Tetrakis(dimethylamido)zirconium (3) reacts with dimethylsilylene- and
isopropylene-bridged bis(indenyl) ligands 4 and 5 to yield the corres
ponding ansa-bis(dimethylamido)zirconocenes rac-1 and rac-2 containing
eta(5)-coordinated pi-aromatic ligand systems.