Q39 · CSIR NET Chemistry, June 2016
Paper: CSIR NET June 2016 · Subject: Inorganic Chemistry · Chapter: Coordination Chemistry · Topic: Molecular Orbital Ligand Field · Marks: 2 · Difficulty: Easy
The complex that shows orbital contribution to the magnetic moment, is
(a)$\left[\mathrm{Cu}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$
(b)$\left[\mathrm{Ni}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$
(c)$\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$
(d)$\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$
Answer
Answer: C ✓ checked by 4AB · confidence high
Explanation
[Co(H₂O)₆]²⁺ has a ⁴T₁g ground term (orbitally degenerate) and shows a large orbital contribution (μ ≈ 4.8–5.2 BM); Cu²⁺ (²E_g), Ni²⁺ (³A₂g) and Cr²⁺ (⁵E_g) do not.
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