Verified Solution • 2025–26 Session moderate

QJEEM22Chad5c: JEE Main 2022 Chemistry - Class 12 JEEM22Chad5c Solution: Consider the following metal complexes : The spin-only magnetic …

Consider the following metal complexes :

[Co(NH3)6]3+\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}

[CoCl(NH3)5]2+\left[\mathrm{CoCl}\left(\mathrm{NH}_{3}\right)_{5}\right]^{2+}

[Co(CN)6]3−\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}

[Co(NH3)5(H2O)]3+\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}

The spin-only magnetic moment value of the complex that absorbes light with shortest wavelength is _____________ B. M. (Nearest integer)

Step-by-Step Verified Solution

In all complexes, Co is present in +3+3 oxidation state and all complexes are low spin or inner orbital complex.

The stronger the ligand, the higher the crystal field splitting.

So, the order of crystal field splitting is

\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}>\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}>\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}> [CoCl(NH3)5]2+\left[\mathrm{CoCl}\left(\mathrm{NH}_{3}\right)_{5}\right]^{2+}

Shortest wavelength is shown by complex having maximum crystal field splitting.

JEE Main 2022 (Online) 25th July Morning Shift Chemistry - Coordination Compounds Question 125 English Explanation
Spin only magnetic moment =0(0+2)=0=\sqrt{0(0+2)}=0 B.M

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