Carbon-Rich Trinuclear Octamethylferrocenophanes

Several trinuclear ferrocenes are obtained by Friedel-Crafts reaction of octamethylferrocene with ferrocenoyl chloride and subsequent modifications. 1,1'-Diferrocenoyloctamethylferrocene (3) is transformed to the divinyl deriv. (4a) by reaction with MeLi and AlCl3.  The reactive 4a cyclizes spontaneously to a [4]ferrocenophane with buta-1,3-diene handle (5) or in the presence of AlCl3 to a [3]ferrocenophane with propene handle (6).  Structure assignments are supported by X-ray crystallog. and NMR spectroscopy, and mechanisms are proposed.  Electrochem. behavior of the compds. was investigated with cyclic voltammetry, and assignments of the redox processes were carried out with the aid of d. functional theory calcns.  The synthesized compds. and demonstrated transformations represent useful tools for prepn. of materials for charge-transport studies in metal-mol.-metal junctions.