Expansion of Antimonato Polyoxovanadates with Transition Metal Complexes: (Co(N₃C₅H₁₅)₂)₂[{Co(N₃C₅H₁₅)₂}V₁₅Sb₆O₄₂(H₂O)]·5H₂O and (Ni(N₃C₅H₁₅)₂)₂[{Ni(N₃C₅H₁₅)₂}V₁₅Sb₆O₄₂(H₂O)]·8H₂O

Two new polyoxovanadates (Co­(N₃C₅H₁₅)₂)₂[{Co­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]·5H₂O (<b>1</b>) and (Ni­(N₃C₅H₁₅)₂)₂[{Ni­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]·8H₂O (<b>2</b>) (N₃C₅H₁₅ = <i>N</i>-(2-aminoethyl)-1,3-propanediamine) were synthesized under solvothermal conditions and structurally characterized. In both structures the [V₁₅Sb₆O₄₂(H₂O)]^6– shell displays the main structural motif, which is strongly related to the {V₁₈O₄₂} archetype cluster. Both compounds crystallize in the triclinic space group <i>P</i>1̅ with <i>a</i> = 14.3438(4), <i>b</i> = 16.6471(6), <i>c</i> = 18.9186(6) Å, α = 87.291(3)°, β = 83.340(3)°, γ = 78.890(3)°, and <i>V</i> = 4401.4(2) ų (<b>1</b>) and <i>a</i> = 14.5697(13), <i>b</i> = 15.8523(16), <i>c</i> = 20.2411(18) Å, α = 86.702(11)°, β = 84.957(11)°, γ = 76.941(11)°, and <i>V</i> = 4533.0(7) ų (<b>2</b>). In the structure of <b>1</b> the [V₁₅Sb₆O₄₂(H₂O)]^6– cluster anion is bound to a [Co­(N₃C₅H₁₅)₂]²⁺ complex via a terminal oxygen atom. In the Co²⁺-centered complex, one of the amine ligands coordinates in tridentate mode and the second one in bidentate mode to form a strongly distorted CoN₅O octahedron. Similarly, in compound <b>2</b> an analogous NiN₅O complex is joined to the [V₁₅Sb₆O₄₂(H₂O)]^6– anion via the same attachment mode. A remarkable difference between the two compounds is the orientation of the noncoordinated propylamine group leading to intermolecular Sb···O contacts in <b>1</b> and to Sb···N interactions in <b>2</b>. In the solid-state lattices of <b>1</b> and <b>2</b>, two additional [M­(N₃C₅H₁₅)₂]²⁺ complexes act as countercations and are located between the [{M­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]^4– anions. Between the anions and cations strong N–H···O hydrogen bonds are observed. In both compounds the clusters are stacked along the <i>b</i> axis in an ABAB fashion with cations and water molecules occupying the space between the clusters. Magnetic characterization demonstrates that the Ni²⁺ and Co²⁺ cations do not significantly couple with the <i>S</i> = 1/2 vanadyl groups. The susceptibility data can be successfully reproduced assuming a distorted ligand field for the Co²⁺ ions (<b>1</b>) and an <i>O</i>_<i>h</i>-symmetric Ni²⁺ ligand field (<b>2</b>)