How many unpaired electrons are there in a strong-field octahedral Fe³⁺ complex?

Question

Quizplus · Accepted Answer

The Fe(II) ion has 6 electrons in its d-orbitals, and the S^2- ion contributes 1 electron to the complex. The ligands involved are strong-field, so they will cause pairing of the electrons in the d-orbitals of Fe(II). In octahedral complexes, electrons occupy the d-orbitals in the order: t2g before eg. Therefore, the 5 electrons will occupy t2g orbitals and the remaining single electron will enter an eg orbital. Hence, the complex has one unpaired electron.

How Many Unpaired Electrons Are There in a Strong-Field Octahedral