Theoretical insights of iron(II)-carbene complexes Cp(CO)(L)FeCHR, LÂ =Â CO, PMe3

Density functional theory has been used to study the geometries, properties and reactivity of the iron(II)-carbene complexes Cp(CO)(L)FeCHR, L = CO, PMe3, R = Me, OMe, ph, CO2Me. Calculation results confirm that the iron-carbene complexes have two types of geometries: the Fe-C(carbene) bonds of the iron-carbene complexes A, D, E, and H (R = Me, CO2Me) show a strong double-bonded character, and thus the Fe-C(carbene) bonds of the complexes B, C, F, and G (R = OMe, ph) show a strong single-bonded character. The Fe-C(carbene) bonds, and the iron and carbon atoms of Fe-C(carbene) bonds are the reactive center for the iron-carbene complexes. The geometry, electronic structure, and frontier orbitals (HOMO and LUMO) are discussed in detail.