Reactions of Aldehydes with Carbon Dioxide at Nickel(0) Centers. A Detailed Kinetic Analysis
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- 作者：Christian Geyer ; Eckhard Dinjus ; and Siegfried Schindler
- 刊名：Organometallics
- 出版年：1998
- 出版时间：January 5, 1998
- 年：1998
- 卷：17
- 期：1
- 页码：98 - 103
- 全文大小：223K
- 年卷期：v.17,no.1(January 5, 1998)
- ISSN：1520-6041
文摘
The reactions of the nickel(0) complex [Ni(bipy)(COD)](COD = cyclooctadiene, bipy =2,2'-bipyridine) with benzaldehyde, propionaldehyde, and carbondioxide/propionaldehydewere investigated. A detailed kinetic analysis revealed that[Ni(bipy)(COD)] reacts reversiblewith aldehydes and activation parameters for the forward and backreactions were calculatedfrom a temperature dependence study: forward reaction (benzaldehyde)
H
= 47.8 ± 0.4kJ/mol, S = -47 ± 1 J/(mol K); backreaction (COD) H = 45 ± 6 kJ/mol,S = -61 ±19 J/(mol K) and forward reaction (propionaldehyde)H = 55 ± 3 kJ/mol,S = -58 ± 9.0J/(mol K); back reaction (COD) H = 39± 0.5 kJ/mol, S = -58 ± 2 J/(molK). It couldbe shown that carbon dioxide did not react with [Ni(bipy)(COD)]directly but with the nickelpropionaldehyde complex to form a five-membered cyclic nickel complex.The reactionproceeded according to an associative mechanism, during which thecarbon dioxide wasinserted into a Ni-O bond by an oxidative coupling step. Theactivation parameters forthis process were H = 43 ± 6 kJ/moland S = -129 ± 19 J/(mol K).
H = 47.8 ± 0.4kJ/mol, S = -47 ± 1 J/(mol K); backreaction (COD) H = 45 ± 6 kJ/mol,S = -61 ±19 J/(mol K) and forward reaction (propionaldehyde)H = 55 ± 3 kJ/mol,S = -58 ± 9.0J/(mol K); back reaction (COD) H = 39± 0.5 kJ/mol, S = -58 ± 2 J/(molK). It couldbe shown that carbon dioxide did not react with [Ni(bipy)(COD)]directly but with the nickelpropionaldehyde complex to form a five-membered cyclic nickel complex.The reactionproceeded according to an associative mechanism, during which thecarbon dioxide wasinserted into a Ni-O bond by an oxidative coupling step. Theactivation parameters forthis process were H = 43 ± 6 kJ/moland S = -129 ± 19 J/(mol K).