Synthesis and characterization of some novel iron complexes with an asymmetric N-alkyl,N’-aryl-β-diketamine ligand

Abstract

An asymmetric N-alkyl,N′-aryl-β-diketiminate ligand L (L = 2-((S)-(-)-1- phenylethylimino)-4- (2,6-diisopropylphenylimido)pentane) was prepared. Synthesis of chloro-bridged dimer [LFe(μ-Cl)]2 is presented here. Upon reduction in the presence of ciscyclooctadiene, rare example of low-valent complex LFe(cod) was obtained. All metal complexes were fully characterized by 1H NMR spectroscopy, X-ray crystallography and elemental analysis. Crystallographic and IR-spectroscopic results clearly reflect that the sterically less hindered and strong electron donating properties of the asymmetric ligand L than the 2,4-bis(2,6-diisopropylphenylimido)pentane symmetric ligand, which is commonly used in the metal complexes that are used in small molecular activation and catalysis. Reactivity and kinetic studies of LFe(cod) towards small molecules, S8 and Se8, were investigated and the products 1 and 2 were obtained. Electrochemical analysis of the [LFe(μ-S)]2 suggests there are two reversible redox events while [LFe(μ-Se)]2 shows only one reversible redox event. Chemical titrations monitored by using UV-Visible spectroscopy for [LFe(μ-S)]2 and [LFe(μ- Se)]2 complexes agreed with the results of electrochemical analysis.