| Autor: |
Jacques Rozière, Deborah J. Jones, Lorraine E. Aleandri, Sigurd Becke, Borislav Bogdanović |
| Rok vydání: |
1994 |
| Předmět: |
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| Zdroj: |
Journal of Organometallic Chemistry. 472:97-112 |
| ISSN: |
0022-328X |
| DOI: |
10.1016/0022-328x(94)80197-5 |
| Popis: |
The complex [TiCl3(THF)3] reacts with catalytically-prepared solid magnesium hydride (MgH2★) or dissolved magnesium hydride (MgH2′) with evolution of hydrogen to give a highly reactive titanium hydride, [HTiCl(THF)∼0.5]x (1). The well-known low valent titanium species, obtained by reduction of TiCl3 with LiAlH4, utilized in the McMurry reaction, has been shown to be 1. An X-ray absorption spectroscopy study (EXAFS) of 1 reveals that the Ti absorber is surrounded by O (from THF) and Cl atoms plus two types of Ti neighbors. Possible structural models for 1 compatible with the EXAFS results are proposed. Complex 1 is an active reagent for the coupling reaction of benzophenone to give tetraphenylethene. During the reaction hydrogen is liberated and the inorganic side product has been shown to be titanium(III) oxychloride; thus the McMurry reaction employing 1 as the reagent can be described by Ph2CO+1THF or→toluen 0.5 PPh2CCPh2 + 0.5H2↑ + [TiOCl(THF)x]. On the basis of these results, a new interpretation of the mechanism for the McMurry reaction is presented. Complex 1 also undergoes a number of carbenoid type reactions, which may proceed via a “titanium carbenoid” intermediate 9a–c. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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