Theoretical insight of substituent effect in para substituted Fe(CO)4–pyridine complexes

Systematic studies on the substituent effect in para substituted Fe(CO)4–pyridine complexes have been studied on the basis of DFT quantum-chemical calculations. The following substituents were taken into consideration: NO2, CN, CHO, F, H, CH3, OH and NH2. Additionally, the Fe–N and Fe–C bonds were characterized on the basis of Atoms in Molecules topological analysis of electron density. It has been found that the substituents in position 4 of the pyridine ring influence the Fe–N bond of Fe(CO)4–pyridine complex in a systematic manner, as a result of with, the pyridine moiety has a diversified ability of participating in the interaction with the Fe atom of Fe(CO)4 moiety. It has also been found, that the electron withdrawing substituents additionally stabilize the Fe–N bond, whereas the electron donating ones weaken it. The substituent effect mainly affects the p-component of the Fe–N bond..