Solid-state study of cyclic thiohydroxamic acids: 1-hydroxy-2(1H)-pyridinethione and 3-hydroxy-4-methyl-2(3H)- thiazolethione

Abstract

Cyclic thiohydroxamic acids such as 1-hydroxy-2(1H)-pyridinethione (1) and 3-hydroxy-4-methyl-2(3H)-thiazolethione (2) find diverse applications as fungicides and alkoxy-radical precursors. Selected physico-chemical properties such as thermal stability can be rationalized by examination of their solid-state structures. We report here a new hydrated form of 2 (denoted 3) that displays enhanced thermal stability and solubility compared with the anhydrous form. These enhanced properties may be attributed to the ionic nature of 3 in the solid state. The oxidized form of 1, 2,2′-dithiobis(pyridine-1-oxide) (DTPO, 4) also finds application as a fungicide. Attempts to produce an analogous disulfide from 2 produced a new thioether product, 3-hydroxy-4-{[3-oxo-4-methyl-2(3H)-thiazol-2-yl]thio}-2(3H)-thiazolethione (5). Co-crystallization of 1 with 2 produced a mixed molecular crystal (6) containing both DTPO and a new thioether derivative of 2, 5,5′-thiobis[3-hydroxy-4-methyl-2(3H)-thiazolethione]. The supramolecular complementarity of the two components gives rise to discrete hydrogen-bonded dimers within the co-crystal. Copyright © 2000 John Wiley & Sons, Ltd. Additional material for this paper is available from the epoc website at http://www.wiley.com/epoc