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Cu/Zn disorder in the kesterite Cu2ZnSnS4 derivatives used for thin film based solar cells is an important issue for photovoltaic performances. Unfortunately, Cu and Zn cannot be distinguished by conventional laboratory X-ray diffraction. This paper reports on a resonant diffraction investigation of a Cu2ZnSnS4 single crystal from a quenched powdered sample. The full disorder of Cu and Zn in the z = 1/4 atomic plane is shown. The structure, namely disordered kesterite, is then described in the I42m space group.

The title compound, (C4H14N2)2[Mo2O4F6]·H2O, was obtained by solvothermal reaction at 443 K for 72 h from a mixture of MoO3, HF, 1,4-diamino-butane (dab), water and ethyl-ene glycol. The structure consists of [Mo2O4F6](4-) anionic dimers containing strongly distorted MoO3F3 octa-hedra (with twofold symmetry), diprotonated dab cations and water mol-ecules (twofold symmetry) in the ratio 1:2:1. The cohesion of the three-dimensional structure is ensured through N-H⋯O, N-H⋯F and O-H⋯F inter-actions.

The syntheses and structure determinations by means of single-crystal X-ray diffraction of commensurate (C(6)H(14)N(2))(2)[Mo(8)O(26)] * 4H(2)O and incommensurate (C(6)H(14)N(2))(2)[Mo(8)O(26)] * 4.66H(2)O, 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. (C(6)H(14)N(2))(2)[Mo(8)O(26)] * nH(2)O results from the self-assembly of [Mo(8)O(26)](4-) anionic chains, C(6)H(14)N(2)(2+) (H(2)DABCO(2+)) cations and water molecules. The [Mo(8)O(26)](4-) chain is built from gamma-[Mo(8)O(28)](8-) octamolybdate clusters, connected to each other through corner sharing. In both compounds, the [Mo(8)O(26)](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 H(2)DABCO(2+) cations is shown to be different from what has been observed previously in monoclinic (H(2)DABCO)(2)[Mo(8)O(26)] * 4H(2)O, and therefore to give a different network of hydrogen bonds.

The structure of nonapotassium cerium tetraphosphorus hexadecasulfide, a zero-dimensional material isostructural with Rb(9)CeP(4)Se(16), is reported.