Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
Among the following $\mathrm{Cr}(\mathrm{III})$ complexes, which one will have the highest octahedral crystal field splitting?
ChemistryCoordination CompoundsTS EAMCETTS EAMCET 2020 (14 Sep Shift 1)
Options:
  • A $\left[\mathrm{CrF}_6\right]^{3-}$
  • B $\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{3+}$
  • C $\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
  • D $\left[\mathrm{Cr}(\mathrm{CN})_6\right]^{3-}$
Solution:
1974 Upvotes Verified Answer
The correct answer is: $\left[\mathrm{Cr}(\mathrm{CN})_6\right]^{3-}$
A strong field ligand will enable higher crystal field splitting. It can be predicted from the relative position of a ligand in spectrochemical series.
In the given octahedral complexes of $\mathrm{Cr}(\mathrm{II})$ ion, the ligands are $\mathrm{F}^{-}, \mathrm{H}_2 \mathrm{O}, \mathrm{NH}_3$ and $\mathrm{CN}^{-}$and their increasing order of field strength in spectrochemical series is
$\mathrm{F}^{-} < \mathrm{H}_2 \mathrm{O} < \mathrm{NH}_3 < \mathrm{CN}^{-} \text {. }$
So, highest octahedral crystal field splitting is present in $\left[\mathrm{Cr}(\mathrm{CN})_6\right]^{3-}$.

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.