The deceptively simple thermolysis of trivalent permethyltitanocene derivatives ({eta}{sup 5}-C{sub 5}Me{sub 5}){sub 2} TiR. Formation of a tetramethylfulvene titanium compound ({eta}{sup 6}-C{sub 5}Me{sub 4}CH{sub 2})({eta}{sup 5}-C{sub 5}Me{sub 5})Ti and RH, catalyzed by permethyltitanocene hydride, ({eta}-C{sub 5}Me{sub 5}){sub 2}TiH
- Univ. of Groningen (Netherlands)
The complexes Cp{sup *}{sub 2}TiR (Cp{sup *} = {eta}{sup 5}-C{sub 5}Me{sub 5}; R=- Me, Et, n-Pr, C{sub 2}H{sub 3}, CH{sub 2}CMe{sub 3}, Ph) undergo thermolysis to yield the fulvene complex Cp{sup *}FvTi (Fv = {eta}{sup 6}-C{sub 5}Me{sub 4}CH{sub 2}) and RH. Kinetic measurements and deuterium labeling studies show that the decomposition is catalyzed by Cp{sup *}{sub 2}TiH, which is formed either by {Beta}-hydrogen elimination from a titanium alkyl Cp{sup *}{sub 2}TiCH{sub 2}CH{sub 2}R at low temperature or by hydrogenolysis of Cp{sup *}{sub 2}TiR or Cp{sup *}FvTi, using dihydrogen eliminated from Cp{sup *}FvTi at elevated temperatures. Permethyltitanocene is not an intermediate. The rate of the catalyzed decomposition of Cp{sup *}{sub 2}TiCH{sub 2}CMe{sub 3} is linear in [Cp{sup *}{sub 2}TiH]. For Cp{sup *}{sub 2}TiMe it is proportional to [Cp{sup *}{sub 2}TiH] and [Cp{sup *}{sub 2}TiMe] and inversely proportional to the starting concentration of Cp{sup *}{sub 2}TiMe. This is explained in a kinetic scheme, where H{sub 2}, eliminated form Cp{sup *}{sub 2}TiH to give Cp{sup *}FvTi, reacts with Cp{sup *}{sub 2}TiR to regenerate Cp{sup *}{sub 2}TiH and liberate RH. The model is supported by the reaction of (Cp{sup *}-d{sub 15}){sub 2}TiD and Cp{sup *}{sub 2}TiCH{sub 2}CMe{sub 3} yielding Cp{sup *}{sub 2}TiD and (Cp{sup *}FvTi-d{sub 29}). 26 refs., 6 figs., 4 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 274285
- Journal Information:
- Journal of the American Chemical Society, Vol. 114, Issue 9; Other Information: PBD: 22 Apr 1992
- Country of Publication:
- United States
- Language:
- English
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