$\left[\mathrm{CoCl}_{4}\right]^{2-}$ is a blue coloured complex. Controlled - treatment of this complex with watger generates two isomeric light pink coloure complexes of composition $\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4} \mathrm{Cl}_{2}\right]$. Identify the correct point groups for $\left[\mathrm{CoCl}_{4}\right]^{2-}$ and two isomeric complexes $\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4} \mathrm{Cl}_{2}\right]$.
(a)$\mathrm{D}_{2\mathrm{h}}$ and ($\mathrm{C}_{2\mathrm{v}}$ and $\mathrm{C}_{2\mathrm{h}}$)
(b)$\mathrm{T}_{\mathrm{d}}$ and ($\mathrm{C}_{2\mathrm{v}}$ and $\mathrm{D}_{4\mathrm{h}}$)
(c)$\mathrm{D}_{4\mathrm{h}}$ and ($\mathrm{C}_{2\mathrm{v}}$ and $\mathrm{D}_{4\mathrm{h}}$)
(d)$\mathrm{T}_{\mathrm{d}}$ and ($\mathrm{C}_{2\mathrm{v}}$ and $\mathrm{C}_{4\mathrm{v}}$)
Answer
Answer: B ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
[CoCl₄]²⁻ is tetrahedral (T_d). cis-[Co(H₂O)₄Cl₂] is C₂v and trans-[Co(H₂O)₄Cl₂] is D₄h.