The C-methylthio derivatives of cobalt bis(dicarbollide) were synthesized by reaction of anhydrous CoCl2 with nido-carborane [7-MeS-7,8-C2B9H11]− and isolated as a mixture of rac-[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− and meso-[1,2′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− isomers. The structures of both isomers were studied using DFT quantum chemical calculations. The most preferable geometry of rotamers and the stabilization energy of C-methylthio derivatives of cobalt bis(dicarbolide) were calculated. The (BEDT-TTF)[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2] salt was prepared and its structure was determined by single crystal X-ray diffraction. The cisoid conformation of the rac-[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]− anion is stabilized by short intramolecular CH⋯S hydrogen and BH⋯S chalcogen bonds between the dicarbollide ligands, that is in good agreement with the data of quantum chemical calculations.
