Electrocatalytic Reduction of Nitrogen to Hydrazine Using a Trinuclear Nickel Complex

Activation
and reduction of N2 have been a major challenge
to chemists and the focus since now has mostly been on the synthesis
of NH3. Alternatively, reduction of N2 to hydrazine
is desirable because hydrazine is an excellent energy vector that
can release the stored energy very conveniently without the need for
catalysts. To date, only one molecular catalyst has been reported
to be able to reduce N2 to hydrazine chemically. A trinuclear
T-shaped nickel thiolate molecular complex has been designed to activate
dinitrogen. The electrochemically generated all Ni­(I) state of this
molecule can reduce N2 in the presence of PhOH as a proton
donor. Hydrazine is detected as the only nitrogen-containing product
of the reaction, along with gaseous H2. The complex reported
here is selective for the 4e–/4H+ reduction
of nitrogen to hydrazine with a minor overpotential of ∼300
mV.