We reinvestigate the low temperature magnetic properties of the ferric whee
l, a 10 spin (S = 5/2) iron(III) complex. The energy levels for a Heisenber
g antiferromagnet with ten S = 5/2 spins are calculated exactly and found t
o be in excellent agreement: with the observed low-temperature experimental
data. By comparing the low-temperature magnetic susceptibility data with t
he exact energy levels, a coupling constant of 9.7 cm(-1) is determined.