Abstract
A reaction mechanism for the hydrogenation of CO2 to formate catalyzed by an Ir(III)pincer trihydride complex has been investigated with density functional theory calculations. Two routes for the formation of formate were considered: (I) the insertion of CO2 into the IrH bond with the assistance of the metal center, and (II) the direct addition of hydride to CO2 via nucleophilic attack. Route II is energetically more favorable than route I. Molecular orbital and natural bond orbital analyses showed that this trihydride complex consists of two kinds of hydrides with distinct IrH bond properties, and the hydride in the plane vertical to the pyridine moiety is highly active. The whole catalytic cycle for CO2 hydrogenation to formate is exothermic by 30.3 kcal mol1, and the rate-limiting step is the regeneration of the active complex, which involves a barrier of 15.6 kcalmol1. The theoretical results are in good agreement with and give a reasonable explanation to the experimental observations. Moreover, the results imply that the type of a metalhydride bond might determine which route the CO2 insertion takes, route I or route II.
| Original language | English |
|---|---|
| Pages (from-to) | 1039-1048 |
| Number of pages | 10 |
| Journal | Bulletin of the Chemical Society of Japan |
| Volume | 84 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - Oct 1 2011 |
Fingerprint
All Science Journal Classification (ASJC) codes
- Chemistry(all)
Cite this
Catalytic hydrogenation of carbon dioxide with a highly active hydride on Ir(III)pincer complex : Mechanism for CO2 insertion and nature of metalhydride bond. / Li, Jun; Yoshizawa, Kazunari.
In: Bulletin of the Chemical Society of Japan, Vol. 84, No. 10, 01.10.2011, p. 1039-1048.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Catalytic hydrogenation of carbon dioxide with a highly active hydride on Ir(III)pincer complex
T2 - Mechanism for CO2 insertion and nature of metalhydride bond
AU - Li, Jun
AU - Yoshizawa, Kazunari
PY - 2011/10/1
Y1 - 2011/10/1
N2 - A reaction mechanism for the hydrogenation of CO2 to formate catalyzed by an Ir(III)pincer trihydride complex has been investigated with density functional theory calculations. Two routes for the formation of formate were considered: (I) the insertion of CO2 into the IrH bond with the assistance of the metal center, and (II) the direct addition of hydride to CO2 via nucleophilic attack. Route II is energetically more favorable than route I. Molecular orbital and natural bond orbital analyses showed that this trihydride complex consists of two kinds of hydrides with distinct IrH bond properties, and the hydride in the plane vertical to the pyridine moiety is highly active. The whole catalytic cycle for CO2 hydrogenation to formate is exothermic by 30.3 kcal mol1, and the rate-limiting step is the regeneration of the active complex, which involves a barrier of 15.6 kcalmol1. The theoretical results are in good agreement with and give a reasonable explanation to the experimental observations. Moreover, the results imply that the type of a metalhydride bond might determine which route the CO2 insertion takes, route I or route II.
AB - A reaction mechanism for the hydrogenation of CO2 to formate catalyzed by an Ir(III)pincer trihydride complex has been investigated with density functional theory calculations. Two routes for the formation of formate were considered: (I) the insertion of CO2 into the IrH bond with the assistance of the metal center, and (II) the direct addition of hydride to CO2 via nucleophilic attack. Route II is energetically more favorable than route I. Molecular orbital and natural bond orbital analyses showed that this trihydride complex consists of two kinds of hydrides with distinct IrH bond properties, and the hydride in the plane vertical to the pyridine moiety is highly active. The whole catalytic cycle for CO2 hydrogenation to formate is exothermic by 30.3 kcal mol1, and the rate-limiting step is the regeneration of the active complex, which involves a barrier of 15.6 kcalmol1. The theoretical results are in good agreement with and give a reasonable explanation to the experimental observations. Moreover, the results imply that the type of a metalhydride bond might determine which route the CO2 insertion takes, route I or route II.
UR - http://www.scopus.com/inward/record.url?scp=80054101896&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=80054101896&partnerID=8YFLogxK
U2 - 10.1246/bcsj.20110128
DO - 10.1246/bcsj.20110128
M3 - Article
AN - SCOPUS:80054101896
VL - 84
SP - 1039
EP - 1048
JO - Bulletin of the Chemical Society of Japan
JF - Bulletin of the Chemical Society of Japan
SN - 0009-2673
IS - 10
ER -