Synthesis and Characterization of Carboxylate-Rich Non-Heme Iron(III) Complexes as Potential Catalysts for Alkene Oxidation

Inspired by biological systems, the field of development of O₂ or H₂O₂ activating catalytic oxidations of hydrocarbons has been actively pursued for several years. Although several iron-based complexes with catalytic activity towards oxidation of hydrocarbons have been reported in the literature, selectivity and efficiency remain largely unresolved issues. In an attempt to develop model catalysts that would promote O₂ or H₂O₂ as terminal oxidants, a dinucleating ligand N,N’-Bis[2-carboxybenzomethyl]-N,N’-Bis[carboxymethyl]-1,3-diaminopropan-2-ol, H₅ccdp, several carboxylate-based exogenous ligands of iron(III) complexes have been synthesized and fully characterized. Under different reaction conditions six new carboxylate-rich iron(III) complexes, K₂[1-(NPTH)₂], K₂[1-(PPA)₂], Na₂[1-(ACA)₂], K₂[1-(ACA)₂], Na₂[1-(DTBA)₂], and [2-(OCH₃)₂] have been synthesized. In these reactions, H₅ccdp ligand has shown considerable flexibility in coordinating with iron(III) ions and the carboxylate-based exogenous ligands to produce the tetra-iron(III) complexes. The complexes have been characterized using UV-Vis, IR, magnetic studies and X-ray crystallography techniques. Furthermore, preliminary investigation has been carried out to show the activity of some of the metal complexes towards an oxidation of cyclohexene using H₂O₂ are terminal oxidants.