We calculate within density functional theory (DFT) and the LSDA+U formalism the electronic properties of a nanostructure in which single-molecule magnets Mn(12) are adsorbed via thiol groups onto the Au(111) surface. Our DFT calculation shows 1.23 electrons being transferred from the surface to the Mn(12) molecule, dominated by the tail on the electronic charge distribution from the gold slab. LSDA+U calculations reveal that the on-site Coulomb repulsion U does not alter the direction of the electronic charge transfer obtained from DFT, because the gold Fermi level still lies above the lowest unoccupied molecular orbital (LUMO). The U term opens up the energy gap between the highest occupied molecular orbital (HOMO) and the LUMO for an isolated standard Mn(12) but it minimally affects the gap for a sulfur-terminated Mn(12). (c) 2008 American Institute of Physics.