Diazenium ions

Dialkyldiazenes are unstable and lose nitrogen with the formation of two alkyl radicals. This is the only process observed when the 1,1-dialkyIhydrazine is oxidised in alkaline solution where none of the diazenium ion survives [144]. Electrochemical oxidation of the cyclic dialkylhydrazine 32 in an unbuffered solution... 

The electrolysis of A/ -methylamides (LXX) results in the formation of iminium intermediates that undergo a [4 + 2]-cycloaddition with olefins [Eq. (26)] [252] to afford heterocycles (LXXI) in 45-58% yield. 1,1-Diphenylhydrazine can be dehydrogenated to the diazenium ion (LXXII) [Eq. (27)], which undergoes cycloadditions with olefins [253]. 

It is interesting and unexpected that diazoethane reacts in a different way under similar conditions (2-3) (McGarrity et al., 1980). In FS03H-SbF5-FS02Cl, only ethyl fluorosulfate (2.8) and the N-protonated diazenium ion (2.9) are observed the C-protonated diazonium ion (2.7) is not detected. 

Alkyl diazonium ions are very reactive intermediates, but have none the less been observed in superacid solution. Dissolving diazomethane in fluorosulphonic acid at -120 °C yielded the methyl diazonium ion (177) and the methylene diazenium ion (178) in the ratio 4 to 1. 

In the oxidation of 202, the tetracyclodiazenium ion 203 is produced in 81% yield. Like the hydrazinium dications, the diazenium dications exhibit relatively high acidities of their a-hydrogen atoms. 

The proton affinity of HN3 has been reported at 179 kcalmol and 176.6 kcalmol-i The QCISD(T)//MP2 level PA value in Table 3 to form H2NNN+ is 188.7 kcalmoP, from which is subtracted the ZPE difference with the neutral parent (Table 3 5) of 7.9 kcalmokk This gives an adjusted PA of 180.8 kcalmoP which is in good agreement with both reported measured values. It has recently been claimed that the true experimental PA of HN3 is somewhat (<9 kcalmol" ) higher than reported experimentally from proton transfer equilibria. The diazenium cations is QCISD(T) calculated to be 24.5 kcal mol less stable than the diazonium ion (Table 3). 

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