Question

The value of the spin only magnetic moment for one of the following configurations is 2.84 BM. The correct one is:

Options

• d⁵ (in strong ligand field)

• d³ (in weak as well as in strong fields)

• d⁴ (in weak ligand fields)

• d⁴ (in strong ligand fields)

Answer 1

d⁴ (in strong ligand fields)

Explanation:

(1) d⁵ - in strong ligand field

μ = `sqrt("n"("n" + 2))`

= `sqrt3`

= 1.73 BM

(2) d³ - in weak as well as in strong fields

μ = `sqrt(3(5))`

= `sqrt15`

= 3.87 BM

(3) d⁴ - in weak ligand fields

μ = `sqrt(4(4 + 2))`

= `sqrt24`

= 4.89 BM

(4) d⁴ - in strong ligand fields

μ = `sqrt(2(4))`

= `sqrt8`

= 2.82 BM

In a strong ligand field, d⁴ results in 2 unpaired electrons due to pairing in the lower t_2g​ orbitals, giving a magnetic moment of 2.84 BM.

Other configurations either have different numbers of unpaired electrons or lead to different magnetic moment values.