Semiempirical gas phase study on tautomerizm of 2-hydroxy amino and mercapto benzimidazoles

Açikkalp, Erol; Yıldız, Kübra; Yarlıgan, S.; Öğretır, Cemi̇l

doi:10.1016/s0166-1280(00)00620-5

Cited by 13 publications

(6 citation statements)

References 6 publications

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“…Several studies have shown that BC and BN are thione tautomers in ethanol [11] and dioxane [12] solutions, respectively. Theoretical studies [13] developed on the benzimidazol-2-tione are in concordance with the experimental observation. On the other hand, it has been reported [2] that in solutions of protic or nonprotic solvents of BS, under normal conditions of temperature and pressure, the thione tautomer is the predominant species.…”

Section: Introductionsupporting

confidence: 79%

¹π→¹π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles

Araya

Vargas

Morales

2005

Spectroscopy Letters

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Indoline-2-thione (BC), benzimidazole-2-thione (BN), benzoxazole-2-thione (BO), and benzothiazole-2-thione (BS) define an interesting series of aromatic compounds containing a NCS synthonic unit in a heterocyclic ring of five centers, substituted by atomic centers of the type C, N, O, or S, where the main electronic absorption bands are localized in the spectral range of ultraviolet A or B.The first two singlet electronic transitions of this series, 1 S 0 ! 1 S 1 (n,p Ã ) and 1 S 0 ! 1 S 2 (p,p Ã ), determine the main spectroscopic characteristic of these compounds in order to be used as potential photochemical actinometers of solar ultraviolet radiation. Furthermore, the second electronic transition, localized in the 270-360 nm ultraviolet spectral range, presents a hipsochromic spectral shift as function of the electronic nature of the heteroatomic centers in the heterocyclic ring. In order to determine a spectroscopic assignment of the main absorption bands in aqueous solution and analyze the effect of the substituent on the electronic charge distributions in the ground and the first two singlet excited electronic states, we have used a semiempirical molecular orbital calculation in the INDO/S-CIS approach. On the other hand, we have carried out a molecular orbital calculation in the AM1 framework, in order to determine the energetic stability of the thiones with respect to the thiol compounds.

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Section: Introductionsupporting

confidence: 79%

¹π→¹π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles

Araya

Vargas

Morales

2005

Spectroscopy Letters

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“…The X-ray structure of 2-mercaptobenzimidazole molecule (compound I a in Figure ) in the solid state has been determined already in the 1970s by Form and Raper 21 and was confirmed later by Murty 22 and Ravikumar . A tautomeric equilibrium between the thione and the thiol form exists, but many works, including a semiempirical gas phase study, have shown that the thione form of MBI is predominant. In the solid state, the molecules form long H-bonded chains along the b axis of the crystal, which corresponds to the y axis of Figure .…”

Section: Resultsmentioning

confidence: 89%

Experimental and Density Functional Theory Study of the Vibrational Properties of 2-Mercaptobenzimidazole in Interaction with Gold

et al. 2006

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The vibrational properties of the 2-mercaptobenzimidazole (MBI) molecule in interaction with gold were examined by a combined approach of FTIR measurements and density functional theory (DFT). A complete assignment of the 42 normal modes of MBI has been performed on the basis of DFT calculations at the B3PW91 level in complement to the Raman and FTIR spectra. Calculations demonstrated that, on the deprotonated MBI molecule, the negative charge is localized on the sulfur atom, favoring the formation of a gold-sulfur bond upon reaction of MBI with gold. This was confirmed by the very good agreement between the calculated spectrum and the experimental spectra of different gold-MBI compounds, indicating that the vibrational properties of adsorbed MBI are chiefly determined by the coordination through the sulfur atom.

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“…This can be explained by the adsorption of these compounds on electrode surface. Computational studies on benzimidazole‐2‐tione show that BNZ, Cl–BNZ, and CH 3 –BNZ are in mercapto tautomeric forms (Açıkkalp et al , 2001). In acidic solutions, mercapto tautomeric forms of BNZ, CH 3 –BNZ, Cl–BNZ can exist as benzimidazolium‐2‐tione ions (InH + ).…”

Section: Discussionmentioning

confidence: 99%

Benzimidazole‐2‐tione and benzoxazole‐2‐tione derivatives as corrosion inhibitors for aluminium in hydrochloric acid

Bereket

Pinarbasi²,

Öğretır³

2004

Anti-Corrosion Methods and Materials

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The effect of benzimidazole‐2‐tione and benzoxazole‐2‐tione derivatives on the corrosion of aluminium in 0.1 M HCl has been investigated by a potentiostatic polarisation technique. Inhibition efficiencies were found to follow the order: benzimidazole‐2‐tione > 5‐methyl benzimidazole‐2‐tione > 5‐chloro benzimidazole‐2‐tione, while that of benzoxazole‐2‐tione derivatives were found to follow the order: 5‐methyl benzoxazole‐2‐tione > benzoxazole‐2‐tione > 5‐chloro benzoxazole‐2‐tione > 5‐nitro benzoxazole‐2‐tione. The inhibitive action of these heterocyclic compounds was mainly due to adsorption on the metal surfaces, which show parallelism with the calculated total negative charge of each of the molecules. Thermodynamic parameters, such as values of free energies of adsorption ΔGads and values of equilibrium constants Kads, were determined. Activation energies Ea, activation enthalpies ΔH* and activation entropies ΔS* were determined from the corrosion currents measured at different temperatures.

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Semiempirical gas phase study on tautomerizm of 2-hydroxy amino and mercapto benzimidazoles

Cited by 13 publications

References 6 publications

¹π→¹π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles

¹π→¹π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles

Experimental and Density Functional Theory Study of the Vibrational Properties of 2-Mercaptobenzimidazole in Interaction with Gold

Benzimidazole‐2‐tione and benzoxazole‐2‐tione derivatives as corrosion inhibitors for aluminium in hydrochloric acid

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Semiempirical gas phase study on tautomerizm of 2-hydroxy amino and mercapto benzimidazoles

Cited by 13 publications

References 6 publications

1π→1π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles

1π→1π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles

Experimental and Density Functional Theory Study of the Vibrational Properties of 2-Mercaptobenzimidazole in Interaction with Gold

Benzimidazole‐2‐tione and benzoxazole‐2‐tione derivatives as corrosion inhibitors for aluminium in hydrochloric acid

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¹π→¹π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles

¹π→¹π* Ultraviolet Absorption Bands and Electronic Charge Transfers in Singlet Excited States of Sulfur Aromatic Heterocycles