research communications
7,12]docosane bis(perchlorate) from synchrotron X-ray data
of 3,14-dimethyl-2,13-diaza-6,17-diazoniatricyclo[16.4.0.0aPohang Accelerator Laboratory, POSTECH, Pohang 37673, Republic of Korea, and bDepartment of Chemistry, Andong National University, Andong 36729, Republic of Korea
*Correspondence e-mail: jhchoi@anu.ac.kr
The 20H42N42+·2ClO4−, has been determined using synchrotron radiation at 220 (2) K. The reveals that protonation has occurred at diagonally opposite amine N atoms. The comprises one half of the organic dication, which lies about a center of inversion, and one perchlorate anion. The macrocyclic dication adopts the most stable endodentate trans-III conformation. The is stabilized by intramolecular N—H⋯N, and intermolecular N—H⋯O and C–H⋯O hydrogen bonds involving the macrocycle N—H and C—H groups as donors and the O atoms of perchlorate anions as acceptors, giving rise to a three-dimensional network.
of the title salt, CKeywords: crystal structure; protonated macrocycle; perchlorate; hydrogen bonding; synchrotron radiation.
CCDC reference: 2079010
1. Chemical context
The macrocyclic compound, 3,14-dimethyl-2,6,13,17-tetraazatricyclo(16.4.0.07,12)docosane (C20H40N4) contains a cyclam backbone with two cyclohexane subunits and two methyl groups are also attached to carbon atoms 3 and 14 of the propyl chains that bridge opposite pairs of N atoms in the structure. The macrocycle is basic and readily captures two or four protons to form the [C20H42N4]2+ dication or the [C20H44N4]4+ tetracation in which all of the N—H bonds are generally available for hydrogen-bond formation (Moon et al., 2021).
Previously, the crystal structures of [Cu(C20H40N4)](NO3)2·3H2O, [Cu(C20H40N4)](NO3)2, [Cu(C20H40N4)](ClO4)2 and [Cu(C20H40N4)(H2O)2](BF4)2·2H2O were reported together with [Zn(C20H40N4)(OCOCH3)2]. In these structures, the copper(II) or zinc(II) cations have tetragonally distorted octahedral environments with the four N atoms of the macrocyclic ligand in equatorial positions and the O atoms of the counter-anions, water molecules or acetato ligands in axial positions (Choi et al., 2006, 2007, 2012a,b; Ross et al., 2012). In these CuII and ZnII complexes, the macrocyclic ligands adopt their most stable trans-III configurations. The crystal structures of (C20H40N4)·2(C11H10O) (Choi et al., 2012c), (C20H40N4)·2(NO2OH) (Moon et al., 2020), [C20H42N4](SO4)·2MeOH (White et al., 2015), [C20H42N4]Br2·2H2O (Moon et al., 2021) and [C20H44N4]Br4·4H2O (Moon et al., 2021) have also been determined.
We report here the preparation of a new dicationic compound, [C20H42N4](ClO4)2, (I) and its structural characterization by synchrotron single-crystal X-ray diffraction.
2. Structural commentary
An ellipsoid plot of the molecular components in (I) with the atom-numbering scheme is shown in Fig. 1. The consists of one half of the macrocyclic dication, which lies about a center of inversion, and one perchlorate anion. The four N atoms are coplanar, and the two methyl substituents are anti with respect to the macrocyclic plane as a result of the molecular inversion symmetry. The [C20H42N4]2+ dication adopts an endodentate conformation and trans-III configuration along the center of the macrocyclic cavity. The endo conformation of the dication may be due to the intramolecular N—H⋯N hydrogen-bonding interaction. Within the centrosymmetric diprotonated amine unit, the C—C and N—C bond lengths range from 1.5173 (18) to 1.5368 (18) Å and from 1.4795 (16) to 1.5044 (16) Å, respectively. The range of N—C—C and C—N—C angles is 108.89 (11) to 113.50 (11)° and 113.46 (11) to 114.61 (11)°, respectively. The bond lengths and angles within the dication are comparable to those found in the free ligand or other cations in (C20H40N4)·2C11H10O (Choi et al., 2012c), [C20H42N4](SO4)·2MeOH (White et al., 2015) and [C20H42N4][Fe{HB(pz)3}(CN)3]2·2H2O·2MeOH (Kim et al., 2004; pz = pyrazolyl). The protonation of the N atoms may depend on the location of the neighboring counter-anions involved in hydrogen bonding. The bond-length difference can be noticed for several N—C bonds. The N—C bond length involving the non-protonated N1 atom is shorter than that involving protonated N2 atom, e.g. N1—C2 [1.4817 (18) Å] and N1—C3 [1.4795 (16) Å] are slightly shorter than N2—C8 [1.5044 (16) Å] and N2—C9 [1.4952 (18) Å]. Each of the two hydrogen atoms of N2 and N2′ (−x + 1, −y + 2, −z + 1) is involved in hydrogen bonding with both of the two remaining nitrogen atoms (Table 1). The intramolecular hydrogen bonding plays a substantial role in maintaining the endodentate geometry of the diprotonated macrocyclic cation. The Cl—O bond distances in the tetrahedral ClO4− anion vary from 1.4218 (19) to 1.4529 (16) Å, and the O—Cl—O angles vary from 106.45 (10) to 110.51 (12)°. The distorted geometry of the ClO4− anion undoubtedly results from its involvement in hydrogen-bonding interactions with the organic cation.
3. Supramolecular features
Three N—H⋯O, C–H⋯O and N—H⋯N hydrogen-bonding interactions occur in the ). The O atoms of the perchlorate anions serve as hydrogen-bond acceptors. The ClO4− anions are connected to the [C20H42N4]2+ dication by N—H⋯O hydrogen bonds. The macrocyclic dication is linked to a neighboring ClO4− anion through a very weak C—H⋯O hydrogen bond. The extensive array of these contacts generates a three-dimensional network structure (Fig. 2), and these hydrogen-bonding interactions help to stabilize the crystal structure.
(Table 14. Database survey
A search of the Cambridge Structural (Version 5.42, Update 1, February 2021; Groom et al., 2016) indicated 121 hits for organic and transition-metal compounds containing the macrocycles (C20H40N4), [C20H42N4]2+ or [C20H44N4]4+. The crystal structures of (C20H40N4)·2C11H10O (Choi et al., 2012c), [C20H42N4](SO4)·2MeOH (White et al., 2015), [C20H42N4]Br2·2H2O (Moon et al., 2021), [C20H44N4]Cl4·4H2O (Moon et al., 2018) and [C20H44N4]Br4·4H2O (Moon et al., 2021) were reported previously and commented on in the Chemical context section.
5. Synthesis and crystallization
Commercially available trans-1,2-cyclohexanediamine and methyl vinyl ketone (Sigma-Aldrich) were used as provided. All chemicals were reagent grade and used without further purification. As a starting material, macrocycle 3,14-dimethyl-2,6,13,17-tetraazatricyclo(16.4.0.07,12)docosane, L, was prepared according to a published procedure (Kang et al., 1991). Macrocycle L (0.034 g, 0.1 mmol) was suspended in methanol (20 mL) and the pH was adjusted to 3.0 with 0.5 M HClO4. The mixture was stirred magnetically for 30 min and the resulting solution was filtered. The neat filtrate was allowed to stand for one week to give block-like colorless crystals of (I) suitable for X-ray structural analysis.
6. Refinement
Crystal data, data collection and structure . All non-hydrogen atoms were refined anisotropically. All C-bound H atoms and the hydrogen atoms of the diprotonated amine (H2A and H2B) were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H distances of 0.97–0.98 Å and an N—H distance of 0.99 Å, and with Uiso(H) values of 1.5 and 1.2 times, respectively, that of the parent atoms. The one N-bound H atom (H1N1) of the amine was assigned based on a difference-Fourier map, and a Uiso(H) value of 1.5Ueq(N1).
details are summarized in Table 2Supporting information
CCDC reference: 2079010
https://doi.org/10.1107/S2056989021004278/vm2247sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989021004278/vm2247Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989021004278/vm2247Isup3.cml
Data collection: PAL BL2D-SMDC (Shin et al., 2016); cell
HKL3000sm (Otwinowski & Minor, 1997); data reduction: HKL3000sm (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXT2018 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: DIAMOND 4 (Putz & Brandenburg, 2014); software used to prepare material for publication: publCIF (Westrip, 2010).C20H42N42+·2ClO4− | F(000) = 576 |
Mr = 537.47 | Dx = 1.412 Mg m−3 |
Monoclinic, P21/n | Synchrotron radiation, λ = 0.630 Å |
a = 10.689 (2) Å | Cell parameters from 41946 reflections |
b = 8.4450 (17) Å | θ = 0.4–33.6° |
c = 14.020 (3) Å | µ = 0.22 mm−1 |
β = 92.90 (3)° | T = 220 K |
V = 1263.9 (4) Å3 | Block, colorless |
Z = 2 | 0.08 × 0.08 × 0.08 mm |
Rayonix MX225HS CCD area detector diffractometer | 3164 reflections with I > 2σ(I) |
Radiation source: PLSII 2D bending magnet | Rint = 0.063 |
ω scan | θmax = 26.0°, θmin = 2.5° |
Absorption correction: empirical (using intensity measurements) (HKL3000sm Scalepack; Otwinowski et al., 2003) | h = −14→14 |
Tmin = 0.957, Tmax = 1.000 | k = −11→11 |
12842 measured reflections | l = −19→19 |
3549 independent reflections |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Hydrogen site location: mixed |
R[F2 > 2σ(F2)] = 0.055 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.172 | w = 1/[σ2(Fo2) + (0.1016P)2 + 0.4023P] where P = (Fo2 + 2Fc2)/3 |
S = 1.11 | (Δ/σ)max < 0.001 |
3549 reflections | Δρmax = 0.86 e Å−3 |
158 parameters | Δρmin = −0.44 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.35546 (11) | 1.04262 (14) | 0.58019 (8) | 0.0179 (2) | |
H1N1 | 0.3881 (18) | 1.135 (3) | 0.5913 (14) | 0.027* | |
N2 | 0.58037 (10) | 0.87373 (14) | 0.61832 (7) | 0.0189 (2) | |
H2A | 0.556980 | 0.771653 | 0.612584 | 0.023* | |
H2B | 0.556374 | 0.923391 | 0.563613 | 0.023* | |
C1 | 0.17869 (17) | 0.8824 (2) | 0.51236 (13) | 0.0357 (4) | |
H1A | 0.104402 | 0.890989 | 0.470004 | 0.054* | |
H1B | 0.158772 | 0.823502 | 0.569045 | 0.054* | |
H1C | 0.243896 | 0.827482 | 0.479816 | 0.054* | |
C2 | 0.22417 (13) | 1.04715 (17) | 0.54095 (10) | 0.0208 (3) | |
H2 | 0.171026 | 1.086474 | 0.591704 | 0.025* | |
C3 | 0.37355 (13) | 0.95865 (16) | 0.67248 (9) | 0.0186 (3) | |
H3 | 0.339745 | 0.850008 | 0.664720 | 0.022* | |
C4 | 0.30834 (15) | 1.03951 (18) | 0.75469 (10) | 0.0254 (3) | |
H4A | 0.337406 | 1.149317 | 0.760396 | 0.030* | |
H4B | 0.217795 | 1.041505 | 0.739748 | 0.030* | |
C5 | 0.33416 (16) | 0.95505 (19) | 0.85002 (10) | 0.0270 (3) | |
H5A | 0.296287 | 1.015186 | 0.900932 | 0.032* | |
H5B | 0.295502 | 0.849816 | 0.847313 | 0.032* | |
C6 | 0.47429 (16) | 0.9383 (2) | 0.87300 (10) | 0.0284 (3) | |
H6A | 0.488076 | 0.877269 | 0.932053 | 0.034* | |
H6B | 0.511244 | 1.043474 | 0.883362 | 0.034* | |
C7 | 0.53896 (14) | 0.85522 (19) | 0.79198 (9) | 0.0258 (3) | |
H7A | 0.629365 | 0.849658 | 0.807106 | 0.031* | |
H7B | 0.506976 | 0.746930 | 0.784522 | 0.031* | |
C8 | 0.51363 (13) | 0.94746 (16) | 0.69916 (9) | 0.0187 (3) | |
H8 | 0.546260 | 1.056300 | 0.708844 | 0.022* | |
C9 | 0.71994 (13) | 0.8814 (2) | 0.63136 (9) | 0.0257 (3) | |
H9A | 0.747588 | 0.810782 | 0.683724 | 0.031* | |
H9B | 0.744648 | 0.989510 | 0.649456 | 0.031* | |
C10 | 0.78531 (13) | 0.83475 (19) | 0.54199 (9) | 0.0239 (3) | |
H10A | 0.750585 | 0.733364 | 0.519265 | 0.029* | |
H10B | 0.874193 | 0.817560 | 0.559494 | 0.029* | |
Cl1 | 0.54918 (4) | 0.43816 (5) | 0.65415 (3) | 0.03296 (16) | |
O1 | 0.45977 (15) | 0.55690 (19) | 0.61926 (13) | 0.0495 (4) | |
O2 | 0.67029 (15) | 0.5118 (2) | 0.65563 (14) | 0.0618 (5) | |
O3 | 0.5462 (2) | 0.3046 (2) | 0.59233 (17) | 0.0762 (6) | |
O4 | 0.51936 (16) | 0.3923 (2) | 0.74864 (12) | 0.0598 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0238 (5) | 0.0176 (5) | 0.0127 (5) | −0.0015 (4) | 0.0047 (4) | 0.0024 (4) |
N2 | 0.0246 (5) | 0.0218 (6) | 0.0109 (4) | 0.0014 (4) | 0.0056 (4) | 0.0023 (4) |
C1 | 0.0388 (8) | 0.0307 (8) | 0.0374 (9) | −0.0110 (7) | −0.0011 (6) | −0.0010 (7) |
C2 | 0.0229 (6) | 0.0235 (7) | 0.0165 (6) | 0.0007 (5) | 0.0065 (4) | 0.0003 (5) |
C3 | 0.0262 (6) | 0.0175 (6) | 0.0128 (5) | 0.0000 (5) | 0.0073 (4) | 0.0028 (4) |
C4 | 0.0347 (7) | 0.0271 (7) | 0.0155 (6) | 0.0061 (6) | 0.0121 (5) | 0.0040 (5) |
C5 | 0.0407 (8) | 0.0275 (7) | 0.0139 (6) | 0.0017 (6) | 0.0128 (5) | 0.0031 (5) |
C6 | 0.0427 (8) | 0.0326 (8) | 0.0105 (6) | −0.0001 (6) | 0.0061 (5) | 0.0000 (5) |
C7 | 0.0349 (7) | 0.0315 (7) | 0.0113 (5) | 0.0049 (6) | 0.0060 (5) | 0.0046 (5) |
C8 | 0.0265 (6) | 0.0194 (6) | 0.0106 (5) | −0.0004 (5) | 0.0063 (4) | 0.0006 (4) |
C9 | 0.0242 (6) | 0.0387 (8) | 0.0146 (6) | 0.0006 (6) | 0.0047 (4) | 0.0006 (5) |
C10 | 0.0264 (6) | 0.0291 (7) | 0.0168 (6) | 0.0062 (5) | 0.0063 (5) | 0.0030 (5) |
Cl1 | 0.0328 (2) | 0.0270 (3) | 0.0393 (3) | −0.00471 (14) | 0.00435 (17) | 0.00776 (14) |
O1 | 0.0454 (8) | 0.0462 (9) | 0.0564 (9) | 0.0068 (6) | −0.0015 (7) | 0.0120 (7) |
O2 | 0.0423 (8) | 0.0658 (11) | 0.0770 (12) | −0.0215 (8) | 0.0003 (8) | 0.0287 (10) |
O3 | 0.1111 (16) | 0.0318 (8) | 0.0893 (14) | −0.0193 (10) | 0.0399 (12) | −0.0118 (9) |
O4 | 0.0577 (9) | 0.0755 (12) | 0.0463 (9) | −0.0126 (9) | 0.0036 (7) | 0.0284 (9) |
N1—C3 | 1.4795 (16) | C5—C6 | 1.523 (2) |
N1—C2 | 1.4817 (18) | C5—H5A | 0.9800 |
N1—H1N1 | 0.86 (2) | C5—H5B | 0.9800 |
N2—C9 | 1.4952 (18) | C6—C7 | 1.530 (2) |
N2—C8 | 1.5044 (16) | C6—H6A | 0.9800 |
N2—H2A | 0.9000 | C6—H6B | 0.9800 |
N2—H2B | 0.9000 | C7—C8 | 1.5290 (18) |
C1—C2 | 1.521 (2) | C7—H7A | 0.9800 |
C1—H1A | 0.9700 | C7—H7B | 0.9800 |
C1—H1B | 0.9700 | C8—H8 | 0.9900 |
C1—H1C | 0.9700 | C9—C10 | 1.5173 (18) |
C2—C10i | 1.5314 (19) | C9—H9A | 0.9800 |
C2—H2 | 0.9900 | C9—H9B | 0.9800 |
C3—C8 | 1.5278 (19) | C10—H10A | 0.9800 |
C3—C4 | 1.5368 (18) | C10—H10B | 0.9800 |
C3—H3 | 0.9900 | Cl1—O3 | 1.4218 (19) |
C4—C5 | 1.528 (2) | Cl1—O4 | 1.4315 (16) |
C4—H4A | 0.9800 | Cl1—O2 | 1.4354 (15) |
C4—H4B | 0.9800 | Cl1—O1 | 1.4529 (16) |
C3—N1—C2 | 114.61 (11) | H5A—C5—H5B | 108.0 |
C3—N1—H1N1 | 103.8 (13) | C5—C6—C7 | 111.23 (13) |
C2—N1—H1N1 | 114.3 (13) | C5—C6—H6A | 109.4 |
C9—N2—C8 | 113.46 (11) | C7—C6—H6A | 109.4 |
C9—N2—H2A | 108.9 | C5—C6—H6B | 109.4 |
C8—N2—H2A | 108.9 | C7—C6—H6B | 109.4 |
C9—N2—H2B | 108.9 | H6A—C6—H6B | 108.0 |
C8—N2—H2B | 108.9 | C8—C7—C6 | 109.34 (13) |
H2A—N2—H2B | 107.7 | C8—C7—H7A | 109.8 |
C2—C1—H1A | 109.5 | C6—C7—H7A | 109.8 |
C2—C1—H1B | 109.5 | C8—C7—H7B | 109.8 |
H1A—C1—H1B | 109.5 | C6—C7—H7B | 109.8 |
C2—C1—H1C | 109.5 | H7A—C7—H7B | 108.3 |
H1A—C1—H1C | 109.5 | N2—C8—C3 | 109.71 (11) |
H1B—C1—H1C | 109.5 | N2—C8—C7 | 111.10 (11) |
N1—C2—C1 | 110.99 (12) | C3—C8—C7 | 111.66 (11) |
N1—C2—C10i | 108.89 (11) | N2—C8—H8 | 108.1 |
C1—C2—C10i | 112.81 (13) | C3—C8—H8 | 108.1 |
N1—C2—H2 | 108.0 | C7—C8—H8 | 108.1 |
C1—C2—H2 | 108.0 | N2—C9—C10 | 112.70 (11) |
C10i—C2—H2 | 108.0 | N2—C9—H9A | 109.1 |
N1—C3—C8 | 109.08 (10) | C10—C9—H9A | 109.1 |
N1—C3—C4 | 113.50 (11) | N2—C9—H9B | 109.1 |
C8—C3—C4 | 108.65 (12) | C10—C9—H9B | 109.1 |
N1—C3—H3 | 108.5 | H9A—C9—H9B | 107.8 |
C8—C3—H3 | 108.5 | C9—C10—C2i | 116.25 (13) |
C4—C3—H3 | 108.5 | C9—C10—H10A | 108.2 |
C5—C4—C3 | 112.33 (12) | C2i—C10—H10A | 108.2 |
C5—C4—H4A | 109.1 | C9—C10—H10B | 108.2 |
C3—C4—H4A | 109.1 | C2i—C10—H10B | 108.2 |
C5—C4—H4B | 109.1 | H10A—C10—H10B | 107.4 |
C3—C4—H4B | 109.1 | O3—Cl1—O4 | 110.51 (12) |
H4A—C4—H4B | 107.9 | O3—Cl1—O2 | 110.20 (14) |
C6—C5—C4 | 111.15 (12) | O4—Cl1—O2 | 110.28 (11) |
C6—C5—H5A | 109.4 | O3—Cl1—O1 | 110.37 (13) |
C4—C5—H5A | 109.4 | O4—Cl1—O1 | 108.95 (11) |
C6—C5—H5B | 109.4 | O2—Cl1—O1 | 106.45 (10) |
C4—C5—H5B | 109.4 | ||
C3—N1—C2—C1 | −67.02 (15) | C9—N2—C8—C7 | −65.28 (15) |
C3—N1—C2—C10i | 168.21 (11) | N1—C3—C8—N2 | −53.86 (14) |
C2—N1—C3—C8 | 173.99 (10) | C4—C3—C8—N2 | −178.05 (10) |
C2—N1—C3—C4 | −64.72 (15) | N1—C3—C8—C7 | −177.48 (11) |
N1—C3—C4—C5 | −177.06 (12) | C4—C3—C8—C7 | 58.32 (15) |
C8—C3—C4—C5 | −55.52 (16) | C6—C7—C8—N2 | 177.49 (12) |
C3—C4—C5—C6 | 54.72 (17) | C6—C7—C8—C3 | −59.68 (16) |
C4—C5—C6—C7 | −55.07 (17) | C8—N2—C9—C10 | −169.40 (12) |
C5—C6—C7—C8 | 57.14 (16) | N2—C9—C10—C2i | 71.50 (17) |
C9—N2—C8—C3 | 170.77 (11) |
Symmetry code: (i) −x+1, −y+2, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N1···O3ii | 0.86 (2) | 2.22 (2) | 3.007 (2) | 152.4 (18) |
N2—H2A···O1 | 0.90 | 2.09 | 2.970 (2) | 164 |
N2—H2A···O2 | 0.90 | 2.56 | 3.239 (2) | 132 |
N2—H2B···N1i | 0.90 | 2.29 | 2.9846 (16) | 134 |
N2—H2B···N1 | 0.90 | 2.39 | 2.8230 (17) | 109 |
C7—H7A···O2iii | 0.98 | 2.57 | 3.423 (3) | 145 |
Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, y+1, z; (iii) −x+3/2, y+1/2, −z+3/2. |
Acknowledgements
This work was supported by a Research Grant of Andong National University. The X-ray crystallography experiment at the PLS-II BL2D-SMC beamline was supported in part by MSIT and POSTECH.
References
Choi, J.-H., Joshi, T. & Spiccia, L. (2012a). Z. Anorg. Allg. Chem. 638, 146–151. Web of Science CSD CrossRef CAS Google Scholar
Choi, J.-H., Ryoo, K. S. & Park, K.-M. (2007). Acta Cryst. E63, m2674–m2675. Web of Science CSD CrossRef IUCr Journals Google Scholar
Choi, J.-H., Subhan, M. A. & Ng, S. W. (2012b). Acta Cryst. E68, m190. Web of Science CSD CrossRef IUCr Journals Google Scholar
Choi, J.-H., Subhan, M. A., Ryoo, K. S. & Ng, S. W. (2012c). Acta Cryst. E68, o102. Web of Science CSD CrossRef IUCr Journals Google Scholar
Choi, J.-H., Suzuki, T. & Kaizaki, S. (2006). Acta Cryst. E62, m2383–m2385. Web of Science CSD CrossRef IUCr Journals Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Kang, S. G., Kweon, J. K. & Jung, S. K. (1991). Bull. Korean Chem. Soc. 12, 483–487. CAS Google Scholar
Kim, J., Han, S., Cho, I.-K., Choi, K. Y., Heu, M., Yoon, S. & Suh, B. J. (2004). Polyhedron, 23, 1333–1339. Web of Science CSD CrossRef CAS Google Scholar
Moon, D. & Choi, J.-H. (2018). Acta Cryst. E74, 1039–1041. CSD CrossRef IUCr Journals Google Scholar
Moon, D., Jeon, S. & Choi, J.-H. (2021). J. Mol. Struct. 1232, 130011. CSD CrossRef Google Scholar
Moon, D., Jeon, S., Ryoo, K. S. & Choi, J.-H. (2020). Asian J. Chem. 32, 697–702. CrossRef CAS Google Scholar
Otwinowski, Z., Borek, D., Majewski, W. & Minor, W. (2003). Acta Cryst. A59, 228–234. Web of Science CrossRef CAS IUCr Journals Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp 307–326. New York: Academic Press. Google Scholar
Putz, H. & Brandenburg, K. (2014). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Ross, A., Choi, J.-H., Hunter, T. M., Pannecouque, C., Moggach, S. A., Parsons, S., De Clercq, E. & Sadler, P. J. (2012). Dalton Trans. 41, 6408–6418. Web of Science CSD CrossRef CAS PubMed Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Shin, J. W., Eom, K. & Moon, D. (2016). J. Synchrotron Rad. 23, 369–373. Web of Science CrossRef IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
White, F., Sadler, P. J. & Melchart, M. (2015). CSD Communication (CCDC 1408165). CCDC, Cambridge, England. Google Scholar
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