organic compounds
5-Phenyl-3-(2-phosphonoethyl)-1,2,3-triazol-1-ium chloride
aCrystal Engineering, Growth and Design Laboratory, Department of Chemistry, University of Crete, Voutes Campus, Crete, GR-71003, Greece, and bLaboratorio de Estudios Cristalográficos, IACT, CSIC-Universidad de Granada, Granada-18100, Spain
*Correspondence e-mail: demadis@uoc.gr
The new triazole-functionalized phosphonic acid 5-phenyl-3-(2-phosphonoethyl)-1,2,3-triazol-1-ium chloride, C10H13N3O3P+·Cl− (PTEPHCl), was synthesized by the `click' reaction of the alkyl azide diethyl-(2-azidoethyl)phosphonate with phenylacetylene to give the diethyl[2-(4-phenyl-1H-1,2,3-triazol-1-yl)ethyl]phosphonate ester, which was then hydrolyzed under acidic conditions (HCl) to give the `free' phosphonic acid. The use of HCl for the hydrolysis caused protonation of the triazole ring, rendering the compound cationic, charged-balanced by a Cl− anion. There are extensive hydrogen-bonding interactions in the structure of PTEPHCl, involving the phosphonic acid (–PO3H2) group, the triazolium ring and the Cl− anion.
Keywords: phosphonate; triazole; hydrogen bonding; click chemistry; crystal structure.
CCDC reference: 2145106
Structure description
The exponential growth of the field of MOFs and coordination polymers over the past few decades is partially due to the design, synthesis and functionalization of appropriate linkers (Zaręba, 2017). Although the field was initiated with compounds that were mainly based on polycarboxylate linkers, its continuous development currently embraces virtually all molecules that are able to bind to metals. Among the plethora of ligands, (poly)phosphonic acids stand out because they can construct networks with high thermal and hydrolytic stability (Clearfield & Demadis, 2012). The field of metal phosphonates also relies on the availability of proper phosphonate linkers that offer structural diversity and can produce metal phosphonate compounds with attractive properties. Most of the published work on new phosphonic acids is based on two synthetic methodologies: (i) the Arbuzov reaction (Babu et al., 2017) and (ii) the Mannich-type (a.k.a. Moedritzer–Irani) reaction (Villemin et al., 2021). The Arbuzov reaction can convert an organic halide to a phosphonic acid group, whereas Mannich-type reactions transform an amine group to an aminomethylenephosphonic group. Both synthetic strategies aim at introducing a phosphonic acid moiety to a pre-formed organic fragment. We recently initiated synthetic efforts that are based on `click' chemistry. Specifically, the approach is based on a `reactive' organic molecule that already contains a phosphonic acid group, but can undergo other transformations elsewhere on the backbone.
The reaction of an organic azide with an alkyne to give a triazole is a well-known process (Mukherjee et al., 2013). Herein, this transformation was performed on an organic azide that already contains a phosphonate group on its backbone to yield a phosphonate-modified triazole. Specifically, an alkyl azide [diethyl-(2-azidoethyl)phosphonate] was reacted with an aromatic alkyne (phenylacetylene) to give diethyl[2-(4-phenyl-1H-1,2,3-triazol-1-yl)ethyl]phosphonate ester. This ester was then hydrolyzed in acidic conditions to give 5-phenyl-3-(2-phosphonoethyl)-1,2,3-triazol-1-ium chloride (PTEPHCl). In the present work, we report the of the above-mentioned triazole-functionalized phosphonic acid PTEPHCl.
Molecular structure
Fig. 1 shows the molecular structure of 5-phenyl-3-(2-phosphonoethyl)-1,2,3-triazol-1-ium chloride. Because HCl was used for the ester hydrolysis, the N3 atom of the triazole ring and the O1 and O2 atoms of the phosphonate group are protonated due to the synthesis of PTEPHCl at low pH, hence a chloride counter-ion (Cl1) is found in the structure.
There are two `long' P—O bonds [P1—O1 = 1.5526 (16) and P1—O2 = 1.5513 (16) Å] and one `short' P—O bond [P1—O3 = 1.4805 (14) Å]. The `long' P—O bonds correspond to the P—O—H moieties and the `short' P—O bond corresponds to the phosphoryl P=O moiety. All P—O bond lengths have the expected values (Colodrero et al., 2013). The bond lengths of the triazolium moiety [N1—N2 = 1.317 (2) Å, N1—C2 = 1.474 (3) Å, N1—C3 = 1.346 (3) Å, N2—N3 = 1.318 (2) Å, N3—C4 = 1.352 (2) Å] are very similar to those in 1,2,4-triazolium chloride (Bujak & Zaleski, 2002).
Hydrogen bonding
The phosphonic acid moiety forms four hydrogen-bonding interactions (Fig. 2 and Table 1). Specifically, each of the two P—O—H groups interacts with a different Cl− counter-ion, with contacts O1⋯Cl1 = 2.9521 (16) Å and O2⋯Cl1 = 2.9422 (17) Å. The phosphoryl P=O group forms a hydrogen bond with the N—H portion of the triazolium ring [O3⋯N3 2.610 (2) Å]. Finally, the benzene ring interacts with a phosphonate oxygen through a weak C—H⋯O contact at 3.476 (3) Å (C6⋯O2).
π–π stacking interactions
There is only one type of very weak π–π stacking interaction in the structure of 5-phenyl-3-(2-phosphonoethyl)-1,2,3-triazol-1-ium chloride. The centroid-to-centroid distance is 4.0423 (15) Å, with the rings being `shifted' from one another (slippage distance between the rings: 2.222 Å) and parallel.
Crystal packing
Fig. 3 shows the packing along the three axes. The π–π stacking interactions are parallel to the b axis. The chloride anions form corrugated sheets [`short' Cl⋯Cl distances at 4.9455 (12) Å and `long' Cl⋯Cl distances at 6.4564 (9) Å] that are parallel to the bc plane.
Synthesis and crystallization
Reagents and materials
All starting materials were obtained from commercial sources and used without further purification. The reagents diethyl 2-bromoethylphosphonate (97%), phenylacetylene (98+%), copper sulfate pentahydrate (99%), zinc nitrate hexahydrate (98%) and ethylenediaminetetraacetic acid (98%) were from Alfa Aesar. Sodium azide and L-ascorbic acid were from Serva. Sodium sulfate was from Merck. Dichloromethane, tetrahydrofuran (THF), hydrochloric acid (37%) and nitric acid (70%) were from Scharlau. Ion-exchange-column deionized water was used.
Synthesis of 5-phenyl-3-(2-phosphonoethyl)-1,2,3-triazol-1-ium chloride (PTEPHCl)
Three distinct steps were followed for the syntheses of the ligand PTEP. The first step was the synthesis of diethyl-(2-azidoethyl)phosphonate, following a properly adapted published procedure (Sheikhi et al., 2018). Specifically, sodium azide (10.6 g, 163.05 mmol) was added to a solution of diethyl-2-bromoethylphosphonate (10.4 g, 42.44 mmol) in water (50 mL). The reaction mixture was stirred at 338 K for 24 h. Then, extraction was carried out with dichloromethane (4 × 50 mL) and the organic phase was collected and dried over sodium sulfate. After filtration, a yellow oil was obtained, which is diethyl-(2-azidoethyl)phosphonate. The second step included the reaction of diethyl-(2-azidoethyl)phosphonate (3 mL, 2.07 mmol) with phenyl acetylene (895 µL, 1.035 mmol) in THF (67.5 mL), in the presence of copper sulfate (1.198 g 0.64 mmol) and L-ascorbic acid (0.218 g, 1.24 mmol) to produce diethyl[2-(4-phenyl-1H-1,2,3-triazol-1-yl)ethyl]phosphonate ester. The reaction mixture was heated at 313 K under vigorous stirring for 48 h. After filtration, the filtrate was mixed with dichloromethane (50 mL) and an aqueous solution of the Cu2+ chelant ethylenediaminetetraacetic acid (50 mL, 0.2 M) and the mixture was stirred for ∼1 h. After extraction with dichloromethane (4 × 50 mL) and evaporation, diethyl[2-(4-phenyl-1H-1,2,3-triazol-1-yl)ethyl]phosphonate ester was obtained in solid form. Finally, the latter (0.5 g) was hydrolyzed with 25 mL of H2O and 30 mL of HCl at 373 K for 48 h, giving 5-phenyl-3-(2-phosphonoethyl)-1,2,3-triazol-1-ium chloride in crystalline form (yield: 0.3 g, 60%). The crystal used for the data collection was handled under inert conditions. It was manipulated while immersed in a perfluoropolyether protecting oil and mounted on a MiTeGen Micromount™.
1H NMR (300 MHz, DMSO-d6) δ 8.51 (s, 1H), 7.93 (d, 2H), 7.67 (m, 3H), 4.82 (m, 2H), 2.52 (m, 2H). 13C NMR (75.5 MHz, DMSO-d6) δ 146.71, 131.27, 129.38, 128.28, 125.53, 121.87, 45.42, 30.45 (d, JCP = 134.5 Hz). 31P NMR (121.5 MHz, DMSO-d6) δ 20.17.
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2
|
Structural data
CCDC reference: 2145106
https://doi.org/10.1107/S2414314622001894/tx4001sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314622001894/tx4001Isup4.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314622001894/tx4001Isup4.cml
Supporting information file. DOI: https://doi.org/10.1107/S2414314622001894/tx4001Isup5.mol
Data collection: APEX3 (Bruker, 2019); cell
SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).C10H13N3O3P+·Cl− | F(000) = 600 |
Mr = 289.65 | Dx = 1.490 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.54178 Å |
a = 11.5857 (6) Å | Cell parameters from 9685 reflections |
b = 7.0616 (4) Å | θ = 4.0–66.7° |
c = 16.6118 (9) Å | µ = 3.86 mm−1 |
β = 108.222 (2)° | T = 298 K |
V = 1290.92 (12) Å3 | Plate, colourless |
Z = 4 | 0.12 × 0.09 × 0.08 mm |
Bruker D8 Venture diffractometer | 2048 reflections with I > 2σ(I) |
φ and ω scans | Rint = 0.046 |
Absorption correction: multi-scan (SADABS; Bruker, 2016) | θmax = 66.7°, θmin = 4.0° |
Tmin = 0.524, Tmax = 0.753 | h = −12→13 |
11621 measured reflections | k = −8→8 |
2268 independent reflections | l = −18→19 |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.042 | w = 1/[σ2(Fo2) + (0.0842P)2 + 0.2113P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.129 | (Δ/σ)max < 0.001 |
S = 1.11 | Δρmax = 0.21 e Å−3 |
2268 reflections | Δρmin = −0.34 e Å−3 |
166 parameters | Extinction correction: SHELXL2019/1 (Sheldrick 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0086 (14) |
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. |
Refinement. All hydrogen atoms were located in difference Fourier maps and included as fixed contributions riding on attached atoms with isotropic thermal displacement parameters 1.2 or 1.5 times those of the respective atom. |
x | y | z | Uiso*/Ueq | ||
P1 | 0.81725 (4) | 0.61394 (8) | 0.26679 (3) | 0.0473 (2) | |
O1 | 0.91887 (15) | 0.4728 (3) | 0.26434 (10) | 0.0660 (5) | |
H1 | 0.946479 | 0.421812 | 0.310754 | 0.099* | |
O2 | 0.78145 (14) | 0.7154 (3) | 0.17962 (10) | 0.0663 (5) | |
H2 | 0.838534 | 0.711018 | 0.160392 | 0.099* | |
O3 | 0.70907 (13) | 0.5261 (2) | 0.28078 (9) | 0.0570 (4) | |
N1 | 0.68960 (15) | 0.9187 (2) | 0.35631 (11) | 0.0480 (4) | |
N2 | 0.59278 (15) | 0.9687 (3) | 0.29376 (10) | 0.0497 (4) | |
N3 | 0.50156 (14) | 0.9160 (2) | 0.32010 (10) | 0.0446 (4) | |
H3 | 0.426572 | 0.931250 | 0.290694 | 0.054* | |
C1 | 0.88515 (18) | 0.7829 (3) | 0.34778 (14) | 0.0530 (5) | |
H1A | 0.902609 | 0.720386 | 0.402270 | 0.064* | |
H1B | 0.962183 | 0.821985 | 0.341559 | 0.064* | |
C2 | 0.8107 (2) | 0.9598 (3) | 0.34921 (17) | 0.0626 (6) | |
H2A | 0.855085 | 1.038465 | 0.396689 | 0.075* | |
H2B | 0.801074 | 1.031479 | 0.297697 | 0.075* | |
C3 | 0.66201 (18) | 0.8378 (3) | 0.42134 (13) | 0.0468 (5) | |
H3A | 0.716089 | 0.792849 | 0.471680 | 0.056* | |
C4 | 0.53734 (17) | 0.8355 (3) | 0.39786 (12) | 0.0406 (4) | |
C5 | 0.45429 (18) | 0.7694 (2) | 0.44224 (12) | 0.0419 (5) | |
C6 | 0.4974 (2) | 0.7322 (3) | 0.52898 (13) | 0.0509 (5) | |
H6 | 0.579280 | 0.748521 | 0.558805 | 0.061* | |
C7 | 0.4176 (3) | 0.6708 (3) | 0.57037 (15) | 0.0634 (6) | |
H7 | 0.446686 | 0.644005 | 0.628029 | 0.076* | |
C8 | 0.2960 (3) | 0.6489 (3) | 0.52761 (18) | 0.0678 (7) | |
H8 | 0.242943 | 0.611045 | 0.556500 | 0.081* | |
C9 | 0.2534 (2) | 0.6829 (4) | 0.44228 (18) | 0.0727 (7) | |
H9 | 0.171424 | 0.665745 | 0.412999 | 0.087* | |
C10 | 0.3319 (2) | 0.7427 (3) | 0.39929 (16) | 0.0573 (6) | |
H10 | 0.302340 | 0.765053 | 0.341264 | 0.069* | |
Cl1 | 0.94890 (5) | 0.76568 (8) | 0.07972 (3) | 0.0583 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
P1 | 0.0364 (3) | 0.0693 (4) | 0.0365 (4) | 0.0015 (2) | 0.0118 (2) | 0.0013 (2) |
O1 | 0.0610 (10) | 0.0914 (12) | 0.0490 (9) | 0.0254 (8) | 0.0223 (7) | 0.0080 (8) |
O2 | 0.0475 (9) | 0.1068 (13) | 0.0442 (9) | 0.0135 (8) | 0.0136 (7) | 0.0171 (8) |
O3 | 0.0468 (8) | 0.0797 (10) | 0.0457 (8) | −0.0157 (7) | 0.0163 (6) | −0.0101 (7) |
N1 | 0.0392 (9) | 0.0508 (9) | 0.0543 (10) | −0.0028 (7) | 0.0150 (7) | −0.0041 (7) |
N2 | 0.0458 (9) | 0.0583 (10) | 0.0469 (10) | 0.0002 (7) | 0.0174 (8) | 0.0004 (7) |
N3 | 0.0383 (8) | 0.0560 (9) | 0.0385 (9) | 0.0008 (7) | 0.0104 (6) | −0.0007 (7) |
C1 | 0.0325 (10) | 0.0742 (14) | 0.0510 (12) | −0.0047 (9) | 0.0110 (9) | −0.0007 (10) |
C2 | 0.0422 (11) | 0.0659 (14) | 0.0816 (16) | −0.0130 (10) | 0.0220 (11) | −0.0053 (12) |
C3 | 0.0401 (10) | 0.0492 (10) | 0.0470 (11) | −0.0016 (8) | 0.0076 (8) | −0.0018 (8) |
C4 | 0.0419 (9) | 0.0394 (9) | 0.0384 (10) | 0.0006 (7) | 0.0097 (7) | −0.0037 (7) |
C5 | 0.0470 (11) | 0.0379 (9) | 0.0414 (11) | 0.0027 (7) | 0.0145 (8) | −0.0006 (7) |
C6 | 0.0610 (13) | 0.0468 (11) | 0.0419 (11) | 0.0008 (9) | 0.0118 (9) | −0.0026 (8) |
C7 | 0.1016 (19) | 0.0488 (12) | 0.0472 (12) | 0.0034 (12) | 0.0339 (12) | 0.0020 (9) |
C8 | 0.0832 (18) | 0.0559 (13) | 0.0814 (18) | 0.0002 (12) | 0.0503 (15) | 0.0100 (12) |
C9 | 0.0525 (13) | 0.0751 (16) | 0.094 (2) | −0.0061 (12) | 0.0289 (13) | 0.0171 (14) |
C10 | 0.0476 (12) | 0.0685 (14) | 0.0525 (13) | −0.0047 (9) | 0.0110 (10) | 0.0134 (10) |
Cl1 | 0.0507 (4) | 0.0795 (4) | 0.0435 (4) | 0.0062 (2) | 0.0130 (3) | −0.0025 (2) |
P1—O1 | 1.5526 (16) | C2—H2B | 0.9700 |
P1—O2 | 1.5513 (16) | C3—H3A | 0.9300 |
P1—O3 | 1.4805 (14) | C3—C4 | 1.373 (3) |
P1—C1 | 1.786 (2) | C4—C5 | 1.460 (3) |
O1—H1 | 0.8200 | C5—C6 | 1.394 (3) |
O2—H2 | 0.8200 | C5—C10 | 1.386 (3) |
N1—N2 | 1.317 (2) | C6—H6 | 0.9300 |
N1—C2 | 1.474 (3) | C6—C7 | 1.383 (3) |
N1—C3 | 1.346 (3) | C7—H7 | 0.9300 |
N2—N3 | 1.318 (2) | C7—C8 | 1.373 (4) |
N3—H3 | 0.8600 | C8—H8 | 0.9300 |
N3—C4 | 1.352 (2) | C8—C9 | 1.368 (4) |
C1—H1A | 0.9700 | C9—H9 | 0.9300 |
C1—H1B | 0.9700 | C9—C10 | 1.387 (3) |
C1—C2 | 1.522 (3) | C10—H10 | 0.9300 |
C2—H2A | 0.9700 | ||
O1—P1—C1 | 106.83 (10) | H2A—C2—H2B | 107.7 |
O2—P1—O1 | 104.80 (9) | N1—C3—H3A | 127.2 |
O2—P1—C1 | 108.71 (11) | N1—C3—C4 | 105.65 (18) |
O3—P1—O1 | 114.92 (11) | C4—C3—H3A | 127.2 |
O3—P1—O2 | 110.35 (9) | N3—C4—C3 | 104.31 (17) |
O3—P1—C1 | 110.89 (9) | N3—C4—C5 | 124.28 (17) |
P1—O1—H1 | 109.5 | C3—C4—C5 | 131.39 (18) |
P1—O2—H2 | 109.5 | C6—C5—C4 | 120.16 (19) |
N2—N1—C2 | 118.78 (18) | C10—C5—C4 | 120.86 (18) |
N2—N1—C3 | 112.94 (16) | C10—C5—C6 | 119.0 (2) |
C3—N1—C2 | 128.26 (18) | C5—C6—H6 | 120.2 |
N1—N2—N3 | 103.64 (15) | C7—C6—C5 | 119.6 (2) |
N2—N3—H3 | 123.3 | C7—C6—H6 | 120.2 |
N2—N3—C4 | 113.45 (16) | C6—C7—H7 | 119.5 |
C4—N3—H3 | 123.3 | C8—C7—C6 | 121.0 (2) |
P1—C1—H1A | 108.2 | C8—C7—H7 | 119.5 |
P1—C1—H1B | 108.2 | C7—C8—H8 | 120.2 |
H1A—C1—H1B | 107.4 | C9—C8—C7 | 119.7 (2) |
C2—C1—P1 | 116.22 (15) | C9—C8—H8 | 120.2 |
C2—C1—H1A | 108.2 | C8—C9—H9 | 119.8 |
C2—C1—H1B | 108.2 | C8—C9—C10 | 120.3 (2) |
N1—C2—C1 | 113.42 (18) | C10—C9—H9 | 119.8 |
N1—C2—H2A | 108.9 | C5—C10—C9 | 120.4 (2) |
N1—C2—H2B | 108.9 | C5—C10—H10 | 119.8 |
C1—C2—H2A | 108.9 | C9—C10—H10 | 119.8 |
C1—C2—H2B | 108.9 | ||
P1—C1—C2—N1 | 56.6 (3) | C2—N1—C3—C4 | 178.52 (19) |
O1—P1—C1—C2 | 167.10 (17) | C3—N1—N2—N3 | −0.6 (2) |
O2—P1—C1—C2 | 54.50 (19) | C3—N1—C2—C1 | 65.1 (3) |
O3—P1—C1—C2 | −67.0 (2) | C3—C4—C5—C6 | 14.3 (3) |
N1—N2—N3—C4 | 0.6 (2) | C3—C4—C5—C10 | −165.7 (2) |
N1—C3—C4—N3 | 0.0 (2) | C4—C5—C6—C7 | 179.59 (18) |
N1—C3—C4—C5 | −178.62 (18) | C4—C5—C10—C9 | −178.9 (2) |
N2—N1—C2—C1 | −116.9 (2) | C5—C6—C7—C8 | −1.1 (3) |
N2—N1—C3—C4 | 0.4 (2) | C6—C5—C10—C9 | 1.0 (3) |
N2—N3—C4—C3 | −0.4 (2) | C6—C7—C8—C9 | 1.9 (4) |
N2—N3—C4—C5 | 178.37 (17) | C7—C8—C9—C10 | −1.2 (4) |
N3—C4—C5—C6 | −164.07 (18) | C8—C9—C10—C5 | −0.2 (4) |
N3—C4—C5—C10 | 15.9 (3) | C10—C5—C6—C7 | −0.4 (3) |
C2—N1—N2—N3 | −178.94 (17) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···Cl1i | 0.82 | 2.15 | 2.9521 (16) | 167 |
O2—H2···Cl1 | 0.82 | 2.16 | 2.9422 (17) | 160 |
N3—H3···O3ii | 0.86 | 1.78 | 2.610 (2) | 162 |
C6—H6···O2iii | 0.93 | 2.58 | 3.476 (3) | 163 |
Symmetry codes: (i) −x+2, y−1/2, −z+1/2; (ii) −x+1, y+1/2, −z+1/2; (iii) x, −y+3/2, z+1/2. |
Funding information
Funding for this research was provided for the research project `Innovative Materials and Applications' (INNOVAMAT, KA 10694) by the Special Account for Research Grants.
References
Babu, B. H., Prasad, G. S., Raju, C. N. & Rao, M. V. B. (2017). Curr. Org. Synth. 14, 883–903. CrossRef CAS Google Scholar
Bruker (2016). SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2019). APEX3. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bujak, M. & Zaleski, J. (2002). Z. Naturforsch. Teil B, 57, 157–164. CrossRef CAS Google Scholar
Clearfield, A. & Demadis, K. D. (2012). Editors. Metal Phosphonate Chemistry: From Synthesis to Applications. London: Royal Society of Chemistry. Google Scholar
Colodrero, R. M. P., Angeli, G. K., Bazaga-Garcia, M., Olivera-Pastor, P., Villemin, D., Losilla, E. R., Martos, E. Q., Hix, G. B., Aranda, M. A. G., Demadis, K. D. & Cabeza, A. (2013). Inorg. Chem. 52, 8770–8783. CrossRef CAS PubMed Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Mukherjee, N., Ahammed, S., Sukalyan Bhadra, S. & Ranu, B. C. (2013). Green Chem. 15, 389–397. CrossRef CAS Google Scholar
Sheikhi, A., Mejlsøe, S. L., Li, N., Bomal, E., van de Ven, T. G. M. & Kakkar, A. (2018). Mater. Chem. Front. 2, 2081–2090. CrossRef CAS 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
Villemin, D., Moreau, B. & Bar, N. (2021). Organics, 2, 98–106. CrossRef Google Scholar
Zaręba, J. K. (2017). Inorg. Chem. Commun. 86, 172–186. 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.