PREPARATION OF THE ANSA-ZIRCONOCENES WITH AN N-METHYLPIPERIDINE BRIDGE

Bridged ligands 4,4-di(cyclopentadienyl)-N-methylpiperidine (4) and 4, 4-di(indenyl)-N-methylpiperidine (5) were prepared by condensation of cyclopentadiene or indene with N-methylpiperidone. Dilithium salts 4a and 5a were subsequently transformed into the corresponding ansa-zirco nocenes 2 and 3. No direct contact Zr ... N was found in the crystal s tructure of 2. The attempt to prepare zirconocene 3 from distannyl der ivative 5b gave an unexpected monoindenyl complex 6 comprising one unr eacted stannylated indenyl group and having direct coordination of Zr by nitrogen.