The interactions of Hg with benzene, thiophene and furan are studied by means of coupled cluster and second order Moller-Plesset perturbation theory (MP2) calculations. Hg forms Mulliken outer pi complexes with benzene, furan and thiophene, with binding energies of -0.15, -0.13 and -0.13 eV, respectively. The (Hg-benzene)(+) complex has a minimum energy structure in the form of a pi(eta(2)) complex with a binding energy of -2.18 eV. A low-energy (3)(Hg-benzene) complex with a binding energy of -1.34 eV has been identified. (c) 2005 Elsevier B.V. All rights reserved.