Dichlorodithionitronium salts

The dichlorodithionitronium cation C1SNSC1+ also serves as a masked SNS+ species because it undergoes cycloaddition reactions with alkynes and olefins. For example, reaction of the dichlorodithionitronium salt with ethyne and propyne in sulfur dioxide below room temperature affords the expected [3+2] cycloadducts 100. Most likely, an intermediate dichloro cycloadduct 99 is formed, which loses chlorine to form the isolated cycloadduct. 

In the reaction of C1SNSC1+ AsFg with olefins the initially formed dichloro cycloadducts are stable. However, dichlorodithionitronium salts do not form cycloadducts with nitriles. 

Addition of dimethyl acetylenedicarboxylate to the mesoionic dehydrodithizone (547) yields the stable betaine 549 by ring-cleavage of the initial dipolar cycloadduct 548, which is destabilized by the presence of eight 7i-electrons in the tetrazoline ring Dichlorodithionitronium hexafluoroarsenate CISNSCI" AsF6 reacts with acetylene in liquid sulphur dioxide to give the 1,3,2-dithiazolium salt 550. ... 

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See also in sourсe #XX -- [ , ]

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