Which of the following are paramagnetic? [NiCl4]2− Ni(CO)4 [Ni(CN)4]2− [Ni(H2O)6]2+ Ni(PPh3)4 Choose the correct answer from the options given below:

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.

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Which of the following are paramagnetic? A. [NiCl4]2− B. Ni(CO)4 C. [Ni(CN)4]2− D. [Ni(H2O)6]2+ E. Ni(PPh3)4 Choose the correct answer from the options given below:

Question

Which of the following are paramagnetic?

[NiCl₄]²⁻
Ni(CO)₄
[Ni(CN)₄]²⁻
[Ni(H₂O)₆]²⁺
Ni(PPh₃)₄

Choose the correct answer from the options given below:

Options

A and C only
B and E only
A and D only
A, D and E only

MCQ

Solution

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.