Metallocene Allyl Reactivity in the Presence of Alkenes Tethered to Cyclopentadienyl Ligands
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- 作者：William J. Evans ; Stosh A. Kozimor ; Jason C. Brady ; Benjamin L. Davis ; Gregory W. Nyce ; Christopher A. Seibel ; Joseph W. Ziller ; and Robert J. Doedens
- 刊名：Organometallics
- 出版年：2005
- 出版时间：May 9, 2005
- 年：2005
- 卷：24
- 期：10
- 页码：2269 - 2278
- 全文大小：223K
- 年卷期：v.24,no.10(May 9, 2005)
- ISSN：1520-6041
文摘
The reactions of the yttrium metallocene allyl complex [(C5Me4)SiMe2(CH2CH=CH2)]2Y(C3H5), 1, with ethylene, trimethylaluminum, and hydrogen have been examined to determinehow the olefins tethered to the cyclopentadienyl ligands interact with these species that aretypically present in olefin polymerizations. Complex 1 was prepared from allylmagnesiumchloride and [(C5Me4)SiMe2(CH2CH=CH2)]2YCl, which can be directly prepared free of solventand alkali metal halide adducts from YCl3(THF)x and [(C5Me4)SiMe2(CH2CH=CH2)]K in THF.1 was characterized by NMR spectroscopy and X-ray crystallography, and the data werecompared to those of three related complexes: the pentamethyl analogue, (C5Me5)2Y(C3H5),2, the ansa analogue, [Me2Si(C5Me4)2]Y(C3H5), 3, and the lutetium complex, (C5Me5)2Lu(C3H5), 4. Although 1 shows no evidence for insertion of the tethered olefins into the Y-(C3H5)bond, comparisons of the synthesis and variable-temperature NMR spectra of 1 with 2-4suggest metal-alkene interaction. Complex 1 polymerizes ethylene and reacts with excessAl2Me6 to generate the allyl-free, tetramethylaluminate-bridged dimer {[(C5Me4)SiMe2(CH2CH=CH2)]2Y[(
-Me)2AlMe2]}2, 5. No involvement of the tethered olefins was observed inconnection with this Y-C(allyl) bond breaking and Y-C(Me) bond making. The tetheredolefins do become involved in the reaction chemistry of 1 in the presence of hydrogen: thetethered olefins of 1 are hydrogenated. A hydride derivative of 1 was not isolated, but 1reacts with H2 in diethyl ether to form the expected hydride decomposition product, theethoxide, {[(C5Me4)SiMe2(CH2CH2CH3)]2Y(OEt)}x, 6. Reaction of 1 with hydrogen in C6D6and with deuterium in C6H6 shows that hydrogenation of the tethered olefin occurs beforeD/H exchange with arenes can occur in this system.
-Me)2AlMe2]}2, 5. No involvement of the tethered olefins was observed inconnection with this Y-C(allyl) bond breaking and Y-C(Me) bond making. The tetheredolefins do become involved in the reaction chemistry of 1 in the presence of hydrogen: thetethered olefins of 1 are hydrogenated. A hydride derivative of 1 was not isolated, but 1reacts with H2 in diethyl ether to form the expected hydride decomposition product, theethoxide, {[(C5Me4)SiMe2(CH2CH2CH3)]2Y(OEt)}x, 6. Reaction of 1 with hydrogen in C6D6and with deuterium in C6H6 shows that hydrogenation of the tethered olefin occurs beforeD/H exchange with arenes can occur in this system.