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3,5-Bis(2-hydroxyphenyl)-1H-1,2,4-triazole based ligands — protonation and metal complex formation

✍ Scribed by Stefan Stucky; Nadine J. Koch; Uwe Heinz; Kaspar Hegetschweiler

Book ID
111491157
Publisher
Versita
Year
2008
Tongue
English
Weight
612 KB
Volume
62
Category
Article
ISSN
0366-6352

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✦ Synopsis

Abstract

3,5-Bis(2-hydroxyphenyl)-1H-1,2,4-triazole (H2La) and 4-[3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazol-1-yl]benzoic acid (H3Lb) have been prepared, and crystal structure of the intermediate 2-(2-hydroxyphenyl)-4H-1,3-benzoxazin-4-one has been determined. Temperature dependent 1H NMR spectroscopic measurements of H2La indicated dynamic behavior with the equilibrium between the two asymmetric tautomers. For H3Lb, pD-dependent 1H NMR spectroscopic measurements showed small but characteristic shifts in the range of 0 ≤ pD ≤ 1, indicative of a triazole nitrogen atom protonation; the corresponding pK a of 0.98 ± 0.04 was determined by spectrophotometric titrations. (H2O, 26°C, 1 M KCl/HCl). Formation of [FeIII(La)]+ (pH 2.5) and [FeIII(La)2]− (pH > 6) was verified by UV-Vis spectroscopy. Complex formation of H3Lb with Al3+ and VO2+ was investigated by 1H NMR spectroscopic titration and cyclic voltammetry, respectively. Single crystals of the phenoxo bridged [VVO(HLb)(EtO)]2·2EtOH were characterized by X-ray structural analysis.

📜 SIMILAR VOLUMES

Bis­[4-phenyl-5-(1H-1,2,4-triazol-3-yl)-
Bis­[4-phenyl-5-(1H-1,2,4-triazol-3-yl)-4H-1,2,4-triazol-3-yl] di­sulfide
✍ Pan, Fu-You ;Yang, Jian-Guo ;Chen, Ding-Ben ;Huang, Ling 📂 Article 📅 2005 🏛 International Union of Crystallography 🌐 English ⚖ 235 KB

The title compound, C 20 H 14 N 12 S 2 , was synthesized by the reaction of 3-hydrazino-1H-1,2,4-triazole with phenyl isocyanate in benzene and by ring closure in an alkaline medium. Intermolecular N-HÁ Á ÁN hydrogen bonds are observed and these form a five-membered ring.

3-(2-Thienyl­methyl)-4,4′-bi-1H-1,2,4-tr
3-(2-Thienyl­methyl)-4,4′-bi-1H-1,2,4-triazol-5(4H)-one
✍ Sancak, Kemal ;Ustabaş, Reşat ;Çoruh, Ufuk ;Er, Mustafa ;Ünver, Yasemin ;Yavuz, 📂 Article 📅 2005 🏛 International Union of Crystallography 🌐 English ⚖ 298 KB

The title compound, C 9 H 8 N 6 OS, crystallizes with two molecules in the asymmetric unit. In the crystal structure, intermolecular N-HÁ Á ÁN hydrogen bonds form a threedimensional network.