Question

Write oxidation state and coordination number of [Co(NH₃)₄Cl₂]⁺ ion. Calculate EAN of iron in [Fe(CN)₆]^4–. Write the IUPAC name of [Zn(NH₃)₄]²⁺.

Answer 1

i. [Co(NH₃)₄Cl₂]⁺

(O.S. of Co + charge on ligands) = +1

∴ (O.S. of Co + 4 × charge of NH₃ molecule + 2 × charge of Cl^– ion) = +1

∴ O.S. of Co + 4 × 0 + 2 × –1 = +1

Oxidation state of Co = +3

In [Co(NH₃)₄Cl₂]⁺, four ammonia molecules and two chloride ions, that is, total six ligands are attached to cobalt ion. All these are monodentate ligands.

∴ Coordination number of Co³⁺ ion in the complex = 6

ii. EAN of iron in [Fe(CN)₆]^4–

Oxidation state of Fe is +2 and ligands donate 12 electrons.

Z = 26, X = 2, Y = 12

EAN of Fe²⁺ = Z – X + Y

= 26 – 2 + 12

= 36

iii. IUPAC name of [Zn(NH₃)₄]²⁺: Tetraamminezinc(II) ion