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 (1) and (Ni­(N3C5H15)2)2[{Ni­(N3C5H15)2}­V15Sb6O42(H2O)]·8H2O (2) (N3C5H15 = N-(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 P1̅ with a = 14.3438(4), b = 16.6471(6), c = 18.9186(6) Å, α = 87.291(3)°, β = 83.340(3)°, γ = 78.890(3)°, and V = 4401.4(2) Å3 (1) and a = 14.5697(13), b = 15.8523(16), c = 20.2411(18) Å, α = 86.702(11)°, β = 84.957(11)°, γ = 76.941(11)°, and V = 4533.0(7) Å3 (2). In the structure of 1 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 2 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 1 and to Sb···N interactions in 2. In the solid-state lattices of 1 and 2, 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 b 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 S = 1/2 vanadyl groups. The susceptibility data can be successfully reproduced assuming a distorted ligand field for the Co2+ ions (1) and an Oh-symmetric Ni2+ ligand field (2).