research communications
Synthesis, structure and Hirshfeld surface analysis of diaquadinitratobis(4-nitroaniline)copper(II)
aNational University of Uzbekistan named after Mirzo Ulugbek, Tashkent, 100174, University str. 4., Uzbekistan, bInstitute of General and Inorganic Chemistry of Uzbekistan Academy of Sciences, Tashkent, 100125, M.Ulugbek Str., 77a, Uzbekistan, and cInstitute of Bioorganic Chemistry of Uzbekistan Academy of Sciences, Tashkent, 100140, M.Ulugbek Str., 83, Uzbekistan
*Correspondence e-mail: atom.uz@mail.ru
A new metal complex, [Cu(NO3)2(C6H6N2O2)2(H2O)2], was synthesized from water–ethanol solutions of Cu(NO3)2 and 4-nitroaniline (PNA). The complex molecules are located on inversion centers in monoclinic crystals with P21/c. The copper(II) ions are monodentately coordinated by two neutral PNA molecules through the nitrogen atom of the amino group, two NO3− anions and two water molecules. The of the central ion is a distorted octahedron as a result of the Jahn–Teller effect. There is a weak intramolecular hydrogen bond between the N—H group and the oxygen atom of one nitrate anion. Six relatively weak intermolecular hydrogen bonds associate the complex molecules into a three-dimensional network. The Hirshfeld surface analysis indicates that 55.8% of the intermolecular interactions are from O⋯H/H⋯O contacts, 13.3% are from H⋯H contacts while other contributions are from C⋯O/O⋯C, C⋯H/H⋯C, O⋯O and other contacts.
Keywords: p-nitroaniline; metal complex; crystal structure; hydrogen bond; Hirshfeld surface analysis.
CCDC reference: 2131922
1. Chemical context
p-Nitroaniline (PNA) or 1-amino-4-nitrobenzene is an organic compound with the formula C6H6N2O2. It is a yellow solid and one of three isomers of nitroaniline. PNA is an intermediate in the production of dyes, antioxidants, pharmaceuticals, gasoline, gum inhibitors, poultry medicines, and serves as a corrosion inhibitor. In particular, it is mainly used industrially as a precursor to p-phenylenediamine, an important dye component (Booth, 2000). The compound is toxic by way of inhalation, ingestion and absorption and can cause long-term damage to the environment if released as a pollutant. Its LD50 is 750.0 mg kg−1 when administered orally and therefore it should be handled with great care. It is well known that the biopharmaceutical properties (water solubility, bioavailability and bioactivity) of active pharmaceutical ingredients (API) may be improved by metal complex formation (Khudoyberganov et al., 2022; Ruzmetov et al., 2022a,b). Moreover, metal complex formation may be responsible for the reduction of the toxicity of metals, especially in therapy applications and respective investigations (Egorova & Ananikov, 2017; Flora & Pachauri, 2010; Ahmed et al., 2020). At the same time, this technique may similarly lead to a reduction in the toxicity of hazardous organic substances when they are part of coordination compounds. In order to test this hypothesis for specific molecules, we synthesized metal complexes of various toxic organic substances. This article describes the synthesis, molecular and and Hirshfeld surface analysis of the p-nitroaniline copper(II) complex.
2. Structural commentary
The molecular structure of the title complex is shown in Fig. 1. The central copper(II) ion is located on a crystallographic inversion center. Each of the two PNA molecules coordinates the metal ion through their NH2 nitrogen atom. Two NO3− groups are attached to the Cu2+ ion via one of their oxygen atoms (O3) in a monodentate fashion. The other two positions of the octahedral coordination sphere are occupied by water molecules. The formula of the obtained complex is [Cu(NO3)2(H2O)2(PNA)2]. The of the central atom is an octahedron with a distortion due to the Jahn–Teller effect. The Cu1—O1W and Cu1—N1 bond lengths are 1.996 (2) and 2.055 (3) Å while the Cu1—O3 distance is elongated to 2.367 (2) Å based on this effect. Orthogonal bond angles are in the range of 84.01 (11)–95.99 (11)°, i.e. their maximum deviation from an ideal value is about 6°. Compensation of the positive charge of the copper ion takes place with the inclusion of the two NO3− ions into the inner coordination sphere. The intramolecular N1—H⋯O4 hydrogen bond in the molecule forms a six-membered ring with S11(6) graph-set notation (Etter, 1990). The NO2 group of PNA is nearly coplanar with the aromatic ring – the corresponding dihedral angle is only 5.8 (6)°.
3. Supramolecular features
There are five proton-acceptor and two proton-donor hydrogen-bonding functional groups in the ). The respective seven intermolecular hydrogen bonds are relatively weak. A notable feature of the hydrogen-bonding pattern is that a considerable proportion of them are of a bifurcated nature – atoms H1A, H1B and H1WA are simultaneously hydrogen-bonded to two acceptors. The hydrogen bonds form different rings of various dimensions, i.e. rings with graph-set notations R22(4), R12(6) and R22(8). The hydrogen bonds summarized in Table 1 connect the complex molecules into a three-dimensional network (Fig. 2). The aromatic moieties are co-planar throughout the but do not engage in π–π stacking interactions.
of the molecule. All these groups realize their hydrogen-bonding capabilities (Table 1The Hirshfeld surfaces were calculated and the two-dimensional fingerprint plots generated using CrystalExplorer2021 (Spackman et al., 2021). Fig. 3 shows the three-dimensional Hirshfeld surface of the PNA copper complex with dnorm (normalized contact distance) plotted over the range of −0.5385 to 1.2851 a.u. The interactions given in Table 1 play a key role in the molecular packing of the complex. The overall 2D fingerprint plot and those delineated into the individual contributions are shown in Fig. 4. The percentage contributions to the Hirshfeld surfaces from the various interatomic contacts are as follows: O⋯H/H⋯O 55.8%, H⋯H 13.3%, C⋯O/O⋯C 9.3%, C⋯H/H⋯C 7.7% and O⋯O 6.1%. Other minor contributions to the Hirshfeld surface are from N⋯H/H⋯N (3.1%), O⋯N/N⋯O (2.2%) and C⋯N/N⋯C (1.5%) contacts.
4. Database survey
A search of the Cambridge Structural Database (CSD, Version 5.43, update of November 2021; Groom et al., 2016) for PNA metal complexes gave only five hits. In all entries, neutral PNA molecules are coordinated through their amine nitrogen atoms. In all cases, two chloride ions are coordinated in order to compensate for the twofold positive charge of the central ion. In the structures with refcodes BEMZAW (Feng, 2012), LUKLEK (Nguyen et al., 2015) and MEFWAY (Chen et al., 2017), the is tetrahedral while in case of compounds with refcodes HEXBUJ (Ip et al., 2012) and WOJKIR (Belghith et al., 2014), the central ion is sixfold coordinated and the complexes are octahedral. There is no precedent for structures with the coordination of water molecules or NO3− anions.
5. Synthesis and crystallization
The salt Cu(NO3)2 (0.187 g, 1.0 mmol) was dissolved in 2 ml of water and 4-nitroaniline (0.276 g, 2 mmol) was dissolved in 2 ml of absolute alcohol at 333 K. The solutions were mixed, filtered and left at room temperature for evaporation. After two weeks, green crystals had formed.
6. Refinement
Crystal data, data collection and structure . C-bound hydrogen atoms were placed in calculated positions (C—H = 0.93) and refined in the riding-model approximation with Uiso(H) = 1.2Ueq(C). Hydrogen atoms of the water molecule and the amino group were freely refined.
details are summarized in Table 2
|
Supporting information
CCDC reference: 2131922
https://doi.org/10.1107/S2056989022010404/yz2022sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989022010404/yz2022Isup3.hkl
Data collection: CrysAlis PRO (Rigaku OD, 2020); cell
CrysAlis PRO (Rigaku OD, 2020); data reduction: CrysAlis PRO (Rigaku OD, 2020); program(s) used to solve structure: SHELXT2018/2 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2019/2 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2020); software used to prepare material for publication: publCIF (Westrip, 2010).[Cu(NO3)2(C6H6N2O2)2(H2O)2] | F(000) = 510 |
Mr = 499.86 | Dx = 1.758 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.54184 Å |
a = 5.4741 (2) Å | Cell parameters from 2724 reflections |
b = 22.5679 (6) Å | θ = 3.9–70.2° |
c = 7.6478 (2) Å | µ = 2.38 mm−1 |
β = 92.286 (3)° | T = 293 K |
V = 944.05 (5) Å3 | Needle, metallic greenish green |
Z = 2 | 0.18 × 0.15 × 0.14 mm |
XtaLAB Synergy, Single source at home/near, HyPix3000 diffractometer | 1832 independent reflections |
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Cu) X-ray Source | 1457 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.062 |
Detector resolution: 10.0000 pixels mm-1 | θmax = 71.5°, θmin = 3.9° |
ω scans | h = −6→6 |
Absorption correction: multi-scan (CrysAlisPro; Rigaku OD, 2020) | k = −27→19 |
Tmin = 0.829, Tmax = 1.000 | l = −9→9 |
8364 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: mixed |
R[F2 > 2σ(F2)] = 0.045 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.123 | w = 1/[σ2(Fo2) + (0.0573P)2 + 0.7131P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max < 0.001 |
1832 reflections | Δρmax = 0.52 e Å−3 |
159 parameters | Δρmin = −0.87 e Å−3 |
0 restraints | Extinction correction: SHELXL-2019/2 (Sheldrick 2015a), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: dual | Extinction coefficient: 0.0033 (5) |
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 | ||
Cu1 | 0.500000 | 0.500000 | 0.500000 | 0.0261 (2) | |
O1W | 0.6912 (5) | 0.57083 (11) | 0.4300 (4) | 0.0379 (6) | |
N1 | 0.6669 (6) | 0.45393 (11) | 0.3061 (4) | 0.0294 (6) | |
O3 | 0.1479 (4) | 0.52675 (14) | 0.3283 (3) | 0.0495 (7) | |
O4 | 0.3458 (5) | 0.53819 (13) | 0.0932 (4) | 0.0554 (7) | |
N3 | 0.1596 (5) | 0.54597 (13) | 0.1725 (4) | 0.0370 (6) | |
C1 | 0.6119 (6) | 0.39265 (13) | 0.2771 (4) | 0.0282 (6) | |
O2 | 0.5581 (9) | 0.17631 (14) | 0.2427 (5) | 0.0967 (14) | |
O5 | −0.0187 (6) | 0.57134 (19) | 0.1086 (5) | 0.0865 (12) | |
C6 | 0.4005 (6) | 0.37830 (15) | 0.1797 (5) | 0.0379 (8) | |
H6 | 0.300983 | 0.408167 | 0.132632 | 0.046* | |
N2 | 0.4156 (10) | 0.21426 (17) | 0.1934 (6) | 0.0727 (13) | |
C2 | 0.7614 (7) | 0.34918 (15) | 0.3474 (5) | 0.0400 (8) | |
H2 | 0.901766 | 0.358992 | 0.413589 | 0.048* | |
C4 | 0.4876 (8) | 0.27703 (16) | 0.2229 (5) | 0.0490 (10) | |
C5 | 0.3390 (8) | 0.32017 (17) | 0.1532 (5) | 0.0488 (9) | |
H5 | 0.197557 | 0.310181 | 0.088452 | 0.059* | |
C3 | 0.6984 (9) | 0.28969 (16) | 0.3173 (6) | 0.0532 (11) | |
H3 | 0.798430 | 0.259361 | 0.360899 | 0.064* | |
O1 | 0.2167 (10) | 0.20459 (17) | 0.1186 (7) | 0.1147 (17) | |
H1A | 0.628 (7) | 0.4740 (17) | 0.220 (5) | 0.032 (9)* | |
H1B | 0.818 (8) | 0.4609 (19) | 0.334 (6) | 0.053 (13)* | |
H1WA | 0.813 (10) | 0.565 (2) | 0.376 (7) | 0.075 (17)* | |
H1WB | 0.621 (10) | 0.595 (3) | 0.379 (7) | 0.071 (18)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cu1 | 0.0308 (4) | 0.0154 (3) | 0.0324 (4) | −0.0018 (2) | 0.0046 (2) | −0.0005 (2) |
O1W | 0.0446 (15) | 0.0204 (11) | 0.0499 (15) | −0.0021 (10) | 0.0169 (12) | 0.0013 (10) |
N1 | 0.0377 (15) | 0.0218 (12) | 0.0287 (14) | −0.0019 (11) | 0.0008 (12) | −0.0001 (11) |
O3 | 0.0377 (13) | 0.0797 (19) | 0.0313 (13) | −0.0009 (13) | 0.0027 (10) | 0.0111 (12) |
O4 | 0.0581 (16) | 0.0696 (19) | 0.0397 (15) | 0.0147 (14) | 0.0168 (12) | 0.0132 (13) |
N3 | 0.0356 (15) | 0.0397 (15) | 0.0352 (15) | 0.0028 (12) | −0.0034 (12) | 0.0006 (12) |
C1 | 0.0340 (16) | 0.0215 (14) | 0.0294 (15) | −0.0018 (12) | 0.0060 (12) | −0.0035 (12) |
O2 | 0.176 (4) | 0.0286 (16) | 0.088 (3) | 0.001 (2) | 0.034 (3) | −0.0019 (17) |
O5 | 0.0543 (19) | 0.124 (3) | 0.079 (2) | 0.039 (2) | −0.0156 (17) | 0.020 (2) |
C6 | 0.0439 (19) | 0.0309 (17) | 0.0389 (18) | −0.0031 (15) | 0.0005 (15) | −0.0043 (14) |
N2 | 0.121 (4) | 0.038 (2) | 0.061 (3) | −0.017 (2) | 0.036 (3) | −0.0115 (18) |
C2 | 0.0434 (19) | 0.0308 (17) | 0.046 (2) | 0.0057 (15) | 0.0022 (16) | −0.0030 (15) |
C4 | 0.074 (3) | 0.0274 (18) | 0.047 (2) | −0.0150 (18) | 0.019 (2) | −0.0110 (15) |
C5 | 0.056 (2) | 0.041 (2) | 0.049 (2) | −0.0184 (18) | 0.0041 (18) | −0.0133 (17) |
C3 | 0.078 (3) | 0.0278 (18) | 0.055 (2) | 0.0184 (18) | 0.018 (2) | 0.0068 (16) |
O1 | 0.138 (4) | 0.059 (2) | 0.146 (4) | −0.045 (3) | −0.002 (4) | −0.036 (2) |
Cu1—O1W | 1.996 (2) | C1—C6 | 1.389 (5) |
Cu1—O1Wi | 1.996 (2) | C1—C2 | 1.373 (5) |
Cu1—N1 | 2.055 (3) | O2—N2 | 1.209 (6) |
Cu1—N1i | 2.055 (3) | C6—H6 | 0.9300 |
Cu1—O3i | 2.367 (2) | C6—C5 | 1.368 (5) |
Cu1—O3 | 2.367 (2) | N2—C4 | 1.485 (5) |
O1W—H1WA | 0.81 (6) | N2—O1 | 1.229 (6) |
O1W—H1WB | 0.76 (6) | C2—H2 | 0.9300 |
N1—C1 | 1.431 (4) | C2—C3 | 1.403 (5) |
N1—H1A | 0.82 (4) | C4—C5 | 1.363 (6) |
N1—H1B | 0.86 (4) | C4—C3 | 1.367 (6) |
O3—N3 | 1.272 (4) | C5—H5 | 0.9300 |
O4—N3 | 1.219 (4) | C3—H3 | 0.9300 |
N3—O5 | 1.217 (4) | ||
O1W—Cu1—O1Wi | 180.0 | O4—N3—O3 | 119.4 (3) |
O1Wi—Cu1—N1i | 87.62 (11) | O5—N3—O3 | 117.8 (3) |
O1Wi—Cu1—N1 | 92.38 (11) | O5—N3—O4 | 122.8 (3) |
O1W—Cu1—N1i | 92.38 (11) | C6—C1—N1 | 118.3 (3) |
O1W—Cu1—N1 | 87.62 (11) | C2—C1—N1 | 120.8 (3) |
O1W—Cu1—O3i | 85.93 (12) | C2—C1—C6 | 120.9 (3) |
O1W—Cu1—O3 | 94.07 (12) | C1—C6—H6 | 120.1 |
O1Wi—Cu1—O3i | 94.07 (12) | C5—C6—C1 | 119.9 (3) |
O1Wi—Cu1—O3 | 85.93 (12) | C5—C6—H6 | 120.1 |
N1i—Cu1—N1 | 180.0 | O2—N2—C4 | 117.7 (5) |
N1i—Cu1—O3i | 95.99 (11) | O2—N2—O1 | 124.6 (4) |
N1—Cu1—O3i | 84.01 (11) | O1—N2—C4 | 117.7 (5) |
N1i—Cu1—O3 | 84.01 (11) | C1—C2—H2 | 120.6 |
N1—Cu1—O3 | 95.99 (11) | C1—C2—C3 | 118.7 (4) |
O3i—Cu1—O3 | 180.0 | C3—C2—H2 | 120.6 |
Cu1—O1W—H1WA | 117 (4) | C5—C4—N2 | 118.1 (4) |
Cu1—O1W—H1WB | 116 (4) | C5—C4—C3 | 122.4 (3) |
H1WA—O1W—H1WB | 105 (5) | C3—C4—N2 | 119.5 (4) |
Cu1—N1—H1A | 101 (3) | C6—C5—H5 | 120.4 |
Cu1—N1—H1B | 100 (3) | C4—C5—C6 | 119.2 (4) |
C1—N1—Cu1 | 120.2 (2) | C4—C5—H5 | 120.4 |
C1—N1—H1A | 111 (3) | C2—C3—H3 | 120.5 |
C1—N1—H1B | 114 (3) | C4—C3—C2 | 118.9 (4) |
H1A—N1—H1B | 109 (4) | C4—C3—H3 | 120.5 |
N3—O3—Cu1 | 122.4 (2) | ||
Cu1—N1—C1—C6 | 81.0 (3) | O2—N2—C4—C3 | −5.9 (6) |
Cu1—N1—C1—C2 | −97.5 (3) | C6—C1—C2—C3 | 0.7 (5) |
Cu1—O3—N3—O4 | 17.1 (4) | N2—C4—C5—C6 | 179.5 (4) |
Cu1—O3—N3—O5 | −163.2 (3) | N2—C4—C3—C2 | −178.6 (4) |
N1—C1—C6—C5 | −178.4 (3) | C2—C1—C6—C5 | 0.2 (5) |
N1—C1—C2—C3 | 179.2 (3) | C5—C4—C3—C2 | 1.6 (6) |
C1—C6—C5—C4 | −0.2 (6) | C3—C4—C5—C6 | −0.7 (6) |
C1—C2—C3—C4 | −1.6 (6) | O1—N2—C4—C5 | −5.2 (6) |
O2—N2—C4—C5 | 173.9 (4) | O1—N2—C4—C3 | 175.0 (4) |
Symmetry code: (i) −x+1, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O4 | 0.82 (4) | 2.30 (4) | 3.021 (4) | 147 (4) |
O1W—H1WA···O3ii | 0.81 (5) | 2.07 (5) | 2.828 (4) | 156 (5) |
O1W—H1WA···O5ii | 0.81 (5) | 2.28 (5) | 2.979 (5) | 145 (5) |
N1—H1A···O4iii | 0.82 (4) | 2.42 (4) | 3.057 (4) | 135 (3) |
N1—H1B···O3ii | 0.86 (4) | 2.34 (4) | 3.103 (4) | 148 (4) |
N1—H1B···O3i | 0.86 (4) | 2.60 (5) | 2.968 (4) | 107 (3) |
O1W—H1WB···O1iv | 0.76 (6) | 2.64 (5) | 3.085 (5) | 120 (5) |
O1W—H1WB···O2iv | 0.77 (6) | 2.26 (6) | 3.022 (5) | 171 (5) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x+1, y, z; (iii) −x+1, −y+1, −z; (iv) −x+1, y+1/2, −z+1/2. |
Funding information
The authors would like to thank the Uzbekistan government for direct financial support of the research.
References
Ahmed, S. A., Hasan, M. N., Bagchi, D., Altass, H. M., Morad, M., Jassas, R. S., Hameed, A. M., Patwari, J., Alessa, H., Alharbi, A. & Pal, S. K. (2020). ACS Omega, 5, 15666–15672. Web of Science CrossRef CAS PubMed Google Scholar
Belghith, Y., Mansour, A. & Nasri, H. (2014). Acta Cryst. E70, m312–m313. CSD CrossRef IUCr Journals Google Scholar
Booth, G. (2000). Editor. Nitro Compounds, Aromatic. In Ullmann's Encyclopedia of Industrial Chemistry. https://doi.org/10.1002/14356007.a17_411 Google Scholar
Chen, A.-L., Huang, F., Hu, M.-L., Jin, Z.-M., Miao, Q. & Tian, B. (2017). Z. Anorg. Allg. Chem. 643, 1045–1048. Web of Science CSD CrossRef CAS Google Scholar
Egorova, K. S. & Ananikov, V. P. (2017). Organometallics, 36, 4071–4090. Web of Science CrossRef CAS Google Scholar
Etter, M. C. (1990). Acc. Chem. Res. 23, 120–126. CrossRef CAS Web of Science Google Scholar
Feng, T.-J. (2012). Acta Cryst. E68, m1351. CSD CrossRef IUCr Journals Google Scholar
Flora, S. J. S. & Pachauri, V. (2010). Int. J. Environ. Res. Public Health, 7, 2745–2788. Web of Science CrossRef CAS PubMed 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
Ip, H.-F., So, Y.-M., Sung, H. H. Y., Williams, I. D. & Leung, W.-H. (2012). Organometallics, 31, 7020–7023. Web of Science CSD CrossRef CAS Google Scholar
Khudoyberganov, O. I., Ruzmetov, A., Ibragimov, A. B., Ashurov, J. M., Khasanov, S. B., Eshchanov, E. U. & Ibragimov, B. T. (2022). Chem. Data Collect. 37, 100802. CSD CrossRef Google Scholar
Macrae, C. F., Sovago, I., Cottrell, S. J., Galek, P. T. A., McCabe, P., Pidcock, E., Platings, M., Shields, G. P., Stevens, J. S., Towler, M. & Wood, P. A. (2020). J. Appl. Cryst. 53, 226–235. Web of Science CrossRef CAS IUCr Journals Google Scholar
Nguyen Thi Thanh, C., Hoang Van, T., Pham Van, T., Nguyen Bich, N. & Van Meervelt, L. (2015). Acta Cryst. E71, 644–646. CSD CrossRef IUCr Journals Google Scholar
Rigaku OD (2020). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, England. Google Scholar
Ruzmetov, A., Ibragimov, A., Ashurov, J., Boltaeva, Z., Ibragimov, B. & Usmanov, S. (2022b). Acta Cryst. E78, 660–664. Web of Science CSD CrossRef IUCr Journals Google Scholar
Ruzmetov, A. Kh., Ibragimov, A. B., Myachina, O. V., Kim, R. N., Mamasalieva, L. E., Ashurov, J. M. & Ibragimov, B. T. (2022a). Chem. Data Collect, 38, 100845. CSD CrossRef 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
Spackman, P. R., Turner, M. J., McKinnon, J. J., Wolff, S. K., Grimwood, D. J., Jayatilaka, D. & Spackman, M. A. (2021). J. Appl. Cryst. 54, 1006–1011. Web of Science CrossRef CAS IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.