Aspects of structural thiohydroxamate chemistry—on a systematic in the 5-(p-methoxyphenyl)-4-methylthiazole-2(3H)-thione series |
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Authors: | Jens Hartung,Uwe Bergsträ ß er,Nina Schneiders,Hartmut Fuess |
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Affiliation: | a Fachbereich Chemie, Organische Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern, Germany b Technische Universität Darmstadt, Strukturforschung, FB11 Material- und Geowissenschaften, Petersenstraße 23, D-64287 Darmstadt, Germany |
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Abstract: | Bond angles at thiohydroxamate oxygen in crystal structures of 3-alkoxy-5-(p-methoxyphenyl)-4-methylthiazole-2(3H)-thiones gradually increased with the size of the 3-alkoxy substituent. This effect was attributed to strain on the basis of (i) a linear free energy relationship (Taft-Dubois correlation) and (ii) signal coalescence from resonances of diastereotopic CH3 groups in solution (O-cumyl substituent; DNMR). Substitution at oxygen along the sequence OR (R=prim-, sec-, and tert-alkyl), OH, and OLi was reflected in a gradual decrease of N,O distances and lengthening of associated C,S bonds. The responsivity for these changes was more pronounced in the thiazole-2(3H)-thione than in the pyridine-2(1H)-thione series. |
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Keywords: | Heterocycle Lithium thiohydroxamate Pyridinethione Steric substituent effect Taft-Dubois parameter Thiazolethione Thiohydroxamic acid X-ray crystallography |
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