Transformation matrices as tool to investigate the changes in the electronic structure of reacting molecules along the reaction coordinate

The calculation of the transformation matrix between the molecular orbitals of the transition state and the educt provides detailed information on the alteration and interaction of the MO's along the reaction coordinate. This is demonstrated for four different kinds of reactions: (a) Conrotatory ringopening of cyclobutene; (b) Addition of methylene to ethylene; (c) Nucleophilic substitution of CH₃CN and CH₃NC by CN^-; (d) 1,2 Rearrangement of methylcarbene to ethylene. MNDO has been employed for the calculations but any other method may be used as well.