AbstractThe crystal and molecular structure of 8, 8‐dimethyl‐8‐azoniabicyclo[5.1. 0]octane iodide has been elucidated. The aziridine ring is bridgedcisto the cycloheptane ring. The cycloheptane ring has been shown to have a distorted chair conformation. No close trans‐annular hydrogen distances have been observed. The compound crystallizes in the space group Pna21with unit cell dimensions a = 17.31, b= 8.58 and c=7.56Å. The final value of R=Σ ‖ Fo| ‐ | Fc‖/Σ| Fo| is 0.145 for the 734 obse