Synthese und Eigenschaften von 3,6-Diorgano-3,6-dithio-1,2,4,5,3,6-tetrathiadiphosphorinanen; eine neue Möglichkeit zur Knüpfung von S—S-Bindungen / Synthesis and Properties of 3,6-D iorgano-3,6-dithio-1,2,4,5,3,6-tetrathiadiphosphorinanes; a New Possibility of Forming S—S Bonds
2014
Hahn, Josef | Nataniel, Tina
The six-membered sulfur-phosphorus heterocycles 3,6-diorgano-3,6-dithio-1,2,4,5,3,6-tetrathiadiphosphorinanes (RP(S)S₂)₂ (R = Me 1a and R = t-Bu 1b) are formed in high yields from the silyl esters of the corresponding trithiophosphonic acids RP(S)(SSiMe₃)₂ and dimethylsulfoxide. They are fairly stable in the crystalline state. In solution sulfur elimination occurs, which in the case of l a leads to the formation of 3,5-dimethyl-3,5-dithio-1,2,4,3,5-trithiadiphospholane, MeP(S)S₂PMe(S)S (4). Likewise lb decomposes to give the corresponding dithiophosphonic acid anhydride (t-BuP(S)S)₂. According to NMR spectroscopic conformational analysis, 1a exists in four isomeric forms: two chair and two twist-boat conformations, which differ in the orientation (cis or trans) of the Me groups. The isomeric distribution indicates that the Me groups prefer the axial positions. As a consequence of steric bulk, 1b is only present in the twist-boat conformation with trans orientation of the t-Bu substituents.
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