Question

Amongst Ni(CO)4, [Ni(CN)4]2– and NiCI42– :

• A. Ni(CO)4 and NiCI42– are diamagnetic and [Ni(CN)4]2– is paramagnetic.
• B. NiCI42– and [Ni(CN)4]2– are diamagnetic and Ni(CO)4 is paramagnetic.
• C. Ni(CO)4 and [Ni(CN)4]2– are diamagnetic and NiCI42– is paramagnetic.
• D. Ni(CO)4 is diamagnetic and, NiCI42– and [Ni(CN)4]2– are paramagnetic.

Answer 1

Answer: (C)

Ni(CO)4 and $Ni(CN)4$2– are diamagnetic and NiCI42– is paramagnetic.

Answer 2

in complex, [ni(co)4] nickel is in zero oxidation state. the co is strong field ligand and, therefore compels for the pairing of electrons. the hybridisation scheme is as shown in figure.

Ni0([ar] 3d8 4s2)

[Ni(co)4]

sp3 hybrid orbitals

four pairs of electrons from four co.

it is tetrahedral and as all electrons are paired so diamagnetic.

in the diamagnetic and square planar complex [ni(cn)4]2–, the nickel is in +2 oxidation state and the ion has the electronic configuration 3d8. the hybridisation scheme is as shown in figure.

Ni2+, [Ar]3d8

**[Ni(CN)**4]2–

dsp2 hybrid orbitals

In the paramagnetic and tetrahedral complex [nicl4]2–, the nickel is in +2 oxidation state and the ion has the electronic configuration 3d8. the hybridisation scheme is as shown in figure.

Ni2+, [Ar]3d8

[NiCl4]2–

sp3 hybrid orbitals