Ordered mesoporous metallic MoO2 materials with highly reversible lithium storage capacity.

Highly ordered mesoporous crystalline MoO(2) materials with bicontinuous Ia3d mesostructure were synthesized by using phosphomolybdic acid as a precursor and mesoporous silica KIT-6 as a hard template in a 10% H(2) atmosphere via nanocasting strategy. The prepared mesoporous MoO(2) material shows a typical metallic conductivity with a low resistivity ( approximately 0.01Omega cm at 300 K), which makes it different from all previously reported mesoporous metal oxides materials. Primary test found that mesoporous MoO(2) material exhibits a reversible electrochemical lithium storage capacity as high as 750 mA h g(-1) at C/20 after 30 cycles, rendering it as a promising anode material for lithium ion batteries.

[pyH](2)[Cu(py)(4)(MX(6))(2)] (MX(6) = ZrF(6)(2)(-), NbOF(5)(2-), MoO(2)F(4)(2)(-); py = Pyridine): Rarely Observed Ordering of Metal Oxide Fluoride Anions.

Single crystals of [pyH](2)[Cu(py)(4)(MX(6))(2)] (MX(6) = ZrF(6)(2)(-), MoO(2)F(4)(2)(-); py = pyridine), analogous to those of the previously reported [pyH](2)[Cu(py)(4)(NbOF(5))(2)], were synthesized by reaction of the metal oxides in (HF)(x)().pyridine/pyridine/water solutions (150 degrees C, autogeneous pressure). The NbOF(5)(2)(-) and MoO(2)F(4)(2)(-) anions generally crystallize with orientational disorder masking the true coordination geometry. The combination of the two different and strongly coordinating cations tetrakis(pyridine)copper(II) and pyridinium causes the anions to adopt regular and ordered orientations. Crystal data: for [pyH](2)[Cu(py)(4)(ZrF(6))(2)], tetragonal, space group I4/mmm (No. 139), with a = 11.047(1) Å, c = 16.763(3) Å, and Z = 2; for [pyH](2)[Cu(py)(4)(MoO(2)F(4))(2)], monoclinic, space group C2/c (No. 15), with a = 19.195(4) Å, b = 11.316(3) Å, c = 18.920(5) Å, beta = 107.68(2) degrees, and Z = 4.

Composition Space Diagrams for Mixed Transition Metal Oxide Fluorides.

Composition space diagrams have been used to study phase stability of mixed transition metal oxide fluorides synthesized by hydrothermal reaction of the metal oxides in (HF)(x)().pyridine/H(2)O/pyridine solution (150 degrees C, autogenous pressure). The combination of early (Ti, Zr, Hf, Nb, Ta, Mo, W) and late (Cu, Cd, Zn) transition metals and the effects of varying the mole ratios of the metals, (HF)(x)().pyridine, and water are examined in this study. Single-crystal products containing [Cu(py)(4)](2+), [Cd(py)(4)](2+), or [Zn(py)(4)](2+) cations and [TiF(6)](2)(-), [ZrF(6)](2)(-), [HfF(6)](2)(-), [NbOF(5)](2)(-), [TaOF(5)](2)(-), [MoO(2)F(4)](2)(-), or [WO(2)F(4)](2)(-) anions are recovered. Relative stability of the crystalline products is governed by the negative charge distribution on the anions, as well as the concentrations of each reactant in solution. Two new structures are reported: Cu(NC(5)H(5))(4)TaOF(5) and Cu(NC(5)H(5))(4)TiF(6).3H(2)O. Crystal data: for Cu(NC(5)H(5))(4)TaOF(5), monoclinic, space group C2/c (No. 15), with a = 10.541(3) Å, b = 13.547(6) Å, c = 16.04(1) Å, beta = 97.73(5) degrees, and Z = 4; for Cu(NC(5)H(5))(4)TiF(6).3H(2)O, monoclinic, space group C2/c (No. 15), with a = 12.767(4) Å, b = 12.048(2) Å, c = 17.787(6) Å, beta = 109.9(1) degrees, and Z = 4.

Structural Comparison of Iron Tetrapolyvanadate Fe(2)V(4)O(13) and Iron Polyvanadomolybdate Fe(2)V(3.16)Mo(0.84)O(13.42): A New Substitution Mechanism of Molybdenum(VI) for Vanadium(V).

Single crystals of the iron tetrapolyvanadate Fe(2)V(4)O(13) and the iron polyvanadomolybdate Fe(2)V(3.16)Mo(0.84)O(13.42) were grown from Fe(2)O(3)/V(2)O(5) and Fe(2)O(3)/V(2)O(5)/MoO(3) melts, respectively. Single-crystal X-ray diffraction revealed that the two structures are closely related. Both contained isolated Fe(2)O(10) octahedral dimers with similar orientations. The unusual U-shaped V(4)O(13)(6)(-) clusters in Fe(2)V(4)O(13) were ordered while the U-shaped [V(3.16)Mo(0.84)O(13.42)](6)(-) clusters in Fe(2)V(3.16)Mo(0.84)O(13.42) were disordered. The substitution of molybdenum(VI) for vanadium(V) revealed a new substitution mechanism, in which a corresponding stoichiometric amount of oxygen was brought into the structure for charge balance with no reduction of the V(5+) and Mo(6+) ions. Crystal data: for Fe(2)V(4)O(13), monoclinic, space group P2(1)/c (No. 14), with a = 8.300(2) Å, b =9.404(6) Å, c = 14.560(2) Å, beta = 102.08(1) degrees, and Z = 4; for Fe(2)V(3.16)Mo(0.84)O(13.42), monoclinic, space group P2(1)/c (No. 14), with a = 7.678(1) Å, b = 9.456(2) Å, c = 8.336(2) Å, beta = 109.50(2) degrees, and Z = 2.