Two three-dimensional {V16Ge4}-based open frameworks stabilized by diverse types of CoII-amine bridges and magnetic properties

Two novel three-dimensional (3D) extended vanadogermanate-based frameworks, [Co(pdn)(2)](3)[Co-2(pdn)(4)][V16Ge4O44(OH)(2)(H2O)]center dot 5H(2)O (1), [Co-2(en)(3)][Co(en)(2)](2)[Co(en)(2)(H2O)][V16Ge4O44(OH)(2)(H2O)]center dot 10.5H(2)O (2), (pdn = 1,2-propanediamine, en = ethylenediamine) have been synthesized under hydrothermal conditions via changing the organic amine. X-ray crystal structure analyses reveal that both frameworks are built of [V16Ge4O44(OH)(2)(H2O)](10-) anions and different Co-amine cations. They represent the first example of incorporating elemental Co into the extended vanadogermanate frameworks. Compound 1 shows a 3D framework with NaCl topology based on {V16Ge4} clusters as nodes, while compound 2 exhibits a 3D (4,6)-connected network with a Schlafli symbol of (4(6).6(7).8(2))(2)(4(2).6(4)), which is found for the first time in polyoxovanadate chemistry. The diverse types of metal-organoamine subunits play critical roles in the formation on the final structures. Furthermore, variable temperature susceptibility measurements on compounds 1 and 2 demonstrate the presence of anticipated rare ferrimagnetic behavior.