We report vibrationally resolved photoelectron spectroscopy (PES) of Au-2(CO)(n)(-) (n = 1-3), in combination with relativistic density functional theory (DFT) and ab initio Calculations. The ground-state transition in the spectrum of Au2CO- is broad, containing vibrational structures both in the bending and in the CO stretching modes and suggesting a large structural change from Au2CO- to Au2CO. The ground-state transitions for both n = 2 and 3 display a well-resolved vibrational progression in the CO stretching mode with frequencies of 2110 +/- 40 and 2160 +/- 40 cm(-1), respectively. The PES data show that chemisorption of the first two CO's each induces a significant red-shift in the electron binding energies. The third CO is physisorbed, inducing only a slight increase in electron binding energies relative to Au-2(CO)(2). Relativistic DFT and ab initio calculations are performed to determine the ground-state structures for Au-2(CO)(n)(-) and Au-2(CO)(n), and the results agree well with the experiment. Au-2(CO), Au-2(CO)(2), and Au-2(CO)(2) are all found to be linear, while Au-2(CO)(-) is bent due to the Renner-Teller effect. A strong spin-orbit effect is found in Au-2(CO)(2) that quenches the Renner-Teller effect, keeping the linear structure for this anion. The physisorption in Au-2(CO)(3) is borne out in CCSD(T) calculations. However, a wide range of DFT methods tested fail to correctly predict the relative energies of the physisorbed versus chemisorbed isomers for Au-2(CO)(3).