Commensurate (C6H14N2)2[Mo8O26]•4H2O and incommensurate (C6H14N2)2[Mo8O26]•4.66H2O:: a structural versatility linked to solvent content

The syntheses and structure determinations by means of single-crystal X-ray diffraction of commensurate (C6H14N2)(2)[Mo8O26]center dot 4H(2)O and incommensurate (C6H14N2)(2)[Mo8O26]center dot 4.66H2O, two new organic-inorganic hybrid compounds based on polyoxomolybdates and differing in their solvent content, are reported. Given the important disorder observed in the latter compound, only a combination of non-harmonic waves, crenel functions and TLS tensors offered a good modelling of the structure. (C6H14N2)(2)[Mo8O26]center dot nH(2)O results from the self-assembly of [Mo8O26](4-) anionic chains, C6H14N22+ (H(2)DABCO(2+)) cations and water molecules. The [Mo8O26](4-) chain is built from gamma-[Mo8O28](8)(-) octamolybdate clusters, connected to each other through corner sharing. In both compounds, the [Mo8O26](4-) chains are separated, in a similar way, by the H(2)DABCO(2+) subunits, acting as charge-compensating cations, and by the water molecules. The orientation of the H2DABCO(2+) cations is shown to be different from what has been observed previously in monoclinic (H(2)DABCO)(2)[Mo8O26]center dot 4H(2)O, and therefore to give a different network of hydrogen bonds.