Kristall- und Molekül-Struktur von 4-Phenyl-1.2.3–thiadiazol-3-oxid / Crystal and Molecular Structure of 4-Phenyl-1,2,3-thiadiazol-3-oxide

Abstract

<jats:title>Abstract</jats:title><jats:p> A final decision between the 2-and 3-oxide structure of the thermally or photo-chemically accessible monoxides of 1,2,3-thiadiazoles is given with the aid of an X-ray analysis of 4-phenyl-1,2,3-thiadiazole-3-oxide. The compound crystallizes in the ortho-rhombic space group Pbca, Z = 8, with a = 7.598(6), b= 18.865(5) and c= 11.225(6) Å. </jats:p><jats:p>The structure was solved by the heavy atom method and refined to R = 0.042 for 1643 independent reflections. The heterocyclic ring is planar within experimental error and the bond distances S-C and S-N are rather short. In the crystal the molecules are linked by an unusual short contact distance between sulphur and oxygen (2.75 Å).</jats:p>

Thiadiazoles

“…Data on IR [19] and UV [20] spectroscopy have been reported for some 1,2,3-thiadiazoles. Characteristic infrared absorptions are at 1560-1475 and 1350-1280 cm À1 (ring skeletal).…”

Chemical Properties of 1,2,3‐Thiadiazoles

“…71 The triplet 1,3-diradical 154 has been characterized by Electron Spin Resonance (ESR) spectroscopy. 72 Another intermediate, the thiirene 155 (R 1 = H, R 2 = Ph), has been shown by 13 C NMR spectroscopy during the photolysis of 5-phenyl-1,2,3-thiadiazole. 60 The lifetime of these thiirenes 155 is short as they rearrange to thioketenes 157.…”

“…However, the thiirene 155 is formed photochemically at 77 K from this thioketene 157 in an EPA glass (diethyl ether-isopentane-ethanol), to which it reverts rapidly. Under these conditions, up to 37% of 13 1,2,3-Thiadiazoles with α, β-unsaturated side chains in the 4-or 5-position are suitable starting materials for polymerization reactions. The resulting polymer chains 199 can be photo-cross-linked by photochemical degradation of the thiadiazole rings leading to bridges having sulfur-containing heterocycles.…”

Lanthaniden-Verschiebungen in der 1H- und 13C-Kernresonanzspektroskopie zur Konstitutionsermittlung von Thiadiazoloxiden / Lanthanide Induced Shifts in the 1H and 13C Nuclear Magnetic Resonance Spectroscopy for Structure Elucidations of Thiadiazole Oxides

“…Diese Problematik tritt z.B. bei der Oxidation von 1.2.3-Thiadiazolen mit Persäuren auf [1]. Dabei werden Mono-, Di-und Trioxide erhalten.…”

“…Dabei werden Mono-, Di-und Trioxide erhalten. Die Belichtung der "thermischen" Monoxide führt zu konstitutionsisomeren Monoxi- den [1]. Mit Hilfe einer Röntgenstrukturanalyse konnte bei la gesichert werden, daß die Persäure-Oxidation zu dem 3-Oxid 2 a führt [1].…”