Diaziridinones (2,3-Diazacyclopropanones). Structure (X Ray). Thermal Decomposition via a Nitrenoid Fragment

The structure of a diazacyclopropanone, bis(p-bromo-a,a-dimethylbenzyl)diaziridinone (3), has been determined by x-ray analysis. The substituents attached to the nitrogen atoms are 56° above and below the plane defined by the ring atoms; the bond lengths in the ring are 1.60 (N-N) and 1.325 Å (N-CO). Thermal decomposition of the diaziridinone affords the following (in moles of product per mole of reactant): p-bromo- α, α-dimethylbenzyl isocyanate (9) (0.35), p-bromo-N-(l-methylethylidene)benzenamine (10) (0.24), N-(l-p-bromophenylethylidene)-methanamine (11) (<0.01), p-bromo-α-methylstyrene (12) (0.15), and p-bromocumene (13) (0.01). The major path of decomposition is fragmentation to the isocyanate 9 and a nitrenoid species which rearranges (aryl migration) to imine 10.