Oxidation of olefins catalyzed by Iron (III) complexes of bis-benzimidazolyl diamide ligands

• Published in: Journal of molecular structure Vol. 1011; pp. 166 - 171
• Main Authors: Ahuja, Gauri, Kumar, Ravinder, Mathur, Pavan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 14.03.2012
• Subjects: Bis-benzimidazole diamide; chlorine; EPR; GC–MS; iron; Iron (III); isomers; Mössbauer; nitrates; Olefin oxidation; oxidation; oxygen; spectroscopy; stoichiometry; temperature; Mössbauer; GC–MS; Iron (III); Bis-benzimidazole diamide; Olefin oxidation; EPR
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2011.12.047

► A new bis-benzimidazole diamide tetradentate ligand (L) has been synthesized. ► Iron (III) complexes of L have been characterized by EPR, CV and Mössbauer analysis. ► Mössbauer and EPR spectroscopy confirms them to be high spin distorted Iron (III) octahedral complexes. ► Catalytic oxidation of olefins using [Fe(b-GBSA)Cl2]Cl and TBHP has been carried out. Iron (III) complexes of bis-benzimidazole based diamide ligands N,N′-bis(1-butyl-benzimidazol-2-yl-methyl)-hexane-1,6-dicarboxamide (L1=b-GBSA) and N,N′-bis(benzimidazol-2-yl-methyl)-benzene-1,4-dicarboxamide (L2=p-GBBA) have been synthesized. These analyze for the stoichiometry [Fe(L)X2]X where (X=Cl− and NO3-). Complexes have been characterized by elemental analysis, UV–Visible, IR, Cyclic Voltammetry, conductance measurements, EPR, Mössbauer, Magnetic susceptibility studies. Isomer shift values (δ) lie in the range of 0.29–0.36mm/s and Quadrupole shift values (ΔEq) lie in the range of 0.73–0.81mm/s. Mössbauer spectroscopy confirms them to be high spin Iron (III) complexes with distorted octahedral geometry, a result which is also confirmed by low temperature EPR spectroscopy. Cyclic voltammograms have been obtained for the Iron (III) complexes. E1/2 values are quite cathodic. The magnetic moment values are found to be in the range for high spin Iron (III) complexes. The oxidation of electron deficient olefins has been studied using [Fe(b-GBSA)Cl2]Cl and [Fe(p-GBBA)Cl2]Cl as a catalyst and TBHP as an alternate source of oxygen. Products have been characterized by GCMS analysis.