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

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 (SDFe/SDO), the charge carried by O atom (Q(O)), and the isotropic fermi contact couplings of O atom (IFCCO) in the Fe=O part, thereby influencing the reactivity of the catalyst. The IC-modification that increases the SDO, Q(O), and IFCCO or decreases the SDFe can make the catalyst more powerful. The order of the correlation between the structure parameters and reactivity is SDO > Q(O) > SDFe approximate to IFCCO > LUMOC-HOMOR >> LUMOC-HOMOC approximate to 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 PF6- > AlCl4- > BF4- > AsF6- > SbF6- > AlF4- > CF3CO2- > CF3SO3- > NO3- > 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. (C) 2010 Elsevier Inc. All rights reserved.