Question

Which of the following configurations has same spin multiplicity irrespective of the ligands strength in an octahedral complex?

• A. $d^4$
• B. $d^5$
• C. $d^3$
• D.
  $d^7$

Answer 1

The correct option is C $d^3$

The number of unpaired electrons in $d^3$ will be same irrespective of whether a ligand is strong field or weak field.
$t_{2g}^3{e}_g^0$

In case of $d^4$,
The electronic configuration for weak field ligand will be:
$t_{2g}^3{e}_g^1$
The electronic configuration for strong field ligand will be:
$t_{2g}^4{e}_g^0$

In case of $d^5$
The electronic configuration for weak field ligand will be:
$t_{2g}^3{e}_g^2$
The electronic configuration for strong field ligand will be:
$t_{2g}^5{e}_g^0$

In case of $d^7$
The electronic configuration for weak field ligand will be:
$t_{2g}^5{e}_g^2$

The electronic configuration for strong field ligand will be
$t_{2g}^6{e}_g^1$