The Structure And Tautomerism Of Cyameluric Acid*

Wagler, Jörg; El‐Gamel, Nadia E. A.; Kroke, Edwin

doi:10.1515/znb-2006-0808

Cited by 28 publications

(11 citation statements)

References 12 publications

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“…Therefore, it can be predicted that the most stable form of free cyameluric acid C 6 N 7 O 3 H 3 has the same structure with C 3h symmetry. This conclusion is strongly supwww.chemeurj.org ported by very recent structural examinations of a DMSO solvate [52] and a trihydrate [53] of cyameluric acid. The thermal stability of 5 and 6 is decreased compared with alkali cyamelurates M 3 Compound 4 can be considered as a tris-trimetylsilyl ester of 1-4-7, containing fourfold coordinated silicon atoms.…”

Section: Resultsmentioning

confidence: 86%

The Tautomeric Forms of Cyameluric Acid Derivatives

El‐Gamel

Seyfarth

Wagler

et al. 2007

Chemistry A European J

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The tautomerism of cyameluric acid C6N7O3H3 (1 a), cyamelurates and other heptazine derivatives has recently been studied by several theoretical investigations. In this experimental study we prepared stannyl and silyl derivatives of cyameluric acid (1 a): C6N7O3[Sn(C4H9)3]3 (3 a), C6N7O3[Sn(C2H5)3]3 (3 b), and C6N7O3[Si(CH3)3]3 (4). In order to investigate the structure of 1 a the mono- and dipotassium cyamelurate hydrates K(C6N7O3H2)2 H2O (5) and K2(C6N7O3H)1 H2O (6) were synthesized by UV/Vis-controlled titration of a potassium cyamelurate solution with aqueous hydrochloric acid. Compounds 3-6 were characterized by FTIR and solid-state NMR spectroscopy as well as simultaneous thermal analysis (TGA, DTA). The single crystal X-ray structures of the salts 5 and 6 show that the hydrogen atoms in both anions are localized on the peripheral nitrogen atoms. This indicates-in combination with the solid-state NMR studies-that the most stable tautomer of solid 1 a is the triketo form with C3h symmetry. However, derivatives of both the hydroxyl and the amido tautomers may be formed depending on the substituent atoms: The spectroscopic data and single crystal structures of compounds C6N7O3[Si(CH3)3]3 (4) and the solvate C6N7O3[Sn(C2H5)3]3C2H4Cl2 (3 b') show that the former is derived from the symmetric trihydroxy form of 1 a, while 3 b' crystallizes as a chain-like polymer, which contains the tin atoms as multifunctional building blocks, that is, bridging pentacoordinated Et3SnO2 and Et3SnON units as well as non-bridging four-coordinated Et3SnN units. The cyameluric nucleus is part of the polymeric chains of C6N7O3[Sn(C2H5)3]3C2H4Cl2 (3 b'), by the action of both tautomeric forms of cyameluric acid, the amide and the ester form.

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Section: Resultsmentioning

confidence: 86%

The Tautomeric Forms of Cyameluric Acid Derivatives

El‐Gamel

Seyfarth

Wagler

et al. 2007

Chemistry A European J

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“…For a review of tri-s-triazines, see: Schwarzer et al (2013). For crystal structures and a comprehensive analysis of cyameluric acid, see: Sattler & Schnick (2006); Wagler et al (2006); Seyfarth et al (2008). For the synthesis of unsymmetrically substituted tri-s-triazines, see: Schwarzer & Kroke (2010, 2011.…”

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confidence: 99%

5,8-Bis[bis(pyridin-2-yl)amino]-1,3,4,6,7,9,9b-heptaazaphenalen-2(1H)-one dimethyl sulfoxide monosolvate dihydrate

Schwarzer¹,

Kroke²

2014

Acta Cryst E

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In the asymmetric unit of the title compound, C26H17N13O·C2H6OS·2H2O, there is one independent heptazine-based main molecule, one dimethyl sulfoxide molecule and two water molecules as solvents. The tri-s-triazine unit is substituted with two dipyridyl amine moieties and a carbonylic O atom. As indicated by the bond lengths in this acid unit of the heptazine derivative [C=O = 1.213 (2) Å, while the adjacent C—N(H) bond = 1.405 (2) Å] it is best described by the keto form. The cyameluric nucleus is close to planar (r.m.s. deviation = 0.061 Å) and the pyridine rings are inclined to its mean plane by dihedral angles varying from 47.47 (5) to 70.22 (5)°. The host and guest molecules are connected via N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonds, forming a four-membered inversion dimer-like arrangement enclosing an R 4 4(24) ring motif. These arrangements stack along [1-10] with a weak π–π interaction [inter-centroid distance = 3.8721 (12) Å] involving adjacent pyridine rings. There are also C—H⋯N and C—H⋯O hydrogen bonds and C—H⋯π interactions present within the host molecule and linking inversion-related molecules, forming a three-dimensional structure.

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“…Cyameluric acid and its salts were characterized by FTIR spectroscopy by Finkel'shtein and Spridonova . In contrast to cyanuric acid C 3 N 3 O 3 H 3 , which was found to exist in the keto‐form, the tautomeric form of cyamluric acid could not be distinguished clearly for a long time and many publications dealt with this question . Different crystal structures finally showed that the keto form is favored in the solid state .…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to cyanuric acid C 3 N 3 O 3 H 3 , which was found to exist in the keto‐form, the tautomeric form of cyamluric acid could not be distinguished clearly for a long time and many publications dealt with this question . Different crystal structures finally showed that the keto form is favored in the solid state . Besides, the crystal structures of cyameluric acid, crystal structures of some alkali metal cyamelurates were reported .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Thiocyameluric Acid C₆N₇S₃H₃, Its Reaction to Alkali Metal Thiocyamelurates and Organic Tris(dithio)cyamelurates

Posern

Höhne

Böhme

et al. 2019

Chemistry A European J

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Thiocyameluric acidC 6 N 7 S 3 H 3 ,the tri-thio analogue of cyameluric acid, is ak ey compound for the synthesis of new s-heptazine (tri-s-triazine) derivatives. Here, two different routes for the synthesis of thiocyamelurica cid and its reaction to tris(aryldithio)-and tris(alkyldithio)cyamelurates C 6 N 7 (SSR) 3 are reported as well as transformation to alkali metal thiocyamelurates M 3 [C 6 N 7 S 3 ], M= Na, K. Thesec ompoundsw ere characterisedb yF TIR, Raman, solution 13 Ca nd 1 HNMR spectroscopies, thermal gravimetric analysis( TGA) and elementala nalysis. The three (de)protonation steps of thiocyamelurica cid were investigated by acid-base titration followed via UV/Vis absorptions pectroscopy.W hile it was not possible to determine the three pK a values, it could be postulated that the acid strength probably increases in the following order:cyanuric acid (C 3 N 3 O 3 H 3 ) < thiocyanuric acid (C 3 N 3 S 3 H 3 ) < cyameluric acid (C 6 N 7 O 3 H 3 ) < thiocyameluric acid (C 6 N 7 S 3 H 3 ). Single crystalso fN a 3 [C 6 N 7 S 3 ]·10 H 2 Oa nd K 3 [C 6 N 7 S 3 ]·6 H 2 Ow ere obtained and the structures analyzed by single crystal X-ray diffraction. Additionally,q uantum chemicalc alculationsw ere performed to get insights into the electronic structure of thiocyameluric acid and to clarify the thiol-thione tautomerism.B ased on ac omparison of calculated and measuredv ibrational spectra it can be concluded that thiocyamelurica cid and the di-and mono-protonated anionsexist in the thione form.Scheme1.Principalstructures of the s-triazine derived cyanurates [C 3 N 3 O 3 ] 3À ,a nd the s-heptazine derived cyamelurates [C 6 N 7 O 3 ] 3À and their thio analogues. For ab etterc omparisonw ith cyameluricacid andcyamelurates we named 2,5,8-trimeracpto-tri-s-triazine and its derivatives thiocyameluric acid, thiocyameluratesa nd the disulfidesa re named dithiocyamelurates.[a] C.Supporting Information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.

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The Structure And Tautomerism Of Cyameluric Acid*

Cited by 28 publications

References 12 publications

The Tautomeric Forms of Cyameluric Acid Derivatives

The Tautomeric Forms of Cyameluric Acid Derivatives

5,8-Bis[bis(pyridin-2-yl)amino]-1,3,4,6,7,9,9b-heptaazaphenalen-2(1H)-one dimethyl sulfoxide monosolvate dihydrate

Synthesis of Thiocyameluric Acid C₆N₇S₃H₃, Its Reaction to Alkali Metal Thiocyamelurates and Organic Tris(dithio)cyamelurates

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The Structure And Tautomerism Of Cyameluric Acid*

Cited by 28 publications

References 12 publications

The Tautomeric Forms of Cyameluric Acid Derivatives

The Tautomeric Forms of Cyameluric Acid Derivatives

5,8-Bis[bis(pyridin-2-yl)amino]-1,3,4,6,7,9,9b-heptaazaphenalen-2(1H)-one dimethyl sulfoxide monosolvate dihydrate

Synthesis of Thiocyameluric Acid C6N7S3H3, Its Reaction to Alkali Metal Thiocyamelurates and Organic Tris(dithio)cyamelurates

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Synthesis of Thiocyameluric Acid C₆N₇S₃H₃, Its Reaction to Alkali Metal Thiocyamelurates and Organic Tris(dithio)cyamelurates