title: Synthesis, structure, spectra and redox activities of model compounds for methanogenic bacteria.
abstract: Synthetically accessible benzimidazoles have been synthesized and the benzimidazole ligands were complexed with nickel(II) nitrate. A nickel(II) complex of N,N'-bis(benzimidazole-2-ylethyl)ethylenediamine was crystallized in single-crystal form and the structure was investigated by X-ray crystallography. The structure of the complex is bicapped axial coordinated octahedral. Ni(bbes)(2+)(2)[bbes=bis(benzimidazole-2-ylethyl)sulfide] exhibits broad low energy bands in electronic spectra and high redox potential in cyclic voltammetry (CV) rather than Ni(enbzim)(2+) [enbzim =N,N'-bis(benzimidazol-2-ylethyl)ethylenediamine], where high energy well separated bands were observed in the visible region and a more negative redox potential was detected in CV. Experimental studies show that an increasing amount of pi-orbital interaction with the Ni(2+)ion, irrespective of chelate ring may favour the higher redox potential. The higher redox potential of methanogenic bacterial [Ni(II)/Ni(I)] than nickel compounds is one of the main factors for the degradation of organic biodegradable compounds and the further transformation to methane.
authors.affiliation: Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, 04510, México D.F., México.
authors.forename: T
authors.initials: T
authors.lastname: Pandiyan
authors.forename: C D
authors.initials: CD
authors.lastname: De Bazúa
authors.forename: M
authors.initials: M
authors.lastname: Soriano-Garcia