JEE Main 2025 · 29 January · Morning Shift · Chemistry · Coordination Compounds
The correct increasing order of stability of the complexes based on...
The correct increasing order of stability of the complexes based on (\Delta_{\mathrm{o}}) value is :
I. (\left[\mathrm{Mn}(\mathrm{CN})_6\right]^{3-})
II. (\left[\mathrm{Co}(\mathrm{CN})_6\right]^{4-})
III. (\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{4-})
IV. (\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{3-})
Options
A(\mathrm{IV} \lt III \lt II \lt I)
B(I \lt II \lt \mathrm{IV} \lt) III
CIII (\lt) II (\lt) IV (\lt) I
DII (\lt) III (\lt) I (\lt) IV
Correct answer
B. (I \lt II \lt \mathrm{IV} \lt) III
Step-by-step solution
Neglecting pairing energy
I. [Mn(CN)B]3−⇒Mn3+,t2g4,CFSE=−0.4×4Δo=−1.6Δ 。
II. [Co(CN)8]4−⇒Co2+,t26eg1,CFSE=−0.4×6+0.6×1=−1.8Δ∘
III. [Fe(CN)8]4−⇒Fe2+,t2g6e0,CFSE=−0.4×6=−2.4Δ0
IV. [Fe(CN)8]3−⇒Fe3+,t2g5e0,CFSE=−0.4×5=−2Δ0
Order of stability III > IV > II > I
