coupling reaction of an in situ generated bis[(dimethylaminoethenyl)cyclopentadienyl]ZrCl2 intermediate. A number of related examples of this condensation reaction at the intact Group 4 bent metallocene framework is described, using different amino-substituents and Ti, Zr and Hf systems. Three examples of the unsaturated ansa-metallocene systems were characterized by X-ray diffraction. In a few cases it was