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3,5-Bis(2-hydroxyphenyl)-1H-1,2,4-triazole based ligands — protonation and metal complex formation
Stucky, Stefan, Koch, Nadine J., Heinz, Uwe and Hegetschweiler, Kaspar 3,5-Bis(2-hydroxyphenyl)-1H-1,2,4-triazole based ligands — protonation and metal complex formation Chemical Papers, Vol.62, No. 4, 2008, 388-397
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Document type:
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Článok z časopisu / Journal Article |
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Collection:
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Chemical papers
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| Author(s) |
Stucky, Stefan
Koch, Nadine J.
Heinz, Uwe
Hegetschweiler, Kaspar
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| Title |
3,5-Bis(2-hydroxyphenyl)-1H-1,2,4-triazole based ligands — protonation and metal complex formation
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| Journal name |
Chemical Papers
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| Publication date |
2008
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| Year available |
2008
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| Volume number |
62
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| Issue number |
4
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| ISSN |
0366-6352
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| Start page |
388
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| End page |
397
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| Place of publication |
Poland
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| Publisher |
Versita
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| Collection year |
2008
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| Language |
english
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| Subject |
250000 Chemical Sciences
250200 Inorganic Chemistry
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| Abstract/Summary |
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.
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