Crystal and molecular structure of the cycloadducts formed by mono-bromo-N-methoxycarbonylazepine and tetracyanoethylene

Abstract

The molecular structure of the cycloadduct from 4-bromo-N-methoxycarbonylazepine and tetracyanoethylene has been shown to be 6-bromo-8,8,9,9-tetracyano-2-methoxycarbonyl-2-azabicyclo[3,2,2]nona-3,6-diene by the results of a single-crystal X-ray investigation. The crystals are monoclinic, a= 19·25 ± 0·03, b= 10·87 ± 0·02, c= 8·98 ± 0·02 Å, β= 101° 30′± 15′. The space group is P2₁/a with four molecules of C₁₄H₈BrN₅O₂,½C₇H₈ in the unit cell. Refinement of the structure produced some anomalous results, and a critical examination of these difficulties led to the detection of a cocrystallised isomer in approximately 15% of the total number of molecular sites. This isomer apparently originated from a cycloaddition involving 3-bromo-N-methoxycarbonylazepine and tetracyanoethylene. The molecular geometry of the ring system of the major isomer is described.