Pushing the σ-Donor Strength in Iridium Pincer Complexes: Bis(silylene) and Bis(germylene) Ligands Are Stronger Donors than Bis(phosphorus(III)) Ligands

Breaking the donor limits: The remarkable coordination chemistry of ECHE (E=Si, Ge) ligands with Group 9 metals (Ir, Rh) and their application in catalytic CH borylation of arenes was investigated. The spectroscopic and structural features of the first [ECE] iridium complexes show the stronger σ-donating properties of the divalent Si and Ge pincer ligands compared to analogous PIII-based ligands.