NEET2017ChemistryCoordination CompoundsActual
The correct increasing order for the wavelengths of absorption in the visible region for the complexes of Co 3 + is:
Options
- ACo en 3 3 + ,   Co NH 3 6 3 + ,   Co H 2 O 6 3 +
- BCo H 2 O 6 3 + ,   Co en 3 3 + ,   Co NH 3 6 3 +
- CCo H 2 O 6 3 + ,   Co NH 3 6 3 + ,   Co en 3 3 +
- DCo NH 3 6 3 + ,   Co en 3 3 + ,   Co H 2 O 6 3 +
Correct answer
A. Co en 3 3 + ,   Co NH 3 6 3 + ,   Co H 2 O 6 3 +
Step-by-step solution
The order of the ligand in the spectrochemical series H 2 O < NH 3 < en Absorbed wavelength ∝ 1 Absorbed   energy Thus, the order of observed energy is: Co H 2 O 6 3 + < Co NH 3 6 3 + < Co en 3 3 + Hence, the wavelength absorbed will be in the opposite order i.e., Co en 3 3 + <   Co NH 3 6 3 + <   Co H 2 O 6 3 + .