Three new organically templated polyoxomolybdates with capping selenite anions

Three new organically templated polyoxomolybdates with selenite anions as capping groups have been synthesized by hydrothermal reactions and structurally characterized. The structure of {Hbipy}(3){KMo4O13(SeO3)} (1; bipy = 4,4'-bipyridine) features a 1D anionic double chain of {KMo4O13(SeO3)}(3-) units. Four (MoO6)-O-VI octahedra in compound 1 form a planar Mo4O13 cluster unit through corner-, edge- and face-sharing. The Mo4O13 cluster unit is further capped by an (SeO3)-O-IV group in a bidentate fashion. These monocapped cluster units are further interconnected by bridging K+ cations into a 1D double chain. Both {H(2)bipy}(2){Mo5O15(SeO3)(2)}-H2O (2) and {H2PP}(2){Mo5O15(SeO3)(2)}-3H(2)O (3; pip = piperazine) contain a bicapped Mo5O15 cluster unit in which five (MoO6)-O-VI octahedra form a planar Mo5O15 cluster unit through edge- and corner-sharing, with the two (SeO3)-O-IV anions as tridentate capping groups on the two open sides of the cluster unit to form an {Mo5O15(SeO3)(2)}(4-) anion. The {Mo5O15(SeO3)(2)}(4-) cluster anions in compounds 2 and 3 are further inter-linked by the organic templates through hydrogen bonds to form a 2D layer. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).