# 9.19     $[Cr(NH_{3})_{6}]^{3+}$is paramagnetic while $[Ni(CN)_{4}]^{2-}$is diamagnetic. Explain why?

D Devendra Khairwa

In  $[Cr(NH_{3})_{6}]^{3+}$ the oxidation state of the compound is +3. Its electronic configuration is d3.  Also, NH3 is a weak field ligand so the pairing of electrons will not occur.

So this compound is paramagnetic in nature.

In $[Ni(CN)_{4}]^{2-}$ the oxidation state of the Ni is +2.  Its electronic configuration is d8.   Also, CN- is a strong field ligand so the pairing of electrons will occur.

Hence the above compound is diamagnetic in nature.

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