Assessing the impact of inductive electronic effects on the metrical parameters and reactivity of a series of ferrous complexes

Reported are four iron(II) complexes with N-benzyl-N,N′-bis(2-pyridylmethyl)-1,2-ethanediamine (LH) and three electronically modified derivatives: N-(4-methoxy)benzyl-N,N′-bis(2-pyridylmethyl)-1,2-ethanediamine (LOMe), N-(4-chloro)benzyl-N,N′-bis(2-pyridylmethyl)-1,2-ethanediamine (LCl), and N-(4-nitro)benzyl-N,N  ′-bis(2-pyridylmethyl)-1,2-ethanediamine (LNO2LNO2). The four ligands react with FeCl2 to form a series of mononuclear species with the general formula [Fe(LR)Cl2]. The cis-α conformation of the ligand places the amine N-donors trans to the Fe–Cl bonds. The identity of the 4-benzyl substituent has profound influences on the lengths of the iron-ligand bonds, the optical spectra, and the redox activities of the [Fe(LR)Cl2] compounds.

Graphical abstractFour iron(II) complexes have been prepared from electronically modified derivatives of the polydentate ligand N-benzyl-N,N′-bis(2-pyridylmethyl)-1,2-ethanediamine. The substituents on the benzyl groups modulate the iron-ligand bond distances, significantly weakening the Fe–Cl bond trans to itself, as well as the Fe(III/II) reduction potential.Figure optionsDownload full-size imageDownload as PowerPoint slide