The Role of C-H•••H-B Interactions in Establishing Rotamer Configurations in Metallabis(dicarbollide) Systems

The aim of this work is to explore the self-interaction capability of the anion [3,3'-Co(1,2-C2B9H11)(2)](-) through C-cluster- H center dot center dot center dot H-B (C-c-H center dot center dot center dot H-B) dihydrogen bonds. A set of theoretical and empirical data aiming to establish the main rules that account for the binding mode between the negatively charged borane framework made by [3,3'-Co(1,2-C2B9H11)(2)](-) and the [NMe4](+) ions have been compiled. The interaction between cation and anion is mainly electrostatic but the covalent contribution is also proven and quantified. The existing intermolecular H center dot center dot center dot H short contacts have been studied and are compared with available data from the Cambridge Structural Database. The results show that the electronic configuration of the transition metal atom in the sandwich complex is not enough to define the preferred rotamer due to the influence of the anion environment and the H center dot center dot center dot H interactions present in the solid state. We present a methodology with widely used theoretical tools to study cation center dot center dot center dot cobaltabisdicarbollide interactions in the solid state.