English

• 1. INTRODUCTION

  Metal-organic frameworks(MOFs) are a class of materials constructed from the joining of organic linkers with metal ions or clusters. MOFs have attracted an immense amount of attention during the past few years not only due to their fascinating capability to form diverse structural architectures^[1],but also for their novel properties,such as gas storage^[2],magnetism^[3],ion sensor^[4],controlled drug entrapment and release^[5],luminescence^[6] and heterogeneous catalysis^[7]. Generally,there are a variety of factors influencing the topological archi-tectures and propertiesof coordination polymers,including the nature of metal ions^[8],organic ligands,solvents,pH^[9],temperature^[10] and so on.

  It has been well established that the ligands play animportant role in constructing the structure,topology and functionality of the resulting MOFs. Byclosely controlling the properties of ligands,such as the shape,functionality,flexibility,conformation,and symmetry,MOFs with fantastic structures and desirable properties can be assembled.Rigid poly-carboxylate and pyridylcarboxylate ligands have been widely used in the construction of high dimen-sional structures with large pores^[11]. It is well-known that the symmetric carboxylate ligands have been focused because these types of ligands often directly contribute to the formation of 3D frame-works with high symmetry,exhibiting high surface areas and high pore volumes^[12]. Aromatic polycar-boxylic acid molecules,such as biphenyl-3,3',5,5'-tetracarboxylic acid (H4bpta) with D₂h symmetry,have been widely used in the construction of interes-ting frameworks with high pore volumes for gas absorption^[13-16]. However,the design and syntheses of high pore volumes with predictable structures a nd properties are still a challenge in coordination che-mistry.

  Water,as the most abundant,cheapest,and envi-ronmentally friendly solvent,is a central theme for both natural substances and artificial chemical. The intrinsic non-inflammability and non-toxicity of water make it an ideal medium in a wide range of preparative chemistry,also due to its highest heat capacity that enables more facile control over an exothermic reaction. In addition,water molecule,due to its reliable donor or acceptor role in the formation of coordination or H-bonded interactions,is usually involved in some elementarychemical events on a molecular scale. Now,we have success-fully built a novel 3D porous framework at room temperature which incorporatesmanganese(II),bi-phenyl-3,3',5,5'-tetracarboxylic acid (H4bpta) and aqua ligands,namely [Mn₂(bpta)(H₂O)₇]n·5nH₂O,(I).

  2. EXPERIMENTAL

  2.1. Generals and measurements

  All reagents and solvents were purchased from commercial sources and used without further puri-fication. The IR spectrium was recorded from a KBr pellet in the range 4000～400 cm^-1 on a Bruker TENSOR27 Spectrometer. Elemental analysis was carried out using a CHNO-Rapid instrument. PXRD data were recorded on a Rikagu Smartlab X-ray diffractometer with Cu-Kα radiation (λ = 1.5406 nm) in the range 5～50° 2θ at a rate of 5°/min. Thermo-gravimetric (TG) study was carried out on a Dupont thermal analyzer with temperature range 25～918 ℃ under N₂ flow with a heating rate of 20 ℃ min^-1.

  2.2. Synthesis of complex (I)

  A solution of MnCl₂·4H₂O (0.0197 g,0.2 mmol) in10 mL of H₂O was mixed with a solution of H4bpta (0.0330 g,0.1 mmol) in 10 mL of ethanol in the presence of 1 mL NaOH (0.2 mmol/L) in a flask. Thenthe reacting solution mixturewith a constant striring was refluxed for 5 h at 353 K. After cooling,the solution was left for about three weeks at room temperature and colorless crystalsof (I) were obtained with a yield of 31%. Elemental analysis: Calcd. (%) for C₁₆H₃₀Mn₂O₂₀ (I): C 29.45; H 4.60. Found (%): C 29.29; H 4.72. IR (KBr disk,cm^-1): 3414(s),1694(m),1648(m),1418(m),1385(m),1304(m),1250(m),1093(w),904(w),763(m),712(m),698(m),656(m).

  2.3. Crystal structure determination

  A colorlessblock single crystal of I with dimen-sions of 0.30mm × 0.30mm × 0.25mm was selected and mounted on a glass fiber. X-ray diffraction intensity data were collected on a smart Bruker APEXII CCD diffractometer equipped with a gra-phite-monochromatic MoKa radiation (λ = 0.71073 Å) using the Multi-scan mode. A total of 17258 reflections were collected and 6230 were inde-pendent (Rint = 0.107) ,of which 2994 were observed withI > 2σ(I). Data reductionwas performed using SAINT and corrected for Lorentz and polarization effects. Adsorption corrections were applied using the SADABS routine^[17]. The crystal structure was solved by direct methodswith SHELXS-2014^[18] and refined by full-matrix least-squares method on F² with SHELXL-2014. H atoms attached to C atoms were placed in calculated positions and refined using a riding-model approximation,with C-H = 0.93 Å (benzene),and with U_iso(H) = 1.2U_eq(C). H atoms of 2 2 water molecules were located from difference (w = 1/[σ2(Fo ) + (0.0642P)+ 0.0100P],where P =Fourier maps and refined as riding in their observed positions,with U_iso(H) = 1.5U_eq(O). The O-H dis-tances are in the range of 0.811～0.836 Å. Com-pound I crystallizes in monoclinic,space group C2/c with a = 23.113(6) ,b = 7.3954(17) ,c = 29.657(7) Å,V = 5062(2) ų, Z = 8,C₁₆H20Mn₂O15·5(H₂O),Mr =652.28,D_c=1.712 g/cm³,F(000) = 2688,μ(MoKα)= 1.089 mm^-1,the final R = 0.0677 and wR = 0.1723 (F_o² + 2F_c²) /3) for 2994 observed with S = 0.955,(∆ρ)_max = 0.67 and (∆ρ)_min = -1.09 e/ų. Selected bond lengths are listed in Table 1,and hydrogen bonding interaction parameters in Table 2. The mo-lecular graphics were prepared by using the SHELXL-2014,DIAMOND^[19] and MERCURY^[20] programs.

  Table 1

  

  Table 1.  Selected BondLengths (Å)

  DownLoad: CSV

  Bond	Dist.
  Mn(1) -O(5) iii	2.127(4)
  Mn(1) -O(1)	2.152(4)
  Mn(2) -O(2)	2.123(4)
  Mn(2) -O(12)	2.176(4)
  Mn(3) -O(3)	2.101(3)
  Mn(3) -O(14) iv	2.170(4)
  Mn(1) -O(5) ii	2.127(4)
  Mn(1) -O(9) i	2.272(3)
  Mn(2) -O(11)	2.150(4)
  Mn(2) -O(10)	2.219(4)
  Mn(3) -O(3) iv	2.101(3)
  Mn(3) -O(15)	2.245(4)
  Mn(1) -O(1) i	2.152(4)
  Mn(1) -O(9)	2.272(3)
  Mn(2) -O(13)	2.166(4)
  Mn(2) -O(9)	2.305(3)
  Mn(3) -O(14)	2.170(4)
  Mn(3) -O(15) iv	2.245(4)
  Symmetry transformation: (i) -x,y,-z+ 1/2; (ii) -x+ 1/2,y-1/2,-z+ 1/2; (iii) x-1/2,y-1/2,z; (iv) -x+ 1/2,-y+ 1/2,-z+ 1

  Table 2

  

  Table 2.  Hydrogen Bond Lengths (Å) and Bond Angles (°)

  DownLoad: CSV

  D-H···A	d(D-H)	d(H···A)	d(D···A)	∠DHA
  O(9) -H(9A)···O(6) i	0.82	1.87	2.660(5)	161
  O(9) -H(9B)···O(20)ii	0.82	1.83	2.643(5)	170
  O(10) -H(10A)···O(5)iii	0.82	2.56	3.218(5)	138
  O(10) -H(10B)···O(1) iv	0.82	1.95	2.702(5)	152
  O(11) -H(11A)···O(8) iv	0.82	1.99	2.792(6)	166
  O(11) -H(11B)···O(4)iii	0.82	1.87	2.636(6)	154
  O(12) -H(12A)···O(6)v	0.82	2.06	2.863(6)	167
  O(12) -H(12B)···O(17)vi	0.82	1.93	2.650(7)	147
  O(13) -H(13A)···O(16)	0.83	1.95	2.773(7)	172
  O(13) -H(13B)···O(18)vi	0.83	1.95	2.761(7)	169
  O(14) -H(14A)···O(7)vii	0.82	2.01	2.787(5)	159
  O(14) -H(14B)···O(7)v	0.82	1.94	2.755(5)	174
  O(15) -H(15A)···O(19)viii	0.82	2.34	3.006(7)	139
  O(15) -H(15B)···O(4)	0.82	1.98	2.750(5)	157
  O(16) -H(16A)···O(6) i	0.81	2.06	2.837(6)	161
  O(17) -H(17A)···O(17) ix	0.82	2.46	2.979(15)	122
  O(17) -H(17B)···O(16)	0.82	2.29	3.099(8)	168
  O(18) -H(18A)···O(17) x	0.83	2.14	2.954(10)	167
  O(18) -H(18B)···O(8)vii	0.82	2.01	2.793(6)	158
  O(19) -H(19A)···O(7)v	0.82	2.00	2.759(6)	153
  O(19) -H(19B)···O(18)	0.82	2.01	2.788(8)	159
  O(20) -H(20A)···O(8)v	0.83	1.98	2.793(6)	167
  O(20) -H(20B)···O(12) xi	0.81	2.35	3.116(7)	158
  Symmetrycodes: (i) -x+ 1/2,y-1/2,-z+ 1/2; (ii) x-1/2,y-1/2,z; (iii) x-1/2,y+ 1/2,z; (iv) -x,y,-z+ 1/2; (v) -x+ 1/2,y+ 1/2,-z+ 1/2; (vi) -x,-y+ 1,-z+ 1; (vii)x,-y+ 1,z+ 1/2; (viii) -x+ 1/2,-y+ 1/2,-z+ 1; (ix) -x,-y,-z+ 1; (x) x,y+ 1,z; (xi) x+ 1/2,y-1/2,z

  3. RESULTS AND DISCUSSION

  3.1. Descriptionof the crystal structure of I

  The title compound,[Mn₂(μ4-bpta)(H₂O)₇]n·5nH₂O (I),crystallizes in monoclinic space group C2/c and is composed of trinuclear [Mn₃(H₂O)₂(R-COO)₂] linkers and mononuclear [MnO₂(H₂O)₄] linkers that are interconnected by the bpta^4- ligands. Its asym-metric unit consists of one and two halves crystallo-graphically independent Mn(II) cations,one fully deprotonated bpta^4- ligand,six coordinated water molecules,one μ₂-aqua ligand and five lattice water molecules.

  As shown in Fig. 1,each Mn atom is octahedrally coordinated by six oxygen atoms from bpta^4- anions and coordinated water molecules. The Mn(1) adopts a six-coordinated octahedral geometry involving fouroxygen atoms (O(1) ,O(1) ⁱ,O(5)ⁱⁱ and O(5)ⁱⁱⁱ) from four individual bpta^4- ligands and two bridging O atoms (O(9) and O(9)ⁱ) of water(symmetry codes: i -x,y,-z + 1/2; ii -x + 1/2,y -1/2,-z + 1/2; iii x -1/2,y -1/2,z). Mn-O bond lengths are in the range of 2.152(4) ～2.272(3) Å. Mn(2) is in a slightly distorted octahedral geometry,coordinated by one O atom of bridging carboxylate groups,one O atom of bridging water and four O atoms of water with bond lengths in the range of 2.123(4) to 2.305(4) Å. The Mn(1) located a 2-fold axis generating a trinuclear [Mn₃(H₂O)₂(R-COO)₂] linker by μ_1,1-O(water) and μ_1,3-O,O΄(carboxylate) bridges with the Mn···Mn separation of 3.873(1) Å. The Mn(1) -O-Mn(2) angle is 115.60(15) ° for the μ₂-O water bridge. In contrast,the Mn(3) ion with an inversion is a mononuclear linker and is also octahedrally coor-dinated to two carboxylate O atoms (O(3) and O(3) iv,symmetry codes: iv -x + 1/2,-y + 1/2,-z + 1) and fourO atoms of aqua disposed in a quite regular octahedron (Mn(3) -O bond distances in the range of 2.101(3) ~2.245(4) Å).

  Figure 1

  

  Figure 1.  Coordination environments of Mn(1) ,Mn(2) and Mn(3) atoms of(I). Displacement ellipsoids are drawn at 30% probabilitylevel (Symmetry codes: (i) -x,y,-z+1/2; (ii)-x+ 1/2,y --1/2,-z+ 1/2; (iii)-x,y,-z+ 1/2; (iv) x -1/2,y -1/2,z)

  DownLoad: Full-Size Img PowerPoint

  In I,each bpta^4- with a dihedral angle of 38.84(11) ° between the two benzene s adopts a μ4-η²:η¹:η¹:η⁰ mode to bridge two trinuclear [Mn₃(H₂O)₂(R-COO)₂] linkers with a space of 12.1338(27) Å. Meanwhile,each trinuclear linker as the 4-connect node is linked by four bpta^4- ligands (Fig. 2a). Thus,four trinuclear linkers and four bpta^4- anions form a flying eagle-shape unit. Further,an array of eagle-shape extends along the ab plane (Fig. 2b) to generate a two-dimensional (2D) layer. Onthe other hand,Mn(3) atom with an inversion in the mononuclear linker [MnO₂(H₂O)₄] acts as the bridges to build the 2D sheets into a 3D porous framework,in which there are 1D water channels along the b axis (Fig. 3) . A calculation by PLATON^[21] indicates the free volume of water channels with an accessible void of 797.1 ų,amounting to 15.7% of the total unit-cell volume. The channels,lying at inversions with an average cross-sectional area of 26.26 Å2 and an average diameter of 5.78 Å,are occupied by lattice water molecules which connect with each other through O-H···O hydrogen bonds. The O···O distances and O-H···O angles fall in the ranges of 2.636(6) ~ 3.218(6) Å and 119.5~174.5°,as shown in Table 2. The other striking feature of this compoundis that the coordination environment of the water chain,as shown in Fig. 4,consistsof a cyclic water decamer and atetramer water cluster. The individual decamer is formed by two types of water molecules. The water molecules O(13) and O(15) iv and their symmetry-related atoms O(13) ⁱ and O(15)ⁱⁱ coor-dinated to Mn(II) to forma strong hydrogen bonding interaction with lattice water molecules O(16) ,O(18) and O(19) and their symmetry-related atoms O(16)ⁱ,O(18) ⁱ and O(19) i. The tetramer water cluster consists of O(17) and O(12) ⁱ and their symmetry-related atoms O(17)ⁱⁱⁱ and O(12)^v,and the two units are connected together by O(17) ···O(17)ⁱⁱⁱ hydrogen bonds (see Fig. 4 for symmetry codes). In the rings andclusters,each water molecule acts as both hydrogen-bond donor and acceptor except O(13) only as the donor. As a building block,the clusters attach to the sides of decamer ring,alternatively by hydrogen bonds between O(17) and O(18) (O(18) ···O(17) = 2.949(10) Å). Thus,the cyclic decamer and tetramer water clusters constructed the 1D infinite water chain along the b direction. A variety of water clusters in the voids of coordination polymers are reported in the literature^[22].

  Figure 2

  

  Figure 2.  (a) Two-dimensionalsheet based on the trinuclear [Mn₃(H₂O)₂(R-COO)₂] linkersand mononuclear [MnO₂(H₂O)₄] linkers. (b) Two-dimensional(2D) layer formed by numerous flying eagle-shaped units in the abplanes

  DownLoad: Full-Size Img PowerPoint

  Figure 3

  

  Figure 3.  Three-dimensional polyhedral view of (I). The yellow tubes represent the free volume of waterchannels. The H atoms of ligands have been omitted for clarity

  DownLoad: Full-Size Img PowerPoint

  Figure 4

  

  Figure 4.  Water chain consisting of alternate cyclic water decamers and tetramer water clustersin the structure of(I),which shows the hydrogen-bonding environment of water molecules. O and H atoms are shown as capped sticks,red represents O and whitefor H. Hydrogen bonds areindicated by blue lines (Symmetry codes:(i) -x,1-y,z; (ii) -1/2 + x,1/2 + y,z; (iii) -x,-y,1 -z; (iv) 1/2 -x,1/2 -y,1 -z; (v) x,-1 + y,z)

  DownLoad: Full-Size Img PowerPoint

  To better understand the framework topology,the twobpta^4- ligandswith the mononuclear Mn(II) cations can be considered as the 4-connected node andthe trinuclear[Mn₃(H₂O)₂(R-COO)₂] linker is also a 4-coonected node. As shown in Fig. 5,the assembly of these three types of nodes results in the generation of a 3D network with the point symbols (4².8⁴) ,as calculated by the TOPOS software^[23].

  Figure 5

  

  Figure 5.  An illustration of the topological structure of I with trinuclear [Mn₃(H₂O)₂(R-COO)₂] linkers as 4-coonected nodes. Two bpta^4- ligands with the mononuclearMn(II) cations reprent the 4-connectednode (Colour key: Mn turquoise,C blue,O red)

  DownLoad: Full-Size Img PowerPoint

  Five Mn(II)compounds involvingthe H4bpta ligand have been reported previously (the Cam-bridge Structural Database (version 5.36,Feb.2015) )^[24]. However,all reported compounds contain the second N-containing ligands,such as DMF,2,2΄-bipy,phen^[25] and 2-(3-(4-(pyridin-4-yl)phenyl)-1H-1,2,4-triazol-5-yl)pyridine^[26]. Four of them are obtained with the binuclear Mn subunits which are linked by carboxylate bridges. Thus,each subunit attaches to the H4bpta ligands and the second ligands to construct the two-or three-dimensional frame-workwhich are much different from the present structure of I. Moreover,the aqua ligand is not engaged in coordinating in these compounds. Com-pound I presents the first example of the trinuclear Mn subunits which are linked by μ_1,1-O(water) and μ_1,3-O,O΄(carboxylate) bridges. The octahedra in such trinuclear units are less distorted and each Mn(II) ion is coordinated by bpta^4- anions and aqua O atoms. We have observed the cyclic water deca-merscontaining metal-water chains in which the water clusters are trapped not only by an organic molecule via hydrogen bonds but also by the metal ion coordination interactions. To our knowledge^{[27, 28]},such cyclic water clusters containing metal-water chains are very rare. This observation indicates that the water decamers are stabilized not only by hydro-genbonds but also by coordination interactions. It should be noted that these compounds are synthe-sized in the hydrothermal reaction with different temperature. It may be attributed to the molecular size of the second N-containing ligand. The larger volume of the second ligand need higher tempera-ture and pressurewhich make it collide more effectively. H₂O molecule has a smaller Van der waals volume (11.44 cm³mol^-1) ^[29],which can collide with another molecule easily. In addition,the H₂O molecule with diverse coordination ability andsteric effect may be included in the final structuresin both ligand and guest roles. So,we can obtain compound I at room temperature and normal pressure. Inves-tigation suggests that the water molecule is one of the key factors in the formation of organic or metal-organic supramolecular frameworks. This work may inspire us to synthesize more attractive MOFs with thehelp of water at room temperature.

  4. PXRD AND THEMOGRAVIMETRIC ANALYSES

  The PXRD patterns for I are present in Fig. 6. The diffraction peaks of both simulated and experimental patterns match well,indicating the phase purities of compound I.

  Figure 6

  

  Figure 6.  Powder X-ray diffraction patterns of (I)

  DownLoad: Full-Size Img PowerPoint

  The TGA of complex I was performed on poly-crystalline samples under a nitrogen atmosphere. The results show two different steps of weight loss,asshown in Fig. 7. The first weight loss of 14.2% occurs in consecutive step and does not stop until heating to 918.6 ℃.

  Figure 7

  

  Figure 7.  TG-DTA of compound (I)

  DownLoad: Full-Size Img PowerPoint

  5. CONCLUSION

  In summary,a novel porous MOF,[Mn₂(bpta)(H₂O)₇]n·5nH₂O (I),has been successfully built at room temperature. It possesses trinu-coordinated water molecules,then the weight loss clear [Mn₃(H₂O)₂(R-COO)₂] and mononuclear [MnO₂(H₂O)₄] building units and exhibits a 3D network built by the 2D eagle-shaped layers and the 1D channelswhich are occupied by water chains. The cooperative association between the symmetric carboxylate ligand and water molecule plays a crucial role in the formation of water clustersand multidimensional architecture. Moreover,the forma-tion of water cluster has a significant influence on the water molecule binding to the metal ion. The diverse structure and cooperative association of watercluster and crystal host in I may be helpful in improving our understanding of contribution of water molecules to construct diverse MOFs.

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  Figure 1  Coordination environments of Mn(1) ,Mn(2) and Mn(3) atoms of(I). Displacement ellipsoids are drawn at 30% probabilitylevel (Symmetry codes: (i) -x,y,-z+1/2; (ii)-x+ 1/2,y --1/2,-z+ 1/2; (iii)-x,y,-z+ 1/2; (iv) x -1/2,y -1/2,z)

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  Figure 2  (a) Two-dimensionalsheet based on the trinuclear [Mn₃(H₂O)₂(R-COO)₂] linkersand mononuclear [MnO₂(H₂O)₄] linkers. (b) Two-dimensional(2D) layer formed by numerous flying eagle-shaped units in the abplanes

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  Figure 3  Three-dimensional polyhedral view of (I). The yellow tubes represent the free volume of waterchannels. The H atoms of ligands have been omitted for clarity

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  Figure 4  Water chain consisting of alternate cyclic water decamers and tetramer water clustersin the structure of(I),which shows the hydrogen-bonding environment of water molecules. O and H atoms are shown as capped sticks,red represents O and whitefor H. Hydrogen bonds areindicated by blue lines (Symmetry codes:(i) -x,1-y,z; (ii) -1/2 + x,1/2 + y,z; (iii) -x,-y,1 -z; (iv) 1/2 -x,1/2 -y,1 -z; (v) x,-1 + y,z)

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  Figure 5  An illustration of the topological structure of I with trinuclear [Mn₃(H₂O)₂(R-COO)₂] linkers as 4-coonected nodes. Two bpta^4- ligands with the mononuclearMn(II) cations reprent the 4-connectednode (Colour key: Mn turquoise,C blue,O red)

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  Figure 6  Powder X-ray diffraction patterns of (I)

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  Figure 7  TG-DTA of compound (I)

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  Table 1.  Selected BondLengths (Å)

  Bond	Dist.
  Mn(1) -O(5) iii	2.127(4)
  Mn(1) -O(1)	2.152(4)
  Mn(2) -O(2)	2.123(4)
  Mn(2) -O(12)	2.176(4)
  Mn(3) -O(3)	2.101(3)
  Mn(3) -O(14) iv	2.170(4)
  Mn(1) -O(5) ii	2.127(4)
  Mn(1) -O(9) i	2.272(3)
  Mn(2) -O(11)	2.150(4)
  Mn(2) -O(10)	2.219(4)
  Mn(3) -O(3) iv	2.101(3)
  Mn(3) -O(15)	2.245(4)
  Mn(1) -O(1) i	2.152(4)
  Mn(1) -O(9)	2.272(3)
  Mn(2) -O(13)	2.166(4)
  Mn(2) -O(9)	2.305(3)
  Mn(3) -O(14)	2.170(4)
  Mn(3) -O(15) iv	2.245(4)
  Symmetry transformation: (i) -x,y,-z+ 1/2; (ii) -x+ 1/2,y-1/2,-z+ 1/2; (iii) x-1/2,y-1/2,z; (iv) -x+ 1/2,-y+ 1/2,-z+ 1

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  Table 2.  Hydrogen Bond Lengths (Å) and Bond Angles (°)

  D-H···A	d(D-H)	d(H···A)	d(D···A)	∠DHA
  O(9) -H(9A)···O(6) i	0.82	1.87	2.660(5)	161
  O(9) -H(9B)···O(20)ii	0.82	1.83	2.643(5)	170
  O(10) -H(10A)···O(5)iii	0.82	2.56	3.218(5)	138
  O(10) -H(10B)···O(1) iv	0.82	1.95	2.702(5)	152
  O(11) -H(11A)···O(8) iv	0.82	1.99	2.792(6)	166
  O(11) -H(11B)···O(4)iii	0.82	1.87	2.636(6)	154
  O(12) -H(12A)···O(6)v	0.82	2.06	2.863(6)	167
  O(12) -H(12B)···O(17)vi	0.82	1.93	2.650(7)	147
  O(13) -H(13A)···O(16)	0.83	1.95	2.773(7)	172
  O(13) -H(13B)···O(18)vi	0.83	1.95	2.761(7)	169
  O(14) -H(14A)···O(7)vii	0.82	2.01	2.787(5)	159
  O(14) -H(14B)···O(7)v	0.82	1.94	2.755(5)	174
  O(15) -H(15A)···O(19)viii	0.82	2.34	3.006(7)	139
  O(15) -H(15B)···O(4)	0.82	1.98	2.750(5)	157
  O(16) -H(16A)···O(6) i	0.81	2.06	2.837(6)	161
  O(17) -H(17A)···O(17) ix	0.82	2.46	2.979(15)	122
  O(17) -H(17B)···O(16)	0.82	2.29	3.099(8)	168
  O(18) -H(18A)···O(17) x	0.83	2.14	2.954(10)	167
  O(18) -H(18B)···O(8)vii	0.82	2.01	2.793(6)	158
  O(19) -H(19A)···O(7)v	0.82	2.00	2.759(6)	153
  O(19) -H(19B)···O(18)	0.82	2.01	2.788(8)	159
  O(20) -H(20A)···O(8)v	0.83	1.98	2.793(6)	167
  O(20) -H(20B)···O(12) xi	0.81	2.35	3.116(7)	158
  Symmetrycodes: (i) -x+ 1/2,y-1/2,-z+ 1/2; (ii) x-1/2,y-1/2,z; (iii) x-1/2,y+ 1/2,z; (iv) -x,y,-z+ 1/2; (v) -x+ 1/2,y+ 1/2,-z+ 1/2; (vi) -x,-y+ 1,-z+ 1; (vii)x,-y+ 1,z+ 1/2; (viii) -x+ 1/2,-y+ 1/2,-z+ 1; (ix) -x,-y,-z+ 1; (x) x,y+ 1,z; (xi) x+ 1/2,y-1/2,z

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