Assembly of Mn-Containing Unprecedented Selenotungstate Clusters

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Assembly of Mn–containing unprecedented selenotungstate clusters with photocatalytic H2 evolution activity Wei-Chao Chen, Chao Qin, Xinlong Wang, Kui-Zhan Shao, Zhong-Min Su, and Enbo Wang Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.6b00285 • Publication Date (Web): 08 Apr 2016 Downloaded from http://pubs.acs.org on April 10, 2016

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Crystal Growth & Design

Assembly of Mn–containing unprecedented selenotungstate clusters with photocatalytic H2 evolution activity Wei-Chao Chen, Chao Qin, Xin-Long Wang,* Kui-Zhan Shao, Zhong-Min Su,* and En-Bo Wang Department Institute of Functional Material Chemistry, Key Lab of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun, 130024, (P. R. China)

The reaction of Na2WO4 and Na2SeO3 in the presence of MnCl2 under moderately acidic conditions

yielded

two

unprecedented

K2Na10[K2⊂{MnSe4W23O85(H2O)6}]·29H2O

(1)

tungstoselenites: and

trimeric

dimeric wheel–shaped

K2Na10[K2⊂{Mn3Se7W39O131(OH)20(H2O)2}]·60H2O (2). The assemblies of 1 and 2 are based upon the structure directing effects of SeIV heteroatoms for generating diverse well–defined vacancy selenotungstate precursors during the formation. The polyoxoanion of 1 contains two novel Wells–Dawson–type–like {Se2W11} fragments, which are constructed from novel {SeW4} and {SeW7} species derived from Wells–Dawson–type {α–Se2W14} fragments and one disorder of Mn/W center. The polyoxoanion of 2 exhibits a crown–type structure composed of a [Se6W38O120(OH)18(H2O)2]6– “host’’ (abbreviated as {Se6W38}) encapsulating SeO32––modified Mn/W and two K+ “guests’’. Remarkably, the crown {Se6W38} shell remains a new type of

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{Se2W12}–based trimeric aggregate in the polyoxometalates chemistry. The two compounds were

characterized

by

single–crystal

X–ray

structure

analysis,

IR

spectroscopy,

thermogravimetric, UV/vis spectroscopy, and ESI–MS. Moreover, their photocatalytic H2 evolution activity were also investigated.

Polyoxometalates (POMs) are an important class of polynuclear anionic metal–oxo clusters commonly formed via the condensation of oxometalate units (traditionally W, Mo or V) and heteroatom “templates” into a range of nanoscale structures.1–4 This, in turn, promises to lead to the architectures with a wide variety of structural diversity and predefined functions.5–10 At present, however, the anticipated design of POMs is still far from reach since there is still much left to understand the complex relationships between synthetic parameters and crystallization methods, thus one–pot self–assembly synthesis is still an important synthetic strategy for nanoscale high–nuclearity polyoxotungstates (POTs).11–15 Recently, selenotungstates display an important subset of POTs.17–28 Within this class, the choice of the heteroanion SeO32– templates not only determines certain redox–active properties of the cluster25, but also has been found to control the range and the formation of the POTs building blocks24, such as the simple {SeW3} species18, the family of Keggin–type fragments {SeWn} (n = 8, 9, 10)18,20,27, the Wells–Dawson– type fragments {Se2Wn} (n = 12, 14, 15, 18)21,22,26,28, etc., especially the reported hexavacant Wells–Dawson–type [Se2W12O46]12–

21,26

building block, which is directly comparable to the

metastable [H2P2W12O48]12– cluster29. It has been used for the construction of trimeric [Se6W39O141(H2O)3]24–

21,26

or tetrameric [Se8W48O176]32–

21

macrocycle, which extremely

enriches the wheel–type POTs30–36 for exploring the host–guest chemistry. However, new species (SeWn, n=4–7) or other {Se2W12}–based macrocycles still have not been discovered yet.17–28


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Here, we isolated two distinct compounds by carefully controlling the reaction parameters under one–pot conditions: K2Na10[K2⊂{MnSe4W23O85(H2O)6}]·29H2O (1) (forms after two weeks) and K2Na10[K2⊂{Mn3Se7W39O131(OH)20(H2O)2}]·60H2O (2) (forms after three weeks) which were formed from simple precursors (from the same one–pot reaction). Compound 1 contains unreported {SeW4} and {SeW7} species, and subsequent connects to form novel Wells– Dawson–type–like {Se2W11} fragments. Compound 2 remains a trimeric wheel–type aggregate based on a new type of {Se2W12}–based crown {Se6W38} shell. The heteroanion SeO32– templates, alkali–metal K+ ions and Mn2+ cations play the crucial role in the self–assembly of the two compounds. Compounds 1 and 2 were synthesized by the simple one–pot reactions37 of Na2WO4·2H2O, Na2SeO3, and MnCl2·4H2O, each of which could be reliably isolated from the same mother liquor. Firstly, we chose Na2WO4·2H2O and Na2SeO3 as the starting materials based on the previous studies18. The acidification of Na2WO4 and Na2SeO3 (W/Se molar ratio 6:1) by acetic acid was necessary in view of its extensive utilization for acidifying Se–based POTs clusters18,24. Moreover, diverse well–defined vacancy selenotungstate precursors trend to form at the W/Se molar ratio of 6:117–28, and furthermore, it is also in accordance with the basic building blocks and final structures: such as the basic Wells–Dawson–type–like {Se2W11} (W:Se molar ratio 5.5:1) fragments, the hexavacant Wells–Dawson–type {Se2W12} (W:Se molar ratio 6:1) fragments and the final Mn–containing selenotungstate units in 1–2: {Se4W23} or {Se7W39} (both W/Se molar ratio approach to 6:1). Subsequently, Mn2+ and K+ were introduced to the acid solution. During the preparation, three important factors should be emphasized: 1) the heteroanion SeO32– templates. The SeIV ions have been intensively exploited for generating a various range of lacunary building blocks21 in situ in solution, allowing for the identification of a



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series of novel POM architectures17–28. For example, simple unreported17–28 {SeW4} or {SeW7} species in 1, as well as Wells–Dawson–type {Se2W12} fragments in 2, may subsequently lead to the further expansion of the class of transition metal substituted selenotungstate materials in the presence of Mn2+ 21,26; 2) the speed of crystallization. A lot of yellow block–shaped crystals of 1 and few yellow needle crystals of 2 (< 5%) were isolated when the filtered solution volatilized normally. In particular, the final yield and quality of 2 (10.4%) was obviously increased when the filtered solution was well sealed by thin film with a few holes and kept undisturbed at room temperature (25 °C) as the previous report38. Thus, 2 could not be harvested very well in the relatively rapid crystallizations. However, 2 was isolated from the filtrate after three weeks still mixed with a small amount of 1 when the initial product (1, 21.5%) was filtered two weeks later even the filtrate was well handled. Hence, we hypothesized that 1 was the kinetic product while 2 should be a thermodynamically stable product38–41; 3) the correct choice of countercations. All attempts to isolate 1 and 2 with organic amine cations or alkali cations other than K+ remained unsuccessful, indicating the essential templating role of K+ during the formation of these polyanions. More importantly, structural analysis reveals that both compounds are templated by potassium cations in the center of the structures.


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Figure 1. Polyhedral and ball–and–stick representation of 1a and its basic building blocks. (W: blue, Mn/W: yellow, Se: green, O: gray, K: pink).

Figure 2. Ball–and–stick representation of the basic building blocks (a) {SeW4} and {SeW7} species, (b) Wells–Dawson–type–like {Se2W11} fragment, and (c) opposite orientations for SeO32– anion templates in 1a (W: blue, Se: green, O: gray).



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Single–crystal X–ray diffraction analysis42 reveals that [K2⊂{MnSe4W23O85(H2O)6}]12– (1a) (Figure 1) assembles with two Wells–Dawson–type–like {Se2W11} anions directly bridged by one disorder binuclear Mn/W centre as well as two mediated K+ ions, occupying the empty cap and equatorial belt positions, respectively, which crystallizes in a monoclinic system with the space group P21/n. The {Se2W11} fragment (Figure 2a) is composed of the unreported {SeW4} and {SeW7} species, which are linked into a Wells–Dawson–type–like assembly via the four shared µ2–oxo bridges (O41, O44, O57, and O58) (Figure 2b). Crucially, the lone pair of electrons on SeO32– anion templates possess opposite orientations as shown in Figure 2c, which are different from the classical Se–templated Wells–Dawson–type species with accordant orientations24,25. This kind of orientation is unique in POMs since it can be utilized in discovering novel structural motifs with pyramidal heteroanions (such as SO32–, TeO32–, AsO33–, etc.). Moreover, the {SeW7} species here remains a half of the Wells–Dawson–type {α–Se2W14} fragment24 and the {SeW4} species here is derivative from {SeW7} species by missing one {W3O15} unit (Figure S1 of the Supporting Information). The bond–valence sum43,44 (BVS) results show that four oxygen atoms existing in two {SeW4} species (O87, O88, O89 and O90) appear to be doubly protonated (Figure S2 and Table S2 of the Supporting Information). To the best of our knowledge, such {Se2W11} fragment has not been discovered in POMs before1–4,17–28. As shown in Figure 1, 1a also contains one binuclear Mn/W centre presenting equivalent octahedral coordination (include two doubly protonated oxygen atoms, Table S2 of the Supporting Information) with half site–occupancy disorder that lies in the cap positions of the two {Se2W11} fragment through connecting two {SeW7} species. Such binuclear archetypes have already been observed as the linkers in other known POMs15. Furthermore, the overall architecture is completed by the incorporation of two K+ ions. They both possess only one shared


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terminal water ligand (O4W) showing the hexagon–pyramidal coordinations. It is noted that this is in line with previous investigations18,27 on the structure control of alkali–metal ions since they are ligated in the cluster center. In all, the binuclear Mn/W centre, K+ ions, as well as the heteroanion SeO32– templates are crucial for the formation of the fragments ({Se2W11}) and the cluster architecture41.



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Figure 3. Polyhedral and ball–and–stick representation of 2a (top) and its “guests” component (down). (W: blue, Mn/W: yellow, Se: green, O: gray, K: pink). Interestingly, compound 2 was isolated from the same mother liquor after three weeks. The polyoxoanion [K2⊂{Mn3Se7W39O131(OH)20(H2O)2}]12– (2a) was isolated as the mixed cation salts K2Na102a·60H2O. Single–crystal X–ray diffraction analyses30–36 confirms that 2a contains a remarkable new cyclic anion [Se6W38O120(OH)18(H2O)2]28– (abbreviated as {Se6W38}) (Figure 3), representing a new type of trimeric aggregate among the {Se2W12}–based selenotungstates. As shown in Figure 4, this {Se6W38} wheel consists of three {Se2W12} subunits and two {WO(H2O)} fragments: two {Se2W12} subunits link each other via two corner–sharing µ2–oxo bonds (O2, monoprotonated according to BVS calculations43,44, Table S3 of the Supporting Information) at the cap positions of each subunit to form the {Se4W24} fragment, which is similar to two neighbouring {Se2W12} subunits in {Se8W48} wheel, whereas the other “separate” {Se2W12} subunit connects such {Se4W24} fragment by two {WO(H2O)} fragments in a corner– sharing mode as reported in {Se6W39} wheel, thus, the {Se6W38} wheel seems to be the “transition state” in the view of connection modes for {Se2W12} subunits among the three {Se2W12}–based wheels (Figure 4). Additionally, the high symmetry for {Se6W38} wheel (C2v) was reduced compared to {Se6W39} wheel (D3h)21,26 and {Se8W48} wheel (D4h)21. Consequently, the permutation and combination of {Se2W12} subunits as well as some extra {WO(H2O)} linkers may acquire more magical {Se2W12}–based molecular wheels topologies. A total of 18 hydroxo and 2 aqua ligands associated with the {Se6W38} are determined based on BVS calculations43,44 (Table S3 of the Supporting Information), which leads to the composition [Se6W38O120(OH)18(H2O)2]10–

compared

to

the

[Se6W39O141(H2O)3]24–

21,26

and

[P6W39O147(H2O)3]30– 31 without any protonations for all µ2–oxo atoms. Hence, contrary to prior


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reports30–36, we have shown some potential attributes in regards to {Se6W38}: 1) the unique wheel generates in situ in aqueous medium using simple ions (Mn2+) under one–pot procedures; 2) it can act as a template that allows to encapsulate suitable transition–metal–oxo clusters30; 3) it is probably also reactive towards some other electrophiles, including lanthanide cations36 and organotin groups28.

Figure 4. Polyhedral representation of {Se2W12}–based wheels. {Se6W39} wheel (left), {Se6W38} wheel (middle), {Se8W48} wheel (right) (W: blue, O: gray). The pumpkin–like inner cavity (roughly 6.80 × 9.20 × 10.2 ≈ 680 Å3) of the “cyclic template/host” (Figure S3 of the Supporting Information) has been “decorated” with two equal SeO32––modified, disordered Mn/W and two K+ “guests” (Figure 3). Electrospray ionization mass spectrometry (ESI–MS) analysis (see below) indicates that the {Se6W38} remains intact in 2 in aqueous medium on account of encapsulated “guests” while {Se6W39} mainly decomposes into the {Se2W12} building block21, this is consistent with the reported “guests” that are inspired to “induce”16 or “secure”31 wheels in POMs host–guest chemistry30–36. As for each SeO32–– modified Mn/W center, SeIV ion with half site–occupancy disorder attaches to each Mn/W center



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forming [Mn1.5Se0.5W0.5O9.5(OH)]12– unit (Figure 3), fills in the empty equatorial belt positions on both lacuna in neighboring {Se2W12} subunits (Figure S4 of the Supporting Information). It is known that the substituted mode here is similar to the previously reported Mn–substituted dimeric selenotungstates21 based on the [Se2W12O46]12– and is also parallel to the lanthanide– containing [P8W48O184]40– anion36, which differs from other transition metal centers encapsulated in wheel–type POMs, they remain aqua–ligand–induced31 capability of “trapping” guest transition metal ions30–36. Crystallographic refinement results in the occupancy factors of 0.25 for W and 0.75 for Mn for each Mn/W position, thus, the above–mentioned {Se4W24} fragment is totally occupied by three MnII and one WVI ions to form the {Mn3W ⊂ Se4W24O80(OH)10} unit (Figure S4 of the Supporting Information). Furthermore, two potassium cations are also encapsulated into the inner cavity of {Se6W38} (Figure 3). Two K sites are in a six–coordination environment with one shared O atom (O3W), four O atoms on the “separate” {Se2W12} subunit (inner surface of {Se6W38}), and four O atoms on SeO32––modified Mn/W centers. The alkali– metal–encapsulated patterns were usually observed in the previous wheel POTs clusters30–36. In the packing arrangement, 2a are connected by the potassium and sodium cations into a purely inorganic chain (Figure S5 of the Supporting Information). Three structural features should be given for 1 and 2: 1) the multiple roles of SeO32− anion: it has been easily employed as the template to generate simple {SeW4}/{SeW7} species and Wells– Dawson–type {Se2W12} fragments, it can also be viewed as the tridentate “inorganic ligands” for modifying Mn/W centers in 2; 2) binuclear Mn/W centers as functions of linkers (1) or substituted groups (2) observed in both compounds lay a foundation of Mn–containing selenotungstate clusters; 3) potassium cations are important for the control of structures18, especially since it is fixed by inner surface of wheels in 2.


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Figure 5. ESI–MS of 2 in H2O. The stability of these two polyoxoanions in water has been investigated. The UV–Vis spectra indicate that 1a and 2a maintained unchanged in solution for several hours’ monitoring process (Figure S6 of the Supporting Information). The ESI–MS spectra of 1 and 2 in water show that the whole clusters are completely present and all the m/z values of the main peaks can be assigned to their different charge/cation states (Figures 5, Figure S7 and Table S5 of the Supporting Information). ESI–MS studies of 2 (Figure 5) dissolved in water confirmed that the compound retained its integrity in solution, and the observed peaks were assigned to be {KNaH6[Mn3Se7W39O131(OH)20(H2O)2]}6–,

{KNa3H5[Mn3Se7W39O131(OH)20(H2O)2]}5–

and

{K2Na2H6[Mn3Se7W39O131(OH)20(H2O)2]}4–, giving envelopes centered at m/z about 1738.5, 2094.2, and 2621.5 respectively (Table S6 of the Supporting Information). One effective strategy to achieve promising POMs–based photocatalysts for H2 production is to dope transition–metal cations (Ni2+,45 Fe3+,22,46 and so on) or introduce the main group cations Sn2+

47

into the photocatalysts to adjust the electronic structure45–47, therefore such Mn–

containing selenotungstate clusters may possess photochemical reactivities. For the sake of 11 Environment ACS Paragon Plus


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studying the conductivity of 1 and 2, the band gaps were measured: as illustrated in Figure S8 and Figure S9 of the Supporting Information, the corresponding well–defined optical absorption associated with HOMO–LUMO (E)48 can be assessed at 2.46 eV and 2.19 eV, respectively. Thus, a new type of all–inorganic and stable Mn–containing POMs–based homogeneous photocatalysts for proton reduction is discovered. 100 mg 1 or 2 was dissolved in 150 mL 20% methanol solution (as sacrificial agent)22,28,34,47,49,50 for the photocatalytic H2 evolution experiment. The H2 evolution rates in three runs were 2041.3, 2075.0 and 1947.5 µmol h–1 g–1 for 1 (Figure 6) and 938.8, 915.0 and 957.5 µmol h–1 g–1 for 2 (Figure 7), respectively. The total evolved H2 of 1 and 2 over 12 h was 2425.5 µmol and 1124.5 µmol, respectively. The corresponding turnover numbers [(moles of H2 formed)/(moles of 1 or 2)] were 169 and 133 with a turnover frequency (TOF) of 14.08 or 11.08 h–1 respectively. The blank reaction (without 1 or 2 as catalyst) showed that there was no H2 produced as the previous reports22,28. The proposed mechanism of photocatalytic H2 production of 1 and 2 is shown in the Supporting Information, Figure S10 and related discussion. In particular, the noticeably higher rate of H2 evolution in the case of 1 versus 2 may be rationalized in terms of its unique structure: 4 aqua ligands (Figure S2 of the Supporting Information) are bonded directly to W atoms in the unreported {SeW4} species, and provides effective pathway(s) for the electron transfer and the subsequent reduction of proton to H/H2.49,50 Thus, POMs with transition–metal–modified and aqua–ligands–rich are the excellent catalysts with photocatalytic H2 evolution activity.


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Figure 6. Time course of H2 evolution from 100 mg of photocatalyst 1 under 500 W mercury lamp irradiation in methanol (30 mL) in 150 mL of water (5/1, v/v).

Figure 7. Time course of H2 evolution from 100 mg of photocatalyst 2 under 500 W mercury lamp irradiation in methanol (30 mL) in 150 mL of water (5/1, v/v).



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In conclusion, two unprecedented Mn–containing selenotungstate clusters have been conventionally synthesized for the first time. 1a contains novel {SeW4} and {SeW7} species derived from Wells–Dawson–type {α–Se2W14} fragments and 2a exhibits {Se2W12}–based trimeric crown POMs templating by Mn ions and K ions, representing a new member in inorganic POMs wheels. Moreover, they both possess photocatalytic H2 evolution activity. Thus, the present work not only adds two novel members to a new purely inorganic family of POMs but also offers a new approach to the development of effective photocatalysts, a much promising clean energy source, for the evolution of H2. ASSOCIATED CONTENT Supporting Information. X–ray crystallographic file in CIF format; structural figures and tables, BVS calculation result of oxygen atoms, the IR, UV–Vis, TGA, XRD, ESI-MS characterizations, and the proposed mechanism of photocatalytic H2 production of 1 and 2. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]; [email protected]. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was financially supported by the NSFC of China (No. 21471027, 21131001), National Key Basic Research Program of China (No. 2013CB834802), the Fundamental Research Funds for the Central Universities (2412015BJ001), Changbai Mountain Scholars of Jilin Province.


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REFERENCES (1) Cronin, L.; Müller, A. Chem. Soc. Rev. 2012, 41, 7333−7334. (2) Miras, H. N.; Vilà-Nadal, L.; Cronin, L. Chem. Soc. Rev. 2014, 43, 5679−5699. (3) Wang, S. S.; Yang, G. Y. Chem. Rev. 2015, 115, 4893–4962. (4) Zhao, J. W.; Li, Y. Z.; Chen, L. J.; Yang, G. Y. Chem. Commun. 2016, 52, 4418–4445. (5) Lv, H. J.; Guo, W. W.; Wu, K. F.; Chen, Z. Y.; Bacsa, J.; Musaev, D. G.; Geletii, Y. V.; Lauinger, S. M.; Lian, T. Q.; Hill, C. L. J. Am. Chem. Soc. 2014, 136, 14015–14018. (6) Yu, L.; Du, X. Q.; Ding, Y.; Chen, H. L.; Zhou, P. P. Chem. Commun. 2015, 51, 17443– 17446. (7) Ma, P. T.; Wan, R.; Wang, Y. Y.; Hu, F.; Zhang, D. D.; Niu, J. J.; Wang J. J. Inorg. Chem. 2016, 55, 918–924. (8) Yang, X. J.; Sun, M.; Zang, H. Y.; Ma, Y. Y.; Feng, X. J.; Tan, H. Q.; Wang, Y. H.; Li, Y. G. Chem.–Asian J. 2014, 9, 470–478. (9) Wang, K. Y.; Bassil, B. S.; Lin, Z. G.; Römer, I.; Vanhaecht, S.; Parac–Vogt, T. N.; Sáenz de Pipaón, C.; Galán-Mascarós, J. R.; Fan, L. Y.; Cao, J.; Kortz, U. Chem.–Eur. J. 2015, 21, 18168−18176. (10) Liao, J. Z.; Wu, X. Y.; Yong, J. P.; Zhang, H. L.; Yang, W. B.; Yu, R. M.; Lu, C. Z. Crystal Growth & Design. 2015, 15, 4952–4958.



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(11) de la Oliva, A. R.; Sans, V.; Miras, H. N.; Yan, J.; Zang, H. Y.; Richmond, C. J.; Long, D. L.; Cronin, L. Angew. Chem. Int. Ed. 2012, 51, 12759–12762. (12) Jin, X. X.; Yu, W. D.; Nie, Y. M.; Liu, M. S.; Yan, J. Dalton Trans. 2016, 45, 3268–3271. (13) Martin-Sabi, M.; Winter, R. S.; Lydon, C.; Cameron, J. M.; Long D. L.; Cronin, L. Chem. Commun. 2016, 52, 919–921. (14) Zhang, D. D.; Cao, F.; Ma, P. T.; Zhang, C.; Song, Y.; Liang, Z. J.; Hu, X. J.; Wang, J. P.; Niu, J. Y. Chem.–Eur. J. 2015, 21, 17683−17690. (15) Winter, R. S.; Cameron, J. M.; Cronin, L. J. Am. Chem. Soc. 2014, 136, 12753–12761. (16) Ismail, A. H.; Bassil, B. S.; Yassin, G. H.; Keita, B.; Kortz, U. Chem.–Eur. J. 2012, 18, 6163−6166. (17) Yan, J.; Gao, J.; Long, D. L.; Mirasand, H. N.; Cronin, L. J. Am. Chem. Soc. 2010, 132, 11410–11411. (18) Yan, J.; Long, D. L.; Cronin, L. Angew. Chem. Int. Ed. 2010, 49, 4117–4120. (19) Gao, J.; Yan, J.; Beeg, S.; Long, D. L.; Cronin, L. J. Am. Chem. Soc. 2012, 135, 1796– 1805. (20) Chen, W. C.; Li, H. L.; Wang, X. L.; Shao, K. Z.; Su, Z. M.; Wang, E. B. Chem.–Eur. J. 2013, 19, 11007–11015. (21) Cameron, J. M.; Gao, J.; Vilà-Nadal, L.; Long, D. L.; Cronin, L. Chem. Commun. 2014, 2155–2157.


Page 17 of 21

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(22) Chen, W. C.; Qin, C.; Wang, X. L.; Li, Y. G.; Zang, H. Y.; Jiao, Y. Q.; Huang, P.; Shao, K. Z.; Su, Z. M.; Wang, E. B. Chem. Commun. 2014, 13265–13267. (23) Cameron, J. M.; Gao, J.; Long, D. L.; Cronin, L. Inorg. Chem. Front. 2014, 1, 178–185. (24) Chen, W. C.; Yan, L. K.; Wu, C. X.; Wang, X. L.; Shao, K. Z.; Su, Z. M.; Wang, E. B. Cryst. Growth Des. 2014, 14, 5099–5110. (25) Busche, C.; Vilà-Nadal, L.; Yan, J.; Miras, H. N.; Long, D. L.; Georgiev, V. P.; Asenov, A.; Pedersen, R. H.; Gadegaard, N.; Mirza, M. M.; Paul, D. J.; Poblet, J. M.; Cronin, L. nature 2014, 515, 545–549. (26) Kalinina, I. V.; Peresypkina, E. V.; Izarova, N. V.; Nkala, F. M.; Kortz, U.; Kompankov, N. B.; Moroz, N. K.; Sokolov, M. N. Inorg. Chem. 2014, 53, 2076–2082. (27) Chen, W. C.; Qin, C.; Li, Y. G.; Zang, H. Y.; Shao, K. Z.; Su, Z. M.; Wang, E. B. Chem.– Asian J. 2015, 10, 1184–1191. (28) Chen, W. C.; Qin, C.; Li, Y. G.; Zang, H. Y.; Shao, K. Z.; Su, Z. M.; Wang, E. B.; Liu, H. S. Chem. Commun. 2015, 51, 2433−2436. (29) Contant, R.; Teze, A. Inorg. Chem. 1985, 24, 4610. (30) Mal, S. S.; Kortz, U. Angew. Chem. Int. Ed. 2005, 44, 3777−3780. (31) Zhang, Z. M.; Yao, S.; Li, Y. G.; Wang, Y. H.; Qi, Y. F.; Wang, E. B. Chem. Commun. 2008, 1650–1652.



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(32) Yao, S.; Zhang, Z. M.; Li, Y. G.; Lu, Y.; Wang, E. B.; Su, Z. M. Cryst. Growth Des. 2010, 10, 135–139. (33) Boyd, T.; Mitchell, S. G.; Gabb, D.; Long, D. L.; Cronin, L. Chem.–Eur. J. 2011, 17, 12010–12014. (34) Jiao, Y. Q.; Qin, C.; Wang, X. L.; Wang, C. G.; Sun, C. Y.; Wang, H. N.; Shao, K. Z.; Su, Z. M. Chem.–Asian J., 2014, 9, 470–478. (35) Izarova, N. V.; Klaß, L.; de Oliveira, P.; Mbomekalle, I. M.; Peters, V.; Haarmann, F.; Kögerler, P. Dalton Trans. 2015, 44, 19200–19206. (36) Zimmermann, M.; Belai, N.; Butcher, R. J.; Pope, M. T.; Chubarova, E. V.; Dickman, M. H.; Kortz, U. Inorg. Chem. 2007, 46, 1737−1740. (37) Synthesis of 1 and 2: Na2WO4·2H2O (2.25 g, 6.78 mmol) and Na2SeO3 (0.2 g, 1.12 mmol) were dissolved in 30 mL water. The pH value of the solution was adjusted to 4.5 by the 50% (1:1) acetic acid solution. After the solution was stirred for around 30 min, solid Mn(CH3COO)2·4H2O (0.10 g, 0.40 mmol) and KCl (0.25 g, 3.33 mmol) were successively added. The final pH was kept at 5.5 by 1 M KOH. This solution was stirred for another 10 min and then heated to 70 oC stirred for 2 h, cooled down to room temperature, filtered and left to evaporate slowly. Yellow block–shaped crystals of 1 were isolated after two weeks. Yield: 0.44 g (21.5 % based on W). IR (KBr disk (Figure S11 of the Supporting Information), ν/cm-1): 3739(w), 1627(s), 957(s), 855(w), 743(w), 647(m). Elemental analysis calc. for H70K4MnNa10O120Se4W23(%): W 60.61, Se 4.53, K 2.24, Na 3.30, Mn 0.79; Found: W 60.28, Se 4.70, K 2.34, Na 3.21, Mn 0.84. Then, the solution was filtered again, sealed by film with a few of tiny pores, and very slowly evaporated at room


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temperature. After three weeks, yellow needle–shaped crystalline products of 2 were obtained. Yield: 0.19 g (9.24 % based on W). IR (KBr disk (Figure S12 of the Supporting Information), ν/cm-1): 3435(w), 1625(s), 953(m), 883(w), 785(m), 692(w). Elemental analysis calc. for H144K4Mn3Na10O213Se7W39 (%): W 60.62, Se 4.67, K 1.32, Na 1.94, Mn 1.39; Found: W 60.70, Se 4.30, K 1.51, Na 1.77, Mn 1.49. (38) Wu, Q.; Li, Y. G.; Wang, Y. H.; Wang, E. B.; Zhang, Z. M.; Clérac, R. Inorg. Chem. 2009, 48, 1606−1612. (39) Winter, R. S.; Yan, J.; Busche, C.; Mathieson, J. S.; Prescimone, A.; Brechin, E. K.; Long, D. L.; Cronin, L. Chem.–Eur. J. 2013, 19, 2976–2981. (40) Winter, R. S.; Cameron, J. M.; Cronin, L. J. Am. Chem. Soc. 2014, 136, 12753–12761. (41) Zhan, C. H.; Cameron, J. W.; Gao, J.; Purcell, J. M.; Long, D. L.; Cronin, L. Angew. Chem. Int. Ed. 2014, 53, 10362−10366. (42) Crystal data for 1: H70K4MnNa10O120Se4W23, Mr = 6976.19, Monoclinic space group P21/n, a = 18.2565(14), b = 34.539(3), c = 21.5479(16) Å, α = 90, β = 92.2450(10), γ = 120°, V = 13576.7(18) Å3, Z = 4, T =296(2) K, Dc = 3.413 g cm−3, µ = 20.817 mm−1, GOOF = 0.988. Of 70311 total reflections collected, 23914 were unique (Rint = 0.0951 after SQUEEZE). R1 [I > 2σ(I)] = 0.0585, wR2 = 0.1382. CCDC−1452366 contains the supplementary crystallographic data for this paper. Crystal data for 2: H144K4Mn3Na10O213Se7W39, Mr = 11827.14, Orthorhombic space group Pmmn, a = 21.4385(15), b = 21.5355(15), c = 23.2867(16) Å, α = 90, β = 90, γ = 120°, V = 10751.2(13) Å3, Z = 2, T =296(2) K, Dc = 3.653 g cm−3, µ = 22.334 mm−1, GOOF = 1.050. Of 55995 total reflections collected, 10027 were unique (Rint = 0.0797 after SQUEEZE).



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R1 [I > 2σ(I)] = 0.0431, wR2 = 0.1239. CCDC−1452367 contains the supplementary crystallographic data for this paper. (see Table S1 of the Supporting Information in detail). (43) Brown, I. D.; Altermatt, D. Acta Crystallogr. Sect. B 1985, 41, 244. (44) Trzesowska, A.; Kruszynski, R.; Bartczak, T. J. Acta Crystallogr. Sect. B 2006, 62, 745. (45) Lv, H. J.; Chi, Y. N.; Leusen, J.; Kögerler, P.; Chen, Z. Y.; Bacsa, J.; Geletii, Y. V.; Guo, W. W.; Lian, T. Q.; Hill, C. L. Chem.–Eur. J. 2015, 21, 17363–17370. (46) Du, X.; Zhao, J.; Mi, J.; Ding, Y.; Zhou, P.; Ma, B.; Zhao, J.; Song, J. Nano Energy, 2015, 16, 247−254. (47) Zhang, Z. Y.; Lin, Q. P.; Zheng, S. T.; Bu, X. H.; Feng, P. Y. Chem. Commun. 2011, 3918–3920. (48) Pankove, J. I. Optical Processes in Semiconductors, Prentice-Hall, Inc., Englewood Cliﬀs, NJ, 1971, 34. (49) Zhang, Z. Y.; Lin, Q. P.; Kurunthu, D.; Wu, T.; Zuo, F.; Zheng, S. T.; Bardeen, C. J.; Bu, X. H.; Feng, P. Y. J. Am. Chem. Soc. 2011, 133, 6394–6397. (50) Li, S. J.; Liu, S. M.; Liu, S. X.; Liu, Y. W.; Tang, Q.; Shi, Z.; Ouyang, S. X.; Ye, J. H. J. Am. Chem. Soc. 2012, 134, 19716–19721.


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For Table of Contents Use Only

Assembly of Mn–containing unprecedented selenotungstate clusters with photocatalytic H2 evolution activity Wei-Chao Chen, Chao Qin, Xin-Long Wang,* Kui-Zhan Shao, Zhong-Min Su,* and En-Bo Wang

Two

unprecedented

Mn–containing

selenotungstates

have

been

obtained:

K2Na10[K2⊂{MnSe4W23O85(H2O)6}]·29H2O (1) is constructed from the novel Se–templated simple species and K2Na10[K2⊂{Mn3Se7W39O131(OH)20(H2O)2}]·60H2O (2) contains the unique {Se6W38} wheel, both exhibiting photocatalytic H2 evolution activity.


Assembly of Mn-Containing Unprecedented Selenotungstate Clusters

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