The “chemical tug-of-war” in carborane clusters: distinct tuning on different sides of the cluster

Abstract

The special C–C bond in icosahedral closo-dicarbadodecaboranes and its high plasticity have been highlighted several times, which is reflected in the ease of tuning the C–C bond distance with different substituents. Apart from this special case, the other bonds within the carborane clusters have not been investigated yet. DFT calculations demonstrated that the elongation of C–B and B–B bonds is ruled by the same effects as the well-investigated C–C bond; however, stretching of B–B generally requires more energy. These results indicate that the bonds of the carborane clusters do not differ significantly; in fact, they possess similar properties. The computational results encouraged us to synthesize the most promising derivatives. The distinct tuning was achieved by the variation of π-donor substituents. In the case of the 9,10-m-carboranyl-disulfanide derivatives, the B9–B10 bond distance is elongated up to 1.92(2) Å.