$$\begin{array}{rl}{\text{RNO}}_2^{}& \stackrel{+\text{e}}{\rightleftharpoons }{\text{RNO}}_2^{-<!--\; -\; -->\cdot <!--\; \cdot \; -->}\\ {\text{RNO}}_2^{-<!--\; -\; -->\cdot <!--\; \cdot \; -->}& \stackrel{+\text{e}}{\rightleftharpoons }{\text{RNO}}_2^{2-<!--\; -\; -->}\end{array}$$