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 Oxidation no. of Co be x and charge on the complex is given as + 2


H2O has Oxidation Number: 0


CN has Oxidation Number: -1


en has Oxidation Number :0



(ii) Let Oxidation number of Co be x and charge on the complex is given as + 1


Br has Oxidation number: 1


en has oxidation number : 0



(iii) Let Oxidation number of Pt be x and charge on the complex is given as -2


Cl has oxidation number : -1



(iv) This complex can also be seen as [Fe(CN)6]3-


Let Oxidation number of Fe be x and charge given on the complex is given as -3


CN has oxidation number : -1



(v) Let Oxidation number of Cr be x and charge given on the complex is given as 0


NH3 has oxidation number : 0


Cl has oxidation number: -1



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