[CH2:1]([Li])[CH2:2][CH2:3][CH3:4].[CH2:6]1[C:14]2[C:9](=[CH:10][CH:11]=[CH:12][CH:13]=2)[CH:8]=[CH:7]1.[C:15]1(C)C=[CH:19][CH:18]=[CH:17][CH:16]=1.[CH3:22][Si:23]([CH3:26])(Cl)Cl>CCCCCC.O.C1COCC1>[CH3:22][Si:23]([CH3:26])([CH:6]1[C:14]2[C:9](=[CH:10][CH:11]=[CH:12][CH:13]=2)[CH:8]=[CH:7]1)[CH:1]1[C:19]2[C:4](=[CH:15][CH:16]=[CH:17][CH:18]=2)[CH:3]=[CH:2]1
Technical-grade indene (90%) was first filtered through aluminum oxide (superactive) for crude purification and drying. 160 ml (400 mmol) of a 2.5M butyllithium solution in hexane were added at room temperature to a solution of 57 ml (446 mmol) of the indene (91-92%) in a solvent mixture comprising 430 ml of toluene and 32 ml of THF, and the mixture was refluxed for 1 hour. The mixture was cooled to room temperature, and 24.2 ml (200 mmol) of dimethyldichlorosilane were added to the orange suspension. The mixture was refluxed for 5 hours and subsequently poured into water. The mixture was extracted several times with ethyl acetate. The combined organic phases were dried over sodium sulfate and freed from solvent under reduced pressure. The residue which remained was dried for several hours in an oil-pump vacuum at 50° C. 56 g (97%) of the ligand system 1 were obtained as a brownish oil (isomer mixture, 2 diastereomers, 1 double-bond isomer). The isomer mixture can be used directly for the preparation of the metallocene.
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