A SYN-[1.1]FERROCENOPHANE WITH APPROXIMATE C(2V) SYMMETRY

The crystal structures of a new phase of [1.1]-ferrocenophane (1) and the monodeuterated analogue [1-H-2][1.1]ferrocenophane (2) have been determined by X-ray diffraction. The compounds are isostructural and crystallize in the monoclinic space group C2/c with Z = 8. Unit cell dimensions for compound 1 are a = 38.96(1), b = 7.498(6), c = 10.712(4) angstrom and beta = 93.96(5)degrees. The structure was refined to a final R = 0.029 (R(w) = 0.036) for 297 parameters and 1879 observed reflections. The molecule has the syn conformation, but exhibits remarkably little distortion with respect to the C2v point group symmetry, despite H .. H contacts of 2.04(4) and 2.13(5) angstrom. The rotation angles (cf. staggering) in the two ''ferrocene units'' are 0.5-degrees and 0.6-degrees, whereas the cyclo-pentadienyl rings are tilted 3.6-degrees and 1.0-degrees with respect to each other. The dihedral angles (i.e. twist angles) between the two cyclopentadienyl rings of the same organic ligand are 1.6-degrees and 3.2-degrees. The distance between the two iron atoms in the same molecule is 4.852(2) angstrom.