organic compounds
O-methylene-α-D-galactopyranose
of 1,2,3,4-di-aFakultät Chemie/Organische Chemie, Hochschule Aalen, Beethovenstrasse 1, D-73430 Aalen, Germany
*Correspondence e-mail: willi.kantlehner@hs-aalen.de
The title compound, C8H12O6, was synthesized by deacetylation of 6-acetyl-1,2,3,4-di-O-methylene-α-D-galactose with sodium methoxide. The central part of the molecule consists of a six-membered C5O pyranose ring with a twist-boat conformation. Both fused dioxolane rings adopt an with C and O atoms as the flap. In the crystal, O—H⋯O and C—H⋯O hydrogen bonds are present between adjacent molecules, generating a three-dimensional network.
Keywords: crystal structure; deacetylation; D-galactose; O—H⋯O hydrogen bonds; C—H⋯O hydrogen bonds.
CCDC reference: 1437272
1. Related literature
For the synthesis of 6-acetyl-1,2,3,4-di-O-methylene-α-D-galactose, see: Bok et al. (1952). For the crystal structures of the α- and β-anomers of D-galactose, see: Sheldrick (1976). For the of 6-O-cyanomethyl-1,2:3,4-di-O-isopropylidene-α-D-galactose, see: Langer et al. (2005). For the of 6-[bis(ethoxycarbonyl)methyl]-6-deoxy-1,2;3,4-di-O-isopropylidene-D-galactopyranose, see: Doboszewski et al. (2010). For the of 1,2,3,5-di-O-methylene-α-D-xylofuranose see: Tiritiris et al. (2015a).
2. Experimental
2.1. Crystal data
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2.3. Refinement
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Data collection: APEX2 (Bruker, 2008); cell SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL2014.
Supporting information
CCDC reference: 1437272
https://doi.org/10.1107/S2056989015021854/zl2651sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989015021854/zl2651Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989015021854/zl2651Isup3.cml
According to the literature (Bok et al., 1952) a solution of 25 g (139 mmol) D-galactose in 20 ml water was mixed with 100 ml glacial acetic acid. 27.5 g (916 mmol) paraformaldehyde was then added at room temperature. Followed by dropwise addition of 12.5 ml concentrated sulfuric acid, the reaction mixture was heated to 373 K for one hour. After subsequent cooling to room temperature, 100 ml water was added to the mixture. The solution was extracted three times with chloroform and the combined extracts were washed with water and dried over sodium sulfate. After evaporation of the solvent, the crude product was destilled under reduced presure using a 20 cm Vigreux column. The fraction at 407 K (0.1 mbar) contained 4.28 g (13%) of 6-acetyl-1,2,3,4-di-O-methylene-α-D-galactose as the product. To a heated solution of 2.96 g (12 mmol) 6-acetyl-1,2,3,4-di-O-methylene-α-D-galactose (Bok et al., 1952) in 25 ml me thanol, 50 mg of sodium methoxide was added. After subsequent cooling to room temperature, 50 ml water was added to the mixture. The solution was extracted two times with diethyl ether and the combined extracts were dried over sodium sulfate. After evaporation of the solvent, the crude product was distilled under reduced presure using a 20 cm Vigreux column. The fraction at 395 K (0.1 mbar) contained 1.6 g (66%) of the title compound, which crystallized spontaneously after several days at room temperature, forming colorless single crystals suitable for X-ray analysis.
The O-bound H atom was located in a difference Fourier map and was refined freely [O2—H12 = 0.87 (3) Å]. The title compound crystallizes in the non-centrosymmetric
P212121; however, in the absence of significant effects, the is essentially meaningless and the was chosen based on known stereocenters unchanged during synthesis. The H atoms in CH2 and CH groups were placed in calculated positions with d(C—H) = 0.99 Å and d(C—H) = 1.00 Å and refined using a riding model, with Ueq(H) set to 1.2 Ueq(C).The synthesis of the protected sugar 1,2,3,4-di-O-methylene-α-D-galactopyranose has been well known for many years (Bok et al., 1952). Its however, remained undetermined. According to the structure analysis of the title compound, which we would like to report now, the central part of the molecule consists of a six-membered C5O ring, which is made up from the carbon atoms C1–C5 and O1 (Fig. 1). The chiral carbon atoms C1/C2/C4/C5 of the pyranose part show R-configuration and C3 shows S-configuration, in agreement with the expected configurations for an α-D-galactose ring. Both fused dioxolane rings adopt an with the carbon atom C7 (ring I) and oxygen atom O3 (ring II) as the flap, respectively. The pyranose ring shows a twist-boat conformation. A similar conformation of the pyranose ring has been observed in 6-[bis(ethoxycarbonyl)methyl]-6-deoxy-1,2;3,4-di-O-isopropylidene-D-galactopyranose (Doboszewski et al., 2010). The C–O and C–C and bond lengths in the molecule are comparable with the data from the analysis of 1,2,3,5-di-O-methylene-α-D-xylofuranose (Tiritiris et al., 2015a) and other related compounds [see, for example: 6-O-cyanomethyl-1,2:3,4-di-O-isopropylidene-α-D-galactose (Langer et al., 2005), and the α- and β-anomers of D-galactose (Sheldrick, 1976)]. In the O—H···O hydrogen bonds between adjacent molecules are present [d(H···O) = 2.01 (3) Å] (Tab. 1), generating infinite one-dimensional chains with base vector [100] (Fig. 2). Taking additional C—H···O hydrogen bonds between adjacent molecules [d(H···O) = 2.45–2.56 Å] (Tab. 1) into account, a three-dimensional network is generated (Fig. 3).
For the synthesis of 6-acetyl-1,2,3,4-di-O-methylene-α-D-galactose, see: Bok et al. (1952). For the crystal structures of the α- and β-anomers of D-galactose, see: Sheldrick (1976). For the of 6-O-cyanomethyl-1,2:3,4-di-O-isopropylidene-α-D-galactose, see: Langer et al. (2005). For the of 6-[bis(ethoxycarbonyl)methyl]-6-deoxy-1,2;3,4-di-O-isopropylidene-D-galactopyranose, see: Doboszewski et al. (2010). For the of 1,2,3,5-di-O-methylene-α-D-xylofuranose see: Tiritiris et al. (2015a).
Data collection: APEX2 (Bruker, 2008); cell
SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).Fig. 1. The structure of the title compound with displacement ellipsoids at the 50% probability level. | |
Fig. 2. O—H···O hydrogen bonds (black dashed lines) between adjacent molecules in the crystal structure of the title compound (ac view). | |
Fig. 3. C—H···O and O—H···O hydrogen bonds (black dashed lines) between adjacent molecules in the crystal structure of the title compound (ac view). |
C8H12O6 | Dx = 1.565 Mg m−3 |
Mr = 204.18 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 2468 reflections |
a = 6.4876 (6) Å | θ = 2.0–30.7° |
b = 6.6364 (5) Å | µ = 0.14 mm−1 |
c = 20.1224 (16) Å | T = 100 K |
V = 866.36 (12) Å3 | Plate, colorless |
Z = 4 | 0.43 × 0.32 × 0.04 mm |
F(000) = 432 |
Bruker Kappa APEXII DUO diffractometer | 2680 independent reflections |
Radiation source: fine-focus sealed tube | 2464 reflections with I > 2σ(I) |
Triumph monochromator | Rint = 0.023 |
φ scans, and ω scans | θmax = 30.7°, θmin = 2.0° |
Absorption correction: multi-scan (Blessing, 1995) | h = −9→6 |
Tmin = 0.705, Tmax = 0.746 | k = −9→8 |
10453 measured reflections | l = −28→25 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.029 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.075 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.044P)2 + 0.0725P] where P = (Fo2 + 2Fc2)/3 |
2680 reflections | (Δ/σ)max < 0.001 |
131 parameters | Δρmax = 0.31 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
C8H12O6 | V = 866.36 (12) Å3 |
Mr = 204.18 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 6.4876 (6) Å | µ = 0.14 mm−1 |
b = 6.6364 (5) Å | T = 100 K |
c = 20.1224 (16) Å | 0.43 × 0.32 × 0.04 mm |
Bruker Kappa APEXII DUO diffractometer | 2680 independent reflections |
Absorption correction: multi-scan (Blessing, 1995) | 2464 reflections with I > 2σ(I) |
Tmin = 0.705, Tmax = 0.746 | Rint = 0.023 |
10453 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.075 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.31 e Å−3 |
2680 reflections | Δρmin = −0.18 e Å−3 |
131 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.34564 (16) | 0.56520 (14) | 0.10994 (5) | 0.0131 (2) | |
C1 | 0.2020 (2) | 0.4035 (2) | 0.11836 (7) | 0.0131 (3) | |
H1 | 0.2178 | 0.3452 | 0.1639 | 0.016* | |
O2 | 0.44408 (19) | 0.15283 (16) | 0.08328 (5) | 0.0213 (2) | |
H12 | 0.479 (4) | 0.093 (4) | 0.0465 (13) | 0.046 (7)* | |
C2 | −0.0156 (2) | 0.4835 (2) | 0.11004 (6) | 0.0144 (3) | |
H2 | −0.1186 | 0.3778 | 0.1224 | 0.017* | |
O3 | 0.12624 (15) | 0.64670 (16) | 0.25197 (5) | 0.0161 (2) | |
C3 | −0.0551 (2) | 0.6797 (2) | 0.15012 (6) | 0.0151 (3) | |
H3 | −0.1768 | 0.6608 | 0.1800 | 0.018* | |
O4 | 0.45725 (16) | 0.63594 (16) | 0.21656 (5) | 0.0173 (2) | |
C4 | 0.1274 (2) | 0.7537 (2) | 0.19020 (6) | 0.0134 (3) | |
H4 | 0.1135 | 0.9015 | 0.1987 | 0.016* | |
O5 | −0.04486 (17) | 0.54598 (15) | 0.04200 (5) | 0.0173 (2) | |
C5 | 0.3420 (2) | 0.70826 (19) | 0.16104 (7) | 0.0129 (2) | |
H5 | 0.4051 | 0.8365 | 0.1447 | 0.016* | |
O6 | −0.10172 (18) | 0.82816 (16) | 0.10055 (5) | 0.0209 (2) | |
C6 | 0.3323 (2) | 0.6556 (2) | 0.27434 (7) | 0.0162 (3) | |
H6A | 0.3608 | 0.5448 | 0.3060 | 0.019* | |
H6B | 0.3596 | 0.7857 | 0.2968 | 0.019* | |
C7 | −0.1757 (2) | 0.7162 (2) | 0.04575 (7) | 0.0193 (3) | |
H7A | −0.1678 | 0.7967 | 0.0044 | 0.023* | |
H7B | −0.3206 | 0.6746 | 0.0530 | 0.023* | |
C8 | 0.2518 (3) | 0.2439 (2) | 0.06717 (7) | 0.0179 (3) | |
H8A | 0.1419 | 0.1405 | 0.0666 | 0.021* | |
H8B | 0.2594 | 0.3057 | 0.0225 | 0.021* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0137 (5) | 0.0135 (4) | 0.0122 (4) | −0.0019 (4) | 0.0031 (4) | −0.0021 (3) |
C1 | 0.0159 (6) | 0.0117 (5) | 0.0117 (6) | −0.0017 (5) | 0.0011 (5) | 0.0002 (4) |
O2 | 0.0284 (6) | 0.0197 (5) | 0.0156 (5) | 0.0096 (5) | −0.0014 (5) | −0.0029 (4) |
C2 | 0.0142 (6) | 0.0171 (6) | 0.0118 (6) | −0.0039 (5) | 0.0002 (5) | 0.0014 (5) |
O3 | 0.0139 (5) | 0.0230 (5) | 0.0115 (4) | −0.0016 (4) | 0.0002 (4) | 0.0030 (4) |
C3 | 0.0129 (6) | 0.0206 (6) | 0.0119 (6) | 0.0025 (5) | 0.0008 (5) | 0.0006 (5) |
O4 | 0.0127 (5) | 0.0262 (5) | 0.0131 (4) | 0.0037 (4) | −0.0017 (4) | −0.0034 (4) |
C4 | 0.0137 (6) | 0.0151 (5) | 0.0113 (6) | 0.0026 (5) | 0.0015 (5) | 0.0003 (5) |
O5 | 0.0174 (5) | 0.0238 (5) | 0.0105 (4) | 0.0015 (4) | −0.0018 (4) | 0.0003 (4) |
C5 | 0.0134 (6) | 0.0125 (5) | 0.0129 (6) | −0.0007 (5) | 0.0000 (5) | −0.0014 (4) |
O6 | 0.0249 (6) | 0.0220 (5) | 0.0158 (5) | 0.0072 (4) | −0.0051 (4) | 0.0008 (4) |
C6 | 0.0155 (6) | 0.0203 (6) | 0.0128 (6) | −0.0005 (5) | −0.0005 (5) | −0.0008 (5) |
C7 | 0.0141 (7) | 0.0295 (7) | 0.0144 (6) | 0.0036 (6) | −0.0020 (5) | 0.0015 (5) |
C8 | 0.0237 (8) | 0.0145 (6) | 0.0155 (7) | 0.0020 (6) | −0.0025 (5) | −0.0022 (5) |
O1—C5 | 1.3997 (16) | C3—H3 | 1.0000 |
O1—C1 | 1.4313 (16) | O4—C6 | 1.4233 (17) |
C1—C8 | 1.5123 (19) | O4—C5 | 1.4275 (17) |
C1—C2 | 1.518 (2) | C4—C5 | 1.5404 (19) |
C1—H1 | 1.0000 | C4—H4 | 1.0000 |
O2—C8 | 1.4237 (19) | O5—C7 | 1.4152 (18) |
O2—H12 | 0.87 (3) | C5—H5 | 1.0000 |
C2—O5 | 1.4430 (16) | O6—C7 | 1.4136 (18) |
C2—C3 | 1.553 (2) | C6—H6A | 0.9900 |
C2—H2 | 1.0000 | C6—H6B | 0.9900 |
O3—C6 | 1.4120 (17) | C7—H7A | 0.9900 |
O3—C4 | 1.4313 (16) | C7—H7B | 0.9900 |
C3—O6 | 1.4342 (17) | C8—H8A | 0.9900 |
C3—C4 | 1.5146 (19) | C8—H8B | 0.9900 |
C5—O1—C1 | 114.24 (10) | C5—C4—H4 | 109.8 |
O1—C1—C8 | 107.79 (11) | C7—O5—C2 | 104.94 (10) |
O1—C1—C2 | 109.29 (10) | O1—C5—O4 | 109.75 (10) |
C8—C1—C2 | 111.62 (11) | O1—C5—C4 | 115.33 (11) |
O1—C1—H1 | 109.4 | O4—C5—C4 | 103.95 (11) |
C8—C1—H1 | 109.4 | O1—C5—H5 | 109.2 |
C2—C1—H1 | 109.4 | O4—C5—H5 | 109.2 |
C8—O2—H12 | 103.1 (18) | C4—C5—H5 | 109.2 |
O5—C2—C1 | 109.12 (11) | C7—O6—C3 | 104.66 (11) |
O5—C2—C3 | 103.29 (11) | O3—C6—O4 | 105.95 (10) |
C1—C2—C3 | 112.93 (11) | O3—C6—H6A | 110.5 |
O5—C2—H2 | 110.4 | O4—C6—H6A | 110.5 |
C1—C2—H2 | 110.4 | O3—C6—H6B | 110.5 |
C3—C2—H2 | 110.4 | O4—C6—H6B | 110.5 |
C6—O3—C4 | 104.54 (10) | H6A—C6—H6B | 108.7 |
O6—C3—C4 | 108.21 (12) | O6—C7—O5 | 104.91 (11) |
O6—C3—C2 | 104.46 (10) | O6—C7—H7A | 110.8 |
C4—C3—C2 | 114.78 (12) | O5—C7—H7A | 110.8 |
O6—C3—H3 | 109.7 | O6—C7—H7B | 110.8 |
C4—C3—H3 | 109.7 | O5—C7—H7B | 110.8 |
C2—C3—H3 | 109.7 | H7A—C7—H7B | 108.8 |
C6—O4—C5 | 108.07 (11) | O2—C8—C1 | 109.23 (11) |
O3—C4—C3 | 107.31 (11) | O2—C8—H8A | 109.8 |
O3—C4—C5 | 103.80 (11) | C1—C8—H8A | 109.8 |
C3—C4—C5 | 116.12 (11) | O2—C8—H8B | 109.8 |
O3—C4—H4 | 109.8 | C1—C8—H8B | 109.8 |
C3—C4—H4 | 109.8 | H8A—C8—H8B | 108.3 |
C5—O1—C1—C8 | −169.46 (11) | C3—C2—O5—C7 | −24.54 (13) |
C5—O1—C1—C2 | 69.05 (13) | C1—O1—C5—O4 | 80.45 (13) |
O1—C1—C2—O5 | 66.87 (13) | C1—O1—C5—C4 | −36.51 (15) |
C8—C1—C2—O5 | −52.27 (14) | C6—O4—C5—O1 | −129.34 (12) |
O1—C1—C2—C3 | −47.39 (14) | C6—O4—C5—C4 | −5.45 (13) |
C8—C1—C2—C3 | −166.53 (11) | O3—C4—C5—O1 | 103.14 (12) |
O5—C2—C3—O6 | 0.05 (14) | C3—C4—C5—O1 | −14.36 (17) |
C1—C2—C3—O6 | 117.79 (12) | O3—C4—C5—O4 | −17.05 (13) |
O5—C2—C3—C4 | −118.27 (12) | C3—C4—C5—O4 | −134.55 (12) |
C1—C2—C3—C4 | −0.54 (16) | C4—C3—O6—C7 | 147.17 (12) |
C6—O3—C4—C3 | 156.74 (11) | C2—C3—O6—C7 | 24.45 (14) |
C6—O3—C4—C5 | 33.27 (13) | C4—O3—C6—O4 | −37.75 (14) |
O6—C3—C4—O3 | 159.69 (11) | C5—O4—C6—O3 | 26.67 (14) |
C2—C3—C4—O3 | −84.12 (13) | C3—O6—C7—O5 | −41.25 (14) |
O6—C3—C4—C5 | −84.77 (14) | C2—O5—C7—O6 | 41.43 (14) |
C2—C3—C4—C5 | 31.42 (16) | O1—C1—C8—O2 | 68.75 (14) |
C1—C2—O5—C7 | −144.91 (11) | C2—C1—C8—O2 | −171.22 (11) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H12···O5i | 0.87 (3) | 2.01 (3) | 2.846 (2) | 161 |
C3—H3···O4ii | 1.00 | 2.49 | 3.447 (2) | 160 |
C4—H4···O3iii | 1.00 | 2.46 | 3.296 (2) | 141 |
C5—H5···O2iv | 1.00 | 2.45 | 3.405 (2) | 160 |
C7—H7A···O1v | 0.99 | 2.48 | 3.455 (2) | 169 |
C7—H7B···O1ii | 0.99 | 2.56 | 3.509 (2) | 162 |
Symmetry codes: (i) x+1/2, −y+1/2, −z; (ii) x−1, y, z; (iii) −x, y+1/2, −z+1/2; (iv) x, y+1, z; (v) x−1/2, −y+3/2, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H12···O5i | 0.87 (3) | 2.01 (3) | 2.846 (2) | 161 |
C3—H3···O4ii | 1.00 | 2.49 | 3.447 (2) | 160 |
C4—H4···O3iii | 1.00 | 2.46 | 3.296 (2) | 141 |
C5—H5···O2iv | 1.00 | 2.45 | 3.405 (2) | 160 |
C7—H7A···O1v | 0.99 | 2.48 | 3.455 (2) | 169 |
C7—H7B···O1ii | 0.99 | 2.56 | 3.509 (2) | 162 |
Symmetry codes: (i) x+1/2, −y+1/2, −z; (ii) x−1, y, z; (iii) −x, y+1/2, −z+1/2; (iv) x, y+1, z; (v) x−1/2, −y+3/2, −z. |
Acknowledgements
The authors thank Dr W. Frey (Institut für Organische Chemie, Universität Stuttgart) for measuring the diffraction data.
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The synthesis of the protected sugar 1,2,3,4-di-O-methylene-α-D-galactopyranose has been well known for many years (Bok et al., 1952). Its crystal structure, however, remained undetermined. According to the structure analysis of the title compound, which we would like to report now, the central part of the molecule consists of a six-membered C5O ring, which is made up from the carbon atoms C1–C5 and O1 (Fig. 1). The chiral carbon atoms C1/C2/C4/C5 of the pyranose part show R-configuration and C3 shows S-configuration, in agreement with the expected configurations for an α-D-galactose ring. Both fused dioxolane rings adopt an envelope conformation with the carbon atom C7 (ring I) and oxygen atom O3 (ring II) as the flap, respectively. The pyranose ring shows a twist-boat conformation. A similar conformation of the pyranose ring has been observed in 6-[bis(ethoxycarbonyl)methyl]-6-deoxy-1,2;3,4-di-O-isopropylidene-D-galactopyranose (Doboszewski et al., 2010). The C–O and C–C and bond lengths in the molecule are comparable with the data from the crystal structure analysis of 1,2,3,5-di-O-methylene-α-D-xylofuranose (Tiritiris et al., 2015a) and other related compounds [see, for example: 6-O-cyanomethyl-1,2:3,4-di-O-isopropylidene-α-D-galactose (Langer et al., 2005), and the α- and β-anomers of D-galactose (Sheldrick, 1976)]. In the crystal structure, O—H···O hydrogen bonds between adjacent molecules are present [d(H···O) = 2.01 (3) Å] (Tab. 1), generating infinite one-dimensional chains with base vector [100] (Fig. 2). Taking additional C—H···O hydrogen bonds between adjacent molecules [d(H···O) = 2.45–2.56 Å] (Tab. 1) into account, a three-dimensional network is generated (Fig. 3).