The crystal field splitting energy of $\left[\ce{Co(oxalate)3}\right]^{3-}$ complex is 'n' times that of the $\left[\ce{Cr(oxalate)3}\right]^{3-}$ complex. Here 'n' is \_\_\_\_ . [Assume $\Delta_{0} \gg P$ ]

JEE Main · 2026 · 23 Jan 2026 · Shift 1 · Coordination Compounds

The crystal field splitting energy of

[Co (oxalate) X_{3}]^{3 -}

complex is 'n' times that of the

[Cr (oxalate) X_{3}]^{3 -}

complex. Here 'n' is ____ . [Assume

Δ_{0} ≫ P

]

Answer: 2

Solution

[Co(ox)_{3}]^{3 -}

the metal is

Co^{3 +}

, a

d^{6}

ion; with

Δ_{0} ≫ P

the configuration is low spin

t_{2 g}^{6} e_{g}^{0}

, giving a crystal field stabilisation energy of

6 \times (- 0.4 Δ_{0}) = - 2.4 Δ_{0}

. In

[Cr(ox)_{3}]^{3 -}

the metal is

Cr^{3 +}

, a

d^{3}

ion with configuration

t_{2 g}^{3} e_{g}^{0}

, giving

3 \times (- 0.4 Δ_{0}) = - 1.2 Δ_{0}

. The ratio of the two stabilisation energies is

\frac{- 2.4 Δ _{0}}{- 1.2 Δ _{0}} = 2

, so

n = 2

JEE Main · 2026 · 23 Jan 2026 · Shift 1 · Integer answer

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