The Influence of the Metal Spin State in the Iron-Catalyzed Alkene Isomerization Reaction Studied with Ultrafast Infrared Spectroscopy
详细信息 查看全文
- 作者：Elizabeth A. Glascoe ; Karma R. Sawyer ; Jennifer E. Shanoski ; Charles B. Harris
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：June 28, 2007
- 年：2007
- 卷：111
- 期：25
- 页码：8789 - 8795
- 全文大小：316K
- 年卷期：v.111,no.25(June 28, 2007)
- ISSN：1932-7455
文摘
The process of iron- and ruthenium-assisted alkene isomerization is investigated with ultrafast time-resolvedinfrared spectroscopy under ambient conditions. M(CO)4(
2-1,4-PD) (M = Ru, Fe; PD = pentadiene) wasirradiated with a 100 femtosecond pulse of 266 nm light in a solution of cyclohexane, and a single carbonylwas photodissociated. When M = Ru, experimental results indicate that both Ru(CO)3(4-1,4-PD) and HRu(CO)3(3-allyl) form within a few picoseconds, and their populations do not change significantly out to 800ps. When M = Fe, the coordinatively unsaturated triplet metal complex, 3Fe(CO)3(2-1,4PD), was observedto form rapidly and rearranged to HFe(CO)3(3-allyl) at a rate of (4.8 ± 0.2) × 108 s-1. Surprisingly, thetriplet iron complex did not coordinate the free alkene on the pentadiene ligand on the ultrafast time scale.The difference in reactivity between the iron- and the ruthenium-assisted alkene isomerization is due todifferences in spin state of the coordinatively unsaturated metal center.
2-1,4-PD) (M = Ru, Fe; PD = pentadiene) wasirradiated with a 100 femtosecond pulse of 266 nm light in a solution of cyclohexane, and a single carbonylwas photodissociated. When M = Ru, experimental results indicate that both Ru(CO)3(4-1,4-PD) and HRu(CO)3(3-allyl) form within a few picoseconds, and their populations do not change significantly out to 800ps. When M = Fe, the coordinatively unsaturated triplet metal complex, 3Fe(CO)3(2-1,4PD), was observedto form rapidly and rearranged to HFe(CO)3(3-allyl) at a rate of (4.8 ± 0.2) × 108 s-1. Surprisingly, thetriplet iron complex did not coordinate the free alkene on the pentadiene ligand on the ultrafast time scale.The difference in reactivity between the iron- and the ruthenium-assisted alkene isomerization is due todifferences in spin state of the coordinatively unsaturated metal center.