Coordination Compounds

Consider the following complex ions P = [FeF6]3- Q = [V(H2O)6]2+ R = [Fe(H2O)6]2+ The correct order of the complex ions, according to their spin only magnetic moment values (in B.M.) is :

1. R < Q < P
2. R < P < Q
3. Q < R < P
4. Q < P < R

Answer

(3) Q < R < P

Solution

F- and H2O are weak-field ligands ⇒ high spin (no pairing in t2g until eg is filled); = n(n+2) BM

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∴ Q (3.87) < R (4.90) < P (5.92)

Answer: (3)