Experimental Electron Density Determination of Unconventionally Bonded Boron

Abstract

Two major aims have been pursued in the course of this thesis. On the one hand, reasons for the different reactivities of two Lewis acids based on tris(pentafluorophenyl)borane, namely bis(pentafluorophenyl)(N-pyrrolyl)borane and bis(pentafluorophenyl)(N-pyrrolidinyl)borane were to be elucidated. On the other hand, the nature of the bonding between a transition metal and a boron atom in borylene complexes was to be examined for two exemplary compounds, a terminal and a bridging borylene complex. In order to answer these questions, experimental electron density studies have been performed on four different compounds. Multipole refinements have been carried out on high-resolution data from low-temperature X-ray diffraction experiments.The electron density distributions obtained were analyzed topologically in accordance with Bader's Quantum Theory of Atoms in Molecules. The chemical interpretation of the resulting descriptors facilitated the elucidation of the questions raised above.