posted on 2016-03-30, 00:00authored byDavide Lionetti, Graham de Ruiter, Theodor Agapie
The reduction of nitric oxide (NO)
to nitrous oxide (N2O) is a process relevant to biological
chemistry as well as to the
abatement of certain environmental pollutants. One of the proposed
key intermediates in NO reduction is hyponitrite (N2O22–), the product of reductive coupling of
two NO molecules. We report the reductive coupling of NO by an yttrium–tricopper
complex generating a trans-hyponitrite moiety supported
by two μ-O-bimetallic (Y,Cu) cores, a previously unreported
coordination mode. Reaction of the hyponitrite species with Brønsted
acids leads to the generation of N2O, demonstrating the
viability of the hyponitrite complex as an intermediate in NO reduction
to N2O. The additional reducing equivalents stored in each
tricopper unit are employed in a subsequent step for N2O reduction to N2, for an overall (partial) conversion
of NO to N2. The combination of Lewis acid and multiple
redox active metals facilitates this four electron conversion via
an isolable hyponitrite intermediate.