Preparation and structures of biferrocenes with alicyclic substituents: Order–disorder of substituents in the crystal structures of cyclohexenylbiferrocene and its charge-transfer salt

• Biferrocenes with alicyclic substituents were prepared.
• The cation in [cyclohexenylbiferrocene][Ni(mnt)2] exhibited a valence-trapped state.
• Disorder of the substituent was suppressed in the [Ni(mnt)2] salt.

Biferrocene derivatives with cyclohexyl, cyclohexenyl, and cyclopentenyl substituents were prepared and crystallographically characterized. The cyclohexenyl substituents exhibited twofold disorder in the crystals. A charge-transfer salt of 1′-cyclohexenylbiferrocene with [Ni(mnt)2] was prepared. The biferrocenium cation in this salt was in a valence-trapped state owing to electrostatic interactions with the anion. The cyclohexenyl substituent in the [Ni(mnt)2] salt exhibited no disorder because of closer packing of the salt.

Biferrocene derivatives with cyclohexyl, cyclohexenyl, and cyclopentenyl substituents were prepared. In the solid state, the cyclohexenyl substituents exhibited twofold disorder. A charge-transfer salt of 1′-cyclohexenylbiferrocene with [Ni(mnt)2] was prepared, which contained a biferrocenium monocation in a valence-trapped state. The cyclohexenyl substituent in the salt exhibited no disorder.Figure optionsDownload as PowerPoint slide