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

The special C-C bond in the 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 requires more energy. These results indicate that the bonds of the carborane clusters do not differ significantly; in fact they possess similar properties. The promising computational results encouraged us to synthetize the most promising derivatives. The distinct tuning was achieved by the variation of π-donor substituents. In the case of the disulfanide derivative of meta-carborane derivative, the B9-B10 bond distance is elongated up to 1.92(2) Å.