Cyclopentadiene chemistry is a staple part of organometallic chemistry, as cyclopentadienes can be used as ligands in ferrocene complexes or as potential precursors to Diels-Alder type polymerizations. The present study compares the effects of a tert-butyl group and an isopropyl group on cyclopentadienide arylation with hexafluorobenzene at 70 C for 70 hours. The isopropyl group was expected to be less sterically hindering than tert-butyl, as the isopropyl groups has one fewer methyl group. This one-step synthesis found that only 1,2-bis(pentafluorophenyl)-4-tert-butylcyclipentadi-1,3-ene was formed when starting with 1-tert-butylcyclopentadi-1,3-ene, whereas 1,2-bis(pentafluorophenyl)-4-isopropylcyclopentadi-1,3-ene and 1,2,3-tris(pentafluorophenyl)-4-isopropylcyclopentadi-1,3-ene formed from 1-isopropylcyclopentadi-1,3-ene. These results support the well-known phenomena that an isopropyl substituent group is less sterically hindering because proximal arylation occurred to make the 1,2,3-tris(pentafluorophenyl)-4-isopropylcyclopentadi-1,3-ene product. These results indicate that only mono- and diarylated products can be synthesized with 1-tert-butylcyclopentadi-1,3-ene; however, mono-, di-, and triarylated products can be made with 1-isopropylcyclopentadi-1,3-ene. Future studies will explore the effects of an ethyl substituent group on cyclopentadiene arylation.

Exploring alkyl substituent effects on cyclopentadienide arylation by Hexafluorobenzene

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