Question

The geometry and magnetic behaviour of the complex $\left[Ni\right(CO{)}_4]$ are ______.

• A. Square planar geometry and paramagnetic
• B. Square planar geometry and diamagnetic
• C. Tetrahedral geometry and paramagnetic
• D. Tetrahedral geometry and diamagnetic

Answer 1

The correct option is D Tetrahedral geometry and diamagnetic

In $Ni(CO{)}_4$, $Ni$ is in the zero oxidation state i.e., it has a configuration of $3d^{8}4s^2$. Since $CO$ is a strong field ligand, it causes the pairing of unpaired 3d electrons.

Also, it causes the 4s electrons to shift to the $3d$ orbital, thereby giving rise to $s{p}^3$ hybridization and hence, tetrahedral shape.

Since no unpaired electrons are present in this case, [Ni(CO)4] is diamagnetic.

Hence, the correct option is D.