Collect. Czech. Chem. Commun. 1997, 62, 1577-1584

Synthesis of Triferrocenylbenzenes by Tantalum(V)-Catalyzed Cyclotrimerization of Ethynylferrocene. The Crystal Structure of 1,3,5-Triferrocenylbenzene

Petr Štěpničkaa, Ivana Císařováa, Jan Sedláčekb, Jiří Vohlídalb and Miroslav Polášekc

a Department of Inorganic Chemistry, Charles University, 128 40 Prague 2, Czech Republic
b Department of Physical and Macromolecular Chemistry, Charles University, 128 40 Prague 2, Czech Republic
c J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23 Prague 8, Czech Republic


Exclusive, high-yield formation of the cyclotrimers of ethynylferrocene (1) was observed when TaCl5 in benzene was employed as catalyst. Analysis of the resulting isomer mixture by means of HPLC and 1H NMR revealed the presence of 1,3,5-triferrocenylbenzene (sym-2) and 1,2,4-triferrocenylbenzene (asym-2) in the ratio of 4 : 6. A small amount of pure sym-2 isomer was isolated, and its solid-state structure was established by single-crystal X-ray diffraction. The molecules of sym-2 possess a distorted up-up-down arrangement of the ferrocenyl groups attached to the benzene ring.

Keywords: Metallocenes; Ferrocene derivatives; Ethynylferrocene; Cyclotrimerization; X-Ray structure; Tantalum(V).