A cobalt(III) complex bearing two 2,2'-bipyridine (bpy) ligands and two aqua ligands, cis-[Co(bpy)(2)(OH2)(2)][OTf](3)center dot H2O (1 center dot[OTf](3)center dot H2O; OTf- = CF3SO3-), was obtained from the reaction of [Co(bpy)(2)(CO3)][OTf]center dot 0.5H(2)O with aqueous HOTf (HOTf = HCF3SO3, trifluoromethanesulfonic acid). The prepared complex was characterized by single-crystal X-ray crystallographic and elemental analyses, and its solution behavior was investigated by H-1 NMR spectroscopy. Our study of 1 center dot[OTf](3)center dot H2O revealed that it is stable in water and acetone upon heating; however, in methanol and ethanol, the complex was unstable upon heating, forming [Co(bpy)(3)](3+). In addition, upon the reaction of 1 center dot[OTf](3)center dot H2O with picolinic acid (Hpic) in acetone at 295 K, [Co(bpy)(2)(pic)][OTf](2) (2 center dot[OTf](2)) was gradually and selectively precipitated from the reaction solution in 82% yield. Moreover, the reaction between 1 center dot[OTf](3)center dot H2O, NaOH, and H2O2 in water at room temperature produced the dinuclear complex [Co-2(bpy)(4)(mu-O-2)(mu-OH)][PF6](3) (3 center dot[PF6](3)) in good yield (92%) and with excellent purity. The structures of 1 center dot[OTf](3)center dot H2O and 2 center dot[PF6](2) were determined by single-crystal X-ray crystallographic analysis. (C) 2021 Elsevier B.V. All rights reserved.