Question

Amongst Ni(CO)₄], [Ni(CN)₄]²⁻ and [NiCl₄]²⁻:

Options

• [Ni(CO)₄] and [NiCl₄]²⁻ are diamagnetic and [Ni(CN)₄]²⁻ is paramagnetic.

• [NiCl₄]²⁻ and [Ni(CN)₄]²⁻ are diamagnetic and [Ni(CO)₄] is paramagnetic.

• [Ni(CO)₄] and [Ni(CN)₄]²⁻ are diamagnetic and [NiCl₄]²⁻ is paramagnetic.

• [Ni(CO)₄]is diamagnetic and [NiCl₄]²⁻ is paramagnetic.

Answer 1

[Ni(CO)₄] and [Ni(CN)₄]²⁻ are diamagnetic and [NiCl₄]²⁻ is paramagnetic.

Explanation:

Ni (28) = [Ar]3d⁸, 4s²

Ni²⁺ = [Ar]3d⁸

There are two unpaired electrons in both Ni (28) and Ni²⁺. Strong field ligands like CO and CN⁻ cause unpaired electrons to couple. Therefore, [Ni(CN)₄]²⁻ and Ni(CO)₄ are diamagnetic. [NiCl₄]²⁻ is paramagnetic because Cl⁻ is a weak field ligand.