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The structure of the layered noncentrosymmetric titanosilicate AM-1 (also known as JDF-L1, disodium titanium tetra­silicate dihydrate), Na4Ti2Si8O22·4H2O, grown as small single crystals without the use of organics, has been refined from single-crystal X-ray diffraction data. The H atom has been located for the first time, and the hydrogen-bonding scheme is also characterized by IR and Raman spectroscopy. All atoms are in general positions except for the Na, the Ti, one Ti-bound O, one Si-bound O and the water O atoms (site symmetries 2, 4, 4, 2 and 2, respectively).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680704812X/br2055sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S160053680704812X/br2055Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](i-O) = 0.002 Å
  • R factor = 0.024
  • wR factor = 0.061
  • Data-to-parameter ratio = 13.1

checkCIF/PLATON results

No syntax errors found



Alert level B PLAT396_ALERT_2_B Deviating Si-O-Si Angle from 150 Deg for O4 176.30 Deg.
Alert level C PLAT031_ALERT_4_C Refined Extinction Parameter within Range ...... 3.00 Sigma PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical . ? PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........ 1
Alert level G REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values From the CIF: _diffrn_reflns_theta_max 27.84 From the CIF: _reflns_number_total 706 From the CIF: _diffrn_reflns_limit_ max hkl 9. 6. 14. From the CIF: _diffrn_reflns_limit_ min hkl -9. -6. -14. TEST1: Expected hkl limits for theta max Calculated maximum hkl 9. 9. 14. Calculated minimum hkl -9. -9. -14. REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF. From the CIF: _diffrn_reflns_theta_max 27.84 From the CIF: _reflns_number_total 706 Count of symmetry unique reflns 459 Completeness (_total/calc) 153.81% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 247 Fraction of Friedel pairs measured 0.538 Are heavy atom types Z>Si present yes PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature 293 K PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature . 293 K PLAT794_ALERT_5_G Check Predicted Bond Valency for Ti (4) 4.18
0 ALERT level A = In general: serious problem 1 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 5 ALERT level G = General alerts; check 4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 ALERT type 3 Indicator that the structure quality may be low 3 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check
checkCIF publication errors
Alert level A PUBL024_ALERT_1_A The number of authors is greater than 5. Please specify the role of each of the co-authors for your paper.
Author Response: As this work is performed as a part of interuniversity project both sides have equal contribution and every one of the co-authors is part of it.

1 ALERT level A = Data missing that is essential or data in wrong format 0 ALERT level G = General alerts. Data that may be required is missing

Comment top

The first synthesis of the layered, non-centrosymmetric titanosilicate AM-1 (chemical formula Na4Ti2Si8O22·4H2O) was reported by Anderson et al. (1995). However, later independent work of Roberts et al. (1996) and Du et al. (1996) reported the same compound with the name JDF-L1 and described a new synthesis approach, as well as a crystal- structure determination. The layered character of AM-1 allows pillaring and intercalation with different organic molecules that can provide certain catalytic properties.

The crystal structure of AM-1 was originally determined by ab initio methods from synchrotron powder X-ray data (Roberts et al., 1995), but the position of the H atom could not be located. Here we report for the first time the successful hydrothermal growth and structure refinement of AM-1 single crystals. The refined single-crystal unit-cell parameters are in good agreement with those reported by Roberts et al. (1996) and Ferdov et al. (2002).

The title compound contains [Ti2Si8O22]4- layers composed of five-member rings built up of four SiO4 tetrahedra and one TiO5 square pyramid (Figs. 1 and 2). The interconnection between two of these rings form small cage-type units. The negative charge of the titanosilicate layers is counter-balanced by Na+ cations residing in the interlayer space. A layer of water molecules is sandwiched between two layers of Na+ ions. The hydrogen atom H bonded to the OW atom could be located for the first time and was refined isotropically. It is involved in a weak hydrogen bond to O3 (OW···O3 = 2.9029 (16) Å), the oxygen ligand strongly bonded to the Ti atom. The hydrogen bonding scheme thus reinforces the structure across the titanosilicate layers (Fig. 2).

Single-crystal Raman and powder and single-crystal IR spectra are presented in Figs. 3 and 4, respectively. The powder IR spectrum is similar to that reported by Du et al. (1996). The Raman spectrum shows a small broad peak at ca 3350 cm-1, and a smaller satellite peak at ca 3200 cm-1(O—H stretching vibrations). A minute broad band at roughly 1617 cm-1 may be attributed to the water bending vibration. The IR spectra in the high-frequency region are similar to the Raman spectrum. The powder IR spectrum shows a very broad, large hump centered at ca 3380 cm-1, with a shoulder at ca 3200 cm-1. The three small peaks between 3000 and 2800 cm-1 are caused by organic impurities in the KBr pellet. The water bending vibration causes the relatively sharp band at 1620 cm-1. The single-crystal IR spectrum contains a broad peak centered at ca 3360 cm-1 but with two shoulders at ca 3480 and 3200 cm-1. Clearly, this reflects a range of O.·O donor-acceptor distances. A positional disorder of the water molecule seems unlikely, since the well refined H atom is characterized by a quite small isotropic displacement parameter. In both Raman and IR spectra, the region below 1200 -1 shows more or less sharp bands due to vibrations involving the TiO5, SiO4 and Na-(O,H2O) units.

Related literature top

For general background, see: Anderson et al. (1995); Roberts et al. (1996); Du et al. (1996); Ferdov et al. (2002); Kostov-Kytin et al. (2004).

Experimental top

The hydrothermal syntheses of AM-1 were carried out from gels of the following molar composition: 5–6 Na2O, 1–1.3 TiO2, 10 SiO2, 675 H2O. In a typical synthesis, 2.96 g of SiO2 (Merck) was added to a solution of 2.2 g NaOH (Merck) in 40 ml distilled water. Then the solution was brought to the boiling point. Subsequently, 0.66 ml TiCl4 (Merck) hydrolyzed in 20 ml distilled water was added to the above solution. After cooling to room temperature the mixture was homogenized for 40 min by a mechanical mixer at 200 rpm. The gel was then transferred into 250 ml teflon-lined autoclaves. The crystallization was performed under static conditions at 473 K for 24 h. After fast cooling with flowing H2O the samples were filtered and washed with distilled water and dried at 323 K overnight.

Refinement top

The structure model of Roberts et al. (1996) was originally used as a starting model, but the coordinates had to be standardized in order to achieve a connected set of atoms. A Flack parameter of -0.01 (6) shows that the crystal was not racemically twinned. The H atom was refined freely.

Structure description top

The first synthesis of the layered, non-centrosymmetric titanosilicate AM-1 (chemical formula Na4Ti2Si8O22·4H2O) was reported by Anderson et al. (1995). However, later independent work of Roberts et al. (1996) and Du et al. (1996) reported the same compound with the name JDF-L1 and described a new synthesis approach, as well as a crystal- structure determination. The layered character of AM-1 allows pillaring and intercalation with different organic molecules that can provide certain catalytic properties.

The crystal structure of AM-1 was originally determined by ab initio methods from synchrotron powder X-ray data (Roberts et al., 1995), but the position of the H atom could not be located. Here we report for the first time the successful hydrothermal growth and structure refinement of AM-1 single crystals. The refined single-crystal unit-cell parameters are in good agreement with those reported by Roberts et al. (1996) and Ferdov et al. (2002).

The title compound contains [Ti2Si8O22]4- layers composed of five-member rings built up of four SiO4 tetrahedra and one TiO5 square pyramid (Figs. 1 and 2). The interconnection between two of these rings form small cage-type units. The negative charge of the titanosilicate layers is counter-balanced by Na+ cations residing in the interlayer space. A layer of water molecules is sandwiched between two layers of Na+ ions. The hydrogen atom H bonded to the OW atom could be located for the first time and was refined isotropically. It is involved in a weak hydrogen bond to O3 (OW···O3 = 2.9029 (16) Å), the oxygen ligand strongly bonded to the Ti atom. The hydrogen bonding scheme thus reinforces the structure across the titanosilicate layers (Fig. 2).

Single-crystal Raman and powder and single-crystal IR spectra are presented in Figs. 3 and 4, respectively. The powder IR spectrum is similar to that reported by Du et al. (1996). The Raman spectrum shows a small broad peak at ca 3350 cm-1, and a smaller satellite peak at ca 3200 cm-1(O—H stretching vibrations). A minute broad band at roughly 1617 cm-1 may be attributed to the water bending vibration. The IR spectra in the high-frequency region are similar to the Raman spectrum. The powder IR spectrum shows a very broad, large hump centered at ca 3380 cm-1, with a shoulder at ca 3200 cm-1. The three small peaks between 3000 and 2800 cm-1 are caused by organic impurities in the KBr pellet. The water bending vibration causes the relatively sharp band at 1620 cm-1. The single-crystal IR spectrum contains a broad peak centered at ca 3360 cm-1 but with two shoulders at ca 3480 and 3200 cm-1. Clearly, this reflects a range of O.·O donor-acceptor distances. A positional disorder of the water molecule seems unlikely, since the well refined H atom is characterized by a quite small isotropic displacement parameter. In both Raman and IR spectra, the region below 1200 -1 shows more or less sharp bands due to vibrations involving the TiO5, SiO4 and Na-(O,H2O) units.

For general background, see: Anderson et al. (1995); Roberts et al. (1996); Du et al. (1996); Ferdov et al. (2002); Kostov-Kytin et al. (2004).

Computing details top

Data collection: COLLECT (Nonius, 2003); cell refinement: SCALEPACK (Otwinowski et al., 2003); data reduction: SCALEPACK and DENZO (Otwinowski et al., 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. Connectivity in AM-1, shown with displacement ellipsoids at the 50% probability level. [Symmetry codes: (i) y + 1/2, 1/2 - x, z; (ii) 1/2 - y, x + 1/2, z; (iii) y- 1/2, 1/2 - x; (iv) -x, 1 - y, z.]
[Figure 2] Fig. 2. Polyhedral representation of AM-1 along [010]. The interconnection between four SiO4 tetrahedra and one TiO5 square pyramid results in five-member rings which are the main building units of the [Ti2Si8O22]4- layers. The interlayer space is filled with Na+ cations and H2O molecules.
[Figure 3] Fig. 3. Single-crystal laser-Raman spectrum of AM-1.
[Figure 4] Fig. 4. Powder (red dashed line) and single-crystal IR spectra of AM-1.
disodium titanium tetrasilicate dihydrate top
Crystal data top
Na4Ti2Si8O22·4H2ODx = 2.386 Mg m3
Mr = 418.27Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4212Cell parameters from 901 reflections
Hall symbol: P 4ab 2abθ = 2.0–30.0°
a = 7.374 (1) ŵ = 1.29 mm1
c = 10.709 (2) ÅT = 293 K
V = 582.31 (16) Å3Plate, colorless
Z = 20.07 × 0.07 × 0.01 mm
F(000) = 416
Data collection top
Nonius KappaCCD
diffractometer
706 independent reflections
Radiation source: fine-focus sealed tube631 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.024
φ and ω scansθmax = 27.8°, θmin = 3.4°
Absorption correction: multi-scan
(SCALEPACK; Otwinowski et al., 2003)
h = 99
Tmin = 0.915, Tmax = 0.987k = 66
1399 measured reflectionsl = 1414
Refinement top
Refinement on F2Hydrogen site location: difference Fourier map
Least-squares matrix: fullAll H-atom parameters refined
R[F2 > 2σ(F2)] = 0.025 w = 1/[σ2(Fo2) + (0.03P)2 + 0.065P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.061(Δ/σ)max < 0.001
S = 1.16Δρmax = 0.30 e Å3
706 reflectionsΔρmin = 0.35 e Å3
54 parametersExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.006 (2)
Primary atom site location: isomorphous structure methodsAbsolute structure: Flack (1983)
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.01 (6)
Crystal data top
Na4Ti2Si8O22·4H2OZ = 2
Mr = 418.27Mo Kα radiation
Tetragonal, P4212µ = 1.29 mm1
a = 7.374 (1) ÅT = 293 K
c = 10.709 (2) Å0.07 × 0.07 × 0.01 mm
V = 582.31 (16) Å3
Data collection top
Nonius KappaCCD
diffractometer
706 independent reflections
Absorption correction: multi-scan
(SCALEPACK; Otwinowski et al., 2003)
631 reflections with I > 2σ(I)
Tmin = 0.915, Tmax = 0.987Rint = 0.024
1399 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.025All H-atom parameters refined
wR(F2) = 0.061Δρmax = 0.30 e Å3
S = 1.16Δρmin = 0.35 e Å3
706 reflectionsAbsolute structure: Flack (1983)
54 parametersAbsolute structure parameter: 0.01 (6)
0 restraints
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Na0.00000.00000.16928 (14)0.0252 (4)
Ti0.00000.50000.22310 (9)0.0119 (2)
Si0.31962 (8)0.23967 (8)0.35624 (7)0.01197 (19)
O10.2502 (2)0.0354 (2)0.32757 (18)0.0179 (4)
O20.2289 (2)0.3811 (2)0.2635 (2)0.0218 (5)
O30.00000.50000.0654 (4)0.0215 (8)
O40.2846 (3)0.2846 (3)0.50000.0351 (8)
OW0.1476 (3)0.1476 (3)0.00000.0343 (8)
H0.148 (5)0.251 (4)0.001 (4)0.036 (11)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Na0.0263 (8)0.0259 (8)0.0235 (8)0.0076 (8)0.0000.000
Ti0.0097 (3)0.0097 (3)0.0163 (5)0.0000.0000.000
Si0.0095 (3)0.0092 (3)0.0173 (4)0.0006 (3)0.0009 (3)0.0011 (3)
O10.0192 (9)0.0095 (8)0.0250 (11)0.0004 (8)0.0037 (8)0.0006 (7)
O20.0124 (9)0.0144 (9)0.0386 (13)0.0008 (7)0.0049 (9)0.0068 (9)
O30.0239 (12)0.0239 (12)0.0167 (19)0.0000.0000.000
O40.0402 (12)0.0402 (12)0.0247 (17)0.0094 (14)0.0137 (11)0.0137 (11)
OW0.0325 (12)0.0325 (12)0.0379 (19)0.0094 (16)0.0092 (13)0.0092 (13)
Geometric parameters (Å, º) top
Si—O21.588 (2)Ti—O21.9505 (18)
Si—O41.5958 (8)Na—OWv2.378 (3)
Si—O11.6202 (18)Na—OW2.378 (3)
Si—O1i1.6223 (18)Na—O2iii2.405 (2)
Ti—O31.689 (4)Na—O2vi2.405 (2)
Ti—O2ii1.9505 (18)Na—O12.519 (2)
Ti—O2iii1.9505 (18)Na—O1v2.519 (2)
Ti—O2iv1.9505 (18)OW—H0.76 (3)
OWv—Na—OW80.69 (13)O2ii—Ti—O2iv87.18 (3)
OWv—Na—O2iii122.24 (5)O2iii—Ti—O2iv87.18 (3)
OW—Na—O2iii96.09 (6)O3—Ti—O2102.81 (7)
OWv—Na—O2vi96.09 (6)O2ii—Ti—O287.18 (3)
OW—Na—O2vi122.24 (5)O2iii—Ti—O287.18 (3)
O2iii—Na—O2vi130.39 (12)O2iv—Ti—O2154.38 (15)
OWv—Na—O1153.59 (4)O2—Si—O4113.50 (9)
OW—Na—O197.48 (7)O2—Si—O1111.04 (10)
O2iii—Na—O184.17 (7)O4—Si—O1108.96 (12)
O2vi—Na—O162.41 (6)O2—Si—O1i105.33 (11)
OWv—Na—O1v97.48 (7)O4—Si—O1i109.36 (11)
OW—Na—O1v153.59 (4)O1—Si—O1i108.47 (13)
O2iii—Na—O1v62.41 (6)Si—O1—Sivi149.48 (13)
O2vi—Na—O1v84.17 (7)Si—O2—Ti142.96 (13)
O1—Na—O1v95.41 (10)Sivii—O4—Si176.3 (2)
O3—Ti—O2ii102.81 (7)Naviii—OW—Na99.31 (13)
O3—Ti—O2iii102.81 (7)Naviii—OW—H118 (3)
O2ii—Ti—O2iii154.38 (15)Na—OW—H116 (3)
O3—Ti—O2iv102.81 (7)
Symmetry codes: (i) y+1/2, x+1/2, z; (ii) y+1/2, x+1/2, z; (iii) y1/2, x+1/2, z; (iv) x, y+1, z; (v) x, y, z; (vi) y+1/2, x1/2, z; (vii) y, x, z+1; (viii) y, x, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
OW—H···O30.76 (3)2.24 (3)2.9029 (16)145 (3)

Experimental details

Crystal data
Chemical formulaNa4Ti2Si8O22·4H2O
Mr418.27
Crystal system, space groupTetragonal, P4212
Temperature (K)293
a, c (Å)7.374 (1), 10.709 (2)
V3)582.31 (16)
Z2
Radiation typeMo Kα
µ (mm1)1.29
Crystal size (mm)0.07 × 0.07 × 0.01
Data collection
DiffractometerNonius KappaCCD
Absorption correctionMulti-scan
(SCALEPACK; Otwinowski et al., 2003)
Tmin, Tmax0.915, 0.987
No. of measured, independent and
observed [I > 2σ(I)] reflections
1399, 706, 631
Rint0.024
(sin θ/λ)max1)0.657
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.025, 0.061, 1.16
No. of reflections706
No. of parameters54
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.30, 0.35
Absolute structureFlack (1983)
Absolute structure parameter0.01 (6)

Computer programs: COLLECT (Nonius, 2003), SCALEPACK (Otwinowski et al., 2003), SCALEPACK and DENZO (Otwinowski et al., 2003), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 2006).

Selected bond lengths (Å) top
Si—O21.588 (2)Ti—O2ii1.9505 (18)
Si—O41.5958 (8)Na—OWiii2.378 (3)
Si—O11.6202 (18)Na—O2iv2.405 (2)
Si—O1i1.6223 (18)Na—O12.519 (2)
Ti—O31.689 (4)
Symmetry codes: (i) y+1/2, x+1/2, z; (ii) y+1/2, x+1/2, z; (iii) x, y, z; (iv) y1/2, x+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
OW—H···O30.76 (3)2.24 (3)2.9029 (16)145 (3)
 

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