JEE Main202628 January 2026Morning ShiftChemistryCoordination CompoundsActual
The correct statement among the following is:
Options
- ANi ( CO )₄ and [ Ni ( CN )₄ ]²⁻ are diamagnetic and [ NiCl ₄ ]²⁻ is paramagnetic.
- BNi ( CO )₄ and [ NiCl ₄ ]²⁻ are diamagnetic and [ Ni ( CN )₄ ]²⁻ is paramagnetic.
- C[ Ni ( CN )₄ ]²⁻ and [ NiCl ₄ ]²⁻ are diamagnetic and Ni ( CO )₄ is paramagnetic.
- DNi ( CO )₄ is diamagnetic and [ NiCl ₄ ]²⁻ and [ Ni ( CN )₄ ]²⁻ are paramagnetic.
Correct answer
A. Ni ( CO )₄ and [ Ni ( CN )₄ ]²⁻ are diamagnetic and [ NiCl ₄ ]²⁻ is paramagnetic.
Step-by-step solution
In Ni(CO)₄ , Nickel is in 0 oxidation state with configuration [Ar]3d^8 4s^2 . CO is a strong field ligand, causing pairing of 4s electrons into 3d orbitals, resulting in 3d¹⁰ configuration. It is sp^3 hybridized and diamagnetic (zero unpaired electrons). In [Ni(CN)₄]²⁻ , Nickel is in +2 oxidation state with configuration [Ar]3d^8 . CN^- is a strong field ligand, causing pairing of the two unpaired electrons in 3d orbitals. It is dsp^2 hybridized (square planar) and diamagnetic. In [NiCl₄]²⁻ , Nickel is in +2 oxida