A Route toward (Aminomethyl)cyclopentadienide Ligands and Their Group 4 Metal Complexes

A new method is described, by which N-functionalized cyclopentadienide ligands are synthesized via the nucleophilic substitution of sodium cyclopentadienide onto Katritzky's (benzotriazolyl) compounds. This route enables the introduction of bulky and basic amines, separated from the cyclopentadienyl ring by a methylene spacer. The method thus represents a valuable alternative to the general fulvene route. The resulting ligands have been coordinated to titanium and zirconium, producing a series of discrete metallocene derivatives with a pendant amine arm. These complexes are extremely sensitive towards moisture, but they can easily be converted into benchtop-stable ammonium chloride derivatives. The ligands and their complexes have been fully characterized by NMR and IR spectroscopy, elemental analysis and/or high resolution ESI-MS. The solid-state structures of ten complexes have been established by single-crystal X-ray diffraction analysis.