Structure of 1(5)-aryl-3-phenyl-5(1)-(2-benzothiazolyl)formazanes

Shmelev, L. V.; Kessenikh, A. V.; Orlova, E. E.; Polyakova, I. N.; Starikova, Z. A.; Lipunova, G. N.; Ol'khovikova, N. B.; Rusinova, L. I.

doi:10.1007/bf00484372

Cited by 4 publications

(6 citation statements)

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“…The ring is easily opened in proton-acceptor solvents, which resulted in an equilibrium between the EZZ and EEZ forms; their ratio depends on the nature of the heterocycle and the solvent. 13 This was manifested in the dependence of the position of the d NH signal in the 1 H NMR spectrum on the solvent polarity as well as in the presence of weak and moderate n NH bands at 3300 ± 3340 cm 71 in the IR spectra.…”

Section: Spatial Structure Of Formazansmentioning

confidence: 99%

“…For example, a comparison of d 13 C in R 1 NH and R 5 NH tautomers of 1,3diphenyl-5-(benzothiazol-2-yl)formazan (13) suggests that this compound exists almost exclusively in the form of a PhN(1) tautomer irrespective of the solvent polarity. 3 The enhancement of the electron-withdrawing properties of the aryl substituent at the N(5) atom (introduction of the p-nitrophenyl group, formazan 14), leads to co-existence of azoaryl tautomer 14a with a considerable amount of the arylhydrazone tautomer 14b.…”

Section: Tautomerism Of Formazansmentioning

confidence: 99%

“…The imino form manifests a characteristic band around 3420 ± 3460 cm 71 , while the band around 3330 ± 3360 cm 71 is more typical of the amino form. 13 C NMR spectroscopy is the most informative method for studying the amino ± imino tautomerism in solutions. These conversions strongly affect the chemical shifts of the carbon atoms in azaheterocycles.…”

Section: Tautomerism Of Formazansmentioning

confidence: 99%

“…A comparison of the d 13 C values in the 13 C NMR spectra of model compounds and the corresponding formazans enabled quantitative determination of the ratios of amino to imino tautomers in solutions of trisubstituted 1(5)-aryl-5(1)-(benzothiazol-2-yl)formazans. 13,16 It was found that the concentration of the imino tautomer in a nonpolar solvent decreases with an increase in the bulk of the substituent at the C(3) atom and the ability of formazans to exist in a`folded' state stabilised by intramolecular H-bonds. Thus in CDCl 3 the contribution of the imino tautomer of formazans 13 (the EZZ isomer) and 4b (the EEZ isomer) could not be reliably established because its percentage did not exceed 5%, whereas that of the imino tautomer of EEE formazan 4a was 20% ± 25% [calculated from signals for the C(4), C(8) and C(9) atoms of the heterocycle].…”

Section: Tautomerism Of Formazansmentioning

confidence: 99%

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Formazans and their metal complexes

Sigeikin¹,

Lipunova²,

Pervova³

2006

Russ. Chem. Rev.

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Section: Spatial Structure Of Formazansmentioning

confidence: 99%

Section: Tautomerism Of Formazansmentioning

confidence: 99%

Section: Tautomerism Of Formazansmentioning

confidence: 99%

Section: Tautomerism Of Formazansmentioning

confidence: 99%

See 2 more Smart Citations

Formazans and their metal complexes

Sigeikin¹,

Lipunova²,

Pervova³

2006

Russ. Chem. Rev.

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“…The following ligands were used in this work: The authors of [3][4][5] used the NMR and X-ray diffraction methods to study the Ni(II), Co(II), and Cd(II) complexes with hetarylformazanes containing substituents R 1 , R 2 , and R 3 that were different from those we used. They established that the complexes under study had octahedral structure (coordination number 6) with the N 1 and N 4 atoms of the formazane fragment and the N 6 atom of heterocycle participating in coordination with a metal.…”

mentioning

confidence: 99%

Complexation of Cu(II) with Hetarylformazanes in Solutions, Polycrystals, and Modified Anionite

et al. 2005

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The reactions of formazanes with transition metal ions can give coordination compounds of different nature and structures, namely, mono-and binuclear complexes, complexes with different surrounding of a central atom and configuration. The reason for such a variety lies in a high flexibility of formazanes, their capability to act as bi-, tri-, or tetradentate ligands with allowance for the substituents [1].Formazanes and their compounds are widely used in chemistry, in particular, as analytical reagents. The polymeric ionites modified with formazanes significantly improve the ionite selectivity toward the adsorbed metal ions [2].The goal of this work was to study the Cu(II) complexes with hetarylformazanes ( HF ) in solutions, modified AN-18 anionite, and in polycrystals. The following ligands were used in this work:The authors of [3][4][5] used the NMR and X-ray diffraction methods to study the Ni(II), Co(II), and Cd(II) complexes with hetarylformazanes containing substituents R 1 , R 2 , and R 3 that were different from those we used. They established that the complexes under study had octahedral structure (coordination number 6) with the N 1 and N 4 atoms of the formazane fragment and the N 6 atom of heterocycle participating in coordination with a metal.A significant broadening of lines in the NMR spectrum of the Cu(II) complexes due to the spin paramagnetism effect does not make it possible to use the NMR method in order to study the structure of the Cu(II) complexes with formazanes. Therefore, we used the Abstract -The Cu(II) complexes with hetarylformazanes (HF) formed in solutions, polycrystals, and AN-18 polymeric ionite modified with HF were studied by EPR method and were found to have almost identical structures. The configuration of the Cu 2+ coordination surrounding (square-planar or pseudotetrahedral) is specified by the substituents at N 1 in formazane fragments. Complexes with coordination unit Cu(4N) were formed mainly, when the ligands were taken in excess, while in the case of the ligand deficiency and with the coordinating OH group in benzene ring, the complexes with the Cu(3NO) coordination unit were formed. The covalence of in-plane metal-ligand σ -bond was found to be affected by the substituents. The formation of binuclear copper complexes in solutions and polycrystals was established in the case of deficiency of the ligand with SO 3 H substituent in benzene ring.

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