Question

Which of the following statements are true about \( [NiCl_4]^{2-} \)?
(a) The complex has tetrahedral geometry.
(b) Co-ordination number of Ni is 2 and oxidation state is +4.
(c) The complex is sp\(^3\) hybridised.
(d) It is a high spin complex.
(e) The complex is paramagnetic.

• A. a, b, d and e
• B. b, c, and d
• C. a, b, c and d
• D. a, c, d and e

Hint:

For transition metal complexes, the geometry, hybridization, and magnetic properties are strongly influenced by the coordination number and the electronic configuration of the metal ion.

Answer 1

The Correct Option is D

For the complex \( [NiCl_4]^{2-} \), the key points to remember are:
- Nickel in \( [NiCl_4]^{2-} \) has an oxidation state of +2, not +4. Therefore, statement (b) is incorrect.
- The complex has a tetrahedral geometry, as typically seen with \( \text{Ni}^{2+} \) complexes, and the coordination number is 4. Statement (a) is correct.
- The complex is sp\(^3\) hybridised because it has a tetrahedral geometry, and 4 equivalent hybrid orbitals are required. Statement (c) is correct.
- \( [NiCl_4]^{2-} \) has two unpaired electrons in its \( d \)-orbitals, making it a high spin complex. Therefore, statement (d) is correct.
- The complex is paramagnetic because of the presence of unpaired electrons. Statement (e) is correct.
Thus, the correct answer is:
\[ \text{(4) a, c, d and e}
\]