Synthesis of C7,C7‘-Ethylene- and C7,C7‘-Methylene-Bridged C 2-Symmetric Bis(indenyl)zirconium and -titanium Dichlorides

• Published in: Organometallics 1998-08, Vol.17 (18), p.3900-3907
• Main Authors: Halterman, Ronald L, Combs, David, Khan, Masood A
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om971050o

We have prepared several novel metallocenes bridged at the 7,7‘-positions of the indenyl moiety. The new metallocenes include the methylene-bridged [dl-bis(4,6-dimethylinden-7-yl)methylidene]titanium dichloride (20) and [dl-bis(4,6-dimethylinden-7-yl)methylidene]zirconium dichloride (21), which were prepared from m-xylene. In addition, [dl-1,2-bis(4-methylinden-7-yl)ethylidene]- and [dl-1,2-bis(4-isopropylinden-7-yl)ethylidene]zirconium dichlorides ( dl- 12a and dl- 12b) and [dl-1,2-bis(4-isopropylinden-7-yl)ethylidene]titanium dichloride ( dl -13) were synthesized from p-cymene and p-xylene, respectively. The structures of metallocene dichlorides dl- 12a, dl- 12b, and dl- 13 were determined by X-ray crystallography and found to have C 1 symmetry in the solid state but in solution exhibit C 2 symmetry, as seen in the 1H NMR spectra at room temperature.