Cluster rearrangement of isonido-ruthenacarboranes [1-(η6-1,4-Me2C6H4)-3(6)-Cl-isonido-1,2,4-RuC2B8H9] under thermal conditions

The heating of the isomeric [1-(η6-1,4-Me2C6H4)-3-Cl-isonido-1,2,4-RuC2B8H9] (1) or [1-(η6-1,4-Me2C6H4)-6-Cl-isonido-1,2,4-RuC2B8H9] (2) complexes (i) in a 1,4-Me2C6H4 solution at 85 °C as well as (ii) in a melt at 165 °C afforded mixtures of isomeric isonido- and closo-ruthenacarboranes, which differ in the positions of the chlorine substituent and the carbon atoms in the cage ligand. Structures of all new isomeric complexes have been established on the basis of analytical and multinuclear NMR data and were characterized by single-crystal X-ray diffraction studies. Also presented are the results of the quantum chemical calculations for the ground and the transition states of the reaction (i), which proved to be basis for the suggestion of interconversion scheme for these isomers.