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The correct statement about the magnetic properties of [Fe(CN)$$_6$$]$$^{3-}$$ and [FeF$$_6$$]$$^{3-}$$ is: (Z = 26).
To determine the magnetic properties of the complexes [Fe(CN)$$_6$$]$$^{3-}$$ and [FeF$$_6$$]$$^{3-}$$, we need to analyze the number of unpaired electrons in each complex. Paramagnetic substances have unpaired electrons, while diamagnetic substances have all electrons paired. The central metal ion is iron (Fe) with atomic number Z = 26, so its electron configuration is [Ar] 4s$$^2$$ 3d$$^6$$.
First, we find the oxidation state of iron in both complexes. For [Fe(CN)$$_6$$]$$^{3-}$$, let the oxidation state of Fe be $$x$$. Cyanide (CN$$^-$$) is a ligand with charge -1, and the complex has an overall charge of -3. So, $$x + 6 \times (-1) = -3$$, which gives $$x - 6 = -3$$, and solving for $$x$$, we get $$x = +3$$. Similarly, for [FeF$$_6$$]$$^{3-}$$, fluoride (F$$^-$$) also has charge -1, so $$y + 6 \times (-1) = -3$$, giving $$y - 6 = -3$$, and $$y = +3$$. Thus, in both complexes, iron is in the +3 oxidation state.
The electron configuration of Fe$$^{3+}$$ is derived by removing three electrons from Fe (which has configuration [Ar] 4s$$^2$$ 3d$$^6$$). The 4s electrons are removed first, followed by one from 3d, so Fe$$^{3+}$$ has configuration [Ar] 3d$$^5$$.
Now, we consider the ligands and their field strengths. Cyanide (CN$$^-$$) is a strong field ligand, causing large splitting of the d-orbitals, leading to a low-spin complex. Fluoride (F$$^-$$) is a weak field ligand, causing small splitting, leading to a high-spin complex.
For [Fe(CN)$$_6$$]$$^{3-}$$ (low-spin d$$^5$$ complex in octahedral field):
For [FeF$$_6$$]$$^{3-}$$ (high-spin d$$^5$$ complex in octahedral field):
Therefore, both complexes are paramagnetic.
Now, evaluating the options:
Hence, the correct answer is Option A.
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