Abstract
Reactions of [Co(NH3)6]Cl3 and K3[Co(C2O4)3] in aqueous solutions result in formation of a new double complex salt, [Co(NH3)6][Co(C2O4)3] (1). The crystal structure of 1 is triclinic [space group $P\bar{1}$ , a = 7.5180(5) Å, b = 9.4283(5) Å, c = 11.4968(7) Å, α = 84.018(4)°, β = 87.508(4)°, γ = 71.254(4)°] and is derived from a CsCl archetype. It is analogous to the previously reported [Ir(NH3)6][Co(C2O4)3] and [Co(NH3)6][Ir(C2O4)3], which are also triclinic and crystallize in the space group $P\bar{1}$ . The difference in the number of water molecules in comparison with the previously studied [Co(NH3)6][Co(C2O4)3]·3H2O (space group $P\bar{3}$ ) can be explained by different methods for obtaining single crystals suitable for X-ray diffraction analysis. These findings expand the data pool on double complex salts with cations and anions based on the same transition metal cation, and underline the effect of incorporated water molecules on the crystal structure.
