2 NIIIO2- + 2 H+ + CO(N-IIIH2)2 CO2 + 3 H2O + 2 N20

This is an oxidation-reduction (redox) reaction:

2 N-III - 6 e- 2 N0 (oxidation)

2 NIII + 6 e- 2 N0 (reduction)

Change the oxidation states