[shafaifer]

I have a molecule (and an exercise) attached to this thread. My friend thinks that "a" is the correct answer but I would go for "d" because; shouldn't a 5 coordinated Fe(III) center contribute to a smaller value of Δ_oct compared to the same influence of a 6-coordinated complex? Then it tends to be high spin and thus Fe(III) will easier be reduced to Fe(II).