9.5 Specify the oxidation numbers of the metals in the following coordination entities:

(i) [Co(H2O)(CN)(en)2]2+

(ii) [CoBr2(en)2]+

(iii) [PtCl4]2–

(iv) K3[Fe(CN)6]

(v) [Cr(NH3)3Cl3]

(i)
Let the oxidation number of Co be x.
The charge on the complex is +2.
(ii) ${\left[Pt{\left(CI\right)}_{4}\right]}^{2-}$
Let the oxidation number of Pt be x.
The charge on the complex is −2.
(iii)

(iv)
i.e,

(v)