The MM3 force field for 12-vertex boranes and carboranes

A model and parameters were developed which allow conformational calculations to be carried out on the 12-vertex boranes, carboranes and their derivatives, within the framework of the MM3 force field. In order to avoid description of all the bond angles, the molecule was represented as a superposition of two rings and two cap groups. The valence bonds between these moieties were described by a Buckingham potential. The statistical analysis of carborane molecules found in the Cambridge Structural Database has been carried out in order to find the mean values of the bond lengths and angles for these molecules. A parameter set was developed and used for the calculations on substituted carboranes, and the results show good agreement with the experimental data. (C) 1997 Elsevier Science S.A.