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
In which of the following octahedral complexes of $\operatorname{Co}($ At. no. 27$)$, will the magnitude of $\Delta_{0}$ be the highest?
ChemistryCoordination CompoundsVITEEEVITEEE 2011
Options:
  • A $\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}$
  • B $\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]^{3-}$
  • C $\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$
  • D $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$
Solution:
1416 Upvotes Verified Answer
The correct answer is: $\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}$
Spectrochemical series. According to the strength of splitting is as:
$$
\begin{array}{l}
\mathrm{CO}>\mathrm{CN}^{-}>\mathrm{NO}_{2}^{-}>\text {en }>\mathrm{NH}_{3}>\text { py }>\mathrm{NCS}^{-} \\
>\mathrm{H}_{2} \mathrm{O}>\mathrm{O}^{2-}>\mathrm{Ox}^{2-}>\mathrm{OH}^{-}>\mathrm{F}>\mathrm{Cl}^{-} \\
>\mathrm{SCN}^{-}>\mathrm{S}^{2-}>\mathrm{Br}^{-}>\mathrm{I}^{-}
\end{array}
$$
Crystal field stabilisation energy (CFSE) for octahedral complex, $\Delta^{\circ}$ dependson the strength of negative ligand. [Higher the strength more will be theCFSE]

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.