We? present infrared spectra of [Cu(CO2)(n)](-) (n = 2-9) clusters in the wavenumber range 1600-2400 cm(-1). The CO stretching modes in this region encode the structural nature of the cluster core and are interpreted with the aid of density functional theory. We find a variety of core species in [Cu(CO2)(n)](-) clusters, but the dominant core structure is a [Cu(CO2)(2)](-) core where the two CO2 ligands are bound to the Cu atom in a bidentate fashion. We compare the results of [Cu(CO2)(n)](-) lusters to those of other [M(CO2)(n)](-) clusters (M = Au, Ag, Co, Ni) to establish trends of how the metal-CO2 interaction depends on the metal partner.