Département de chimie moléculaire

A detailed B3LYP study of the regiochem.-detg. event in the Pauson-Khand reaction (PKR), i.e., the formation of the cobaltacycle from the olefin-coordinated dicobalt complex, with ethylene as the olefin and propyne as a prototypical nonsym. alkyne, is presented. In summary, ethylene does not appear to react principally from an equatorial position but, through facile pseudorotation, from an axial position, the one of lowest activation energy for C-C bond formation. It is now clear that productive axial coordination of an olefin must be considered in theor. as well as synthetic PKR studies. [on SciFinder(R)]