SYNTHESIS AND STRUCTURE OF A CHARGE-COMPENSATED FERRACARBORANE, COMMO-[3,3'-FE(4-(ME2S)-1,2-C2B9H10)2], AND ITS CHARGE-TRANSFER SALT WITH 2,3-DICHLORO-5,6-DICYANO-P-BENZOQUINONE

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 angstrom) to the cation in 2 (Fe-C2B3 1.54 angstrom). 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 angstrom). The cation and anion layers are crossed-linked by weak CH ... 0 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 theta value of -2.5 K. The single-crystal electrical conductivity of 2 at room temperature is less than 10(-8) S cm 1.