The sandwich complex commo-[3,3′-Fe{4-(Me₂S)-1,2-C₂B₉H₁₀}₂]1 was synthesised. Its meso and DD/LL isomers are easily separated by fractional recrystallization from acetone and were spectroscopically characterized. The charge-transfer salt [3,3′-Fe{4-(Me₂S)-1,2-C₂B₉H₁₀}₂]⁺[ddq]˙^–2 was formed between the DD/LL-1 racemate and 2,3-dichloro-5,6-dicyano-p-benzoquinone (ddq). X-Ray crystallography revealed an increase in the iron-dicarbollide distance on oxidation of DD/LL-1(Fe–C₂B₃ 1.50 Å) to the cation in 2(Fe–C₂B₃ 1.54 Å). The latter is the first example of a cationic bis(dicarbollyl)metal complex to be crystallographically characterized. The cations and anions pack to form alternating layers in the crystal of 2. Within the [ddq]˙^– layer the anions form zigzag chains linked via intermolecular N ⋯ Cl electrostatic interactions (N ⋯ Cl 3.21 Å). The cation and anion layers are crossed-linked by weak CH ⋯ O hydrogen bonds between the oxygen atoms of the [ddq]˙^– anions and some of the cage CH hydrogen atoms of the cations. Between 5 and 270 K the corrected molar susceptibility of 2 follows the Curie–Weiss law, with a θ value of –2.5 K. The single-crystal electrical conductivity of 2 at room temperature is less than 10 ^–8 S cm^–1.