Thianthrene tetraoxide

Tellurium replaces sulphur dioxide in dibenzothiophene dioxide," and in thianthrene tetraoxide" and 2,2 -biphenylmercury." ... 

The thermal reaction of thianthrene tetraoxide (233) with selenium (39JCS151) or tellurium (58Ac(R)738) yields dibenzoselenophene and dibenzotellurophene respectively. The corresponding thermal reaction of 2,5-diaryldithiin 1,1,4,4-tetraoxides (234) with selenium gives acceptable yields of 2,5-diarylselenophenes and in one case a small amount of the 2,4-isomer (76JHC57). It has been established fairly convincingly that the reaction proceeds via formation of the arylacetylene and its subsequent reaction with selenium. 

Thianthren and its a-dioxide, and tetroxide Equivalent conformations, folded about the S—S line by 140+10° in thianthren and about 138° in its a-dioxide or ca. 130° in the tetraoxide, are deduced for these flexible ( flapping ) solutes in B Aroney et al., 1965a... 

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