Question

The spin only magnetic moment of $[NiCl_4]^{2-}$ is_ _ _ _ (Nearest integer).

Hint:

Tetrahedral complexes are always high spin due to small crystal field splitting. For \(d^8\) tetrahedral, unpaired electrons = 2.

Answer 1

Correct Answer: 3

Step 1: Understanding the Concept:
Magnetic moment depends on the number of unpaired electrons (\(n\)). We need to determine the oxidation state of the central metal ion and its electronic configuration under the influence of the ligands.
Step 2: Key Formula or Approach:
Spin-only magnetic moment \(\mu = \sqrt{n(n + 2)}\text{ B.M.}\)
: Detailed Explanation:
1. Oxidation state of Ni in \([NiCl_{4}]^{2-}\): \(x + 4(-1) = -2 \Rightarrow x = +2\).
2. Electronic configuration of \(Ni^{2+}\) (\(Z = 28\)): \([Ar] 3d^{8}\).
3. Ligand nature: \(Cl^{-}\) is a weak field ligand. It does not cause pairing of electrons.
4. Arrangement in \(d^{8}\):
- In a tetrahedral complex (CN=4 with weak field), the \(e\) orbitals are lower and \(t_{2}\) higher.
- Configuration: \(e^{4} t_{2}^{4}\).
- Distribution in \(d\) subshell: \(\uparrow \downarrow\) \(\uparrow \downarrow\) \(\uparrow \downarrow\) \(\uparrow\) \(\uparrow\)
- Number of unpaired electrons (\(n\)) \(= 2\).
5. Calculation:
\[ \mu = \sqrt{2(2 + 2)} = \sqrt{8} \approx 2.83\text{ B.M.} \]
The nearest integer is \(3\).
Step 3: Final Answer:
The spin only magnetic moment is approximately \(3\text{ B.M.}\)