Question

Which of the following are paramagnetic?

1. [NiCl₄]²⁻
2. Ni(CO)₄
3. [Ni(CN)₄]²⁻
4. [Ni(H₂O)₆]²⁺
5. Ni(PPh₃)₄

Choose the correct answer from the options given below:

विकल्प

• A and C only

• B and E only

• A and D only

• A, D and E only

Answer 1

A and D only

Explanation:

[NiCl₄]²⁻ and [Ni(H₂O)₆]²⁺: Nickel is in the +2 oxidation state (3d⁸). Since Cl⁻ and H₂O are weak-field ligands, they do not force electrons to pair up. This leaves 2 unpaired electrons in both, making them paramagnetic.

Ni(CO)₄, [Ni(CN)₄]²⁻ and Ni(PPh₃)₄: These complexes contain strong field ligands (CO, CN⁻, Phh₃). These ligands force all electrons to pair up (creating d¹⁰ or square planar d⁸ configurations), making them diamagnetic.