of its authentic infrared spectrum,
which proved identical to that of the observed photoproduct. We investigated
the singlet and triplet potential energy surfaces associated with
this isomerization process using density functional theory and multireference
calculations. The observed rearrangement of compound 5 to compound 7 is computed to be endothermic (3.3 kcal/mol).
We were unable to observe the reverse reaction (7 → 5) under the photochemical conditions.