Read the passage carefully and answer the questions.
The coordination compounds are of great importance. These compounds are widely present in the mineral, plants and animal world and are known to play many important functions in the area of analytical chemistry, metallurgy, biological systems, industry and medicine. For example, coordination compounds find use in many qualitative and quantitative chemical analysis. Some important metal extraction and purification make use of complex formation. Hardness of water can be estimated by stable complex formation of \( \text{Ca}^{2+} \) and \( \text{Mg}^{2+} \)
Wilkinson catalyst used for hydrogenation of alkenes is a complex of ……………
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Rhodium
Coordination compounds are used as catalysts in many industrial processes. Because such a complex dissolves in the same phase as the reactants, it acts as a homogeneous catalyst. The best known example is Wilkinson’s catalyst, \( \ce{[(Ph3P)3RhCl]} \), chloridotris(triphenylphosphine)rhodium(I), which catalyses the hydrogenation of alkenes.
The oxidation state of rhodium follows from the charges: triphenylphosphine is a neutral ligand and chloride is −1, and the complex is neutral:
\( \displaystyle x + 3(0) + (-1) = 0 \Rightarrow x = +1 \)
In its presence hydrogen adds across the C=C double bond at room temperature:
\( \displaystyle \ce{R-CH=CH2 + H2} \xrightarrow{\ce{[(Ph3P)3RhCl]}} \ce{R-CH2-CH3} \)
So Wilkinson’s catalyst is a complex of rhodium.
NCERT (2026-27 edition):
Importance and Applications of Coordination Compounds – …
