Here in the complex, potassium pentacyanonitrosylvandate (0), the number of potassium atoms per molecule and the coordination number of central metal ion are 5, 6 respectively as oxidation number of V in this complex is '0' thus the charge on pentacyanonitrosylvandate is -5. Thus formula of the complex is ${\mathrm{K}}_5\left[\mathrm{V}\right(\mathrm{C}\mathrm{N}{)}_5\mathrm{N}\mathrm{O}]$ .