  We investigate single molecule magnet transistors (SMMTs) with ligands that
support transport resonances. We find the lowest unoccupied molecular orbitals
of Mn12-benzoate SMMs (with and without thiol or methyl-sulfide termination) to
be on ligands, the highest occupied molecular orbitals being on the Mn12
magnetic core. We predict gate controlled switching between Coulomb blockade
and coherent resonant tunneling in SMMTs based on such SMMs, strong spin
filtering by the SMM in both transport regimes, and that if such switching is
observed then the magnetic easy axis of the SMM is parallel to the direction of
the current through the SMM.
