Details

Autor(en) / Beteiligte

• Phillips, Leo
• Cooper, Mervyn K
• Haaland, Arne
• Samdal, Svein
• Giricheva, Nina I
• Girichev, Georgiy V

Titel

The molecular structure, equilibrium conformation and barrier to internal rotation in decachloroferrocene, Fe(η-C5Cl5)2, determined by gas electron diffractionDedicated to two good friends and respected colleagues, Professor Heinz Oberhammer on the occasion of his 70th birthday, and Professor David W. H. Rankin on the occasion of his retirement

Erscheinungsjahr

2010-05

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The molecular structure of decachloroferrocene has been determined by gas electron diffraction supported by quantum chemical calculations. The equilibrium conformation has staggered ligand rings and D 5 d symmetry. The barrier to internal rotation is, however, only 0.8(2) kJ mol −1 . This barrier is so low that even at room temperature the vast majority of molecules in the gas phase would have sufficient thermal energy to undergo virtually non-hindered internal rotation. While the eclipsed equilibrium conformation of unsubstituted ferrocene is determined by attractive dispersion interaction between the two cyclopentadienyl ligands, the staggered equilibrium conformation of Fe(η-C 5 Cl 5 ) 2 is due to steric repulsion between Cl atoms at different rings. The ligands are non-planar: the C-Cl bonds are bent 3.7(3)° out of the plane of the C 5 ring away from the metal atom. The Fe-C, C-C and C-Cl bond distances ( r a ) are: 205.0(4) pm, 143.4(3) pm and 170.2(4) pm respectively. While the equilibrium structure of ferrocene is eclipsed, D 5 h , the equilibrium conformation of decachloroferrocene is staggered, D 5 d ; the barrier to internal rotation in the latter is only 0.8 kJ mol −1 , or about one fifth of the barrier in ferrocene.