Question

Of the following complex ions, which is diamagnetic in natures?
A. (a) `[CoF_6]^(3-)`
B. (b) `[NiCl_4]^(2-)`
C. (c) `[Ni(CN)_4]^(2-)`
D. (d) `[CuCl_4]^(2-)`

Answer 1

Correct Answer - C
`Ni^(2+)` has two unpaired `(3d^(8))` electrons. `CN^(-)` is strong field ligand and thus all the eight electrons are paired giving `dsp^2`-hybridization.
`{:(,,,Hybri d,No . of),(,,,isation,unpaired),(,,,,el ectrons),((a),[Co]^(+3),[Ar]^(18)3d^6,sp^3d^2,4),((b),[Ni]^(+2),[Ar]^(18)3d^(8),sp^3,2),((c),[Ni]^(+2),[Ar]^(18)3d^(8),dsp^2,0as CN^(-)has),(,,,, caused fo rced pairi ng),((d),[Cu]^(+2),[Ar]^(18)3d^9,sp^3,1):}`