A novel alkenyl-substituted ansa-zirconocene complex with dual application as olefin polymerization catalyst and anticancer drug

The alkenyl substituted fulvene compound, (C5H4)double bond; length as m-dashCMe(CH2CH2CHdouble bond; length as m-dashCMe2) (1), reacts with one equivalent of LiMe to give the lithium derivative Li{C5H4(CMe2CH2CH2CHdouble bond; length as m-dashCMe2)} (2). The reaction of 2 with Me2Si(C5Me4H)Cl gave the ansa-ligand precursor Me2Si(C5Me4H)(C5H4(CMe2CH2CH2CHdouble bond; length as m-dashCMe2)) (3), which after the subsequent reaction with 2 equivalents of LiBun yielded the dilithium salt Li2{Me2Si(C5Me4)(C5H3(CMe2CH2CH2CHdouble bond; length as m-dashCMe2))} (4). The alkenyl-substituted zirconocene complex [Zr{Me2Si(η5-C5Me4)(η5-C5H3(CMe2CH2CH2CHdouble bond; length as m-dashCMe2))}Cl2] (5) was synthesized by the equimolar reaction of 4 and ZrCl4. 5 was characterized by spectroscopic methods and by single crystal X-ray diffraction studies. The zirconocene compound 5 has been tested as a catalyst in the polymerization of ethylene at different temperatures and Al:Zr ratios, and also in the co-polymerization of ethylene and 1-octene, observing modest co-monomer incorporations. In addition, the cytotoxic activity of 5 was tested against tumour cell lines 8505C anaplastic thyroid cancer, A253 head and neck tumour, A549 lung carcinoma, A2780 ovarian cancer and DLD-1 colon carcinoma. Complex 5 showed the best cytotoxic activity on A2780 ovarian cancer (IC50 value of 36.8 ± 5.9 μM). This represents the highest reported cytotoxic activity of a zirconocene complex on A2780 ovarian cancer. In addition, the cytotoxic activities of 5, have been compared with those obtained using cisplatin.