Geometries, binding energies, and vibrational frequencies of RgMF, Rg = He, Ne; M = Cu, Ag, Au, are investigated by using the CCSD(T)/V5Z method with scalar relativistic effects taken into account. The results show that helium is more readily bound in RgMF than neon (because of its smaller atomic radius), resulting in weak, but significant, helium-metal bonding in HeCuF and HeAuF. The binding energies for these two compounds are 1632 and 1543 cm(-1), respectively, so it is quite likely that they may be formed under appropriate experimental conditions. The mechanism of bonding is also analyzed. (C) 2009 Elsevier B. V. All rights reserved.