Haptotropic Shifts in (C5H5)Fe and Mn(CO)3 Complexes of 4H-Cyclopenta[def]phenanthrene (cppH): X-ray Crystal Structure and NMR Fluxionality of (η1-cpp)Mn(CO)3(PEt3)2

The favored pathways for the haptotropic shifts from (η6-cpp)ML n to (η5-cpp)ML n , where cppH is 4H-cyclopenta[def]phenanthrene and ML n = Fe(C5H5) or Mn(CO)3, have been investigated by means of extended Hückel molecular orbital calculations, and energy hypersurfaces for these processes have been obtained. These data suggest the intermediacy of an exocyclic (η3-cpp)ML n species, stabilized by the presence of a naphthalene-type 10π aromatic …