Synthesis, molecular structure, and racemate-meso interconversion for rac-(Me{sub 2}Si){sub 2}{l_brace}{eta}{sup 5}-C{sub 5}H-3-(CHMe{sub 2})-5-Me{r_brace}{sub 2}MCl{sub 2} (M = Ti and Zr)
- Japan Polyolefins Co., Ltd., Oita (Japan)
- California Inst. of Tech., Pasadena, CA (United States). Arnold and Mabel Beckman Labs. of Chemical Synthesis
Doubly [SiMe{sub 2}]-bridged group IV metallocenes, rac-(Me{sub 2}Si){sub 2}({eta}{sup 5}-C{sub 5}H-3-(CHMe{sub 2})-5-Me){sub 2}-MCl{sub 2} (M = Ti, Zr), have been synthesized, and a crystal structure of rac-(Me{sub 2}Si){sub 2}{l_brace}{eta}{sup 5}-C{sub 5}H-3-(CHMe{sub 2})-5-Me{r_brace}{sub 2}TiCl{sub 2} has been determined by X-ray diffraction methods. Racemate-meso interchange occurs in benzene solution just above room temperature, affording an approximately 1:1 mixture of rac-(Me{sub 2}Si){sub 2}{l_brace}{eta}{sup 5}-C{sub 5}H-3-(CHMe{sub 2})-5-Me{r_brace}{sub 2}TiCl{sub 2} and meso-(Me{sub 2}Si){sub 2}{l_brace}{eta}{sup 5}-C{sub 5}H-3-(CHMe{sub 2})-5-Me{r_brace}{sub 2}TiCl{sub 2}. Measurements of the kinetics of the approach to equilibrium reveal {Delta}H{sup {double_dagger}} = 18(1) kcal{center_dot}mol{sup {minus}1} and {Delta}S{sup {double_dagger}} = {minus}7(2) eu. The corresponding zirconium compound is configurationally stable.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 315981
- Journal Information:
- Organometallics, Vol. 17, Issue 25; Other Information: PBD: 7 Dec 1998
- Country of Publication:
- United States
- Language:
- English
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