Exploring the potential energy surface of B4H42−: an exception of the Wade–Mingos rules

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 σ and π 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.