Amongst [ Ni ( CO )4],[ Ni ( CN )4]2- and [ NiCl 4]2-

Question

Amongst [ Ni ( CO )4],[ Ni ( CN )4]2- and [ NiCl 4]2- (A) [ Ni ( CO )4] and [ NiCl 4]2- are diamagnetic and [ Ni ( CN )4]2- is paramagnetic (B) [ NiCl 4]2- 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 [ NiCl 4]2- is paramagnetic (D) [ Ni ( CO )4] is diamagnetic and [ NiCl 4]2- and [ Ni ( CN )2]2- are paramagnetic.

Tardigrade Admin · Accepted Answer

CO and CN- are strong field ligands and force electrons to pair up so that a diamagnetic low spin complex is resulted. However Cl - is a weak field ligand and hence does not force electrons to pair up so that a paramagnetic high spin complex results.

Q. Amongst $[N i (CO)_{4}], [N i (CN)_{4}]^{2 -}$ and $[N i C l_{4}]^{2 -}$

$[N i (CO)_{4}]$ and $[N i C l_{4}]^{2 -}$ are diamagnetic and $[N i (CN)_{4}]^{2 -}$ is paramagnetic

$[N i C l_{4}]^{2 -}$ and $[N i (CN)_{4}]^{2 -}$ are diamagnetic and $[N i (CO)_{4}]$ is paramagnetic

$[N i (CO)_{4}]$ and $[N i (CN)_{4}]^{2 -}$ are diamagnetic and $[N i C l_{4}]^{2 -}$ is paramagnetic

$[N i (CO)_{4}]$ is diamagnetic and $[N i C l_{4}]^{2 -}$ and $[N i (CN)_{2}]^{2 -}$ are paramagnetic.

$CO$ and $C N^{-}$ are strong field ligands and force electrons to pair up so that a diamagnetic low spin complex is resulted. However $C l^{-}$ is a weak field ligand and hence does not force electrons to pair up so that a paramagnetic high spin complex results.

Q. Amongst [Ni(CO)4​],[Ni(CN)4​]2− and [NiCl4​]2−

[Ni(CO)4​] and [NiCl4​]2− are diamagnetic and [Ni(CN)4​]2− is paramagnetic

[NiCl4​]2− and [Ni(CN)4​]2− are diamagnetic and [Ni(CO)4​] is paramagnetic

[Ni(CO)4​] and [Ni(CN)4​]2− are diamagnetic and [NiCl4​]2− is paramagnetic

[Ni(CO)4​] is diamagnetic and [NiCl4​]2− and [Ni(CN)2​]2− are paramagnetic.