Compound 2 crystallizes in the triclinic space group P 1 (Table ). The complex anion lies on a special Wyckoff position, with the inversion center located in the middle of the bridge, rendering the complex anion inversion symmetric. The two capping ligands are oriented in a perpendicular fashion to the bridging ligand. The coordination geometry around each Co(II) center is of particular interest, since this was found to be decisive for the magnitude and the sign of D. For 2, just as in the mononuclear compound 1, a distorted tetrahedral coordination geometry with N-Co-N angles between 79.8(2)°and 133.3(2)°is found, giving distortion values of τ 4 = 0.73 and τ δ = 0.68, which are similar to the those found for previously reported 3. Using the coordination polyhedron of 1 (see Fig. ) as a reference for a SHAPE geometry analysis, a very low distortion value of 0.037 is found for 2. Consequently, an equally large, negative D as for Å). See supporting information Fig. and Table for additional bond lengths. These geometrical parameters indicate a dianionic state of the capping ligands and a trianionic, radical state of the bridge. The charge of the ligands is compensated by the two Co(II) ions and six K + ions, which are shared between two neighboring molecules. The K + ions are part of two different structural motifs in the extended structure of 2 (see supporting information Fig. ). In one dimension, the K + ions are axially coordinated by the oxygen atoms of the sulfonyl groups, and equatorially by 18-crown-6. In the second dimension, the K + ions form a sandwich-like structure with the aryl backbones of the capping ligands. Finally, four water molecules complete the coordination sphere of the K + ions. These two different connection motifs lead to an interwoven 2D sheet of perpendicular strands in the extended crystal structure of 2, which is a remarkable differ-ence to 3, where only single strands were observed. Consequently, this suggests the importance of the η 2 -coordination of the K + ions as a design criterion for stable ionic networks that allows improved crystal growth in comparison to unconnected structures. This observation is in line with our recent results on the analogous dinuclear Ni(II) and Zn(II) complexes.