Supramolecular Polymers with [Co(en)₃]³⁺ Cores (en = ethylenediamine)

From aqueous solutions containing Λ-[Co­(en)3]­I3 (1, 2), Δ-[Co­(en)3]­I3 (5), or racemic [Co­(en)3]­I3 (3, 4) AgI and PbI2 respectively were precipitated by addition of Ag2EDC, [Ag­(en)]­[Ag­(BDC)], PbADC or (NH4)­[Ag5(BTC)2(NH3)­(H2O)2] and filtered off (en = ethylenediamine, H2EDC = fumaric acid, H2BDC = terephthalic acid, H2ADC = acetylenedicarboxylic acid, H3BTC = trimesic acid). After slow evaporation of the remaining solutions single crystals of ∞1{Λ-[Co­(en)3]­EDC3/2}·5.625H2O (P21, Z = 4, 1), ∞1{Λ-[Co­(en)3]­BDC3/2}·10H2O (P1, Z = 2, 2), ∞2{[Co­(en)3]­ADC3/2}·4H2O (P1̅, Z = 2, 3), ∞2{[Co­(en)3]­BTC}·5.55H2O (P21/c, Z = 8, 4), and ∞2{Δ-[Co­(en)3]­EDC­(NO3)}·2H2O (C2, Z = 4, 5) were obtained. In all compounds the [Co­(en)3]3+ cores are connected in a T-shaped mode via N–H···O hydrogen bonds to the carboxylates to form complex networks. Water molecules are bound via O–H···O hydrogen bonds to the networks, further increasing their complexity. It is noteworthy that the chirality of the starting material (Λ- or Δ-[Co­(en)3]­I3) is maintained during the reaction thus leading to non-centrosymmetric polymers, whereas with racemic [Co­(en)3]­I3 centrosymmetric polymers are obtained.