NEET 2024, Chemistry Q12: Colour, Magnetism And Stability Of Co-ordination Compounds

NEET2024Chemistry

Given below are two statements:

Statement I: Both $[Co(NH_{3})_{6}]^{3 +}$ and $[CoF_{6}]^{3 -}$ complexes are octahedral but differ in their magnetic behavior.

Statement II: $[Co(NH_{3})_{6}]^{3 +}$ is diamagnetic whereas $[CoF_{6}]^{3 -}$ is paramagnetic.

In the light of the above statements, choose the correct answer from the options given below:

A
Statement I is true but Statement II is false.
B
Statement I is false but Statement II is true.
C
Both Statement I and Statement II are true.
D
Both Statement I and Statement II are false.

Solution

NH $_{3}$ is a strong-field ligand: with Co(III) it pairs all $d^{6}$ electrons in $t_{2 g}$ , giving a diamagnetic, low-spin complex.

F $^{-}$ is a weak-field ligand: the same $d^{6}$ Co(III) splits as $t_{2 g}^{4} e_{g}^{2}$ with four unpaired electrons, giving a paramagnetic, high-spin complex.

Both complexes are octahedral, so both statements are correct.

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NEET 2024, Chemistry Q12: Colour, Magnetism And Stability Of Co-ordination Compounds

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