Which one of the following is a tetrahedral complex as well as diamagnetic in nature?
- (a)$[\text{Ni}(\text{CN})_4]^{2-}$
- (b)$[\text{NiCl}_4]^{2-}$
- (c)$[\text{Cu}(\text{NH}_3)_4]^{2+}$
- (d)$[\text{Ni}(\text{CO})_4]$
Answer
Answer
AIWritten by AI (gemini) - it can contain mistakes.
Correct option: (d)
Answer: (d) $[\text{Ni}(\text{CO})_4]$
In $[\text{Ni}(\text{CO})_4]$, nickel is in zero oxidation state ($3d^8 4s^2$). Strong field carbonyl ligands cause pairing of the $4s$ electrons into $3d$ orbitals to give $3d^{10}$, leaving $4s$ and $4p$ orbitals for $sp^3$ hybridization (tetrahedral geometry). With no unpaired electrons, the complex is diamagnetic.
From ISC 2026 Chemistry Paper 1, question 1(B)(i).