A >22 Å long metal-complex anion and a 1D cationic coordination polymer, both based on 4,4′-bipyridine-N,N′-dioxide, yielding a 3D and 2-fold interpenetrated fsc net of the hydrogen-bonded metal-organic 1D polymer

The cationic one-dimensional (1D) coordination polymer chain 1∞{[Co(μ-bpdo)(H2O)4]2+} and the metal-complex anion trans-[Co(SO4)2(bpdo)2(H2O)2]2−, both based on the 4,4′-bipyridine-N,N′-dioxide (bpdo) ligand, form a complementary supramolecular pair 1∞{[Co(μ-bpdo)(H2O)4]2+}n n[Co(SO4)2(bpdo)2(H2O)2]2− (1) with respect to charge balance and hydrogen bonding. With a length of >22.14 Ǻ along the bpdo–Co–bpdo axis the metal-complex trans-[Co(SO4)2(bpdo)2(H2O)2]2− is one of the longest and anisotropic counter anions (aspect ratio 22.14:8.11:4.17) observed so far in coordination polymers. Hydrogen-bonding of the anion links the cationic metal-organic 1D polymer into a 2-fold interpenetrated three-dimensional (3D) fsc (or sqc11) 4,6-c 2-nodal net of stoichiometry (4-c)(6-c) with square-planar, 4-connected (Co in anion) and octahedral, 6-connected (Co in cation) nodes in a 1:1 ratio. The 4-c point symbol is (44.62), the 6-c one (44.610.8) yielding a point symbol for the fsc net of (44.62)(44.610.8). The synthesis of 1 requires the presence of a Schiff base. Synthesis under the same conditions in the absence of the Schiff base yields the molecular complex and cocrystal [Co(bpdo)(H2O)5]SO4·1/2bpdo (2) which is related (as pseudo-polymorph) to the known solvate [Co(bpdo)(H2O)5]SO4·2H2O (3) (CSD Refcodes RAXMUZ and RAXMUZ01).