Abstract : The structural peculiarities (C1-C6 distances, bending of the ligand, conformation of organometallic group relative to the ligand, etc.), the isomerism and the mechanisms of inter-ring haptotropic rearrangements (IRHR) in Cr(CO)3 and CoCp complexes of 1,6-methano[10]annulene were investigated by DFT. An activation barrier of 28.0 kcal/mol, lower than that corresponding to naphthalene, was computed for the η6, η6-IRHR in the mononuclear chromium complex. In the case of the mononuclear cobalt species, activations barrier of 33.8 and 31.3 kcal/mol were computed for the η4, η4-IRHR in the trans and cis isomers, respectively.
