Adamantane-2,6-diyl dications

Several 2,6-disubstituted adamantane-2,6-diyl dications 181 have been prepared and characterized.398 They are stable only when they contain charge delocalizing substituents such as cyclopropyl or phenyl groups. Recently, a DFT... 

Attempted preparation of the other adamantane 1,3-diyl dications was also futile. Thus, ionization of 2-methyl-5-bromoadamantane in FS03H-SbF5/S02 gave only the monocation donor-acceptor complex (48). Even the ionization of the 5-bromo-2-adamantanone gave the carboxonium donor-acceptor complex (49)." ... 

Other adamantane-based dications have also been prepared. Although systems such as diadamanta-4,9-diyl dication (35) and TT-bisadamanta-3,3 -diyl dication (36) have been prepared (both 1,6-dications), experimental data suggests that these systems are more related to the monopositive adamantyl cations rather than distonic superelectrophilic systems.14 However, the adamanta-l,3-dimethyldiyl dication (38) has been prepared in superacid media (eq 16).15... 

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