Charge-assisted Hydrogen-bonded Linear Second-sphere Assemblies MII(DABP)3]3[Cr(C2O4)3]2·14H2O (M = Cu, Ni, Fe, Zn, and Mn) with a Discrete (H2O)14 Cluster of S6 Symmetry

Abstract

A series of isomorphous second-sphere coordination compounds [MII(DABP)3]3[Cr(C2O4)3]2·14H2O (DABP = 5,5′-diamino-2,2′-bipyridine; M = Cu (1), Ni (2), Fe (3), Zn (4), and Mn (5)) have been constructed through multiple charge-assisted N–H-–O hydrogen-bonding interactions between the oxalate ligands in [Cr(C2O4)3]3– (unit B) and the NH2 groups in the [M(DABP)3]2+ complex (unit A). The chiral [M(DABP)3]2+ cations and [Cr(C2O4)3]3– anions with the same Λ (or Δ) configuration interdigitate alternately, affording linear A3B2 secondary building units. Two adjacent A3B2 units adopting opposite configurations are linked by a six-cornered star-shaped 14-water cluster of S6 symmetry (unit C) to form a racemic 1D linear chain –A3B2(Λ)–C–A3B2(Δ)–C–. The microstructure of compound 1 shows a 3D flower-like morphology.