Structures and properties of new ferrocene-based paramagnetic anion octamethylferrocenedisulfonate and its TTF salt

• We prepared octamethylferrocenedisulfonate as tetraphenylphosphonium salts.
• Recrystallisation gave yellow and green salts, the latter of which is paramagnetic.
• The TTF salt was obtained, in which the ferrocenyl part is paramagnetic.

The structure and properties of a new ferrocene-based disulfonate anion, octamethylferrocenedisulfonate (Fe(C5(CH3)4(SO3))2), obtained as tetraphenylphosphonium (PPh4) salts, are described. Recrystallisation gave two types of salts, yellow crystals and green powder. The former composition was found to be (PPh4)2[Fe(C5(CH3)4(SO3))2], where Fe(C5(CH3)4(SO3))2 is dianionic. The green powder was determined to be (PPh4)[Fe(C5(CH3)4(SO3))2]·0.4H2O, in which the iron complex is monoanionic despite it having two anionic sulfo groups. The ferrocenyl part has a charge of + 1 and temperature-dependent magnetic susceptibility indicates that the green salt is paramagnetic. Metathesis of either PPh4 salts with (TTF)3(BF4)2 (TTF = tetrathiafulvalene) gave the same compound, (TTF)[Fe(C5(CH3)4(SO3))2]·3.5H2O, in which the anion is paramagnetic. This is the first TTF-type salt that contains a non-diamagnetic ferrocenyl-based counter-ion. The structure and properties of the TTF salt are reported.

New ferrocene-based paramagnetic anion octamethylferrocenedisulfonate and its TTF-based charge transfer salt were prepared.Figure optionsDownload as PowerPoint slide