Synthesis, structure, and characterization of novel two- and three-dimensional vanadates: Ba2.5(VO2) 3(SeO3)4·H2O and La(VO 2)3(TeO6)·3H2O

Article abstract of DOI:10.1021/ic052103u

Two new vanadates, Ba_2.5(VO₂)₃(SeO ₃)₄·H₂O and La(VO₂) ₃(TeO₆)·3H₂O, have been synthesized by hydrothermal methods using BaCO₃, Ba(OH)₂·H ₂O, La(NO₃)₃·6H₂O, V ₂O₅, TeO₂, and H₂SeO₃ as reagents. The structures were determined by single-crystal X-ray diffraction. Ba_2.5(VO₂)₃(SeO₃) ₄·H₂O exhibits a two-dimensional layered structure consisting of VO₅ square pyramids and SeO₃ polyhedra, whereas La(VO₂)₃(TeO₆)·3H₂O has a three-dimensional framework structure composed of VO₄ tetrahedra and TeO₆ octahedra. Infrared and Raman spectroscopy, UV-vis diffuse reflectance spectroscopy, and thermogravimetric analysis are also presented. Crystal data: Ba_2.5(VO₂)₃-(SeO ₃)₄·H₂O, trigonal, space group P3 (No. 147) with a = b = 12.8279(15) A, c = 7.2631(9) A, V = 1035.1(2) A³, and Z = 2; La(VO₂)₃(TeO ₆)·3H₂O, trigonal, space group R3c (No. 161) with a = b = 9.4577(16) A, c = 23.455(7) A, V = 1816.9(7) A³, and Z = 6.

Full text of DOI:10.1021/ic052103u

Inorg. Chem. 2006, 45, 3602−3605
Synthesis, Structure, and Characterization of Novel Two- and
Three-Dimensional Vanadates: Ba (VO ) (SeO ) H O and
‚
3 4
2.5
2 3
2
La(VO ) (TeO )‚3H O
2
3
6
2
T. Sivakumar, Kang Min Ok, and P. Shiv Halasyamani*
Department of Chemistry and Center for Materials Chemistry, UniVersity of Houston,
36 Fleming Building, Houston, Texas 77204-5003
1
Received December 8, 2005
Two new vanadates, Ba2.5(VO
methods using BaCO , Ba(OH)
determined by single-crystal X-ray diffraction. Ba2.5(VO
2
)
3
(SeO
3
)
4
‚
H
2
O and La(VO
2
)
O
3
(TeO
, TeO
(SeO
polyhedra, whereas La(VO
6
)
‚
3H
, and H
O exhibits a two-dimensional layered structure
(TeO 3H O has a three-dimensional
octahedra. Infrared and Raman spectroscopy, UV vis
2
O, have been synthesized by hydrothermal
3
2
‚
2
H O, La(NO
3
)
3
‚
6H O, V
2
2
5
2
2
SeO as reagents. The structures were
3
2
)
3
3 4 2
) ‚H
consisting of VO
5
square pyramids and SeO
3
2
)
3
6
)
‚
2
framework structure composed of VO
4
tetrahedra and TeO
6
−
2 3
diffuse reflectance spectroscopy, and thermogravimetric analysis are also presented. Crystal data: Ba2.5(VO ) -
(
SeO
3
)
4
‚
H
2
O, trigonal, space group P3
2; La(VO (TeO 3H O, trigonal, space group R3c (No. 161) with a
1816.9(7) Å , and Z 6.
h
(No. 147) with a
)
b
)
12.8279(15) Å, c
)
7.2631(9) Å, V
) 1035.1(2)
3
Å , and Z
2
)
)
2 3
6
3
)
‚
2
)
b
)
9.4577(16) Å, c )
3.455(7) Å, V
)
)
Introduction
Vanadium-based oxides have been attracted considerable
materials. In vanadates, vanadium has been observed in
three-, four-, five-, and six-coordinate environments.1
Although vanadium has readily accessible oxidation states,
from +2 to +5, tetra- or pentavalent vanadium is observed
in the majority of compounds synthesized by hydrothermal
-6,17
1
-6
attention not only because of the structural versatility of
7
-10
vanadium but also their ability to act as intercalation,
ion-exchange,1 sorption, magnetic,
1
11
12-14
15,16
and cathode
1
8-23
reactions.
In this paper, we report on the hydrothermal
*
To whom correspondence should be addressed: E-mail: psh@uh.edu.
synthesis, crystal structure, and characterization of two new
vanadates containing not only the tetrahedral or square
pyramidal coordination of vanadium with cis-dioxovana-
Phone: 713-743-3278. Fax: 713-743-0796.
(
(
1) Wadsley, A. D. Acta Crystallogr. 1955, 8, 695.
2) Nielsen, K.; Fehrmann, R.; Eriksen, K. M. Inorg. Chem. 1993, 32,
825.
3) Oka, Y.; Saito, F.; Yao, T.; Yamamoto, N. J. Solid State Chem. 1997,
34, 52.
4
5+
+
dium(V) ((V O
dimensionalities, two-dimensional Ba2.5(VO
2
) vanadyl) moiety but also with different
2
(SeO ‚H O
(
2
)
3
3
)
4
1
(
(
4) Ueda, Y. Chem. Mater. 1998, 10, 2653.
and three-dimensional La(VO
2
)
6 2
(TeO )‚3H O.
3
5) Khan, M. I.; Yohannes, E.; Nome, R. C.; Ayesh, S.; Golub, V. O.;
O’Connor, C. J.; Doedens, R. J. Chem. Mater. 2004, 16, 5273.
6) Kurata, T.; Uehara, A.; Hayashi, Y.; Isobe, K. Inorg. Chem. 2005,
Experimental Section
(
(
(
(
44, 2524.
Reagents. BaCO
8%), La(NO ‚xH
(Aldrich, 99+%), and H
3
(Aldrich, 99+%), Ba(OH)
O (Aldrich, 99.9%), V (Aldrich, 99.6+%),
SeO (Alfa Aesar, 99%) were used
2
‚H
2
O (Aldrich,
7) Whittingham, M. S.; Jacobson, A. J. Intercalation Chemistry; Aca-
demic Press: New York, 1982.
8) Jacobson, A. J.; Johnson, J. W. Angew. Chem., Int. Ed. Engl. 1983,
9
TeO
)
3 3
2
2 5
O
2
2
3
22, 412.
as received.
9) Jacobson, A. J.; Johnson, J. W.; Brody, J. F.; Scanlon, J. C.;
Lewandowski, J. T. Inorg. Chem. 1985, 24, 1782.
10) Kang, H. Y.; Lee, C. W.; Wang, S. L.; Lii, K. H. Inorg. Chem. 1992,
(16) Folkesson, B. J. Appl. Electrochem. 1990, 20, 907.
(17) Chirayil, T.; Zavalij, P. Y.; Whittingham, M. S. Chem. Mater. 1998,
10, 2629.
(18) Whittingham, M. S.; Guo, J.-D.; Chen, R.; Chirayil, T.; Janauer, G.;
Zavalij, P. Solid State Ionics 1995, 75, 257.
(19) Oka, Y.; Yao, T. Nippon Kessho Gakkaishi 1998, 40, 397.
(20) Livage, J. Coord. Chem. ReV. 1998, 178-180, 999.
(21) Oka, Y.; Yao, T.; Yamamoto, N. J. Solid State Chem. 2000, 152, 486.
(22) Dai, Z.; Shi, Z.; Li, G.; Zhang, D.; Fu, W.; Jin, H.; Xu, W.; Feng, S.
Inorg. Chem. 2003, 42, 7396.
(23) Lutta, S. T.; Chernova, N. A.; Zavalij, P.; Whittingham, M. S. J. Mater.
Chem. 2004, 14, 2922.
(
(
(
(
(
(
31, 4743.
11) Kang, H. Y.; Meyer, L. M.; Haushalter, R. C.; Schweitzer, A. L.;
Zubieta, L.; Dye, J. L. Chem. Mater. 1996, 8, 43.
12) Papoutsakis, D.; Jackson, J. E.; Nocera, D. G. Inorg. Chem. 1996,
35, 800.
13) Bideau, J. L.; Papoutsakis, D.; Jackson, J. E.; Nocera, D. G. J. Am.
Chem. Soc. 1997, 119, 1313.
14) Zhang, Y.; Warren, C. J.; Haushalter, R. C. Chem. Mater. 1998, 10,
1059.
15) Whittingham, M. S. Mater. Res. Bull. 1978, 13, 959.
3602 Inorganic Chemistry, Vol. 45, No. 9, 2006
10.1021/ic052103u CCC: $33.50
© 2006 American Chemical Society
Published on Web 04/01/2006

NoWel Two- and Three-Dimensional Vanadates
-
3
Syntheses. For Ba2.5(VO
mol) of BaCO
2
)
3
(SeO
3
-
)
4
3
‚H
2
O, 0.4934 g (2.5 × 10
, and 0.7248 g
O.
Table 1. Crystallographic Data for Ba2.5(VO2)3(SeO3)4‚H2O and
La(VO ) (TeO )‚3H O
2 3
6
2
3
, 0.4547 g (2.5 × 10 mol) of V
2
O
5
-
3
(
5.62 × 10 mol) of H
For La(VO (TeO )‚3H
xH
O, 0.1819 g (1 × 10 mol) of V
mol) of TeO were combined with 10 mL of H
2
SeO
O, 0.3249 g (1 × 10 mol) of La(NO
, and 0.1596 g (1 × 10
O. The respective
3
were combined with 10 mL of H
2
formula
fw
space group
a (Å)
b (Å)
c (Å)
Ba2.5(VO2)3(SeO3)4‚H2O
1117.99
P 3h (No. 147)
12.8279(15)
12.8279(15)
7.2631(9)
90
La(VO2)3(TeO6)‚3H2O
665.33
R3c (No. 161)
9.4577(16)
9.4577(16)
23.455(7)
90
90
120
1816.9(7)
6
-3
2
)
3
6
2
3 3
) ‚
-
3
-3
2
2 5
O
2
2
solutions were placed in 23-mL Teflon-lined autoclaves and
subsequently sealed. The autoclaves were gradually heated to 230-
‚H O, 230 °C for
2
d, and for La(VO (TeO )‚3H O, 240 °C for 2 d) and cooled
slowly to room temperature at 6 °C h . The mother liquor was
decanted from the products, and the products were recovered by
R (°)
â (°)
90
240 °C, held for 2-4 d (for Ba2.5(VO
)
2 3
(SeO
3
)
4
γ (°)
120
1035.1(2)
2
3
4
2
)
3
6
2
V (Å )
-
1
Z
T (°C)
λ (Å)
293.0(2)
0.71073
3.601
293.0(2)
0.71073
3.616
Fcalcd (g cm-3)
-1
filtration and washed with distilled water. For Ba2.5(VO
2
) (SeO
3
3
)
4
‚
µ (mm
R(F)a
)
13.53
8.139
H
2
O, light yellow crystals were found in 60% yield based on V O .
2 5
0.0585
0.1894
0.0252
0.0932
For La(VO
2
)
3
(TeO
6
)‚3H
2
O, colorless crystals were found in 70%
(SeO ‚H O, a yield of nearly
0% was obtained by using the above procedure with the reagents
2 b
Rw(Fo )
2 5
yield based on V O . For Ba2.5(VO
2
)
3
)
3 4
2
a
R(F) ) ∑||Fo| - |Fc||/∑|Fo|. Rw(Fo ) ) [∑w(Fo - Fc ) /∑w(Fo2)2]1/2.
b
2
2
2 2
9
-
3
Ba(OH)
2
‚H
2
O (1.542 g, 8.14 × 10 mol), V (0.8184 g, 4.5 ×
SeO
(1.7395 g, 13.5 × 10 mol) were combined
O at 240 °C for 4 d.
2
-3
O
5
Table 2. Selected Bond Distances (Å) for Ba2.5(VO2)3(SeO3)4‚H2O and
La(VO2)3(TeO6)‚3H2O
-3
10
mol), and H
2
3
with 10 mL of H
2
Ba2.5(VO2)3(SeO3)4‚H2O
La(VO2)3(TeO6)‚3H2O
Single-Crystal X-ray Diffraction. For Ba2.5(VO
) (SeO )
2 3 3 4
2
‚H O
) -
2 3
Se1-O1 × 3
1.708(9)
Te1-O1 × 3
1.916(6)
1.895(6)
1.800(6)
1.847(6)
1.632(6)
1.643(6)
3
a light yellow block (0.08 × 0.19 × 0.27 mm ) and for La(VO
Se2-O2
1.724(9)
1.711(9)
1.651(9)
2.006(9)
1.952(8)
1.981(9)
1.642(9)
1.647(9)
Te1-O2 × 3
V1-O1
3
(
TeO
6
)‚3H
2
O a colorless block (0.10 × 0.12 × 0.15 mm ) were
Se2-O3
Se2-O4
V1-O2
V1-O3 (VdO)
V1-O4 (VdO)
used for single-crystal data analyses. Data were collected using a
Siemens SMART diffractometer equipped with a 1K CCD area
detector using graphite-monochromated Mo KR radiation. A
hemisphere of data was collected using a narrow-frame method
with scan widths of 0.30 in. and an exposure time of 25 s per frame.
The first 50 frames were remeasured at the end of the data collection
to monitor instrument and crystal stability. The maximum correction
V1-O1
V1-O2
V1-O3
V1-O5 (VdO)
V1-O6 (VdO)
placed in separate capillary tubes during the experiment. Excitation
+
was provided by a coherent Ar ion laser at a wavelength of 457
applied to the intensities was <1%. The data were integrated using
-
1
the Siemens SAINT program,24 with the intensities corrected for
nm with 100 mW laser power and 4 cm slit widths.
UV-Vis Diffuse Reflectance Spectroscopy. UV-vis diffuse
reflectance data for all of the reported compounds were collected
on a Varian Cary 500 scan UV-vis-NIR spectrophotometer over
the spectral range 300-1500 nm at room temperature. Poly-
(tetrafluoroethylene) was used as a reference material. Reflectance
spectra were converted to absorbance with the Kubelka-Munk
values.28
Lorentz, polarization, air absorption, and absorption attributable to
the variation in the path length through the detector faceplate.
Ψ-scans were used for the absorption correction on the hemisphere
of data. The data were solved by direct methods using SHELXS-
7 and refined using SHELXL-97. All of the atoms were refined
with anisotropic thermal parameters and converged for I > 2(I).
All calculations were performed using the WinGX-98 crystal-
lographic software package.27 Relevant crystallographic data and
selected bond distances are given in Tables 1 and 2, respectively.
25
26
9
Thermogravimetric Analysis (TGA). Thermogravimetric analy-
ses were carried out on a TGA 2050 thermogravimetric analyzer
(
TA instruments). The sample was contained within a platinum
Powder X-ray Diffraction. Powder X-ray diffraction was used
to confirm the phase purity of each sample. The X-ray powder
diffraction data were collected on a Scintag XDS2000 diffractometer
at room temperature (Cu KR radiation, θ-θ mode, flat plate
geometry) equipped with Peltier germanium solid-state detector in
the 2θ range 5-60° with a step size of 0.02 and a step time of 10
s.
-
1
crucible and heated in oxygen at a rate of 5 °C min to 1000 °C.
Results and Discussion
Structures. Ba2.5(VO
2
)
3
(SeO
3
)
4
2
‚H O exhibits a two-
dimensional layered structure consisting of layers of VO
5
+
square pyramids linked to SeO
cations and H
3
polyhedra in which the Ba2
Infrared and Raman Spectroscopy. Infrared spectra were
recorded on a Matteson FTIR 5000 spectrometer in the 400-4000
2
O molecules occupy the interlayer region (see
Figure 1). Interestingly, each layer consists of eclipsed 12-
membered rings constructed from VO square pyramids and
SeO polyhedra. These 12-membered rings are surrounded
-
1
cm range with the sample pressed between two KBr pellets.
Raman spectra were recorded at room temperature under the control
of Spex DM3000 microcomputer system using a conventional
scanning Raman instrument equipped with a Spex 1403 double
monochromator (with a pair of 1800 grooves/mm gratings) and a
Hamamatsu 928 photomultiplier detector. The powder samples were
5
3
by smaller eight-membered rings, and the water molecule
resides in the middle of the 12-membered rings (see Figure
2
). The dehydration of water molecule leads to 12-MR
channels (∼9.7 × 7.0 Å) that are surrounded by 8-MR
channels (∼8.7 × 2.3 Å). No structural change is observed
(
(
(
(
24) SAINT, v. Program for Area Detector Absorption Correction; Siemens
5
+
after dehydration. Each V is bonded to five oxygen atoms
in a distorted square pyramidal environment with two “short”
Analytical X-ray Instruments: Madison, WI, 1995.
25) Sheldrick, G. M. SHELXS-97-A program for automatic solution of
crystal structures; University of G o¨ ttingen: G o¨ ttingen, Germany, 1997.
26) Sheldrick, G. M. SHELXL-97-A program for crystal structure refine-
ment; University of G o¨ ttingen: G o¨ ttingen, Germany, 1997.
27) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(
1.642(9) and 1.647(9) Å) and three “normal” bonds (1.952-
(28) Kubelka, P.; Munk, F. Z. Tech. Phys. 1931, 12, 593.
Inorganic Chemistry, Vol. 45, No. 9, 2006 3603

Sivakumar et al.
Figure 1. Ball-and-stick diagram of Ba2.5(VO2)3(SeO3)4‚H2O in the ab
plane. Note the 12-membered rings that are surrounded by 8-membered
rings.
Figure 3. Ball-and-stick representation of the three-dimensional La(VO2)3-
(TeO6)‚3H2O is shown. The water molecules have been removed for clarity.
Figure 4. Ball-and-stick representation of the TeO6 and VO4 polyhedra
in La(VO2)3(TeO6)‚3H2O. Note that each TeO6 polyhedron is surrounded
by six VO4 tetrahedra.
Figure 2. Ball-and-stick representation of the 12- and 8-membered rings
in Ba2.5(VO2)3(SeO3)4‚H2O.
distances ranging from 1.895(6) to 1.916(6) Å. All six
5
+
oxygen atoms are further bonded to V cation (see Figure
(
8)-2.006(9) Å). Three of the five oxygen atoms are further
29
4
). Bond valence calculations resulted in values of 3.26
4+
bonded to Se cations, whereas the two “short” V-O bonds
remain terminal. The two unique Se cations (Se(1) and
Se(2) ) are bonded to three oxygen atoms. All three oxygen
atoms of Se(1) are further bonded to V , whereas in Se-
3+
6+
5+
for La , 6.19 for Te , and 5.02 for V . La(VO
O is acentric, crystallizing in the noncentrosymmetric
NCS) space group R3c. Powder SHG measurements were
2 3 6
) (TeO )‚
4+
4+
3H
2
(
4+
4+
5+
performed, however, the SHG efficiency is below the
4+
(2) , two of the three oxygen atoms are further bonded to
30
detection limit of our instrument. In this material, the two
5+
V , the “short” Se(2)-O bond (1.651(9) Å) remains
terminal. In connectivity terms, the structure may be written
as [(3(VO3/2
balance maintained by the interlayer cation, Ba . Bond
valence calculations resulted in values of 1.90 for Ba ,
metal oxide polyhedra that could contribute to the SHG are
5+
6+
4 6
the V O tetrahedra and the Te O octahedra. With the
2-
+
0 5-
O
2/1) (SeO3/2) 3(SeO2/2
O
1/1) ] with charge
5+
former, the tetrahedral coordination of V , although inher-
ently NCS (chiral but not polar), are not aligned macroscopi-
cally, whereas with the latter, Te , similar to Sn and Sb ,
does not undergo a substantial distortion from the center of
its oxide octahedron. Thus, both the VO and TeO polyhedra
2
+
29
2+
6+
4+
5+
4
+
4+
5+
3
.96 for Se(1) , 4.12 for Se(2) , and 4.93 for V .
La(VO (TeO )‚3H O exhibits a three-dimensional frame-
work structure consisting of VO
octahedra that are separated by La3+ cations and H
)
2 3
6
2
4
6
4
tetrahedra and TeO
6
contribute minimally to any possible SHG, resulting in a very
weak response.
2
5
O
+
molecules that reside in the tunnels (see Figure 3). Each V
Significantly, both of the vanadium polyhedra (distorted
VO square pyramid and distorted VO tetradedra) in the
is bonded to four oxygen atoms in a distorted tetrahedral
environment with two “short” (1.632(6) and 1.643(6) Å) and
two “normal” bonds (1.800(6) and 1.847(6) Å). Two of the
four oxygen atoms are further bonded to a Te6+ cation,
whereas the two short V-O bonds remain terminal (see
Figure 4). In connectivity terms, the structure may be written
5
4
two reported structures, two-dimensional Ba (VO ) (SeO ) ‚
2.5
2 3
3 4
H O and three-dimensional La(VO ) (TeO )‚3H O, exhibit
2
2 3
6
2
5+
+
a dioxovanadium(V) ((V O ) vanadyl) feature attributable
2
to the short terminal V-O bonds (VdO). The short V-O
bond distances (1.63-1.65 Å) are consistent with those of
-
0 3-
31,32
as [3(VO2/2
O
2/1) (TeO6/2) ] with charge balance maintained
reported values (1.62-1.67 Å) in the literature.
In
by the La3 cation. Each Te is bonded to six oxygen atoms
+
6+
(
30) Porter, Y.; Ok, K. M.; Halasyamani, P. S. Chem. Mater. 2001, 13,
910.
in a nearly regular octahedral environment with Te-O bond
1
(
31) Sykora, R. E.; Ok, K. M.; Halasyamani, P. S.; Wells, D. M.; Albrecht-
(29) Brown, I. D.; Altermatt, D. Acta Crystallogr. 1985, B41, 244.
Schmitt, T. E. Chem. Mater. 2002, 14, 2741.
3604 Inorganic Chemistry, Vol. 45, No. 9, 2006

NoWel Two- and Three-Dimensional Vanadates
Table 3. Infrared and Raman Vibrations (cm-1) for
Ba2.5(VO2)3(SeO3)4‚H2O and La(VO2)3(TeO6)‚3H2O
absorption at 2.7 and 2.2 eV for Ba2.5(VO
La(VO (TeO )‚3H O, respectively. The onset is attributed
by the absorption of light in approximately the green region
2
)
3
(SeO
3
)
4
2
‚H O and
2
)
3
6
2
Ba2.5(VO2)3(SeO3)4‚H2O
La(VO2)3(TeO6)‚3H2O
5
+
+
VdO
V-O
Se-O
O-H
VdO
V-O
Te-O
O-H
2
due to (V O ) vanadyl units. It is likely that the visible
absorption in the reported compounds can be attributed to
charge transfer in the vanadyl units. The onset of absorption
IR
9
9
9
63
34
10
863
915
496
759
740
657
3494
1622
962
949
938
912
884
792
505
737
565
3433
1620
values for the reported compounds is in good agreement with
+
the previous study of compounds containing VO
2
vanadyl
5
5
4
58
36
70
3
1
32
units such as vanadyl iodates and vanadyl tellurate.
Thermogravimetric Analysis. Both Ba2.5(VO (SeO
O and La(VO (TeO )‚3H O decompose at 340 and 460
C, respectively. The TGA curve of Ba2.5(VO (SeO ‚H
shows a continuous decomposition up to 770 °C with a
plateau around 350 °C attributable to the loss of H
followed by the sublimation of SeO : calcd(exptl) 41.40%-
37.87%). Dehydration of Ba2.5(VO (SeO ‚H O, at 340
)
2 3
3 4
) ‚
Raman
966
H
2
2
)
3
6
2
9
9
9
59
39
13
857
827
809
756
728
677
620
534
884
859
794
494
441
781
718
648
°
)
2 3
)
3 4
2
O
958
942
908
4
4
47
09
2
O
487
2
(
2
)
3
3
)
4
2
addition, the dioxovanadium(V) unit in all of the reported
compounds adopt a cis configuration (OdVdO) with
O-V-O bond angle ranging from 105 to 107° (∠ O-V-O
°C for 1 h (calcd(exptl) 1.61%(1.70%)) yields anhydrous
Ba (VO ) (SeO ) and occurs isostructurally as revealed by
2.5
2 3
3 4
powder XRD (see Figure S5, Supporting Information).
However, the nitrogen adsorption isotherm for Ba (VO ) -
in the VO
05.9(5)°, and ∠ O-V-O in the VO
TeO )‚3H O is 106.8(3)°). Infrared, Raman, and UV-vis
5
square pyramid of Ba2.5(VO
2
)
3
(SeO
3
)
4
‚H
2
O is
2.5
2 3
1
(
4
tetrahedra of La(VO
)
2 3
-
(SeO3)4 indicates nonporous behavior (see Figure S12,
Supporting Information). The TGA curve of La(VO ) -
6
2
2
3
+
diffuse reflectance spectroscopy data also confirm the VO
vanadyl feature.
2
(TeO )‚3H O reveals a weight loss between 150 and 250
6
2
°C attributable to the loss of 2 mol of H O molecules: calcd-
2
Infrared and Raman Spectroscopy. The infrared and
Raman spectra of Ba2.5(VO (SeO ‚H O and La(VO
TeO )‚3H O reveal the presence of a VO
attributable to the VdO (short terminal V-O bonds)
(exptl) 5.41%(5.16%). At around 350 °C, an additional mole
2
)
3
3
)
4
2
2
)
3
-
of H O is lost, resulting in the formation of anhydrous La-
2
+
(
6
2
2
vanadyl unit
(VO ) (TeO ): calcd(exptl) 2.86%(2.34%). The anhydrous
2
3
6
La(VO ) (TeO ) could also be indexed in R3c space group
2
3
6
-
1
vibrations in the region ca. 900-970 cm and V-O
with a ) b ) 9.256(5) Å (2.1% reduced), c ) 22.79(2) Å
-
1
3
vibrations in the region ca. 700-900 cm . The stretches
(2.8% reduced), and V ) 1691(2) Å (see Figure S6 and
-
1
7
81-565 and 759-470 cm can be attributed to Te-O and
Table S1, Supporting Information), revealing that the struc-
ture of anhydrous La(VO ) (TeO ) is similar to the hydrated
Se-O vibrations, respectively. The infrared and Raman
vibrations and their assignments are listed in Table 3. The
assignments are consistent with those previously reported.
2
3
6
phase La(VO ) (TeO )‚3H O. At 460 °C, the loss of 1 mo
2
3
6
2
31-40
2 3 6
of oxygen from La(VO ) (TeO ) results in the formation of
UV-Vis Diffuse Reflectance Spectroscopy. The UV-
vis diffuse reflectance spectra for the title compounds have
LaVO : calcd(exptl) 2.62%(2.42%). The reactions occurring
4
during the heating of La(VO ) (TeO )‚3H O may be written
2
3
6
2
been deposited in the Supporting Information. Ba2.5(VO
SeO ‚H O is yellow, whereas La(VO (TeO )‚3H O is
yellow-green (La(VO (TeO ) is yellow). These spectra
2
)
3
-
as
(
3
)
4
2
2
)
3
6
2
-
2H O
-H O
2
2
2
)
3
6
La(VO ) (TeO )‚3H O
8 La(VO ) (TeO )‚H O 350 °C8
2 3 6 2
50 °C
2
3
6
2
2
show that the absorption is approximately 2.2-2.7 eV.
Absorption (K/S) data were calculated from the following
Kubelka-Munk function:28
-
1/2O2
6
+
La(VO ) (Te O )
8 LaVO + TeO + V O
4 2 2 5
2
3
6
4
60 °C
The TGA curves for both of the materials have been
deposited in the Supporting Information.
2
(
1 - R)
K
S
F(R) )
)
2R
Acknowledgment. We thank the Robert A. Welch
Foundation for support. This work was also supported by
the NSF-Career Program through Grant No. DMR-0092054
and by the NSF-Chemical Bonding Center. We also ac-
knowledge Prof. R. Czernuszewicz for assistance in obtaining
the Raman spectra.
with R representing the reflectance, K the absorption, and S
the scattering. In a K/S vs E (eV) plot, extrapolating the linear
part of the rising curve to zero provides the onset of
(
(
32) Sullens, T. A.; Albrecht-Schmitt, T. E. Inorg. Chem. 2005, 44, 2282.
33) Frost, R. L.; Erickson, K. L.; Weier, M. L.; Carmody, O. Spectrochim.
Acta 2005, 61A, 829.
Supporting Information Available: X-ray crystallographic files
for Ba2.5(VO
2
)
3
(SeO
3
)
4
‚H
2
O and La(VO
2
)
3 6 2
(TeO )‚3H O in CIF
(34) Devi, R. N.; Vidyasagar, K. J. Chem. Soc., Dalton Trans. 1998, 3013.
(35) Ok, K. M.; Halasyamani, P. S. Chem. Mater. 2002, 14, 2360.
(36) Ok, K. M.; Halasyamani, P. S. Inorg. Chem. 2004, 43, 4248.
(37) Vaughey, J. T.; Harrison, W. T. A.; Dussack, L. L.; Jacobson, A. J.
Inorg. Chem. 1994, 33, 4370.
format; ORTEP diagrams, experimental and observed powder XRD
patterns, IR spectra, Raman spectra, UV-vis diffuse reflectance
curves, nitrogen adsorption isotherm for the dehydrated material,
and TGA curves for two reported materials. This material is
available free of charge via the Internet at http://pubs.acs.org.
(38) Zheng, S.-T.; Zhang, J.; Yang, G.-Y. Inorg. Chem. 2005, 44, 2426.
(39) Yu, R.; Ok, K. M.; Halasyamani, P. S. Dalton Trans. 2004, 392.
(40) Frost, R. L.; Erickson, K.; Weier, M. L. Spectrochem. Acta 2004, 60A,
2419.
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Inorganic Chemistry, Vol. 45, No. 9, 2006 3605