The intrinsic gas-phase stability of the IrCl63- trianion and its inicrosolvated clusters, IrCl(6)(3-)center dot(H2O)(n) n = 1-10, have been investigated using density functional theory (DFT) calculations. Although IrCl63+ is known to exist as a stable complex ion in bulk solutions, our calculations indicate that the bare trianion is metastable with respect to decay via both electron detachment and ionic fragmentation. To estimate the lifetime of IrCl63-, we have computed the electron tunneling probability using an adaption of the Wentzel-Kranier-Brillouin theory and predict that the trianion will decay spontaneously via electron tunneling on a time scale of 2.4 x 10(-13) s. The global minimum structure for IrCl(6)(3-)center dot H2O was found to contain a bifurcated hydrogen bond, whereas for IrCl(6)(3-)center dot(H2O)(2), two low energy minima were identified, one involving two bifurcated water-ion hydrogen bonds and a second combining a bifurcated hydrogen bond with a water-water hydrogen bond. Clusters based on each of these structural motifs were obtained for all of the n = 3-10 systems, and the effect of solvation on the possible decay pathways was explored. The calculations reveal that solvation stabilizes IrCl63- with respect to both electron detachment decay and ionic fragmentation. with the magnitude of the repulsive Coulomb barrier for ionic fragmentation increasing smoothly with sequential solvation. This study is the first to compare the propensity for electron detachment versus ionic fragmentation decay for a sequentially solvated triply charged anion.