Crystal Structure of Zeolite LTA Containing Extraframework Tungsten(VI)

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Crystal Structure of Zeolite LTA Containing Extraframework Tungsten(VI) Ions Hyeon Seung Lim, Joon Young Kim, Nam Ho Heo, and Karl Seff J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.7b12686 • Publication Date (Web): 22 Feb 2018 Downloaded from http://pubs.acs.org on March 1, 2018

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The Journal of Physical Chemistry

Crystal Structure of Zeolite LTA Containing Extraframework Tungsten(VI) Ions

Hyeon Seung Lim,† Joon Young Kim,† Nam Ho Heo,*,† and Karl Seff §

†

Laboratory of Structural Chemistry,

Department of Applied Chemistry, School of Applied Chemical Engineering, Kyungpook National University, Daegu 41566, Korea

§

Department of Chemistry, University of Hawaii,

2545 The Mall, Honolulu, Hawaii 96822, United States

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(abstract) Tungsten(VI) has been introduced into zeolite LTA (A) by the reaction of fully dehydrated Tl-A (|Tl12|[Si12Al12O48]-A) with WCl6 (g, 7.0 x 102 Pa) at 453 K for 48 h under anhydrous conditions. The crystal structure of the product, |(WCl)0.6(Tl7Cl6)0.5Tl8.5|[Si12Al12O48]-A, was determined by single-crystal crystallography using synchrotron X-radiation. composition was confirmed by energy dispersive X-ray analysis.

Its

It was refined in the

space group Pm 3m (a = 12.061(1) Å) using all data to the final error index R1 = 0.085 for the 628 unique reflections for which Fo > 4σ(Fo). WCl6 reacted with Tl+ ions in the zeolite to form WCl5+ and Tl7Cl6+.

WCl5+ lies opposite 6-rings in half of the large cavities; its W6+

ion coordinates tetrahedrally to its Cl- ion and to three 6-ring oxygen atoms.

The other half

of the large cavities contain Tl7Cl6+; one Tl+ ion at the very center of a large cavity coordinates octahedrally to six Cl- ions, each of which bonds in turn to a Tl+ ion in an 8-ring. The remaining Tl+ ions occupy well established cation positions near 6-rings.

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1. INTRODUCTION 1.1. Tungsten and Zeolites Tungsten compounds have been widely studied for their intrinsic catalytic properties in various important reactions such as the hydrogenation of ethylene1 and nitriles,2 hydrodeoxygenation of oleic acid,3 and as a catalyst precursor for the ring-opening metathesis polymerization of exo-dicyclopentadiene.4 Tungsten compounds have also been studied for their electrocatalytic5 and photocatalytic6 properties.

Tungsten,

because it is a heavy element, could also be used in gamma radiation shielding materials;7 the development of lead-free shielding materials is increasing due to the toxicity of lead.8 Tungsten could be an excellent substitute for lead; its mass attenuation coefficients are only slightly lower.9

Kim et al. reported a nano-W dispersed polymer with greatly enhanced

radiation attenuation for gamma radiation shielding.9 Studies of tungsten species within zeolites are limited, probably because tungsten ions cannot be exchanged into zeolites by conventional aqueous methods. This is because tungsten has few soluble salts, and the tungsten ions in those hydrolyze strongly in solution, causing their oxides or hydroxides to precipitate.

Additionally, the resulting H+ ions,

produced at high concentration, would exchange into the zeolite and, if the zeolite has a high aluminum content, destroy it.10, 11 Nonetheless, other methods have led to some success.

When ultrastable zeolite Y

(USY) was impregnated with ammonium meta-tungstate, (NH4)6[H2W12O40]·xH2O, at low pH (~2.7),12 most of the tungsten was dispersed on the external surface of the zeolite as



WO3.

It was suggested that tungsten species such as WO42- could locate within a zeolite

after impregnation at high pH (11).12

In later work USY was impregnated with tungsten

acids, and WO3 was again found dispersed on the surface, but some tungsten species were found within the zeolite.13 Tungsten has also been encapsulated in zeolite Y cavities as WO3 by the photooxidation of intrazeolitic hexacarbonyltungsten by O2.14-16

1.2. Objectives and Methodology. The objectives of this work were (1) to achieve tungsten ion exchange into a high alumina zeolite by the thallous ion exchange (TIE) method,11 thus bypassing the difficulties associated with conventional aqueous ion exchange,11 and (2) to observe the positions and coordination environments of the extraframework tungsten species in the product zeolite.

2. EXPERIMENTAL SECTION 2.1. Exchange with Tl+. Clear colorless single crystals (cubes) of zeolite A (|Na12(H2O)x|[Si12Al12O48]–LTA, Na12–A·xH2O, Na12–A, or Na–A) were synthesized by J. F. Charnell17 in G. T. Kokotailo's laboratory.

One of these crystals was lodged in a

thin Pyrex capillary. Aqueous TlC2H3O2 (0.10M, Strem Chemicals, 99.999%) was allowed to flow past it (dynamic ion exchange) to prepare fully Tl+-exchanged zeolite A (|Tl12(H2O)y|[Si12Al12O48]-LTA, Tl12-A, or Tl-A).18

This or similar procedures had been

shown to be suitable for the preparation of the fully Tl+-exchanged zeolites Tl-A,19, 20 Tl-


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X,21, 22 Tl-Y,23, 24 and ZSM-5.25

2.2. Reaction with WCl6.

A break-off sealed tube of anhydrous WCl6 powder

(Sigma-Aldrich, ≥ 99.99%) was attached as a side arm to the reaction vessel, above the capillary containing the hydrated Tl-A crystal. for dehydration.

This was then connected to a vacuum line

After dehydration (Table 1), the capillary and side arm portion of the

apparatus were sealed off from the vacuum line.

The internal seal was then broken, the

WCl6 powder was transferred to the tube above the capillary, and the side arm was sealed off and discarded. The remaining linear reaction vessel was then heated to 453 K to allow WCl6(g) to react with the zeolite crystal under anhydrous conditions (Table 1).

Then, to

eliminate any unreacted WCl6 in or near the crystal, only the capillary end of the reaction vessel was maintained at 453 K for another 24 h. Finally, after the entire reaction vessel had cooled to room temperature, the capillary containing the product crystal was sealed off under vacuum by torch.

Under the microscope the crystal was seen to be colorless with

grey powder on its surface and grey sparkling crystallites within.

2.3. X-Ray Diffraction. Synchrotron X-ray diffraction data for the single crystal were collected at the Pohang Accelerator Laboratory (PAL), Korea, by the omega scan method using the BL2D-SMDC program.26

Highly redundant data sets were harvested by

collecting 72 sets of frames with a 5o scan and an exposure time of 1 s per frame.

The

basic data files were prepared using the HKL3000 program and the reflections were indexed



by the automated indexing routine of the DENZO program.27

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These were corrected for

Lorentz and polarization effects; negligible corrections for crystal decay were also applied. The space group Pm 3m, standard for zeolite A unless high precision is achievable, was determined by the program XPREP.28

Additional experimental and crystallographic data

are presented in Table 1.

2.4. SEM-EDX Analysis. The single crystal was removed from its capillary (exposed to the atmosphere) after diffraction data collection and attached to a sample holder with carbon tape. Scanning electron microscopy energy dispersive X-ray (SEM-EDX) analysis was done to determine its composition. A Horiba X-MAX N50 EDX spectrometer and a Hitachi SU8220 field emission scanning electron microscope at 294 K and 9.0 x 10-4 Pa with a beam energy of 20 keV and current of 5 nA were used.

Compositional element

maps were subsequently prepared using Trumap, a feature of the EDX software.

The

results show that tungsten, thallium, and chlorine are all present in the single crystal (Figure 1 and Table 2).

2.5. Two Additional Crystals. Attempts were made to increase the tungsten content of the zeolite.

The procedure in section 2.2 was repeated at two somewhat higher

temperatures, 463 K and 473 K.

Unfortunately both crystals diffracted much more poorly

and the occupancy at W became much less.

They were not studied further.


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3. STRUCTURE DETERMINATION Full-matrix least-squares refinements (SHELXL2014)29 in the space group Pm 3 m were done on F2 using all 955 unique reflections measured. They were initiated with the atomic parameters of the framework atoms [(T(Si,Al)), O1, O2, and O3] in dehydrated Tl12A.30

Fixed weights were used initially.

The initial refinements with anisotropic thermal

parameters for all framework atoms converged to the high error indices (defined in footnotes to Table 1) R1 = 0.56 and R2 = 0.87 (Table 3, step 1).

The detailed progress of

structure determination as subsequent peaks were found in difference Fourier functions and identified as extraframework atoms are presented in Table 3. The final weights were assigned using the formula w = 1/[σ2(Fo2) + (aP)2 + bP] where P = [max(Fo2,0) + 2Fc2]/3, and a and b are refined parameters.

Their final values are given in Table 1.

In step 10 of structure determination (Table 3), the Cl1/W occupancy ratio was 4(3), where 1.0 is the maximum allowed value. Accordingly, the constraint 1:1 was imposed for Cl1:W (step 11). A chloride ion completes the tetrahedral coordination sphere about W. Tl3 appeared as a very firm position at the center of the large cavity, far from the zeolite framework. The only peak on the subsequent difference Fourier function that could bind to it was at Cl2.

Including Cl2 in refinement caused the R values to decrease only

modestly (Table 3, step 12).

Although not indicated by occupancy refinement (step 12),

the symmetry at Cl2 indicated that Cl2 was octahedral about Tl3, supporting Tl3 at its



position of very high symmetry.

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When the occupancy constraint of 1:6 was imposed for

Tl3:Cl2, the error indices actually decreased sharply (step 13). Each ion at Cl2 also bonds to a Tl+ ion at Tl2 on an 8-ring, so Cl2:Tl2 should be 1:1. Altogether, the occupancies at these three positions were constrained to be Tl3:Cl2:Tl2 = 1:6:6 (Table 3, step 14).

In the same way, the occupancy at Tl13 appeared to be eight

times that found at Tl3 (Tl13/Tl3 = 6.8(3)).

The occupancies at these four positions, then,

were constrained to be Tl3:Cl2:Tl2:Tl13 = 1:6:6:8 (Table 3, step 15). The refined occupancy at W was 0.49(7) (Table 3, step 17).

However, to have six Cl-

ions at Cl2 in its large cavity (not just five at an octahedral position about Tl3), the occupancies at W and Cl1 should be 20% greater, so their occupancies were fixed at 0.6. The net reaction per unit cell (overlooking, for the moment, the Tl-Cl bonds that form) is therefore 6/5WCl6(g) → 6/5WCl5+ + 6Cl-.

(1)

In addition, the occupancies at Tl3, Cl2, Tl2, and Tl13 were fixed at ½, 3, 3, and 4, respectively, in accordance with the Tl3:Cl2:Tl2:Tl13 = 1:6:6:8 constraint (Table 3, step 18). Thus half of the large cavities contain Tl3-6Cl2-6Tl2-8Tl13 units and the other half have 1.2 W-Cl1 groups (80% have one and 20% have two).

To fully occupy the 6-rings in the

latter half of the large cavities, the number of ions at Tl12 was fixed at 6.8 (3.4 in Table 3, step 18). The final structural parameters are presented in Table 4, and selected interatomic


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distances and angles are given in Table 5. The long Tl-O distances affirm that the Tl ions are all in the 1+ oxidation state, and that they are not W6+, W5+, nor W4+ ions, whose ionic radii31 and therefore approach distances to framework oxygen atoms would be much shorter. Atomic scattering factors for neutral atoms were used, and all were modified to account for anomalous dispersion.32, 33

Additional crystallographic details are given in Table 1.

4. DESCRIPTION OF THE STRUCTURE 4.1. Framework Geometry. The mean T-Oi (i = 1-3) bond length, 1.662 Å, is close to the mean (1.675 Å) of the Si4+-O (1.61 Å) and Al3+-O (1.74 Å) bonds reported in both dehydrated Ca-LSX34 and hydrated Na-A.35

As is often seen, T-O3, 1.692(4) Å, is

noticeably longer than T-O1, 1.623(3) Å, and T-O2, 1.642(4) Å (Table 5). This is because most of the non-framework cations in this structure coordinate to O3 atoms (Table 5).19, 36, 37 For the same reason, the T-O3-T angle is the smallest (Table 5).

4.2. Extraframework Ions. 4.2.1. WCl5+. The ionic radius at W, obtained by subtracting the conventional O2radius38 from the W-O3 bond length, 2.120(14) - 1.32 = 0.80 Å, is considerably longer than that of W6+, 0.60 Å,31 W5+, 0.62 Å,31 and W4+, 0.66 Å.31

However, the W6+-O2- bond

lengths in tungsten oxides found in zeolite Y15, 16 are shorter than 2.12 Å; they range between 1.75 and 1.96 Å. Furthermore, W occupies only 1.2 of the eight 6-rings, so the



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W-O3 bond length cannot be trusted to be accurate (O3 is likely to have refined to a position that represents the O3 atoms in the majority of the 6-rings), so this distance is likely to be a poor indicator of the oxidation state at W.

However, because six Cl- ions are

present in the structure for each WCl6 molecule that reacted, we may conclude that no chloride ions were lost as Cl2 (e.g., WCl6 → WCl4 + Cl2). Therefore the oxidation state of the tungsten ion did not change upon reaction with Tl-A; it remained 6+. Half of the large cavities contain an average of 1.2 WCl5+ ions (W-Cl1); each lies on a 3-fold axis opposite a 6-ring (Figure 2a).

Each ion at W is 4-coordinate, bonding to the Cl-

ion at Cl1 and to three O3 oxygens of its 6-ring at 2.120(14) Å. Each W6+ ion extends 0.54 Å into the large cavity from the (111) plane of its O3 oxygen atoms. The W-Cl1 bond length, 2.69(15), is in reasonable agreement with the sum of the corresponding radii,31 0.60 + 1.81 = 2.41 Å.

4.2.2. Tl7Cl6+. The 0.5 Tl+ ions per unit cell at Tl3 (1.0 in half of the large cavities) lie at an unusual position, at the very centers of the large cavities; they do not bond to the anionic zeolite framework. Cl- ions at Cl2 (Figure 2b).

Instead, each coordinates octahedrally to six

The Tl3-Cl2 bond length, 3.13(5) Å, is close to the sum of

conventional radii:38 Tl+-Cl- = 1.47 + 1.81 = 3.28 Å, respectively.

In turn, each chloride

ion at Cl2 bonds to Tl2 at 2.93(5) Å, also in acceptable agreement with the above sum of radii. These seven Tl+ and six Cl- ions form Tl7Cl6+ (Figure 2b).


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The Tl+ ions at Tl2 lie on 8-rings where they bond to 8-ring oxygen atoms.

Tl2 bonds

to two O2 oxygen atoms at 3.041(11) Å and one O1 atom at 3.166(17) Å (Figure 3b). These distances are both in general agreement with the sum of the corresponding ionic radii, 2.79 Å,38 and they lie within or near the range seen in dehydrated Tl12-A,30 from 2.60(3) to 3.11(5) Å for 8-ring Tl+ ions.

4.2.3. Tl+ ions at Tl13. The six Cl- ions at Cl2 interact further with a cube of eight T1+ ions at Tl13 (Figure 2b); each chloride ion approaches four of these eight at 3.674(10) Å, very much longer than the Cl2-Tl2 bonds, 2.93(5) Å, or the Cl2-Tl3 bonds, 3.13(5) Å. These interactions serve to support the Tl7Cl6+ cluster at its position of high symmetry, centered in the large cavity, and to position Cl2 at y = z = ½ where each is equidistant from the four ions at Tl13.

The Tl13-O3 bond length is also long, about 0.3 Å longer than the

other two 6-ring Tl-O bond lengths, Tl11-O3 and Tl12-O3 (Table 5).

It is clear that the

ions at Tl13 are being drawn away from the zeolite framework to be involved with Tl7Cl6+. Thus half of the large cavities contain 7 + 8 = 15 Tl+ ions and 6 Cl- ions (Figures 2b and 3b). Because all six bonds about Tl13 are long, the ions at Tl13 are less tightly held as can be seen by the somewhat high thermal motion at Tl13 (Figure 2b). The thermal motion at Cl2 is even higher; this appears to be the reason why the Cl2 position refined to low occupancy values during structure determination (Table 3, step 12).

Furthermore, because

high thermal motion is often far from harmonic, the thermal ellipsoids at Tl13 and



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especially Cl2 may be poor representations of their electron densities; this may be responsible for the relatively high final error indices.

4.2.4. Remaining Tl+ ions. Per unit cell 4.63(3) Tl+ ions were found at Tl11 and Tl12 (Table 4).

Of the five Tl+ positions in the structure, these two do not bond to Cl- ions.

Tl11 and Tl12 are at well established 3-fold-axis positions opposite 6-rings, and their approach distances to framework oxygen atoms are similar to those in dehydrated Tl12-A.30 Tl11 is in the sodalite cavity and Tl12 is in the large cavity (Figures 2, 3, and 4). Each bonds to three O3 oxygen atoms at 2.756(9) and 2.598(10) Å, respectively, close to the sum of the corresponding ionic radii, 2.79 Å.38

5. DISCUSSION 5.1. Net Reactions.

The reaction that occurred between WCl6(g) and fully

dehydrated Tl12-A, per unit cell, appears to be Tl12-A + 0.6WCl6(g) → (WCl)0.6(Tl7Cl6)0.5Tl8.5-A

(2)

Or, within the zeolite, 6WCl6(g) + 35Tl+ → 6WCl5+ + 5Tl7Cl6+

(3)

Upon reaction the coordination about the tungsten ion has changed from octahedral to tetrahedral. WCl6 + 3O6-ring → WCl(O6-ring)3 + 5Cl


(4)

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It can be seen in reactions 2 and 3 that no TlCl exited the zeolite, and therefore that TIE11 did not occur.

Perhaps this is because this crystal was prepared at a lower

temperature (453 K) than that used in previous work with Zr,Cl,Tl-A39 (553 K and 623 K) and Hf,Cl,Tl-A40 (523 K). Perhaps also TlCl is simply more firmly held (Figures 2b and 3b) in this crystal.

5.2. Reaction Endpoint. The reaction appears to have proceeded until half of the large cavities were full with Tl7Cl6+ and eight additional Tl+ ions at Tl13. The 6-rings in the remaining half of the large cavities are fully occupied by 6.8 Tl+ ions and 1.2 WCl5+ ions (80% 7 and 1, 20% 6 and 2).

5.3. Arrangement of Clusters. Large cavities containing Tl7Cl6+ cannot be adjacent; this would superimpose ions at Tl2.

Accordingly, the two kinds of unit cells, those with

Tl7Cl6+ (Figure 3b) and those with 6.8 Tl+ and 1.2 WCl5+ ions (Figure 3a), must alternate throughout the structure.

5.4. Crystal Decomposition at 463 K and 473 K. The crystals described in section 2.5 were damaged by treatment with WCl6 at 463 K and 473 K.

Perhaps the W6+ ions,

seeking more regular coordination and a higher coordination number, possibly without Clions, began to disrupt the structure of the zeolite framework. Note in this regard that the W-O3 distances in this structure are likely to be stretched due to the strain that each W6+ ion causes to the zeolite framework (Figure 2, caption a), and that this destabilizes the zeolite.



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Damage by this mechanism may also have been facilitated by the loss of Cl- ions as TlCl(g), as was the original objective of this work (TIE, section 1.2). In addition, because filled or partially filled cavities appear to stabilize zeolites, the loss of TlCl(g) could have destabilized the zeolite by destroying the Tl7Cl6+ ions which fill half of its large cavities. Here is an example of such stabilization: the hydrogen form of zeolite X, H92-X, does not exist (H+ exchange destroys zeolite X), but H92-X prepared with La2O3 in its sodalite cavities and 6-rings is stable at 673 K (its actual decomposition temperature has not been determined).41

In contrast, largely ammonium exchanged zeolite

Y, (NH4)64Na6K2-Y, decomposed at about 600 K (deamination was complete at about 450 K),42 even though zeolite Y is substantially more acid stable than zeolite X. Much lower lanthanide ion concentrations served to stabilize H-Y in catalytic cracking applications.43

6. CONCLUSIONS Tungsten ions, W6+, were introduced into zeolite A (LTA) as WCl5+ at an extraframework position by reaction with WCl6(g). WCl5+ lies opposite 6-rings in half of the large cavities; W6+ is tetrahedral, bonding to its Cl- ion and three framework oxygen atoms.

The other half of the large cavities contain Tl7Cl6+ clusters.

In these, one Tl+ ion

at the center of a large cavity coordinates to six Cl- ions, each of which bonds in turn to a Tl+ ion in an 8-ring.

These two kinds of large cavities alternate in the structure.


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■ ASSOCIATED CONTENT Supporting Information. Observed and calculated structure factors squared with esds. This material is available free of charge via the Internet at http://pubs.acs.org. ■ AUTHOR INFORMATION Corresponding Author * Tel.: +82 53 950 5589; Fax: +82 53 950 6594; E-mail address: [email protected] ■ ACKNOWLEDGEMENT We gratefully acknowledge the Pohang Accelerator Laboratory, Pohang, Korea for the use of their synchrotron, diffractometer, and computing facilities.

This work was supported by a

National Research Foundation of Korea (NRF) Grant NRF-2017R1E1A1A01074837 funded by the Korean government (MSTI)



■ REFERENCES 1. Moreno-Castilla, C.; Alvarez-Merino, M.; Carrasco-Marin, F.; Fierro, J., Tungsten and Tungsten Carbide Supported on Activated Carbon: Surface Structures and Performance for Ethylene Hydrogenation. Langmuir 2001, 17, 1752-1756. 2. Chakraborty, S.; Berke, H., Homogeneous Hydrogenation of Nitriles Catalyzed by Molybdenum and Tungsten Amides. ACS Catal. 2014, 4, 2191-2194. 3. Hollak, S. A.; Gosselink, R. W.; van Es, D. S.; Bitter, J. H., Comparison of Tungsten and Molybdenum Carbide Catalysts for the Hydrodeoxygenation of Oleic Acid. ACS Catal. 2013, 3, 2837-2844. 4. Kamphaus, J. M.; Rule, J. D.; Moore, J. S.; Sottos, N. R.; White, S. R., A New SelfHealing Epoxy with Tungsten (VI) Chloride Catalyst. J. R. Soc. Interface 2008, 5, 95-103. 5. Park, C. Y.; Seo, J. M.; Jo, H.; Park, J.; Ok, K. M.; Park, T. J., Hexagonal Tungsten Oxide Nanoflowers as Enzymatic Mimetics and Electrocatalysts. Sci. Rep. 2017, 7, 40928. 6. Yang, L.; Liu, B.; Liu, T.; Ma, X.; Li, H.; Yin, S.; Sato, T.; Wang, Y., A P25/(NH4)xWO3 Hybrid Photocatalyst with Broad Spectrum Photocatalytic Properties under UV, Visible, and Near-Infrared Irradiation. Sci. Rep. 2017, 7, 45715. 7. Erdem, M.; Baykara, O.; Doğru, M.; Kuluöztürk, F., A Novel Shielding Material Prepared From Solid Waste Containing Lead for Gamma Ray. Radiat. Phys. Chem. 2010, 79, 917-922. 8. Nambiar, S.; Yeow, J. T., Polymer-Composite Materials For Radiation Protection. ACS Appl. Mater. Int. 2012, 4, 5717-5726. 9. Kim, J.; Seo, D.; Lee, B. C.; Seo, Y. S.; Miller, W. H., Nano‐W Dispersed Gamma Radiation Shielding Materials. Adv. Eng. Mater. 2014, 16, 1083-1089. 10. Baes, C. F. J.; Mesmer, R. E., The Hydrolysis of Cations; Krieger Publishing Company, Malabar, FL, 1986, p 252. 11. Seff, K., A General Method for the Ion Exchange of Zeolites Utilizing the Volatility of Thallous Compounds as Leaving Products. J. Phys. Chem. C 2010, 114, 13295-13299. 12. Cid, R.; Neira, J.; Godoy, J.; Palacios, J.; Mendioroz, S.; Agudo, A. L., Characterization of Tungsten-Modified Ultrastable Y Zeolite Catalysts and Their Activity in Thiophene Hydrodesulfurization. J. Catal. 1993, 141, 206-218. 13. Costa, A. A.; Braga, P. R.; de Macedo, J. L.; Dias, J. A.; Dias, S. C., Structural Effects of WO3 Incorporation on USY Zeolite and Application to Free Fatty Acids Esterification. Microporous Mesoporous Mater. 2012, 147, 142-148. 14. Moller, K.; Bein, T.; Ozkar, S.; Ozin, G. A., Intrazeolite Phototopotaxy: EXAFS Analysis of Precursor 8{W(CO)6}-Na56Y and Photooxidation Products 16(WO3)-Na56Y and 28(WO3)-Na56Y. J. Phys. Chem. 1991, 95, 5276-5281. 15. Ozin, G. A.; Ozkar, S.; Prokopowicz, R. A., Smart Zeolites: New Forms of Tungsten and Molybdenum Oxides. Acc. Chem. Res. 1992, 25, 553-560. 16. Ozin, G. A.; Prokopowicz, A., Intrazeolite Nonstoichiometric Tungsten Oxides n[WO3]-Na Y (0 < n ≤ 32, 0 ≤ x ≤ 1). J. Am. Chem. Soc. 1992, 114, 8953-8963. x 56 17. Charnell, J. F., Gel Growth of Large Crystals of Sodium A and Sodium X Zeolites. J. Cryst. Growth 1971, 8, 291-294. 18. Vance Jr, T. B.; Seff, K., Hydrated and Dehydrated Crystal Structures of Seventwelfths Cesium-Exchanged Zeolite A. J. Phys. Chem. 1975, 79, 2163-2167. 19. Nsanzimana, J. M. V.; Kim, C. W.; Heo, N. H.; Seff, K., Using the Thallous Ion Exchange Method to Exchange Tin into High Alumina Zeolites. 1. Crystal Structure of |(Sn2+)5.3 (Sn4+)0.8 (Cl–)1.8|[Si12 Al12 O48]-LTA. J. Phys. Chem. C 2015, 119, 3244-3252. 20. Heo, N. H.; Choi, H. C.; Jung, S. W.; Park, M.; Seff, K., Complete Redox Exchange of Indium for Tl+ in Zeolite A. Crystal Structures of Anhydrous Tl12-A and In10-A•In. Indium 16 ACS Paragon Plus Environment

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Appears as In2+, In+, and In0. The Clusters (In5)8+ and (In3)2+ Are Proposed. J. Phys. Chem. B 1997, 101, 5531-5539. 21. Heo, N. H.; Park, J. S.; Kim, Y. J.; Lim, W. T.; Jung, S. W.; Seff, K., Spatially Ordered Quantum Dot Array of Indium Nanoclusters in Fully Indium-Exchanged Zeolite X. J. Phys. Chem. B 2003, 107, 1120-1128. 22. Heo, N. H.; Jung, S. W.; Park, S. W.; Park, M.; Lim, W. T.; Seff, K., Crystal Structures of Fully Indium-Exchanged Zeolite X. J. Phys. Chem. B 2000, 104, 8372-8381. 23. Kim, J. Y.; Heo, N. H.; Seff, K.; Kim, C. W.; Park, Y.-K.; Kang, N. Y., First Successful Application of the Thallous Ion Exchange (TIE) Method. Preparation of Fully IndiumExchanged Zeolite Y (FAU, Si/Al = 1.69). J. Phys. Chem. C 2014, 118, 24655-24661. 24. Jeong, G. H.; Lee, Y. M.; Kim, Y.; Vaughan, D. E. W.; Seff, K., Single Crystal Structure of Fully Dehydrated fully Tl+-Exchanged Zeolite Y, |Tl71|[Si121Al71O384]-FAU. Microporous Mesoporous Mater. 2006, 94, 313-319. 25. Heo, N. H.; Kim, C. W.; Kwon, H. J.; Kim, G. H.; Kim, S. H.; Hong, S. B.; Seff, K., Detailed Determination of the Tl+ Positions in Zeolite Tl−ZSM-5. Single-Crystal Structures of Fully Dehydrated Tl−ZSM-5 and H−ZSM-5 (MFI, Si/Al = 29). Additional Evidence for a Nonrandom Distribution of Framework Aluminum. J. Phys. Chem. C 2009, 113, 19937-19956. 26. Shin, J. W.; Eom, K.; Moon, D., BL2D-SMC, The Supramolecular Crystallography Beamline at the Pohang Light Source II, Korea. J. Synchrotron Radiat. 2016, 23, 369-373. 27. Otwinowski, Z.; Minor, W., Processing of X-ray Diffraction Data Collected in Oscillation Mode. Methods Enzymol. 1997, 276, 307-326. 28. XPREP, Version 6.12. Program for Automatic Space Group Determination, Bruker AXS Inc.: Madison, WI, 2001. 29. Sheldrick, G. M., A Short History of SHELX. Acta Crystallogr., Sect. A 2008, 64, 112122. 30. Riley, P. E.; Seff, K.; Shoemaker, D. P., Crystal Structures of Hydrated and Dehydrated Thallium-Exchanged Zeolite A. J. Phys. Chem. 1972, 76, 2593-2597. 31. Haynes, W. M. Handbook of Chemistry and Physics, 91th ed., CRC Press, Boca Raton, FL, 2010/2011, p 12-12. 32. Cromer, D. T., Anomalous Dispersion Corrections Computed from Self-Consistent Field Relativistic Dirac-Slater Wave Functions. Acta Crystallogr. 1965, 18, 17-23. 33. International Tables for X-ray Crystallography; Kynoch Press, Birmingham, U.K., 1974; Vol. IV, p 148. 34. Vitale, G.; Bull, L. M.; Morris, R. E.; Cheetham, A. K.; Toby, B. H.; Coe, C. G.; Mac Dougall, J. E., Combined Neutron and X-ray Powder Diffraction Study of Zeolite Ca LSX and a 2 H NMR Study of Its Complex with Benzene. J. Phys. Chem. 1995, 99, 16087-16092. 35. Fischer, R. X.; Sehovic, M.; Baur, W. H.; Paulmann, C.; Gesing, T. M., Crystal Structure and Morphology of Fully Hydrated Zeolite Na-A. Z. Kristallogr. 2012, 227, 438-445. 36. Pluth, J. J.; Smith, J. V., Crystal Structure of Dehydrated Ca-Exchanged Zeolite A. Absence of Near-Zero-Coordinate Ca2+ ion. Presence of Al Complex. J. Am. Chem. Soc. 1983, 105, 1192-1195. 37. Riley, P. E.; Seff, K., Crystal Structures of Dehydrated Partially Cobalt(II)-Exchanged Zeolite A and of Its Carbon Monoxide Adduct. Inorg. Chem. 1974, 13, 1355-1360. 38. Weast, R. C. Handbook of Chemistry and Physics, 64th ed., CRC Press, Boca Raton, FL, 1983/1984, , p F-170. 39. Kim, J. Y.; Park, J. M.; Kim, H. J.; Heo, N. H.; Seff, K., Exchange of a Tetrapositive Cation into a Zeolite and a New Inorganic Scintillator. I. Crystal Structures and Scintillation Properties of Anhydrous Zr1.7Tl5.4Cl1.7–LTA and Zr2.1Tl1.6Cl3.0–LTA. J. Phys. Chem. C 2015, 119, 18326-18339. 40. Kim, J. Y.; Kim, H. J.; Heo, N. H.; Seff, K., Progress toward Zeolite-Based Self-



Luminous Sensors for Radioactive Isotopes such as 201Tl and 137Cs: Structures and Luminescence of Hf,Cl,Tl-A and Hf,Cl,Cs,Na-A. J. Phys. Chem. C 2017, 121, 19619-19633. 41. Park, H. S.; Seff, K., Crystal Structures of Fully La3+-Exchanged Zeolite X: An Intrazeolitic La2O3 Continuum, Hexagonal Planar and Trigonally Monocapped Trigonal Prismatic Coordination. J. Phys. Chem. B 2000, 104, 2224-2236. 42. Lim, W. T.; Seo, S. M.; Kim, G. H.; Lee, H. S.; Seff, K., Six Single-Crystal Structures Showing the Dehydration, Deamination, Dealumination, and Decomposition of NH4+Exchanged Zeolite Y (FAU) with Increasing Evacuation Temperature. Identification of a Lewis Acid Site. J. Phys. Chem. C 2007, 111, 18294-18306. 43. Ballivet, D.; Pichat, P.; Barthomeuf, D., High Temperature Properties of Lanthanum Y Zeolites. Adv. Chem. Ser. 1973, 121, 469-479.


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TABLE 1. Experimental Conditions and Crystallographic Data 0.075 crystal (a cube) edge length (mm) + 294, 24, 5 Tl ion exchange (T (K), t (h), V (mL)) dehydration of Tl-A (T (K), t (h), P (Pa)) 673, 72, 1.5 x 10-4 reaction with WCl6 (T (K), t (h), P (Pa)) 453, 72, 7.0 x 102 X-ray source PLS(2D-SMC)a 0.6200 wavelength (Å) detector ADSC Quantum-210 63 crystal-to-detector distance (mm) crystal color colorless data collection temperature (T (K)) 294(1) space group, No. Pm3m, 221 unit cell constant, a (Å) 12.061(1) 66.82 maximum 2θ for data collection (deg) 51,280 no. of reflections measured 955 no. of unique reflections measured, m 628 no. of reflections with Fo > 4σ(Fo) 47 no. of variables, s 20.3 data/parameter ratio, m/s 0.161, 3.71 weighting parameters: a, b 0.087, 0.113, 0.282 Final error indices: R1b, R1*c, R2d 1.12 Goodness of fite a

Beamline 2D-SMC at the Pohang Accelerator Laboratory, Pohang, Korea. bR1 = Σ|Fo - |Fc||/ΣFo; R1 is calculated using only those reflections for which Fo > 4σ(Fo). cR1* is calculated using all unique reflections. dR2 = [Σw(Fo2Fc2)2/Σw(Fo2)2]1/2 is calculated using all unique reflections measured. e Goodness of fit = (Σw(Fo2-Fc2)2/(m-s))1/2.

Note to Editor: The subscript o above in Fo (nine times) is a lower case letter o. This also appears two times in paragraph 1 of section 3. Throughout this ms, the subscripts o and c stand for "observed" and "calculated".



TABLE 2. Crystal Composition (Atomic %) by Crystallographic and SEM-EDX Analyses element

SXRDa

Si

13.59

13.91

Al

13.59

13.33

O

54.34

50.7

W

0.68

0.51

Tl

13.73

11.84

Cl

4.08

9.7

SEM-EDXb

a

b Single crystal X-ray diffraction. The zeolite crystal can be expected to have suffered some decomposition by the action of the electron beam. This can be a significant source of error. It may also have been changed upon exposure to the atmosphere by the H+ generated from the hydrolysis of W6+.


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TABLE 3. Steps of Structure Determination as Non-framework Atomic Positions Were Found number of ions per unit cella step WCl5+ ion contents of the second large cavity Tl11 Tl12 W Cl1 Tl3 Cl2 Tl2 Tl13 c 1 2 4.9(3) 3 3.6(4) 2.5(4) 4 0.71(7) 3.8(3) 2.0(3) 5 1.01(5) 3.89(16) 3.13(10) 2.78(16) 6 1.12(4) 4.08(12) 0.418(22) 3.72(9) 3.20(13) 7 1.12(4) 4.10(12) 0.17(5) 0.411(22) 3.67(9) 3.30(13) 8 1.19(4) 3.47(11) 0.20(5) 0.9(7) 0.473(20) 2.91(6) 2.36(12) 9d 1.18(4) 3.47(11) 0.20(5) 0.9(7) 0.473(20) 2.91(6) 2.36(12) e 10 1.20(4) 3.48(10) 0.21(5) 0.9(6) 0.468(19) 2.89(6) 2.36(11) 11f 1.19(4) 3.60(9) 0.20(5) 0.20(5) 0.488(20) 2.92(6) 2.43(10) 12 1.19(4) 3.52(9) 0.23(5) 0.23(5) 0.473(19) 0.27(18) 2.89(6) 2.39(9) g 13 1.21(4) 3.65(9) 0.58(8) 0.58(8) 0.480(20) 2.88(12) 3.00(6) 3.39(10) 14h 1.21(4) 3.68(9) 0.53(8) 0.53(8) 0.500(11) 3.00(6) 3.00(6) 3.41(10) i 15 1.19(4) 3.45(8) 0.75(10) 0.75(10) 0.478(10) 2.86(6) 2.86(6) 3.82(8) 16 j 1.23(3) 3.28(8) 0.46(7) 0.46(7) 0.500(10) 3.00(6) 3.00(6) 4.00(8) 17k 1.22(3) 3.28(8) 0.49(7) 0.49(7) 0.498(9) 2.99(6) 2.99(6) 3.99(8) 18 l 1.23(3) 3.4 0.6 0.6 ½ 3 3 4 a

error indicesb R1 0.56 0.38 0.35 0.30 0.15 0.104 0.102 0.1014 0.1008 0.0976 0.0987 0.0984 0.0923 0.0928 0.0953 0.0865 0.0859 0.0869

R2 0.87 0.74 0.71 0.67 0.44 0.363 0.360 0.3278 0.3275 0.3190 0.3224 0.3175 0.2966 0.3012 0.3064 0.2847 0.2827 0.2817

Numbers in parentheses are the estimated standard deviations (esds) in the units of the least significant figure given for the corresponding parameter. Defined in footnotes to Table 1. cThe atoms of the zeolite framework were refined anisotropically. dAn extinction parameter (EXTI) was introduced and refined. eTl11 and W1 were refined anisotropically. fW1:Cl1 was constrained to be 1:1. gTl3:Cl2 was constrained to be 1:6 h Tl3:Cl2:Tl2 was constrained to be 1:6:6. iTl3:Cl2:Tl2:Tl13 was constrained to be 1:6:6:8. jTl12, Tl2 and Tl13 were refined anisotropically. kCl2 was refined anisotropically. lThe occupancies at W and Cl1 were fixed at 0.6 and that at Tl12 was fixed at 3.40 (see section 3): those at Tl3, Cl2, Tl2, and Tl13 were fixed at ½, 3, 3, and 4, respectively. b

21


The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

TABLE 4. Positional, Thermal, and Occupancy Parametersa occupancyc atomic Wyckoff U11 or Uisob U22 U33 U23 U13 U12 x y z position position varied constrained fixed d d d T 24(k) 0 18257(19) 36635(18) 443(12) 411(11) 353(10) 28(7) 0 0 24 19832(139) 50000d O1 12(h) 0d 946(93) 1059(111) 302(41) 0d 0d 0d 12 O2 12(i) 0d 30322(60) 30322(60) 731(62) 445(28) 445(28) 143(34) 0d 0d 12 O3 24(m) 11589(58) 11589(58) 32398(74) 615(26) 615(26) 677(44) 30(28) 30(28) 146(33) 24 Tl11 8(g) 9703(19) 9703(19) 9703(19) 559(15) 559(15) 559(15) -62(8) -62(8) -62(8) 1.23(3) Tl12 8(g) 26170(9) 26170(9) 26170(9) 452(5) 452(5) 452(5) -1(3) -1(3) -1(3) 3.43(15) 3.4e W 8(g) 21117(181) 21117(181) 21117(181) 1342(92) 1342(92) 1342(92) -43(102) -43(102) -43(102) 0.46(7) f 0.6e,f Cl1 8(g) 33996(687) 33996(687) 33996(687) 1019(291) 0.46(7) f 0.6e,f d d d 50000 50000 1069(23) Tl3 1(b) 50000 0.499(19) 0.5e,g d d d d d Cl2 6(f) 24012(407) 50000 50000 1345(336) 3680(562) 3680(562) 0 0 0 3.1(4) 3.0e,g d d d d d 46080(35) 50000 Tl2 12(h) 0 992(21) 827(23) 1132(34) 0 0 0 3.02(6) 3.0e,h Tl13 8(g) 28717(42) 28717(42) 28717(42) 1449(24) 1449(24) 1449(24) 134(22) 134(22) 134(22) 3.73(19) 4.0e,i a Positional parameters x 105 and thermal parameters x 104 are given. Numbers in parentheses are the estimated standard deviations (esds) in the units of the least significant figure given for the corresponding parameter. bThe anisotropic temperature factor is exp[-2π2a-2(U11h2 + U22k2 + U33l2 + 2U23kl + 2U13hl + 2U12hk)]. c Occupancy factors are given as the number of atoms or ions per unit cell. dExactly, by symmetry. eThese occupancies were fixed as described in section 3. f W:Cl1 was constrained to be 1:1. gTl3:Cl2 was constrained to be 1:6. hThe occupancy at Tl2 (an 8-ring position) was fixed at 3.00, its maximum value by symmetry. iTl3:Tl13 was constrained to be 1:8.

22


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TABLE 5. Selected Interatomic Distances (Å) and Angles (deg)a

distances T-O1 1.623(3) T-O2 1.642(4) T-O3 1.692(4) weighted mean 1.662 Tl11-O3 Tl12-O3

2.756(9) 2.598(10)

W-O3b W-Cl1

2.120(14) 2.69(15)

Tl2-O1 Tl2-O2 Tl13-O3 Tl2-Cl2 Tl3-Cl2 Tl13…Cl2

3.166(17) 3.041(11) 2.955(11) 2.93(5) 3.13(5) 3.674(10)

Tl11…Tl11 Tl11…Tl12 Tl11…Tl13

4.054(8) 3.440(4) 3.972(10)

angles

O1-T-O2 O1-T-O3 O2-T-O3 O3-T-O3

110.9(7) 110.8(4) 106.3(4) 111.4(7)

T-O1-T T-O2-T T-O3-T

166.6(12) 145.2(7) 134.0(6)

O3-Tl11-O3 O3-Tl12-O3

80.2(3) 86.2(3)

O3-W-O3 O3-W-Cl1

113.7(8) 104.8(10)

O1-Tl2-O2 O2-Tl2-O2 O3-Tl13-O3 Cl2-Tl3-Cl2

51.31(7) 102.62(13) 73.8(3) 90, 180c

a

The numbers in parentheses are the estimated standard deviations (esds) in the units of the least significant digit given for the corresponding value. bThis value is expected to be 0.2 to 0.3 Å too long (see section 4.2.1). cOctahedral, exact values by symmetry.



TABLE 6. Unit Cell Charge Budget atom position ionsa occupancyb W Tl3 Tl11 Tl12 Tl13 Tl2 Cl1 Cl2

Page 24 of 30

M-O,c Å

r,d Å

CNe

2.120(14)

0.80

4

3.6+

6

0.5+

charge x occ.

6+

0.6

+

½

+

1.23(3)

2.756(9)

1.44

3

1.23(3)+

+

3.4

2.598(10)

1.28

3

3.4+

+

4.0

2.955(11)

1.64

6

4.0+

+

3.0

3.041(11)

1.72

4

3.0+

Cl

-

0.6

1

0.6-

Cl

-

3.0

6

3.0-

W

Tl Tl

Tl Tl Tl

ΣW = 0.6, ΣTl = 12.13, ΣCl = 3.6 Σ charges =12.13 b c Extraframework ions. Occupancy, ions per unit cell. Shortest M-O (metal ion to framework oxygen) bond lengths. dRadii of M ions obtained by subtracting 1.32 Å (the conventional radius of the oxide ion38) from the shortest M-O bond lengths. eCoordination numbers. a


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(figure captions) Fig 1.

EDX spectrum (counts vs. photon energy in keV) and element maps for the constituents of hydrated (WCl)0.6(Tl7Cl6)0.5Tl8.5-A.

Fig 2.

Stereoviews of the contents of the two kinds of large cavities: (a) WCl5+ bonds to three 6-ring oxygen atoms of the zeolite framework.

It is expected that the three

W-O3 bonds shown are each 0.2 - 0.3 Å too long (see section 4.2.1). Thus this drawing fails to show the distortion that a W6+ cation should give to its 6-ring, drawing its three O3 oxygen atoms closer to it and introducing substantial strain to the zeolite structure.

Due to low occupancy, this work has not been able to

observe that distortion; (b) an ion at Tl3 bonds to six ions at Cl2, each of which bonds to an ion at Tl2 and more weakly to eight ions at Tl13. The zeolite A framework is drawn with open bonds; solid bonds are used to show the clusters; the weaker Cl2…Tl13 interactions are indicated by dashed lines. T represents the tetrahedral framework atoms Si and Al. Ellipsoids of 20% probability are shown.

Fig 3.

Stereoviews of the two large cavities: (a) with WCl5+; (b) with Tl7Cl6+ and surrounding Tl+ ions.

The weaker bonds between Cl2 and Tl13 (Figure 2b) have

been omitted for clarity.

Fig 4.

See the caption to Figure 2 for other details.

Stereoview of a representative sodalite cavity.

See the caption to Figure 2 for

other details.



Figure 1. Lim, Kim, Heo, and Seff


Page 26 of 30

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Note to editor: These stereoviews are the correct width, ca. 4 1/4 inches black to black, for clearest viewing.

This width is dictated by the average distance between adult human eyes.

it is enlarged it will not be viewable in stereo.


If


Page 28 of 30


Note to editor: These stereoviews are the correct width, ca. 4 1/4 inches black to black, for clearest viewing.

This width is dictated by the average distance between adult human eyes.

it is enlarged it will not be viewable in stereo.


If

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Note to editor: This stereoview is the correct width, ca. 4 1/4 inches black to black, for clearest viewing. This width is dictated by the average distance between adult human eyes. enlarged they will not be viewable in stereo.


If they are


TOC Graphic


Page 30 of 30

Crystal Structure of Zeolite LTA Containing Extraframework Tungsten(VI)

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