The reactions of ammonia, pyridine (py), N-methyl imidazole (N-Melm), tetrahydrothiophene (tht), and piperidine (pip) with Re(CO)(3)(H2O)(3)(+), 1(+), were investigated employing aqueous conditions under atmospheric dioxygen. The reaction of [1]Br in aqueous ammonia led to [Re(CO)(3)(NH3)(3)]Br ([2]Br) as the only product isolated. For the aqueous reactions of [1]Br with py, N-Melm, and tht, mixtures of products are formed because of competition between the bromide and added ligand, even when the ligand is present in excess. Substitution of the PF6- anion for Br- leads to the clean formation of [Re(CO)(3)L-3][PF6] ([3][PF6]-[5][PF6]) for py, N-Melm, and tht, respectively, as the only products observed. Reaction of [1][PF6] with pip produces the dimeric species, (PiP)(CO)(3)Re(mu-OH)(2)Re(CO)(3)(PiP), 6. Reactions of [I]Br were also performed in methanol for comparison purposes. The reaction with pip in this solvent led to the analogous dimer, (PiP)(CO)(3)Re(mu-OMe)(2)Re(CO)(3)(pip), 7; however, reactions with py, N-Melm, and tht gave Re(CO)(3)L2Br, 8-10, respectively, as the only products. The crystal structures of compounds [2]Br-10 are reported.