Dyotropic rearrangements of Cp₂Zr ligand complexes; a theoretical study

Abstract

The dyotropic rearrangements in Cp₂Zr ligand complexes such as Cp₂Zr(X) (CH₂SR) (3) have been studied by molecular orbital theory. The higher reactivity for the compound with X = Ph in comparison to that with X = Me, Cl, or CH₂Ph is related to the energy match of MO's of the migrating fragment with those of the remaining fragment along an assumed reaction coordinate. The ease of conversion of Cp₂Zr(C₄H₃O)₂ (5) into a zircona-cyclic species 6 can be similarly accounted for. Other substituents that should make the above reactions faster are suggested on the basis of the studies. A general discussion is presented on the migratory aptitudes and the difficulties involved in assigning migratory aptitudes that are independent of the specific reaction.