Kinetic Analysis of the Reaction of Isoprene with Carbon Dioxide and a Nickel(0) Complex
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- 作者：Christian Geyer and Siegfried Schindler
- 刊名：Organometallics
- 出版年：1998
- 出版时间：September 28, 1998
- 年：1998
- 卷：17
- 期：20
- 页码：4400 - 4405
- 全文大小：108K
- 年卷期：v.17,no.20(September 28, 1998)
- ISSN：1520-6041
文摘
The reactions of the nickel(0) complex [Ni(bipy)(COD)] (COD = cyclooctadiene, bipy =2,2'-bipyridine) with isoprene (ip) in the absence and presence of carbon dioxide wereinvestigated. A detailed kinetic analysis revealed that [Ni(bipy)(COD)] reacts reversiblewith ip and activation parameters for the forward and back reactions were calculated froma temperature dependence study to be the following: 
H
= 35 ± 5 kJ/mol, S = -79 ± 16J/(mol K) forward reaction (ip dependence); H = 58 ± 2 kJ/mol, S = 58 ± 10 J/(mol K)back-reaction (COD dependence at low temperatures). It could be shown that CO2 did notreact with [Ni(bipy)(COD)] directly but with the nickel ip complex to form the product complex((3-5-
3)-3-methyl-3-pentenylato)nickel bipyridine. The reaction proceeded in an associativeway, during which CO2 was inserted into a Ni-C bond in an oxidative coupling step. Theactivation parameters were calculated to be H = 25 ± 7 kJ/mol and S = - 184 ± 24J/(mol K).
H = 35 ± 5 kJ/mol, S = -79 ± 16J/(mol K) forward reaction (ip dependence); H = 58 ± 2 kJ/mol, S = 58 ± 10 J/(mol K)back-reaction (COD dependence at low temperatures). It could be shown that CO2 did notreact with [Ni(bipy)(COD)] directly but with the nickel ip complex to form the product complex((3-5-3)-3-methyl-3-pentenylato)nickel bipyridine. The reaction proceeded in an associativeway, during which CO2 was inserted into a Ni-C bond in an oxidative coupling step. Theactivation parameters were calculated to be H = 25 ± 7 kJ/mol and S = - 184 ± 24J/(mol K).