Q134 / 200 · MHT CET - Medical 2026 (24 April Shift 1) · Chemistry
Identify the geometry and magnetic behavior of the complex $[\text{Ni}(\text{CO})_4]$.
- Asquare planar geometry and diamagnetic
- Correct answerBtetrahedral geometry and diamagnetic
- Csquare planar geometry and paramagnetic
- Dtetrahedral geometry and paramagnetic.
Solution
The oxidation state of $\text{Ni}$ in $[\text{Ni}(\text{CO})_4]$ is $0$.
The electronic configuration of $\text{Ni}(0)$ is $[\text{Ar}] 3d^8 4s^2$.
Since $\text{CO}$ is a strong field ligand, it causes the pairing of electrons. The two $4s$ electrons are forced into the $3d$ orbitals, resulting in a completely filled $3d^{10}$ configuration.
The empty $4s$ and three $4p$ orbitals undergo $sp^3$ hybridization to accommodate the four electron pairs from the four $\text{CO}$ ligands.
Due to $sp^3$ hybridization, the geometry of the complex is tetrahedral.
Since all electrons are paired, the complex is diamagnetic.
Answer: tetrahedral geometry and diamagnetic
The electronic configuration of $\text{Ni}(0)$ is $[\text{Ar}] 3d^8 4s^2$.
Since $\text{CO}$ is a strong field ligand, it causes the pairing of electrons. The two $4s$ electrons are forced into the $3d$ orbitals, resulting in a completely filled $3d^{10}$ configuration.
The empty $4s$ and three $4p$ orbitals undergo $sp^3$ hybridization to accommodate the four electron pairs from the four $\text{CO}$ ligands.
Due to $sp^3$ hybridization, the geometry of the complex is tetrahedral.
Since all electrons are paired, the complex is diamagnetic.
Answer: tetrahedral geometry and diamagnetic
Hence, the correct answer is option: 'B'.