The first synthesised examples of di-siloxy-substituted cyclopentadienyl zirconocenes, their synthesis, structure and activity in ethylene polymerisation

Bis-(1,2-(RMe2SiO)2)ZrCl2 complexes with R = Me-(5a), iPr-(5b) and tBu-(5c) have been synthesised in good yields and characterised. Compounds 5a–c are the first synthesised examples of multi-siloxy-substituted cyclopentadienyl metallocenes. The siloxy-substituents have a for siloxy substituted metallocenes unique steric arrangement, with one almost in the same plane, and the other nearly perpendicular to the plane of the cyclopentadienyl ligand of the zirconocene. The ethylene/1-hexene co-polymerisation activity using methylalumoxane as co-activator gives low activities, with compound 5c (262.92 kg(PE)/g(Zr)/h) being the most active.