SYNTHESIS OF TRIFERROCENYLBENZENES BY TANTALUM(V)-CATALYZED CYCLOTRIMERIZATION OF ETHYNYLFERROCENE - THE CRYSTAL STRUCTURE OF 1,3,5-TRIFERROCENYLBENZENE

摘要

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 H-1 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. [References: 19]