To understand the interactions between nucleobases and coinage metal cations, we conducted combined photodissociation and density functional theory studies on A2M+ and G2M+ (A=adenine, G=guanine, M=Cu, Ag, and Au) cations. The nucleobase-metal complexes were produced by laser ablation and detected by a reflectron time-of-flight mass spectrometer. The mass peaks of A2M+ and G2M+ cations have high intensities in the mass spectra of AnM+ and GnM+ complexes, indicating that these cations have relatively high stabilities. They were mass-selected and then photodissociated by 266nm photons. Their photodissociation spectra clearly show that the loss of adenine or guanine is the predominant channel for these complexes. The density functional theory calculations show that A2M+ and G2M+ complexes prefer planar structures with the metal cations interacting with the N atoms in the carbon-nitrogen rings of adenine and guanine. The calculated bond dissociation energies of different dissociation channels are in good agreement with the experimental observed fragment ions.