Based on the topology of C-60 and the resulting non-disjoint nature of
the lowest unoccupied molecular orbitals, Ne propose a new model for
ferromagnetic exchange in C-60-TDAE. Within the Hubbard model, we find
that the ferromagnetic exchange integral is stabilized to first order
in the inter-ball transfer integral, while the antiferromagnetic coup
ling is stabilized only to second order. This difference is adequate t
o counter the larger phase space available for stabilizing the antifer
romagnetic state. Thus, the ground state is found to be ferromagnetic
for reasonable inter-ball transfer integrals.