MOLECULAR-STRUCTURE OF DECAMETHYLFERROCENE STUDIED BY GAS-PHASE ELECTRON-DIFFRACTION - DETERMINATION OF EQUILIBRIUM CONFORMATION AND BARRIER TO INTERNAL-ROTATION OF THE LIGAND RINGS

The molecular structure of decamethylferrocene, (η-C5Me5)2Fe, has been determined by gas phase electron diffraction. The FeC and C(Cp)C(Cp) bond distances, 2.064(3) and 1.439(2) Å, respectively, are indistinguishable from those in ferrocene, Cp2Fe. But, while the equilibrium conformation of gaseous Cp2Fe is eclipsed (D5h), the equilibrium conformation of (C5Me5)2Fe is staggered (D5d) with a barrier to internal rotation of the ligand rings V5 = 1.0(0.3) kcal mol-1. And while the CH bonds in Cp2Fe are bent about 4° out of the plane of the C5 ring towards the metal atom, the C(Cp)C(Me) bonds in (C5Me5)2Fe are bent 3.4(0.5)° out of the plane in the opposite direction. © 1979.