Alkyne Exchange Reactions of Silylalkyne Complexes of Tantalum: Mechanistic Investigation and Its Application in the Preparation of New Tantalum Complexes Having Functional Alkynes (PhC
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- 作者：Toshiyuki Oshiki ; Atsushi Yamada ; Kimio Kawai ; Hirotaka Arimitsu ; Kazuhiko Takai
- 刊名：Organometallics
- 出版年：2007
- 出版时间：January 1, 2007
- 年：2007
- 卷：26
- 期：1
- 页码：173 - 182
- 全文大小：168K
- 年卷期：v.26,no.1(January 1, 2007)
- ISSN：1520-6041
文摘
Silylalkyne complexes of tantalum with the general formula TaCl3(R1C
CR2)L2 (1, R1 = R2 = SiMe3,L2 = DME; 2, R1 = SiMe3, R2 = Me, L2 = DME; 6, R1 = R2 = SiMe3, L = py; 7, R1 = SiMe3, R2 =Me, L = py) reacted with an internal alkyne to give corresponding alkyne complexes via an alkyneexchange reaction. These silylalkyne complexes were newly prepared and structurally characterized. Kineticmeasurements revealed that the rates of the exchange reactions of the DME complexes 1 and 2 werefirst-order dependent on the concentration of the complex and the reaction proceeded via dissociativepathway. The exchange reaction rates of the bis(pyridine) complexes 6 and 7 were slower. In contrast tothe DME complexes, the exchange reaction of 6 proceeded via an associative interchange pathway, andthe exchange mechanism for 7 was an associative pathway. During the exchange, two pyridine ligandscoordinated strongly to the tantalum center and the intermediate is proposed to be a bis(alkyne) complex.New tantalum complexes having functional alkynes (PhCCR (R = COOMe, CONMe2)) were preparedfrom the silylalkyne complexes via the alkyne exchange reaction.
CR2)L2 (1, R1 = R2 = SiMe3,L2 = DME; 2, R1 = SiMe3, R2 = Me, L2 = DME; 6, R1 = R2 = SiMe3, L = py; 7, R1 = SiMe3, R2 =Me, L = py) reacted with an internal alkyne to give corresponding alkyne complexes via an alkyneexchange reaction. These silylalkyne complexes were newly prepared and structurally characterized. Kineticmeasurements revealed that the rates of the exchange reactions of the DME complexes 1 and 2 werefirst-order dependent on the concentration of the complex and the reaction proceeded via dissociativepathway. The exchange reaction rates of the bis(pyridine) complexes 6 and 7 were slower. In contrast tothe DME complexes, the exchange reaction of 6 proceeded via an associative interchange pathway, andthe exchange mechanism for 7 was an associative pathway. During the exchange, two pyridine ligandscoordinated strongly to the tantalum center and the intermediate is proposed to be a bis(alkyne) complex.New tantalum complexes having functional alkynes (PhCCR (R = COOMe, CONMe2)) were preparedfrom the silylalkyne complexes via the alkyne exchange reaction.