Abstract

An analysis of the potential energy surface of B4H42- which, according to Wade-Mingos rules should have a tetrahedral structure, is presented. Our results indicate that the global minimum has a planar diamond-like boron skeleton and that the nearest local minimum lies 7.8 kcal mol-1 above it. This isomer corresponds to a Jahn-Teller distorted tetrahedral B4H4 structure as a result of the gain of two electrons. Furthermore, the analysis of the bonding pattern using the Adaptive Natural Density Partitioning method indicates a double sigma and pi delocalization providing high stability. These results show that B4H42- is an exception to the Wade-Mingos rules and open the door to future experimental characterization of this compound.