Gold-Mediated Expulsion of Dinitrogen from Organic Azides

Organoazides
and their nitrogen expulsion chemistry have attracted
the attention of many scientists because they serve as a useful source
of nitrene fragments and interesting nitrene rearrangement products.
Gold-mediated reactions are also of significant current interest.
This manuscript describes several important discoveries based at the
intersection of these fields. In particular, we report the first isolable
gold organoazides ([(SIPr)­AuN­(1-Ad)­NN]­[SbF6], [(SIPr)­AuN­(2-Ad)­NN]­[SbF6] and [(SIPr)­AuN­(Cy)­NN]­[SbF6]; SIPr = a N-heterocyclic carbene; 1-AdNNN = 1-azido­adamantane;
2-AdNNN = 2-azidoadamantane; CyNNN = azidocyclohexane), and their
gold-mediated nitrogen expulsion chemistry, and the isolation of formal
nitrene rearrangement products of “1-AdN”, “2-AdN”
and “CyN” (including the elusive 4-azahomoadamant-3-ene)
as their gold complexes. We have also performed a computational study
to understand and explain the observed structure of gold-coordinated
1-AdNNN and 2-AdNNN and their nitrogen elimination pathways, which
implies that the conversion of the organoazide complex to the imine
is a concerted process without a nitrene/nitrenoid intermediate. Kinetic
studies of [(SIPr)­AuN­(2-Ad)­NN]­[SbF6] from 30 to 50 °C
indicate that nitrogen elimination is a first-order process. The experimentally
determined activation parameters are in good agreement with the calculated
values.