The EAN of metal atoms in $\left[\mathrm{Fe}(\mathrm{CO}{)}_2{\left({\mathrm{NO}}^{+}\right)}_2\right]$ and ${\mathrm{Co}}_2(\mathrm{CO}{)}_8$ respectively are:

If X, Y, and Z are the amount of electrons a metal gives up, the amount of electrons that ligands give away, and the atomic number, then EAN is

EAN=Z−X+Y

For $\left[Fe\right(CO{)}_2\left(N{O}^{+}{)}_2\right],$

$\mathrm{EAN}=26+2+8$

$\mathrm{EAN}=36$

$C{o}_2(CO{)}_8$

$\mathrm{EAN}=27+0+9$

$\mathrm{EAN}=36$