Synthesis and structure of bis(methylsulfanyl) derivatives of iron bis(dicarbollide)

Bis(methylsulfanyl) derivatives of iron(II) bis(dicarbollide) [8,8′-(MeS)2-3,3′-Fe(1,2-C2B9H10)2]2- (42−), [4,4′-(MeS)2-3,3′-Fe(1,2-C2B9H10)2]2- (52−), and [4,7′-(MeS)2-3,3′-Fe(1,2-C2B9H10)2]2- (62−) were prepared by the treatment of the corresponding dimethylsulfonium derivatives 1–3 with potassium butylthiolate. Their oxidation by air in aqueous solution results in the corresponding derivatives of iron(III) bis(dicarbollide) [8,8′-(MeS)2-3,3′-Fe(1,2-C2B9H10)2]- (7-), [4,4′-(MeS)2-3,3′-Fe(1,2-C2B9H10)2]- (8-) and [4,7′-(MeS)2-3,3′-Fe(1,2-C2B9H10)2]- (9-). The structures of (Bu4N)2[8,8′-(MeS)2-3,3′-Fe(1,2-C2B9H10)2] and (Me4N)[4,7′-(MeS)2-3,3′-Fe(1,2-C2B9H10)2] were determined through single-crystal X-ray diffraction. In the solid state, the rotation of the dicarbollide ligands with respect to each other is hampered due to formation of weak intramolecular CH⋯S(Me) hydrogen bonds between the ligands resulting in stabilization of transoid-conformation in the case of 8,8′-isomer and gauche-conformation in the case of 4,4′-and 4,7′-isomers. The synthesized bis(methylsulfanyl) derivatives of iron bis(dicarbollide) can be considered as a versatile platform for design of molecular switches.