Question

If ${\Delta }_o$ and ${\Delta }_t$ represent crystal field splitting energies for d-orbitals for octahedral and tetrahedral geometries respectively, then for $d^6$ (high spin in both cases), what are CFSE (ignore the pairing energy) respectively?

• A. $0.6{\Delta }_o$ and $0.6{\Delta }_t$
• B. $0.4{\Delta }_o$ and $0.4{\Delta }_t$
• C. $0.4{\Delta }_o$ and $0.6{\Delta }_t$
• D. $0.6{\Delta }_o$ and $0.4{\Delta }_t$

Answer 1

The correct option is C $0.4{\Delta }_o$ and $0.6{\Delta }_t$

For octahedral $d^6$(high spin) CFSE is 4(-0.4) + 2(0.6)= -0.4 ${\Delta }_o$
For tetrahedral $d^6$(high spin) CFSE is 3(-0.6) + 3(0.4)= -0.6 ${\Delta }_t$