42 / 2023-08-13 09:57:15

Pincer Ligands with Pendant Phosphazene Arms: Stabilization of Main-Group and Transition Metal Complexes

pincer ligand,phosphazene,metal complexes

Phosphorus in Synthetic Chemistry > 2) Phosphorus compounds as ligands

The “pincer” motif has become an intriguing platform for ligand design, due to many successful applications of pincer ligands. Phosphazenes are strong, neutral electron donors, which have been employed in building pincer ligands. Bis(iminophosphoranyl) pyridine ligands could stabilize transition metal complexes.^1,2 Herein, a bis(iminophosphoranyl) pyridine ligand [2,6-(MesN=PPh₂)₂C₅H₃N] (L₀) is used to stabilize main-group metal complexes – chloro-tetrylenium salts. (Fig. 1) Moreover, an unprecedented anionic pincer ligand [2,6-(MesN=PPh₂)₂C₅H₄N]^‑ (L_H) has been facilely synthesized by the reaction of L₀ with K-selectride. L_H can stabilize main-group and transition metal complexes L_HCrCl, L_HCoCl, L_HZnCl, L_HGeCl, and so on, which display different geometries. X-ray diffraction analysis and theoretical study show that the phosphazene arms of L_H strongly coordinate to the metal centers, while the central amide group alternatively donates one or two pairs of electrons to bind with different metal centers.