question_answer

Of the following complex ions, which is diamagnetic in nature?

A) \[{{[Ni{{(CN)}_{4}}]}^{2-}}\]       

B)        \[{{[CuC{{l}_{4}}]}^{2-}}\]            

C)        \[{{[Co{{F}_{6}}]}^{3-}}\]             

D)        \[{{[NiC{{l}_{4}}]}^{2-}}\]             

Correct Answer: A

Solution :

Electronic configuration of \[N{{i}^{2+}}\] in \[{{[Ni{{(CN)}_{4}}]}^{2-}}\] is \[N{{i}^{2+}}=3{{d}^{8}}4{{s}^{o}}\] \[\text{N}{{\text{i}}^{\text{2+}}}\]has \[ds{{p}^{2}}\] hybridisation, as \[\text{C}{{\text{N}}^{-}}\]is a strong field ligand. \[\therefore {{[Ni{{(CN)}_{4}}]}^{2-}}\]is diamagnetic (because of the absence of unpaired electrons).