Tuning Lewis Acidity: Design of Titanium Complexes with hemilabile Pyridine‐based Ligands

Abstract The formation of titanium(IV) complexes with Cp , N , N and Cp , O , N tridentate ligands via insertion of the pyridine‐containing precursors into the pentafulvene moiety of the titanium complexes is reported. After consecutive methylation and treatment with B(C 6 F 5 ) 3 according to a well‐established method, cationic complexes with the weakly coordinating MeB(C 6 F 5 ) 3 − anion were obtained. Further introduction of moderately strong coordinating triflato ligands provides insight into the nucleophilicity of the respective pyridinyl ligands. The Lewis acidity of the complexes is determined by well‐established protocols. Depending on the donor strength, the triflato ligand is displaced by the pyridinyl ligand to produce a cationic complex with a triflate anion. The highly Lewis acidic cationic titanium(IV) complexes are able to perform reactions such as H 2 functionalization and C−H activation reactions. The additional 15 N NMR values of the pyridine‐based ligand and UV/Vis spectra are key features of these ligand systems and further support the coordination mode determination.