Theoretical study on the structure–reactivity relationships of acetylacetone–Fe catalyst modified by ionic compound in C–H activation reaction

• Published in: Journal of catalysis 2010-06, Vol.272 (2), p.320-332
• Main Authors: Hu, Xingbang, Sun, Yong, Mao, Jianyong, Li, Haoran
• Format: Article
• Language: English
• Subjects: Acetylacetone–Fe; Anion; Catalysis; Cation; Chemical reactions; Chemistry; C–H activation; Exact sciences and technology; General and physical chemistry; Ionic compound; Iron catalysts; Methane; Structure–reactivity relationship; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2010.04.016

The structure–reactivity relationships of 41 different acetylacetone–Fe catalysts were summarized. Some effective modification methods to enhance the reactivity were proposed. The reactivity of acetylacetone–Fe can be tuned by introducing an ionic compound (IC) group onto the ligand in the investigation into 41 different catalysts. This IC-modification alters the spin density carried by Fe/O atoms (SD Fe/SD O), the charge carried by O atom ( Q O), and the isotropic fermi contact couplings of O atom (IFCC O) in the Fe O part, thereby influencing the reactivity of the catalyst. The IC-modification that increases the SD O, Q O, and IFCC O or decreases the SD Fe can make the catalyst more powerful. The order of the correlation between the structure parameters and reactivity is SD O > Q O > SD Fe ≈ IFCC O > LUMO C–HOMO R ≫ LUMO C–HOMO C ≈ Q Fe. Changing the anion of the IC-catalyst is a more effective way to increase the reactivity compared with changing the cation, and the order is PF 6 - > AlCl 4 - > BF 4 - > AsF 6 - > SbF 6 - > AlF 4 - > CF 3 CO 2 - > CF 3 SO 3 - > NO 3 - > Cl - . Long distance between the IC part and the catalytic active center however weakens the influence induced by the IC-modification. These structure–reactivity relationships are expected to be used in catalyst design.