In this study, we explore the coordination complexes of the resorcinol bis(diphenylphosphinite) (POCOP) pincer ligand with Group 13 (aluminum, gallium and indium) metal centers. We report the synthesis of six new Group 13 POCOP complexes that have all been structurally characterized. The aluminum and indium complexes all crystallize in a five-coordinate "closed" geometry; however, for gallium, an "open" four-coordinate complex is additionally observed in the solid state, similar to an intramolecular frustrated Lewis pair.
Pahar et al. (Fri,) studied this question.