Hernández J. Guadalupe, J. Narayanan, T. Pandiyan
Mar 15, 2011
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Journal
Journal of Molecular Structure
Abstract
Abstract Ruthenium complex of N,N ′ - bis(benzimidazol-2-yl-ethyl)ethylenediamine (L 1 ) was prepared and characterized by analytical methods. Structural and spectral properties of N,N ′ - bis(benzimidazol-2-yl-ethyl)ethylenediamine (L 1 ), its dianionic structure (L 2 ), and their complexes such as [RuL 1 Cl(PPh 3 )] + and [RuL 2 Cl(PPh 3 )] + were studied by DFT. In the structures, the ruthenium ion is positioned in an equatorial plane formed by amine, benzimidazole nitrogens in a distorted octahedral geometry, and chloride and triphenylphospine are axially coordinated. Furthermore, the molecular orbital of [Ru(L)Cl(PPh 3 )]Cl (L = L 1 or L 2 ) proves that the HOMOs are localized over the benzimidazole and amine moieties, favoring a strong bond with the metal. DFT-TDDFT was used to analyze the molecular orbitals contribution to MLCT bands that were observed in the visible region; interestingly, the calculated spectrum of [RuL 1 Cl(PPh 3 )] + qualitatively agrees only with high energy bands (465 nm and 350 nm) of the experimental spectrum, and other visible bands (≈580 and ≈790 nm) observed in the experimental spectrum coincide with the TD-DFT of [RuL 2 (PPh 3 )Cl] + . However, electrochemical studies show existence of only [RuL 1 Cl(PPh 3 )] + in the solution.