Variations of molecular geometry from electron diffraction

Gas-phase electron diffraction is one of the principal tools for the determination of accurate molecular geometry. Re- cently, research efforts have focused on the determination of structural changes in series of compounds or even during some chemical happenings rather than on the study of individual struc- tures. Internal rotation, substituent effects, the transition from vapor to crystal phase, and the formation of new bonds are among the chemical changes whose structural consequences are being examined. The study of unstable molecules and reaction products is facilitated by combined electron diffraction/quadrupole mass spectrometric experiments.