Chemistry · Colour and magnetic properties

The calculated spin-only magnetic moments (BM) of the anionic and cationic speci

The calculated spin-only magnetic moments (BM) of the anionic and cationic species of \( \left[\boldsymbol{F} e\left(\boldsymbol{H}_{2} \boldsymbol{O}\right)_{6}\right]_{2} \) and \( \left[\boldsymbol{F e}(\boldsymbol{C} \boldsymbol{N})_{\mathbf{6}}\right], \) respectively, are:

  • A. 4 .9 and 0
  • B. 2.84 and 5.92
  • C. 0 and 4.9
  • D. 0 and 5.92

Step-by-step solution

[Fe(H2O)6]^{2+} is a high-spin d6 complex with 4 unpaired electrons, giving μ = √(4×6) = √24 ≈ 4.9 BM. [Fe(CN)6]^{4-} is a low-spin d6 complex with 0 unpaired electrons, giving μ = 0 BM. The anionic species is the cyanide complex (0 BM) and the cationic species is the aqua complex (4.9 BM), so the order is 0 then 4.9.
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