Crystal Growth of Reduced Materials

Crystal Growth, Characterization, and Properties of Reduced Early Transition Metal Compounds Grown via Hydrothermal and Molten Salt Flux Methods Anthony J. D. Cortese, Branford Wilkins, Gregory Morrison, Jeongho Yeon, Mark D. Smith, Hans-Conrads zur Loye Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208 Abstract

NaxLn1-xMoO4 Ln = La, Nd, Sm, Eu

A limited number of compounds containing reduced early transition metals are known due to the difficulty of their preparation. Four vanadium tartrate hybrid materials, A2[(VO)2(C4H4O6)(C4H2O6)(H2O)2]•･(H2O)2 A = Cs, Rb; K2[(VO)2(C4H2O6)2(H2O)2]•･(H2O)2; and Na2[(VO)2(C4H4O6)(C4H2O6)(H2O)7]•･(H2O)2, were prepared via a novel two step hydrothermal technique. Six lanthanide molybdenum oxides, Ln5Mo2O12 Ln = Tb, Dy, Ho and Er, Ln~5Mo3O16 Ln = Nd, Sm; four new sodium lanthanide molybdenum oxides, NaxLn1-xMoO4 Ln = La, Nd, Sm, and Eu; a lanthanum molybdenum oxychloride, La20Mo12O63Cl4; and a barium sodium siliconiobate, Ba3Na0.32Nb6Si4O26 were prepared via high temperature flux methods in sealed evacuated fused silica tubes. These materials have been characterized via powder and single crystal X-ray diffraction, UV/Vis spectroscopy, and IR spectroscopy. Magnetism has been probed using a SQUID/ VSM magnetometer. Second harmonic generation has been investigated for A2[(VO)2(C4H4O6)(C4H2O6)(H2O)2]•･(H2O)2 A = Cs, Rb, K2[(VO)2(C4H2O6)2(H2O)2]•･ (H2O)2, La20Mo12O63Cl4, and Ba3Na0.32Nb6Si4O26.

La20Mo12O63Cl4 La20Mo12O63Cl4 S.G. P-62m a/Å 10.2241(2) b/Å 10.2241(2) c/Å 15.0768(4) Z 1 R1 0.0254 wR2 0.0494

Figure 4. Temperature dependance of the molar magnetic susceptibility (blue), χm, and inverse susceptibility (red), 1/χm, of Na0.6Eu0.4MoO4.

Figure 3. Absorbance data for La (blue), Nd (black), Sm (red), and Eu (green).

Figure 2 (at right). Mo1/ La1/La2/La3 oxychloride layer viewed down the c axis. La2 and La3 are located on top of one another in the c direction and connect to Mo3 and Mo2 layers, respectively. Cl1 and Cl2 are located on top of one another in the c direction. Figure 5. Calculated (red) and experimental (blue) PXRD patterns for La20Mo12O63Cl4

Figure 3 (at left). Mo2/ La3/La4 oxychloride layer viewed down the c axis. Two La3 are located on top of one another in the c direction and connect to Mo1 layers. Cl2 and Cl1 are located on top of one another in the c direction.

Figure 2. Calculated (red) and experimental (blue) PXRD patterns for La (top left), Nd (top right), Sm (bottom left), and Eu (bottom right).

Ln = S.G. a/Å c/Å Z R1 wR2

La I41/a 5.3414(2) 11.7393(6) 4 0.0271 0.0434

Ln = S.G. a/Å c/Å Z R1 wR2

Nd I41/a 5.2854(2) 11.5675(6) 4 0.0185 0.0474

Ln = S.G. a/Å c/Å Z R1 wR2

Sm I41/a 5.2560(2) 11.4921(2) 4 0.0252 0.0664

Ln = S.G. a/Å c/Å Z R1 wR2

Eu I41/a 5.2797(2) 11.5869(7) 4 0.0161 Figure 1. NaxLn1-xMoO4 viewed down the a axis. Na/Ln, Mo, 0.0334 and O shown in orange, cyan, and red.

Ln5Mo2O12 Ln = Tb, Dy, Ho, Er A2[(VO)2(C4H4O6)(C4H2O6)(H2O)2]•(H2O)2 A = Cs, Rb; 1, 2

K2[(VO)2(C4H2O6)2(H2O)2]•(H2O)2; 3

Figure 1. La20Mo12O63Cl4 viewed down the a axis. Mo1, Mo2, Mo3, La, and Cl shown in aqua, cyan, navy, orange, and green. Some La-O bonds omitted for clarity. Molybdenum layers stack in A, B, A, C fashion.

Na2[(VO)2(C4H4O6)(C4H2O6)(H2O)7]•(H2O)2; 4 Figure 3. MoO6 1D chains showing alternating Mo - Mo distances. Mo and O shown in cyan and red.

Figure 4. Calculated (red) and experimental (blue) PXRD patterns for Er (left) and Ho (right).

Nd4.910Mo3O16 & Sm4.952Mo3O16 Ln = S.G. a/Å Z R1 wR2

Figure 1. 1 and 2 viewed down the a axis. V, A, O, C, H shown in blue, yellow, red, grey, and white. Hydrogen bonds shown as red/white stripped cylinders.

Figure 6. Absorbance data for La20Mo12O63Cl4.

Figure 4 (above). Mo3/La2/La5 oxide layer viewed down the c axis. Two La2 are located on top of one another in the c direction and connect to Mo1 layers.

Sm Pn-3n 10.8934(4) 4 0.0202 0.0435

Ln = S.G. a/Å Z R1 wR2

Nd Pn-3n 10.9959(7) 4 0.0205 0.0383

Figure 2. 4 viewed down the a axis. V, Na, O, C, H shown in blue, yellow, red, grey, and white. Hydrogen bonds shown as red/white stripped cylinders. Figure 5. Temperature dependance of the molar magnetic susceptibility (blue), χm, and inverse susceptibility (red), 1/χm, of Er (left) and Ho (right).

Figure 1. Ln5Mo2O12 viewed down the c axis. Ln, Mo, and O shown in orange, cyan, and red.

Figure 3. V2O12 dimer of 1 and 2. The dimer of 4 is similar. V, O, C, H shown in blue, red, grey, and white. Hydrogen bond shown as a red/white stripped cylinder.

Figure 4. V2O9 dimer of 3. V, O, C, H shown in blue, red, grey, and white.

Figure 6. Absorbance data for Tb (black), Dy (red), Ho (blue), and Er (green).

Figure 5. 3 viewed in the bc plane. V, K, O, C, H shown in blue, yellow, red, grey, and white.

Ln = S.G. a/Å b/Å c/Å β/° Z R1 wR2

Er C2/m 12.1871(18) 5.7044(8) 7.4581(11) 107.884(3) 2 0.0367 0.0877

Ln = S.G. a/Å b/Å c/Å β/° Z R1 wR2

Ho C2/m 12.2959(14) 5.7377(7) 7.5300(9) 107.816(2) 2 0.0423 0.0852

Figure 7. Calculated (red) and experimental (blue) PXRD patterns for 1, 2, 3, and 4.

Figure 3. Nb3O15 trimeric columns. Nb and O shown in cyan and red.

Figure 1. Ba3Na0.32Nb6O12(Si2O7)2 viewed down the c axis. Ba, Na, Nb, Si, and in pink, yellow, cyan, and blue. Na shown at full occupancy for clarity.

Figure 2. Local coordination environments of Ln~5Mo3O16. Ln1, Ln2, Mo, and O shown in orange, purple, cyan, and red.

Figure 4. Calculated (red) and experimental (blue) PXRD patterns for Nd.

Figure 3. Ln~5Mo3O16 viewed down the a axis. Ln1, Ln2, Mo, and O shown in orange, purple , cyan, and red. Ln2 - Mo bonds not shown for clarity.

Conclusions

Ba3Na0.32Nb6O12(Si2O7)2

Figure 2. Local coordination environments of Ba3Na0.32Nb6O12(Si2O7)2. Ba, Na, Nb, Si, and O shown in pink, yellow, cyan, blue, and red.

Figure 6. Temperature dependance of the molar magnetic susceptibility (blue), χm, and inverse susceptibility (red), 1/χm, of Nd.

Figure 5. Absorbance data for Nd.

Figure 2. Local coordination environments of Ln5Mo2O12. Ln, Mo, and O shown in orange, cyan, and red.

Figure 6. 3 viewed in the ab plane. V, K, O, C, H shown in blue, yellow, red, grey, and white.

Figure1. Local coordination environments of Ln~5Mo3O16. Ln1, Ln2, Mo, and O shown in orange, purple, cyan, and red.

Ba3Na0.32Nb6O12(Si2O7)2 S.G. P-62m a/Å 8.9998(10) b/Å 8.9998(10) c/Å 7.8119(17) Z 1 R1 0.0189 wR2 0.0381

Four oxovanadium(IV) tartrates, four sodium lanthanide molybdenum(V/VI) oxides, four lanthanide molybdenum(IV/V) oxides, one lanthanum molybdenum(V/VI) oxychloride, one barium sodium siliconiobate(IV/V), and two lanthanide molybdenum(V/VI) oxides have been synthesized via a novel two step reduction technique and high temperature flux methods. Their crystal structures were determined by single crystal X-ray diffraction. Magnetic properties and absorbance have been determined via SQUID-VSM and UV/Vis, respectively. Several compounds exhibit magnetic ordering. Several compounds have absorption edges that fall in the visible region, indicating semiconducting behavior. Conductivity measurements are underway. SHG properties have been investigated for applicable compounds, with several having comparable activity to a known standard.

Acknowledgments Figure 8. Temperature dependance of the molar magnetic susceptibility (blue), χm, and inverse susceptibility (red), 1/χm, of 1, 2, and 4. Temperature dependance of the molar magnetic susceptibility (red), χm, and fit (blue) of 3.

A= S.G. a/Å b/Å c/Å Z R1 wR2

Cs P212121 8.0320(6) 10.4016(8) 23.3623(17) 4 0.0210 0.0487

A= S.G. a/Å b/Å c/Å Z R1 wR2

Rb P212121 7.9061(8) 10.2647(11) 22.814(2) 4 0.0238 0.0543

Figure 9. Powder SHG data of 1, 2, and 3 relative to α-SiO2. Absorbance data for 1 (red), 2 (green), 3(blue), and 4 (black).

A= S.G. a/Å b/Å c/Å Z R1 wR2

K C2221 8.4341(13) 17.311(3) 25.140(4) 4 0.0339 0.0616

A= S.G. a/Å b/Å c/Å Z R1 wR2

Na P212121 8.5931(5) 10.4332(6) 24.2289(13) 4 0.0398 0.0877

Figure 5. Temperature dependance of the molar magnetic susceptibility (blue), χm, and inverse susceptibility (red), 1/ χm, of Ba3Na0.32Nb6O12(Si2O7)2..

Figure 6. UV/Vis spectrum for Ba3Na0.32Nb6O12(Si2O7)2.

Figure 7. IR spectrum for Ba3Na0.32Nb6O12(Si2O7)2.

Figure 4. Calculated (red) and experimental (blue) PXRD patterns for Ba3Na0.32Nb6O12(Si2O7)2.

Research was supported by the U.S. Department of Energy, Office of Basic Energy Studies, Materials Sciences and Engineering Division under DESC-0001061 and the National Science Foundation under DMR-1301757. SHG measurements were performed at the University of Houston by T. Thao Tran of the P. Shiv Halasyamani Group, and are gratefully acknowledged.