Rigid Ligand Environments at Beryllium, From Spectroscopic Probes to Small Molecule Activation

In beryllium scorpionate complexes, three of the four available coordination sites at the beryllium atom are occupied by a strongly binding κ 3 ‐ligand. This can be utilised to investigate the binding properties of the ligand coordinated to the fourth coordination site in detail and to enforce unprecedented reactivities. The use of trispyrazolylborate allowed the extensive characterisation of beryllium‐pseudohalide and ‐carbon bonds as well as the activation of CO 2 , SO 2 , and H 2 . Phosphorus‐based beryllium scorpionates can be used to construct spectroscopic probes to determine electron densities and ligating properties. Additionally, these complexes show unprecedented transmetalation reactions.