Structural features of selenate based {Mo132} keplerate capsules

New nanosized keplerate [{Mo6O21(H2O)6}12{Mo2O4(SeO4)}30]72– was prepared by ligand substitution in the corresponding acetate complex in the presence of ammonium selenate. Three novel keplerate-type compounds (NH4)72[{Mo6O21(H2O)6}12{Mo2O4(SeO4)}30]·250H2O (2), [C(NH2)3]72[{Mo6O21(H2O)6}12{Mo2O4(SeO4)}30]·250H2O (3) and (NH4)36(NMe2H2)36[{Mo6O21(H2O)6}12{Mo2O4(SeO4)}30]·250H2O (4) have been isolated and characterized by single crystal x-ray diffraction (SCXRD). The detailed structural analysis revealed presence of the inverted {Mo6O21(H2O)6} pentagonal building blocks in all structures. Pore blocking effect via coordination of guanidinium cations was demonstrated by 77Se NMR and UV-vis spectroscopy in solution and by X-ray analysis in the structure of 3. All compounds were characterized by IR and Raman spectroscopy and elemental analysis.