A general approach to growing crystals containing lower valent cations involving a solvothermal reduction step is presented and illustrated using several new materials prepared via this approach. Cesium vanadate, Cs2V3O8, a member of the fresnoite families of structures, crystallizes in the noncentrosymmetric polar space group, P4bm, with a = 8.9448(4) �, and c = 6.0032(3) �. The material exhibits a two-dimensional layered crystal structure consisting of corner-shared V5+O4 and V4+O5 polyhedra. The layers are separated by the cesium cations. The alignment of the individual polyhedra results in a macroscopic polarity for Cs2V3O8. The presence of V4+, (d1), in the layered crystal structure results in two dimensonal antiferromagnetic interactions.  Uranium flouride, U3F12�H2O, crystallizes in the monoclinic space group Cm, a = 12.1594(11) �, b = 11.8457(11) �, c = 8.5409(8) �, and beta = 128.787(2)�.  The structure of U3F12�H2O is extremely complex with a volume of almost 1000 �3 containing uranium in four unique coordination environments.  The magnetism of the U4+, (f2), cations will be discussed.   [U6O16(OH)2(C4H4N2)(HCOO)]�(H2O)3 crystallizes in the space group Immm, a = 7.1938(4) �, b = 11.4611(6) �, and c = 14.8854(7) �.  The three dimensional structure, consisting of U6O16(OH)2 layers that are pillared by pyrazine and formate groups, contains five U6+, (f0), and one rare U5+, (f1), cation.  Time permitting, other examples will also be presented. In these three cases the reactions are carried out using starting materials in their highest oxidation states, (V5+, U6+) that are converted to their lower oxidation states during either a single or a two step solvothermal reduction process.  This general method will be discussed.

Crystal growth of materials containing lower-valent cations involving a solvothermal reduction step

246th National Meeting (2013)

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