Question

Which of the following system has maximum number of the unpaired electrons in an inner octahedral complex ?

• A. $d^4$
• B. $d^9$
• C. $d^7$
• D. $d^5$

Answer 1

Answer: (A)

$d^7$ and $d^9$ does not form an inner d-orbital complex.
In case of $d^4⟶4$ unpaired $e^{-}s$ are present is an inner octahedral complex if the weak ligand is present; in case of strong ligand no unpaired $e^{-}$.
In case of $d^5⟶$ the no. of unpaired $e^{-}$depends on the strength of the ligand.
Because in the presence of weak ligand inner orbital octahedral complex is not possible.
But in case of a strong field only $1$ unpaired $e^{-}$present.