Sample Exercise
Predict the number of unpaired electrons in 6-coordinate high-spin and low-spain complexes of Fe3+
SOLUTION The Fe3+ ion possesses five 3d electrons. In a high-spin complex, these are all umpaired. In a low-spincomplex the electrons are confined to the lower-energy set of d orbitals, with the result that there is one unpaired electron:
Practice Exercise
For which d electron configurations does the possibility of a distinction between high-spin and low-spin arrangement exist in octahedral complexes? Anwer : d4, d5, d6, d7