Novel polymeric heteropolytungstates and -molybdates

A review is given on the synthesis of a series of novel heteropolytungstates and -molybdates with polymeric network structures containing bismuth, chromium, copper, ruthenium, rhodium, cerium and europium as heteroatoms, Their crystal structures were determined by single crystal X-ray methods. The compounds reported are: Na-6[Rh-4(CH3COO)(8),W12O38(OH)(2)]. 25H(2)O (1): K6Na2[Ru(H2O)(2) (W12O40(OH)(2)]. 10 H2O (2), K20Na6 [(Cu(H2O)(2)W12O40(OH)(2))(2) (W12O40 (OH))(2)]. 31H(2)O (3), Ce(H2O)(7)[CrMo6O18(OH)(6)]. 4H(2)O (4), and Na3H2[Eu-3(H2O)(18)(Bi2W22O76)]. 29H(2)O (5). lis a common feature they all contain oligomeric isopolymetalate orheteropolymetalate groups of known structure and size which are linked by various transition metal or rare earth metal centers to form a number of novel extended polymeric heteropolymetalate networks. A polymeric lever structure is formed in 1 by two-dimensional linking of dirhodium tetraacetate units and [W12O38(OH)(2)](6-) isopolyanions. In 2 paratungstate-B units are linked by octahedral RuO4(H2O)(2) polyhedra to form polymeric anionic chains. Similar chains are present in 3, however with Cu being III a square planar CuO2(H2O)(2) coordination, and additional molecular non-coordinated paratungstate anions are present in the crystal. In 4 nine-coordinate CeO2(H2O)(7) polyhedra share corners with two neighbouring anions of composition [CrMo6O18(OH)(6)](3-) to form polymeric chain molecules of alternating cerium polyhedra and hexamolybdochromate(III) units. In 5 structurally remarkable [Bi2W22O76](14-) groups share edges with eight-coordinate EuO2(H2O)(6) polyhedra, again to form three-dimensional polymeric heteropoly networks. (C) Academie des Sciences/Elsevier, Paris.