Bridged ferrocenes. II. The crystal and molecular structure of 1,1′,2,2′,4,4′-tris(trimethylene)ferrocene

The crystal and molecular structure of 1,1′,2,2′,4,4′-tris(trimethylene)ferrocene has been determined by X-ray diffraction. This compound forms monoclinic needles of space group C2/c with sixteen molecules in the unit cell, a 30.899(6), b 9.416(1), c 25.145(1) Å and β 127.31(1)°. The structure was solved from three-dimensional Patterson and Fourier syntheses and was refined by least squares. The structure consists of two crystallographically independent molecules showing similar geometries. The two cyclopentadienyl rings are eclipsed and the dihedral angle between the two rings, is 2.4°. The average iron to ring-carbon distance is 1.992 Å. The distance between the rings (3.15 Å) is significantly shorter than in ferrocene, and the rings appear to be slightly non-planar.