Chemical Activation as a Probe of Reaction Mechanism. Synthesis and Thermal Decomposition of 2,3-Diazabicyclohex-2-enes

Article abstract of DOI:10.1021/ja00327a025

Gas-phase thermolysis of 2,3-diazabicyclo<2.1.1>hex-2-ene (1) produces highly vibrationally excited (chemically activated) bicyclo<1.1.0>butane (2).The excited 2 rearranges to butadiene, in competition with collisional deactivation by a bath gas.Quantitative modeling using RRKM theory and a stepladder model for collisional deactivation indicates that, of the substantial amount of excess energy available to the products of thermolysis of 1, the great majority lies in the hydrocarbon fragment (2).Within the framework of a mechanistic criterion developed previously by Bauer, this result suggests that 1 decomposes by a stepwise, one-bond cleavage involving an intermediate diazenyl diradical.The synthetic approach to structures such as 1 is developed, as are certain other aspects of the chemistry of 1 and its dimethyl derivative 7.