Co-Ordination Compounds Question 270
Question: Which of the following is diamagnetic?
Options:
A) $ {{[Fe{{(CN)}_6}]}^{3-}} $
B) $ {{[Co{{(ox)}_3}]}^{3-}} $
C) $ {{[ FeF_6 ]}^{3-}} $
D) $ {{[CoF_6]}^{3-}} $
Show Answer
Answer:
Correct Answer: B
Solution:
$ {{[Fe{{(CN)}_6}]}^{3-}} $ has magnetic moment of a single unpaired electron whereas $ {{[FeF_6]}^{3-}} $ has a magnetic moment of five unpaired electrons.
$ {{[CoF_6]}^{3-}} $ is paramagnetic with four unpaired electrons while $ {{[Co{{(C_2O_4)}_3}]}^{3}} $ is diamagnetic.
This anomaly is explained by valence bond theory in terms of formation of inner and outer orbital coordination entities.
$ {{[Co{{(C_2O_4)}_3}]}^{3-}} $ is an inner orbital complexes having $ d^{2}sp^{3} $ hybridization.
