JEE Main 2024 Chemistry question
Consider the following complexes: (A) [CoCl(NH₃)₅]²⁺, (B) [Co(CN)₆]³⁻, (C) [Co(NH₃)₅(H₂O)]³⁺, (D) [Cu(H₂O)₄]²⁺. The correct order of A, B, C and D in terms of wavenumber of light absorbed is:
Answer: (B)
Solution
The wavenumber absorbed increases with the crystal-field splitting: [Cu(H₂O)₄]²⁺ < [CoCl(NH₃)₅]²⁺ < [Co(NH₃)₅(H₂O)]³⁺ < [Co(CN)₆]³⁻.