The energy demands for the reduction reactions were determined from energy-resolved collision induced dissociation experiments with mass-selected [(bipy)Au III X2] + and [(bipy)Au II X] + (Figure and Figure ). The extrapolation of the energydependent relative fragmentation cross-section for the elimination of the halogen atom provides the experimental Au-X bonddissociation energy (see the Experimental Details). The energy difference between the energy demands for the Au III → Au II and Au II → Au I reductions decrease in the order of X: I > Br > Cl (Table ). Hence, the iodo complexes provide the largest interval of energies that allow the formation of the gold(II) complexes from their gold(III) precursors. However, with respect to the low stability of the gold(III) iodo precursors, the bromine complexes are probably the best candidates for studying gold(II) complexes in the gas phase.