Determine the number of unpaired electrons expected for [fe(no2)6]3−and for [fef6]3− in terms of crystal field theory.

A. One unpaired electron

B. 5 unpaired electrons

Explanation:

In A ,Fe is in +3 oxidation state and Electronic configuration- [Ar]3d5

And NO2 is a strong field ligand hence it causes pairing in t2g orbitals and results one unpaired electron in dZX orbital.

In B, also Fe is in +3 oxidation state but F is weak field ligand hence causes no pairing of Electrons hence it results 5 unpaired electrons with electronic configuration t2g^3 eg^2

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