Unique Occurrence of Cationic and Anionic Bis-1,2-diaminocyclohexane Copper(II) Units in a Double Complex Salt

Abstract

The reaction of (±)-trans-diaminocyclohexane (dach) with copper(ii) sulfate in water resulted in the spontaneous formation of a double complex salt of type [Cu(dach)2(H2O)2][Cu(dach)2(SO4)2]·6H2O, whose X-ray structure confirmed the presence of the same square-planar Cu(dach)22+ coordination motif in both the complex cation and anion. Each copper centre adopts a Jahn–Teller-distorted octahedral geometry. Both axial positions of the metal centre in the complex cation are occupied by water molecules, whereas two monodentate sulfato ions occupy the corresponding sites in the complex anion, leading to a trans N4O2-donor coordination environment in each ion.