Large equatorial ligand effects on C-H bond activation by nonheme iron(IV)-oxo complexes.
In this article, we present density functional theory (DFT) calculations on the iron(IV)-oxo catalyzed methane C-H activation reactions for complexes in which the Fe(IV)═O core is surrounded by five negatively charged ligands. We found that it follows a hybrid pathway that mixes features of the classical σ- and π-pathways in quintet surfaces. These calculations show that the Fe-O-H arrangement in this hybrid pathway is bent in sharp contrast to the collinear character as observed for the classical quintet σ-pathways before. The calculations have also shown that it is the equatorial ligands that play key roles in tuning the reactivity of Fe(IV)═O complexes. The strong π-donating equatorial ligands employed in the current study cause a weak π(FeO) bond and thereby shift the electronic accepting orbitals (EAO) from the vertically orientated O pz orbital to the horizontally orientated O px. In addition, all the equatorial ligands are small in size and would therefore be expected have small steric effects upon substrate horizontal approaching. Therefore, for the small and strong π-donating equatorial ligands, the collinear Fe-O-H arrangement is not the best choice for the quintet reactivity. This study adds new element to iron(IV)-oxo catalyzed C-H bond activation reactions.
State Key Lab of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University , Liutiao Road 2, Changchun 130023, People's Republic of China.
Xiaoli
X
Sun
Caiyun
C
Geng
Ruiping
R
Huo
Ulf
U
Ryde
Yuxiang
Y
Bu
Jilai
J
Li
D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D008697:Methane / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009570:Nitriles / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D011789:Quantum Theory
D008024:Ligands; D009570:Nitriles; C066317:ferryl iron; D002244:Carbon; D006859:Hydrogen; D007501:Iron; D008697:Methane; D010100:Oxygen