Question

Valence bond theory describes the bonding in complexes in terms of coordinate-covalent bonds resulting from the overlap of filled ligand orbitals with vacant metal hybrid orbitals. This theory explains the magnetic behavior and geometrical shape of coordination compounds. The magnetic moment of a complex compound can be determined experimentally and theoretically by using spin only formula.

Magnetic moment = $\sqrt{n(n+2)}$ B.M. (where n = No. of unpaired electrons}.

The value of spin only magnetic moment for an octahedral complex of the following configuration is 2.84 B.M. The correct statement is :

• A. $d^4$ (in weak field ligand)
• B. $d^2$ (in weak field and in strong field ligand)
• C. $d^3$ (in weak field and in strong field ligand)
• D. $d^5$ (in strong field ligand)

Answer 1

The correct option is B $d^2$ (in weak field and in strong field ligand)

$d^4$ (in weak field ligand)
$t_{2g}^3{e}_g^1$
Magnetic moment- $\sqrt{24}-4.9BM$
$d^2$ (in weak field and in strong field ligand)
$t_{2g}^2{e}_g^0$
Magnetic moment- $\sqrt{8}-2.84BM$
$d^3$ (in weak field and in strong field ligand)
$t_{2g}^3{e}_g^0$
Magnetic moment- $\sqrt{15}-3.89BM$
$d^5$ (in strong field ligand)
$t_{2g}^5{e}_g^0$
Magnetic moment- $\sqrt{3}-1.7BM$