
%0 Journal Article
%A Guard, JAM 
%A Steel, PJ 
%T Heterocyclic Tautomerism. V. X-Ray Crystal Structures of Two 5-Substituted 1,2,4-Thiadiazol-3-ones
%J Australian Journal of Chemistry
%D 1995/09/01
%V 48
%N 9
%P 1609-1615
%K 
%R https://doi.org/10.1071/CH9951609
%U https://www.publish.csiro.au/paper/CH9951609 
%X Contrary to a recent report, 3-hydroxy-5-phenyl-1,2,4-thiadiazole is shown to exist as the OH tautomer (2a). At 130 K crystals of (2a) are monoclinic, P21/n, a 5.453(3), b 4.956(2), c 27.28(2) &#506;, &#946; 94.12(5)&#176;, Z = 4; the structure was refined to a conventional R[I > 2&#963;(I)] 0.051. 5-Benzoylamino-1,2,4-thiadiazol-3-one is shown to exist as the N(2)H tautomer (3b) but with a contribution to the structure from a bicyclic or zwitterioni resonance contributor containing an S-O bond. At 130 K crystals of (3b) are monoclinic, Pn , a 3.771(1), b 15.465(4), c 8.105(1) &#506;, &#946; 98.72(2)&#176;, Z = 2; the structure was refined to a conventional R[I > 2&#963;(I)] 0.038. 
