High-resolution infrared spectra are reported for two isomers of the magnesium-HCN binary complex, corresponding to the magnesium bonding at the nitrogen and hydrogen ends of the molecule. Stark spectra are also reported for these complexes, from which the corresponding dipole moments are determined. Ab initio calculations confirm that the potential energy surface has two minima, consistent with the experimentally determined structures. The wave functions of the two dimensional intermolecular coupled cluster singles doubles (triples) potential energy surface, calculated with the collocation method, are also reported for the magnesium-HCN system and are used to calculate the vibrationally averaged dipole moment for both isomers, which are then compared to experiment. (C) 2003 American Institute of Physics.