Outward-directing phenolic/phenolate groups on copper carboxylate dimers have a powerful structure-directing influence, leading to the generation of an assortment of hydrogen-bonded networks.
Keywords: crystal structure, hydrogen-bonded network, 4-hydroxybenzoic acid, short hydrogen bond, crystal engineering, topology, paddle wheel complex, carboxylate dimer
Abstract
The well-known copper carboxylate dimer, with four carboxylate ligands extending outwards towards the corners of a square, has been employed to generate a series of crystalline compounds. In particular, this work centres on the use of the 4-hydroxybenzoate anion (Hhba−) and its deprotonated phenolate form 4-oxidobenzoate (hba2−) to obtain complexes with the general formula [Cu2(Hhba)4–x (hba) xL 2–y ] x−, where L is an axial coligand (including solvent molecules), x = 0, 1 or 2, and y = 0 or 1. In some cases, short hydrogen bonds result in complexes which may be represented as [Cu2(Hhba)2(H0.5hba)2 L 2]−. The main focus of the investigation is on the formation of a variety of extended networks through hydrogen bonding and, in some crystals, coordinate bonds when bridging coligands (L) are employed. Crystals of [Cu2(Hhba)4(dioxane)2]·4(dioxane) consist of the expected Cu dimer with the Hhba− anions forming hydrogen bonds to 1,4-dioxane molecules which block network formation. In the case of crystals of composition [Et4N][Cu2(Hhba)2(H0.5hba)2(CH3OH)(H2O)]·2(dioxane), Li[Cu2(Hhba)2(H0.5hba)2(H2O)2]·3(dioxane)·4H2O and [Cu2(Hhba)2(H0.5hba)2(H0.5DABCO)2]·3CH3OH (DABCO is 1,4-diazabicyclo[2.2.2]octane), square-grid hydrogen-bonded networks are generated in which the complex serves as one type of 4-connecting node, whilst a second 4-connecting node is a hydrogen-bonding motif assembled from four phenol/phenolate groups. Another two-dimensional (2D) network based upon a related square-grid structure is formed in the case of [Et4N]2[Cu2(Hhba)2(hba)2(dioxane)2][Cu2(Hhba)4(dioxane)(H2O)]·CH3OH. In [Cu2(Hhba)4(H2O)2]·2(Et4NNO3), a square-grid structure is again apparent, but, in this case, a pair of nitrate anions, along with four phenolic groups and a pair of water molecules, combine to form a second type of 4-connecting node. When 1,8-bis(dimethylamino)naphthalene (bdn, ‘proton sponge’) is used as a base, another square-grid network is generated, i.e. [Hbdn]2[Cu2(Hhba)2(hba)2(H2O)2]·3(dioxane)·H2O, but with only the copper dimer complex serving as a 4-connecting node. Complex three-dimensional networks are formed in [Cu2(Hhba)4(O-bipy)]·H2O and [Cu2(Hhba)4(O-bipy)2]·2(dioxane), where the potentially bridging 4,4′-bipyridine N,N′-dioxide (O-bipy) ligand is employed. Rare cases of mixed carboxylate copper dimer complexes were obtained in the cases of [Cu2(Hhba)3(OAc)(dioxane)]·3.5(dioxane) and [Cu2(Hhba)2(OAc)2(DABCO)2]·10(dioxane), with each structure possessing a 2D network structure. The final compound reported is a simple hydrogen-bonded chain of composition (H0.5DABCO)(H1.5hba), formed from the reaction of H2hba and DABCO.
Introduction
In 1953, the structure of the copper(II) acetate tetra-μ-acetato-bis[aquacopper(II)], [Cu2(OAc)4(H2O)2], was reported and shown to consist of a pair of CuII centres bridged by four carboxylate groups (van Niekerk & Schoening, 1953 ▸). This remarkable compound, possessing a beautiful blue colour and an elegant structure, is one of the classic coordination complexes and, as a result, is a common synthetic target in undergraduate chemistry laboratory programs. The four carboxylate ligands extend outwards towards the vertices of an approximate square, and thus the binuclear unit has been employed as a square-planar connector in both discrete and polymeric supramolecular systems formed from bridging ligands possessing two or more carboxylate groups (Eddaoudi et al., 2001 ▸; Chui et al., 1999 ▸; Lee et al., 2021 ▸). The binuclear tetracarboxylate moiety has been commonly referred to as a ‘paddle wheel unit’, with the Cu⋯Cu direction colinear with the ‘wheel axle’ and the carboxylate groups serving as ‘paddles’.
Over the last decade our group has been interested in coordination polymers formed from the combination of metal ions with the anions of 4-hydroxybenzoic acid (H2hba; Scheme 1), resulting in a variety of polymeric networks with compositions such as Zn(hba) and Co(hba) (White et al., 2015 ▸), and Cu3(hba)2(OH)2 (Abrahams et al., 2022 ▸), which formed as solvates. Whilst these networks contain the hba2− ligand in the presence of transition-metal ions, the reactions with Group 1 and 2 metal ions often failed to remove the phenolic proton of H2hba, even when the metal hydroxide was employed. These reactions commonly resulted in only the Hhba− monoanion being formed (Abrahams et al., 2021 ▸). In some instances, the ligand formed a strong hydrogen bond with an adjacent ligand to create a dimeric unit with a 1− charge, i.e. (H1.5hba)2. In this unit, the O atoms involved are closely separated (approximately 2.45 Å), with the H atom between the two halves of the dimer either at the mid-point of the two O atoms or disordered over two closely separated positions.
The observation that the phenolic protons were retained in the generation of hydrogen-bonded networks prompted an investigation into whether the binuclear CuII dimer unit, combined with 4-hydroxybenzoic acid in either its monoanionic or dianionic form, was able to serve as a square-planar hydrogen-bonding unit in extended structures. Within such structures, negatively charged phenolate groups could serve as hydrogen-bond acceptors, whilst phenolic groups could serve as both acceptors and donors. This current work describes a series of 11 compounds (1–11) involving Hhba−/hba2− ligands in which the geometry of the Cu dimer leads to the generation of a variety of hydrogen-bonded complexes and networks. The structure of a 1:1 cocrystal (12) formed from the combination of H2hba and DABCO (DABCO is 1,4-diazabicyclo[2.2.2]octane) is also reported. Compound 12 serves as a convenient starting material for the generation of compound 4.
Experimental
Synthesis and crystallization
1–11 are compounds of copper. Compound 12 is a cocrystal of H2hba and DABCO, denoted (H0.5DABCO)(H1.5hba), which was used in the synthesis of 4.
[Cu2(Hhba)4(dioxane)2]·4(dioxane), 1
Cu(OAc)2·H2O (0.40 g, 2.0 mmol) and H2hba (0.55 g, 4.0 mmol) were dissolved in 1,4-dioxane (40 ml). The solution was heated, with stirring, for 2.5 h at approximately 80 °C. The solvent was allowed to evaporate slowly and blue crystals separated from the solution after several days.
[NEt4][Cu2(Hhba)2(H0.5hba)2(CH3OH)(H2O)]·2(dioxane), 2
Cu(OAc)2·H2O (0.10 g, 0.50 mmol) and H2hba (0.28 g, 2.0 mmol) were dissolved in 1,4-dioxane (10 ml). The solution was heated, with stirring, for 1.5 h at approximately 80 °C. Methanol (10 ml) and water (1 ml) were added, followed by the dropwise addition, with stirring, of a 25 wt% solution of Et4NOH in water (1.3 ml). The solvent was allowed to evaporate slowly and blue crystals separated from solution after several days.
Li[Cu2(Hhba)2(H0.5hba)2(H2O)2]·3(dioxane)·4H2O, 3
Cu(OAc)2·H2O (0.40 g, 2.0 mmol) and H2hba (0.55 g, 4.0 mmol) were dissolved in 1,4-dioxane (30 ml). The solution was heated, with stirring, for 2.5 h at approximately 80 °C.
To a 2 ml sample of this solution was added LiOH·H2O (0.011 g, 0.27 mmol) and methanol (1 ml). The solvent was allowed to evaporate slowly and a mixture of dark-green crystals of 3 and pale-green crystals separated from the solution after several days. The pale-green crystals were shown by X-ray diffraction to be the mononuclear molecular complex [Cu(Hhba)2(H2O)3]·H2O. The structure of this complex has been reported previously [Cambridge Structural Database (CSD) refcodes BAPHEF (Shnulin et al., 1981 ▸) and ICUJUN (Liu & Li, 2007 ▸); CSD Version 5.45, March 2024 release; Groom et al., 2016 ▸].
[Cu2(Hhba)2(H0.5hba)2(H0.5DABCO)2]·3CH3OH, 4
Cu(OAc)2·H2O (0.016 g, 0.080 mmol) and (H0.5DABCO)(H1.5hba) (0.46 g, 1.3 mmol) were dissolved in CH3OH (12 ml). The solvent was allowed to evaporate slowly and dark-green crystals formed after one day. [The synthesis of (H0.5DABCO)(H1.5hba), 12, is described below.]
[Et4N]2[Cu2(Hhba)2(hba)2(dioxane)2][Cu2(Hhba)4(dioxane)(H2O)]·CH3OH, 5
Cu(OAc)2·H2O (0.040 g, 0.20 mmol) and H2hba (0.055 g, 0.040 mmol) were dissolved in 1,4-dioxane (10 ml). The solution was heated, with stirring, for 4 h at approximately 80 °C and methanol (10 ml) was added. A few drops of a 25 wt% solution of Et4NOH in water were added slowly with stirring until the precipitate that formed upon addition of each drop only just dissolved. Solvent was allowed to evaporate slowly and dark-blue crystals separated from solution after several days.
[Cu2(Hhba)4(H2O)2]·2Et4N(NO3), 6
H2hba (0.55 g, 4.0 mmol) was added to a 25 wt% solution of Et4NOH in water (8.0 ml) and heated, with stirring, at approximately 80 °C for 30 min. Water was evaporated from the solution and the resulting white solid dried by vacuum sublimation. A solution of the white solid (0.10 g) in methanol (2 ml) was added to a solution of Cu(NO3)2·3H2O (0.10 g, 0.41 mmol) in methanol (2 ml). A yellow–green precipitate formed immediately which redissolved with stirring. The solvent was allowed to evaporate slowly and blue crystals separated from the solution after several days.
[Hbdn]2[Cu2(Hhba)2(hba)2(H2O)2]·3(dioxane)·H2O, 7
Cu(OAc)2·H2O (0.10 g, 0.50 mmol) and H2hba (0.14 g, 1.0 mmol) were added to 1,4-dioxane (10 ml). The solution was heated, with stirring, at approximately 70 °C for 10 min. 1,8-Bis(dimethylamino)naphthalene (bdn, ‘proton sponge’; 0.070 g, 0.33 mmol) and acetonitrile (2 ml) were added, and the mixture heated for a further 30 min. The solvent was allowed to evaporate slowly and green crystals separated from solution after several days.
[Cu2(Hhba)4(O-bipy)]·H2O, 8
Cu(OAc)2·H2O (0.20 g, 1.0 mmol), 4,4′-bipyridine N,N′-dioxide (O-bipy; 0.10 g, 0.53 mmol) and H2hba (0.20 g, 1.4 mmol) were added to water (10 ml) and xylene (1 ml). The mixture was heated at 110 °C in a Teflon-lined autoclave for 5 h to yield dark-green crystals.
[Cu2(Hhba)4(O-bipy)2]·2(dioxane), 9
Cu(OAc)2·H2O (0.10 g, 0.50 mmol), O-bipy (0.050 g, 0.27 mmol) and H2hba (0.050 g, 0.36 mmol) were added to 1,4-dioxane (10 ml). The mixture was heated at 110 °C in a Teflon-lined autoclave for 1 d to yield dark-green crystals.
[Cu2(Hhba)3(OAc)(dioxane)]·3.5dioxane, 10
Cu(OAc)2·H2O (0.40 g, 2.0 mmol) and H2hba (0.55 g, 4.0 mmol) were dissolved in 1,4-dioxane (40 ml). The solution was heated, with stirring, for 4 h at approximately 80 °C. The solvent was allowed to evaporate slowly and dark-blue crystals separated from solution after several days.
<!?up>[Cu2(Hhba)2(OAc)2(DABCO)2]·10(dioxane), 11
Cu(OAc)2·H2O (0.10 g, 0.50 mmol), H2hba (0.069 g, 0.50 mmol) and 1,4-diazabicyclo[2.2.2]octane (DABCO; 0.061 g, 0.54 mmol) were added to 1,4-dioxane (50 ml). A 0.01 M NaOH solution (50 µl) was then added. The mixture was heated at 115 °C in a Teflon-lined autoclave for 2 d to yield small green crystals.
(H0.5DABCO)(H1.5hba), 12
Separate 5 ml methanol solutions of H2hba (1.34 g, 10 mmol) and DABCO (2.75 g, 25 mmol) were prepared. The two solutions were heated to approximately 40 °C, mixed and then heated for a further 15 min. Acetone (20 ml) was added and the solution allowed to evaporate. Colourless crystals formed after approximately 1 h.
Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1 ▸. The H atoms of water molecules, phenolic groups and carboxylic acid groups were commonly located in difference Fourier maps and were generally refined with O—H distances restrained to 0.85 Å and U iso(H) values of 1.5U eq(O).
Table 1. Experimental details.
Data for compounds 4 and 5 were collected at the Australian Synchrotron (beamlines MX1 and MX2, respectively). An Oxford Diffraction Supernova diffractometer was used for compounds 8 and 12. Other diffraction data were measured using a Rigaku XtalLAB Synergy S (Dualflex, HyPix) diffractometer. Cu Kα1 radiation was employed on the laboratory-based diffractometers. Absorption corrections on the synchrotron data employed the multi-scan method using XDS (Kabsch, 2010 ▸). The multi-scan method was also used for diffractometer data employing CrysAlis PRO (Rigaku OD, 2018 ▸). Data were collected at 100 K, except for 8 and 12 (130 K). H atoms were treated by a mixture of independent and constrained refinement.
| 1 | 2 | 3 | 4 | |
|---|---|---|---|---|
| Crystal data | ||||
| Chemical formula | [Cu2(C7H5O3)4(C4H8O2)2]·4C4H8O2 | (C8H20N)[Cu2(C7H5O3)2(C7H4.5O3)2(CH4O)(H2O)]·2C4H8O2 | [Li(C4H8O2)(H2O)3][Cu2(C7H5O3)2(C7H4.5O3)2(H2O)2]·2C4H8O2·H2O | [Cu2(C7H5O3)2(C7H4.5O3)2(C6H12.5N2)2]·3CH4O |
| M r | 1204.14 | 1031.02 | 1047.81 | 995.99 |
| Crystal system, space group | Orthorhombic, P c c n | Triclinic, P
|
Triclinic, P
|
Triclinic, P
|
| a, b, c (Å) | 27.7701 (8), 21.2278 (4), 9.3888 (1) | 10.1659 (4), 10.7383 (6), 12.9878 (4) | 9.7711 (8), 10.1924 (6), 12.5863 (7) | 8.8860 (18), 10.702 (2), 12.360 (3) |
| α, β, γ (°) | 90, 90, 90 | 76.132 (4), 69.646 (3), 75.304 (4) | 73.615 (5), 79.528 (6), 83.412 (6) | 73.13 (3), 73.07 (3), 81.68 (3) |
| V (Å3) | 5534.7 (2) | 1267.74 (10) | 1179.86 (15) | 1073.8 (4) |
| Z | 4 | 1 | 1 | 1 |
| μ (mm−1) | 1.66 | 1.63 | 1.85 | 1.07 |
| Crystal size (mm) | 0.14 × 0.13 × 0.05 | 0.17 × 0.12 × 0.05 | 0.14 × 0.07 × 0.03 | 0.18 × 0.11 × 0.07 |
| Data collection | ||||
| T min, T max | 0.567, 1.000 | 0.885, 1.000 | 0.610, 1.000 | 0.321, 0.432 |
| No. of measured, independent and observed [I > 2σ(I)] reflections | 18728, 5586, 4112 | 17988, 5262, 4672 | 10093, 4145, 3048 | 15021, 3849, 2994 |
| R int | 0.049 | 0.047 | 0.070 | 0.061 |
| (sin θ/λ)max (Å−1) | 0.634 | 0.634 | 0.602 | 0.617 |
| Refinement | ||||
| R[F 2 > 2σ(F 2)], wR(F 2), S | 0.063, 0.187, 1.04 | 0.068, 0.200, 1.06 | 0.089, 0.261, 1.09 | 0.089, 0.263, 1.05 |
| No. of reflections | 5586 | 5262 | 4145 | 3849 |
| No. of parameters | 354 | 459 | 338 | 325 |
| No. of restraints | 2 | 419 | 42 | 364 |
| Δρmax, Δρmin (e Å−3) | 0.47, −0.48 | 0.73, −1.00 | 1.21, −1.32 | 1.14, −0.76 |
| 5 | 6 | 7 | 8 | |
|---|---|---|---|---|
| Crystal data | ||||
| Chemical formula | (C8H20N)[Cu2(C7H4O3)2(C7H5O3)2(C4H8O2)2][Cu2(C7H5O3)4(C4H8O2)(H2O)]·CH4O | (C8H20N)2[Cu2(C7H5O3)4(H2O)2](NO3)2 | (C14H19N2)2[Cu2(C7H5O3)2(C7H4O3)2(H2O)2]·3(C4H8O2)·H2O | [Cu2(C7H5O3)4(C10H8N2O2)]·H2O |
| M r | 1923.89 | 1096.07 | 1420.47 | 881.72 |
| Crystal system, space group | Orthorhombic, P n m a | Triclinic, P
|
Triclinic, P
|
Monoclinic, C2/c |
| a, b, c (Å) | 12.833 (3), 54.548 (11), 12.119 (2) | 10.4964 (3), 10.6595 (2), 12.3226 (3) | 10.2155 (2), 12.0897 (3), 15.7111 (4) | 11.9851 (8), 17.7472 (11), 17.1294 (10) |
| α, β, γ (°) | 90, 90, 90 | 97.271 (2), 101.042 (2), 108.130 (2) | 69.581 (3), 75.988 (2), 79.651 (2) | 90, 92.637 (5), 90 |
| V (Å3) | 8483 (3) | 1260.15 (6) | 1754.64 (8) | 3639.6 (4) |
| Z | 4 | 1 | 1 | 4 |
| μ (mm−1) | 1.08 | 1.72 | 1.38 | 2.12 |
| Crystal size (mm) | 0.13 × 0.09 × 0.06 | 0.16 × 0.13 × 0.09 | 0.19 × 0.16 × 0.12 | 0.32 × 0.06 × 0.05 |
| Data collection | ||||
| T min, T max | 0.321, 0.432 | 0.720, 1.000 | 0.890, 1.000 | 0.898, 1.000 |
| No. of measured, independent and observed [I > 2σ(I)] reflections | 151309, 13753, 11493 | 14549, 5136, 4648 | 21601, 6618, 5772 | 6868, 3663, 3386 |
| R int | 0.054 | 0.048 | 0.036 | 0.024 |
| (sin θ/λ)max (Å−1) | 0.753 | 0.634 | 0.610 | 0.629 |
| Refinement | ||||
| R[F 2 > 2σ(F 2)], wR(F 2), S | 0.050, 0.148, 1.02 | 0.038, 0.101, 1.08 | 0.064, 0.189, 1.05 | 0.034, 0.098, 1.05 |
| No. of reflections | 13753 | 5136 | 6618 | 3663 |
| No. of parameters | 585 | 408 | 361 | 263 |
| No. of restraints | 67 | 263 | 3 | 2 |
| Δρmax, Δρmin (e Å−3) | 1.42, −0.84 | 0.47, −0.54 | 1.05, −0.62 | 0.36, −0.57 |
| 9 | 10 | 11 | 12 | |
|---|---|---|---|---|
| Crystal data | ||||
| Chemical formula | [Cu2(C7H5O3)4(C10H8N2O2)2]·2C4H8O2 | [Cu2(C7H5O3)3(C2H3O2)(C4H8O2)]·3.5C4H8O2 | [Cu2(C7H5O3)2(C2H3O2)2(C6H12N2)2]·10C4H8O2 | C6H13N2 +·C7H5O3 − |
| M r | 1228.09 | 993.92 | 1624.77 | 250.29 |
| Crystal system, space group | Orthorhombic, P b c a | Monoclinic, I2/a | Monoclinic, P c | Monoclinic, P21/n |
| a, b, c (Å) | 17.5993 (3), 16.4583 (2), 19.7389 (2) | 19.4801 (2), 13.0774 (2), 34.5443 (5) | 9.7404 (3), 20.3001 (4), 22.9088 (7) | 15.3994 (5), 10.6592 (3), 16.9261 (6) |
| α, β, γ (°) | 90, 90, 90 | 90, 97.702 (1), 90 | 90, 118.494 (4), 90 | 90, 110.424 (4), 90 |
| V (Å3) | 5717.46 (13) | 8720.7 (2) | 3981.1 (2) | 2603.67 (15) |
| Z | 4 | 8 | 2 | 8 |
| μ (mm−1) | 1.59 | 1.90 | 1.36 | 0.75 |
| Crystal size (mm) | 0.09 × 0.07 × 0.05 | 0.26 × 0.09 × 0.06 | 0.34 × 0.25 × 0.14 | 0.22 × 0.16 × 0.13 |
| Data collection | ||||
| T min, T max | 0.344, 1.000 | 0.764, 1.000 | 0.533, 1.000 | 0.952, 1.000 |
| No. of measured, independent and observed [I > 2σ(I)] reflections | 23256, 5876, 4731 | 37963, 9032, 6906 | 27595, 12037, 9752 | 11079, 5386, 3805 |
| R int | 0.056 | 0.071 | 0.040 | 0.039 |
| (sin θ/λ)max (Å−1) | 0.634 | 0.635 | 0.635 | 0.632 |
| Refinement | ||||
| R[F 2 > 2σ(F 2)], wR(F 2), S | 0.044, 0.129, 1.06 | 0.065, 0.191, 1.09 | 0.098, 0.287, 1.21 | 0.044, 0.120, 1.01 |
| No. of reflections | 5876 | 9032 | 12037 | 5386 |
| Δρmax, Δρmin (e Å−3) | 0.59, −0.68 | 1.12, −1.24 | 1.38, −0.70 | 0.19, −0.24 |
| Absolute structure | – | – | Refined as an inversion twin | – |
| Absolute structure parameter | – | – | 0.46 (6) | – |
In 2, H atoms were involved in short hydrogen bonds (O⋯O distances less than 2.45 Å) between the symmetry-related O atoms of phenolate groups, and single peaks were observed in difference Fourier maps midway between the atoms. These peaks were assigned as H atoms and refined independently. Short hydrogen bonds were also present in 3 and 4 between the symmetry-related O atoms of phenol groups; however, single peaks midway between the O atoms were not observed. In these cases, H atoms were located on both O atoms with 0.5 occupancies and O—H distances restrained to 0.85 Å.
The H2hba and DABCO molecules are closely aligned in 12 (N⋯O distances of approximately 2.52 Å) and single peaks were observed in difference Fourier maps almost midway between the N and O atoms. These peaks were assigned as H atoms and refined independently.
Other H atoms were placed in calculated positions and refined as riding atoms, with U iso(H) = 1.2U eq(C) for methylene and aromatic C atoms, U iso(H) = 1.5U eq(C) for methyl C atoms, and with C—H = 0.95 Å for aromatic groups, 0.99 Å for methylene group and 0.98 Å for methyl groups. The H atoms of two disordered water molecules (containing O11 and O13) were not modelled in 3. Details of the refinements can be found in the embedded CIF files.
The mask process within OLEX2 (Dolomanov et al., 2009 ▸) was employed in the structure refinements for 4, 7 and 10, which represent structures for which not all solvent molecules could be satisfactorily modelled.
Results and discussion
Labelled structures of compounds 1–12 showing displacement ellipsoids for non-H atoms are presented in Figs. 1 ▸ and 2 ▸.
Figure 1.
The structures of compounds 1–6, showing the copper dimer units and the atom-labelling schemes. For clarity, the labels of the C and H atoms are not shown. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented by spheres of arbitrary size. The red dotted lines represent hydrogen-bonding interactions. In 2, only one configuration of the disordered dioxane molecules is shown, and in 4, only one configuration of the DABCO molecules is shown.
Figure 2.
The structures of compounds 7–11, showing the copper dimer units and the atom-labelling schemes. The structure of the cocrystal formed from the combination of H2hba and DABCO (12) is also shown. For clarity, the labels of the C and H atoms are not shown. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented by spheres of arbitrary size. The red dotted lines represent hydrogen-bonding interactions. In 9, only one configuration of the disordered dioxane molecules is shown, and in 11, only one configuration of the DABCO molecules is shown.
Our general strategy towards the synthesis of hydrogen-bonded copper(II) complexes incorporating Hhba− anions involves the addition of H2hba to Cu2(OAc)4·2H2O. In this reaction, the acetate anion can serve as the base for H2hba. The combination of Cu2(OAc)4·2H2O with H2hba in a 1:4 ratio in 1,4-dioxane (dioxane) yields a compound of composition [Cu2(Hhba)4(dioxane)2]·4(dioxane) (1). As anticipated, the dimeric copper carboxylate complex is formed, as indicated in Fig. 3 ▸, with the Hhba− units extending towards the vertices of an approximate square. Each phenolic group of the coordinated Hhba− serves as a proton donor to a dioxane molecule. In addition, a dioxane molecule is coordinated to opposing axial sites on each of the symmetry-related CuII centres.
Figure 3.
The structure of [Cu2(Hhba)4(dioxane)2]·4(dioxane) (1), showing the links to two coordinated dioxane molecules and hydrogen-bond interactions with four non-coordinated dioxane molecules. Colour code for this and later figures, as applicable: Cu dark blue, C black, O red, N and Li pale blue, and H pale pink. Hydrogen bonds are indicated by black and white striped connections. For clarity, H atoms not involved in hydrogen bonding have been omitted in this and most of the following figures.
The compound [NEt4][Cu2(Hhba)2(H0.5hba)2(CH3OH)(H2O)]·2(dioxane) (2) is formed by the combination of Cu2(OAc)4(H2O)2 and H2hba in dioxane, followed by the addition of NEt4OH in an aqueous methanol solution. It was anticipated that the addition of the base (NEt4OH) would serve to generate at least some hba2− anions. The Cu dimeric complex present in 1 is also evident in 2, however, with disordered water and methanol molecules occupying the axial sites in place of the dioxane molecules. A centre of inversion lies between the two CuII centres. The complex has formally lost one phenolic H atom, resulting in the formation of the anionic complex [Cu2(Hhba)2(H0.5hba)2(CH3OH)(H2O)]−. The four organic groups extend outwards towards the vertices of an approximate square and thus the complex may be considered as a 4-connecting node. Hydrogen bonding between phenolic and phenolate groups results in the generation of a second 4-connecting node within a two-dimensional (2D) network. As indicated in Fig. 4 ▸(a), the second type of 4-connecting node consists of three H atoms that bind four O atoms in a zigzag arrangement. The two central O atoms are separated by a H atom, which was refined to a position midway between the two symmetry-related O atoms. The O⋯H⋯O separation of 2.446 (5) Å is indicative of a strong interaction, and the dimer unit formed by this interaction may be represented as (H0.5hba)2 3−. Interestingly, the O⋯O separation between O atoms is similar to that seen in (H1.5hba)2 − (Abrahams et al., 2021 ▸). Phenolic groups above and below the central pair of O atoms form additional hydrogen bonds which are a little longer [O—H⋯O = 2.601 (4) Å], resulting in a short hydrogen-bonded planar zigzag chain (O—H⋯O⋯H⋯O⋯H—O).
Figure 4.
The structure of [NEt4][Cu2(Hhba)2(H0.5hba)2(CH3OH)(H2O)]·2(dioxane) (2), showing (a) the hydrogen-bonded 4-connected node, (b) the 4,4-network with the dioxane molecules and NEt4 + ions in the square cavities (only one of the two orientations of each tetraethylammonium ion is shown), and (c) the intersheet hydrogen-bond interactions involving the coordinated water/methanol molecules which extend into sheets above and below.
An anionic 2D 4,4-network (square-grid network) is generated by linking the [Cu2(Hhba)2(H0.5hba)2(CH3OH)(H2O)]− complexes through hydrogen bonds involving the phenolic/phenolate groups [Fig. 4 ▸(b)]. Two types of square-shaped cavities are formed within the network, with orientationally disordered tetraethylammonium counter-ions occupying the larger cavities. Disordered dioxane molecules, which were crystallographically modelled with partial occupancies, occupy the slightly smaller square cavities and space between networks.
The 2D square-grid layers described above form hydrogen bonds with adjacent parallel layers through the coordinated water/methanol molecules. The coordinated molecules serve as hydrogen-bond donors, bonding to a terminus of the hydrogen-bonded O—H⋯O⋯H⋯O⋯H—O chain. In the case of the coordinated water molecule, a hydrogen bond extends to a dioxane molecule located in one of the small square cavities of an adjacent sheet, as indicated in Fig. 4 ▸(c).
Crystals of Li[Cu2(Hhba)2(H0.5hba)2(H2O)2]·3(dioxane)·4H2O (3) are generated using LiOH as a base. A similar 4,4-network [Fig. 5 ▸(a)] to that found in 2 is formed. The binuclear unit is once again located on a centre of inversion and thus the asymmetric unit within the anionic network is very similar to that of compound 2. As with 2, there are two types of cavities in the sheet, one slightly larger than the other. The larger cavities, which are all crystallographically identical, are occupied by dioxane molecules, each of which is bound to a Li centre through one of the O atoms. Three water molecules complete the coordination sphere of the Li centre. The other O atom of the dioxane serves as a hydrogen-bond acceptor to a water molecule. A centre of inversion lies at the centre of the dioxane and thus the Li+ centre is disordered across a pair of symmetry-related sites. These components are part of an infinite chain consisting of water molecules, Li+ ions and bridging and branching dioxane molecules [Fig. 5 ▸(b)]. The chains pass through the larger square cavities of adjacent 4,4-networks, as indicated in Fig. 5 ▸(a). Branching dioxane molecules occupy the smaller square cavities.
Figure 5.
The structure of Li[Cu2(Hhba)2(H0.5hba)2(H2O)2]·3(dioxane)·4H2O (3), showing (a) the square-grid structure with the Li+ cation coordinated by water and dioxane molecules located in the larger of the two types of square cavities, and (b) part of the infinite Li+–solvent chain.
The compound [Cu2(Hhba)2(H0.5hba)2(H0.5DABCO)2]·3CH3OH (4) is formed from the reaction of Cu2(OAc)4·2H2O and (H0.5DABCO)(H1.5hba) (12) in methanol. DABCO molecules occupy the axial sites on the Cu dimer complex and are rotationally disordered around the axis which passes through the two N centres. A similar [Cu2(Hhba)2(H0.5hba)2]− hydrogen-bonded 2D network to that present in compounds 2 and 3 is apparent in 4, but rather than cations occupying square cavities, the charge on the anionic complex is balanced by a proton located between a pair of coordinated DABCO ligands ([DABCO⋯H⋯DABCO]+), which forms a linear link between anionic sheets, as indicated in Fig. 6 ▸(a). The binuclear Cu complex now serves as a 6-connecting node, with the DABCO ligands extending in a direction perpendicular to the familiar 2D network which was a feature of compounds 2 and 3 [Fig. 6 ▸(b)]. The result is a three-dimensional (3D) hydrogen-bonded network with relatively large intraframework voids that are large enough to accommodate a second equivalent network, as depicted in Fig. 6 ▸(c).
Figure 6.
The structure of [Cu2(Hhba)2(H0.5hba)2(H0.5DABCO)2]·3CH3OH (4), showing (a) [DABCO⋯H⋯DABCO]+ links between [Cu2(Hhba)2(H0.5hba)2]− hydrogen-bonded sheets, (b) a single network with [Cu2(H0.5hba)2(Hhba)2]− hydrogen-bonded sheets linked by [DABCO⋯H⋯DABCO]+ connections and (c) a pair of interpenetrating networks. Only a single orientation of each of the rotationally disordered DABCO units is represented in each figure.
An anionic 2D hydrogen-bonded network is also a feature of the compound [Et4N]2[Cu2(Hhba)2(hba)2(dioxane)2][Cu2(Hhba)4(dioxane)(H2O)]·CH3OH (5), but there are clear differences in the 4-connecting nodes that are formed by the aggregation of phenolic and phenolate groups. In each of the compounds 1–4, there is only one crystallographically unique binuclear complex, each possessing a centre of symmetry between the two CuII centres. In 5, however, two crystallographically distinct binuclear CuII complexes are present. The first of these consists of four Hhba− anions bound to a pair of centrosymmetrically-related CuII centres which are represented by dark-blue spheres in Fig. 7 ▸(a). The second complex is comprised of two crystallographically distinct CuII centres (the larger light-blue spheres) which are bound to two Hhba− anions and two hba2− anions. The hba2− anions are cis to each other in the binuclear complex. The phenolate O atoms of the hba2− anions serve as hydrogen-bond acceptors from three phenolic groups, resulting in a 4-connecting hydrogen-bonding node. The O⋯O separations in the [O−⋯(H—O)3] node are in the range 2.571 (2)–2.616 (2) Å. Charge balance for the anionic network is achieved with tetraethylammonium ions that occupy every second square cavity of the 2D network, which extends in the bc plane. The 2D sheets stack in an ABAB… fashion [Fig. 7 ▸(b)], with tetraethylammonium ions sandwiched between [O−⋯(H—O)3] nodes of adjacent sheets. Dioxane and water molecules, which are bound to the axial positions of the binuclear complexes, exhibit varying degrees of disorder and protrude into the vacant square cavities of adjacent sheets.
Figure 7.
The structure of [Et4N]2[Cu2(Hhba)2(hba)2(dioxane)2][Cu2(Hhba)4(dioxane)(H2O)]·CH3OH (5), showing (a) the anionic 2D structure and (b) a pair of sheets indicating the ABAB… stacking.
The compound [Cu2(Hhba)4(H2O)2]·2Et4N(NO3) (6) is formed when Cu(NO3)2·3H2O is used as the source of CuII and the reaction mixture includes H2hba and Et4NOH. The expected binuclear complex, with water molecules occupying the axial positions, is formed with a centre of symmetry between the metal centres. Each of the carboxylate ligands retains the phenolic proton to give the neutral [Cu2(Hhba)4(H2O)2] complex. Four phenolic groups combine with a pair of nitrate anions and a pair of coordinated water molecules, from adjacent metal complexes, to form an unusual hydrogen-bonded motif, as shown in Fig. 8 ▸(a). An interesting feature of this motif is the association of nitrate anion pairs, which make relatively close face-to-face contacts, with N⋯O separations of 2.883 (2) Å. Inspection of the Cambridge Structural Database (CSD, Version 5.45, March 2024 release; Groom et al., 2016 ▸) reveals numerous examples of similar face-to-face interactions of nitrate anions. The aggregation of the phenolic groups, the two nitrate anions and a pair of coordinated water molecules leads once again to the generation of a 2D network, as depicted in Fig. 8 ▸(b). If the link from the coordinated water molecule to adjacent parallel layers is considered, then the overall structure is that of a 3D network. To balance the charge of the nitrate anion pairs, a tetraethylammonium cation is required for every square cavity. There are two crystallographically distinct tetraethylammonium ions, each of which is disordered over a pair of sites in each square cavity.
Figure 8.
The structure of [Cu2(Hhba)4(H2O)2]·2(Et4NNO3) (6), showing (a) the hydrogen bonding from four phenolic groups to a pair of nitrate anions, and from water molecules to pairs of phenolic groups, and (b) the 2D network. Hydrogen bonds are indicated by black and white striped connections, whilst close interionic contacts between nitrate anions are indicated by pink and white striped connections. Only a single orientation of each of the disordered Et4N+ units is represented in part (b).
The employment of the organic base 1,8-bis(dimethylamino)naphthalene (bdn), more commonly known as a proton sponge, leads to the formation of crystals of composition [Hbdn]2[Cu2(Hhba)2(hba)2(H2O)2]·3(dioxane)·H2O (7). In this compound, the binuclear complex carries an overall 2− charge, with two hba2− ligands trans to each other and extending along the a-axis direction. The trans-phenolate groups act as hydrogen-bond acceptors from coordinated water molecules belonging to complexes on either side along the direction of the a axis. In addition to acting as a proton acceptor via the trans hba2− anions, the complex also serves as a proton donor to the complexes on either side through the coordinated water molecules. Thus, each complex forms a pair of double hba2− bridges, as indicated in Fig. 9 ▸(a). In addition to the centre of symmetry between the CuII centres, there is a centre of symmetry between the pair of hba2− anions. Similarly, along the b axis, there are Hhba− double bridges between complexes with a non-coordinated water molecule interspersed between the phenolic group and the coordinated water molecule [Fig. 9 ▸(b)]. The presence of these two types of double bridges results in the generation of a 4,4-network in which the binuclear complex serves as the sole 4-connecting node. Pairs of Hbdn+ cations, in a face-to-face arrangement, occupy the approximately square cavities [Figs. 9 ▸(c) and 9(d)]. The 2D layers that are generated are separated by disordered solvent molecules.
Figure 9.
The structure of [Hbdn]2[Cu2(Hhba)2(hba)2(H2O)2]·3(dioxane)·H2O (7), showing (a) the double hba2− bridges between CuII pairs along the a axis, (b) the double Hhba− bridges between CuII pairs along the b axis, with an additional water molecule between the phenolic group and the coordinated water molecule, (c) a pair of face-to-face Hbdn+ cations and (d) the 2D network extending in the ab plane, with the cations located in the cavities.
The addition of 4,4′-bipyridine N,N′-dioxide (O-bipy) to Cu(OAc)2·2H2O and H2hba under solvothermal conditions yields a one-dimensional (1D) coordination polymer of composition [Cu2(Hhba)4(O-bipy)]·H2O (8). The O atoms of O-bipy coordinate to the axial positions of a binuclear Cu2(Hhba)4 complex, resulting in a coordination polymer chain that extends in the [201] direction [Fig. 10 ▸(a)]. Hydrogen-bonding interactions involving trans-Hhba− anions lead to the generation of chains, as indicated in Fig. 10 ▸(b). Within the crystal structure, these hydrogen-bonded chains extend in both the [110] and the [1
0] directions. If the links between Cu2(Hhba)4 units, shown in Figs. 10 ▸(a) and 10(b), are taken into account, the binuclear unit may be considered as a 4-connected node within a network which has the same topology as the CdSO4 net, i.e. Schlafli (point) symbol 65·81. Whilst the CdSO4 network is not as common as some of the better-known networks based on 4-connecting nodes, there are examples reported in the literature including one based upon a CuII–tetracarboxylate dimer (Moulton et al., 2003 ▸). The remaining two Hhba− arms of the complex participate in hydrogen-bonding interactions with non-coordinated water molecules, which, in turn, form hydrogen-bonded links to the coordinated O atoms of the O-bipy ligands. The result is a complex 3D hydrogen-bonded network structure.
Figure 10.
The structure of [Cu2(Hhba)4(O-bipy)]·H2O (8), showing (a) the 1D chains formed by the bridging O-bipy ligands and (b) the hydrogen-bonded chains linking Cu2(Hhba)4 units together. The chains depicted in part (b) extend in both the [110] and the [1
0] directions.
Under solvothermal conditions using dioxane as solvent, O-bipy reacts with Cu(OAc)2·2H2O and H2hba to form crystals of composition [Cu2(Hhba)4(O-bipy)2]·2(dioxane) (9), in which only one O atom of each O-bipy is coordinated to the neutral binuclear complex. Within this structure, a square-grid hydrogen-bonded network lying parallel to the ab plane is generated, with links between phenolic groups and the coordinated O-bipy O atom, as indicated in Fig. 11 ▸(a). Additional connections from each binuclear unit extend along the c axis. These connections are double bridges and consist of a hydrogen-bonding link between the non-coordinated O atom of O-bipy and a phenolic group of a Hhba− ligand [Fig. 11 ▸(b)]. The double Hhba⋯O-bipy bridges extending from the binuclear units to symmetry-related parallel units result in a 3D network that has the topology of the simple (primitive) cubic net, which is also known as the α-polonium net [Fig. 11 ▸(c)]. The intraframework space is occupied by a symmetry-related second network.
Figure 11.
The structure of [Cu2(Hhba)4(O-bipy)2]·2(dioxane) (9), showing (a) part of the hydrogen-bonding 2D network that extends parallel to the ab plane, (b) double hydrogen-bonded bridges that link the sheets depicted in part (a), and (c) part of the resulting 3D network.
In the preparation of the copper compounds described above, except for 6, the binuclear copper acetate complex served as the source of CuII. In the following two examples (10 and 11), only partial replacement of the acetate by the Hhba− ligands has occurred. In [Cu2(Hhba)3(OAc)(dioxane)]·3.5(dioxane) (10), the binuclear unit is again present, but with the CuII ions coordinated by three Hhba− anions and one acetate anion. In this case, the binuclear units are bridged by dioxane molecules to form a chain that extends along the a axis, as indicated in Fig. 12 ▸(a). Hydrogen-bonding interactions involving the phenolic groups and acetate O atoms result in linked parallel chains [Fig. 12 ▸(b)]. The remaining phenolic groups interact with disordered dioxane solvent molecules.
Figure 12.
The linear chain structure of [Cu2(Hhba)3(OAc)(dioxane)]·3.5(dioxane) (10), showing (a) the chain formed by bridging dioxane ligands that extends along the a axis and (b) the hydrogen-bonded corrugated sheet network. Non-coordinated dioxane molecules have been omitted.
In [Cu2(Hhba)2(OAc)2(DABCO)2]·10(dioxane) (11), two trans-acetate anions remain coordinated, with coordinated DABCO molecules occupying the axial positions in the complex. The [Cu2(Hhba)2(OAc)2(DABCO)2] unit serves as a 4-connecting node within a 2D 4,4-network, as depicted in Fig. 13 ▸(a), with hydrogen bonds formed between the phenolic groups and the non-coordinated DABCO N atom. Not surprisingly, there is a pronounced bend in the connection between the complexes associated with the C—O—H bond angle. The 2D layers stack on top of each other, with the methyl groups of the acetate ion extending above and below the mean plane of the 2D network [Fig. 13 ▸(b)]. Dioxane solvent molecules occupy the voids between neighbouring sheets.
Figure 13.
The structure of [Cu2(Hhba)2(OAc)2(DABCO)2]·10(dioxane) (11), showing (a) the 2D hydrogen-bonded network and (b) the crystal packing of the sheets.
The final compound described in this article is the 1:1 cocrystal formed from the combination of DABCO and H2hba, which was used as a reactant in the formation of compound 4.
The crystal structure determination indicates two DABCO and two 4-hydroxybenzoic acid molecules in the asymmetric unit. Hydrogen-bonded chains that extend in the [10
] direction are generated as indicated in Fig. 14 ▸. Each chain contains only one type of DABCO and 4-hydroxybenzoic acid molecule. The orientations of the 4-hydroxybenzoic acid in the two crystallographically distinct chains, as represented in Fig. 14 ▸, are opposite to each other and thus the two chains are antiparallel. The cocrystal adopts the centrosymmetric space group P21/n and thus each chain depicted in Fig. 14 ▸ also has a symmetry-related counterpart which is antiparallel.
Figure 14.
The crystal structure of (H0.5DABCO)(H1.5hba) (12), showing the formation of hydrogen-bonded chains that extend in the [10
] direction.
In the structure refinement, peaks of electron density near C atoms were consistent with the expected positions for H atoms. Similarly, electron-density peaks corresponding to the phenolic H atom appeared at a distance consistent with an O—H covalent bond. For each of the two carboxylic acid groups, peaks of electron density are located at positions further from the O atom than expected based upon normal O—H covalent bonds. These peaks were assigned as H atoms and the position of each was refined, leading to O⋯H separations of 1.28 (3) Å. The assigned H atoms are 1.25 (3) and 1.24 (3) Å from the N atoms of the neighbouring DABCO molecules. The two N⋯O separations of 2.518 (2) and 2.515 (2) Å are remarkably short for N⋯O hydrogen bonds. The N⋯O separations between the phenolic O atom and the neighbouring N atom of the DABCO are significantly longer [2.640 (2) and 2.619 (2) Å], but still relatively short for an N⋯O hydrogen bond.
General structural comments
For the Cu dimer compounds considered, compound 1 is the only one not to form a network-based material involving coordinate and/or hydrogen-bond interactions. The failure of 1 to form a network may be attributed to the dioxane molecules which bind to the phenolic groups of the neutral Cu2(Hhba)4 units and block any prospect of network formation. In compounds 7–11, the Cu dimer unit serves as a single node within a 2D (7, 10 and 11) or 3D (8 and 9) network, whilst in 2–6, there are two types of nodes.
In compounds 2–6, the Cu dimer serves as a node, with a second node formed from either the aggregation of phenolic and phenolate groups (2–5) or, alternatively, from the involvement of nitrate anions (6). In the networks involving two types of nodes (2–6), cations are present in the structure. In the structures of 2, 3, 5 and 6, the cations occupy square-shaped cavities, whereas in 4, a proton shared between the non-coordinated N atoms of DABCO ligands serves as a link between Cu dimer nodes.
An average charge of 1− per Cu dimer unit appears to favour the formation of a second type of node in the hydrogen-bonded networks that are generated. In each of 2–5, four O atoms are held together by three H atoms. Whilst the hydrogen-bonded nodes formed in 2–4 are similar, consisting of a planar zigzag arrangement of O atoms with a short hydrogen bond between the central two O atoms, the corresponding node in 5 consists of a clearly defined phenolate O atom serving as a hydrogen-bond acceptor from three phenol groups. In the remaining structures (7–11), the phenol groups only serve to provide links between Cu dimer nodes.
In compounds 8–11, the Cu dimer unit is neutral, with all hba ligands present as Hhba−. These circumstances appear to favour single node (Cu dimer) networks with phenolic groups facilitating links between nodes rather than forming nodes based upon the aggregation of phenolic groups. Although four phenolic groups are involved in a second type of node in 6, the nitrate ion pairs play a key role in the generation of the second type of node.
Compound 7 represents a special case in which the Cu dimer has a 2− charge, i.e. [Cu2(Hhba)2(hba)2]2−. This dianion is also present in 5, but the presence of equal numbers of neutral [Cu2(Hhba)4] means that the average charge on a Cu dimer in 5 is 1−. On the basis of the other structures, it might be expected that the presence of phenolic and phenolate groups in 7 would promote the formation of a second type of node, but instead, only one type of node is apparent with double ligand bridges between the Cu dimer nodes. A possible explanation for the adoption of the network, which is depicted in Fig. 9 ▸(b), is the complementary interaction between pairs of face-to-face Hbdn+ cations and the anionic network containing appropriately sized cavities.
Compounds 10 and 11 represent rare examples of mixed carboxylate systems for binuclear copper(II) dimers. According to Hassanein et al. (2015 ▸), of the 1300 Cu carboxylate dimers reported, only nine were heteroleptic. In the specific case of acetate-containing dimers, the CSD contains just one compound (refcode HIQQEE02; Luo et al., 2010 ▸) with one acetate ligand in combination with three other ferrocenecarboxylate ligands.
In the structures described in this investigation, there are examples of H atoms refining to a position halfway or nearly halfway between a pair of atoms which form a hydrogen bond. The limitations of X-ray diffraction data in accurately determining the positions of H atoms make it difficult to distinguish between disordered asymmetric hydrogen bonds and truly symmetric hydrogen bonds. In the cases where we have refined the structure with a symmetric (or close to symmetric) hydrogen bond, we wish to stress that the assignments of the H-atom positions are only tentative.
Conclusion
The network structures described in this work demonstrate that Cu dimer units involving the hba2−/Hhba− ligands can form a variety of networks. Clearly, hydrogen bonding has played a major role in the formation of the networks. Of particular importance has been the network nodes formed from multiple hydrogen bonds. In compounds 2–4, the planar zigzag motif has shown itself to be an effective 4-connecting node with the ligands extending outwards to the corners of an approximate square. A different type of hydrogen-bonding motif involving three phenol groups serving as donors to a single phenolate group can also produce a 4-connecting node, as seen in 5.
An unusual and beautiful example of a hydrogen-bonding node is apparent in 6, where a pair of nitrate anions, four phenol groups and a pair of coordinated water molecules combine to generate a network which accommodates tetraethylammonium cations in square windows. In the remaining structures involving copper dimer complexes, hydrogen bonding plays a key structural role in the arrangement of the molecular components although they do not contain hydrogen-bonded nodes within networks.
Clearly there are numerous opportunities for exploiting the ability of the phenolic/phenolate groups within CuII tetracarboxylate dimers to create a wide variety of extended structures. Furthermore, the work has demonstrated, using coligands such as DABCO/HDABCO+ and O-bipy, that additional connectivity of the Cu dimer can be achieved by utilizing the axial positions on the Cu centres. The use of different countercations provides further opportunities for crystal engineering. For these reasons, and given the diversity of structures described in this current work, there would appear to be plenty of scope for extending this family of compounds.
Supplementary Material
Crystal structure: contains datablock(s) compound_1, compound_2, compound_3, compound_4, compound_5, compound_6, compound_7, compound_8, compound_9, compound_10, compound_11, compound_12, global. DOI: 10.1107/S2053229624004534/jx3083sup1.cif
Structure factors: contains datablock(s) compound_1. DOI: 10.1107/S2053229624004534/jx3083compound_1sup2.hkl
Structure factors: contains datablock(s) compound_2. DOI: 10.1107/S2053229624004534/jx3083compound_2sup3.hkl
Structure factors: contains datablock(s) compound_3. DOI: 10.1107/S2053229624004534/jx3083compound_3sup4.hkl
Structure factors: contains datablock(s) compound_4. DOI: 10.1107/S2053229624004534/jx3083compound_4sup5.hkl
Structure factors: contains datablock(s) compound_5. DOI: 10.1107/S2053229624004534/jx3083compound_5sup6.hkl
Structure factors: contains datablock(s) compound_6. DOI: 10.1107/S2053229624004534/jx3083compound_6sup7.hkl
Structure factors: contains datablock(s) compound_7. DOI: 10.1107/S2053229624004534/jx3083compound_7sup8.hkl
Structure factors: contains datablock(s) compound_8. DOI: 10.1107/S2053229624004534/jx3083compound_8sup9.hkl
Structure factors: contains datablock(s) compound_9. DOI: 10.1107/S2053229624004534/jx3083compound_9sup10.hkl
Structure factors: contains datablock(s) compound_10. DOI: 10.1107/S2053229624004534/jx3083compound_10sup11.hkl
Structure factors: contains datablock(s) compound_11. DOI: 10.1107/S2053229624004534/jx3083compound_11sup12.hkl
Structure factors: contains datablock(s) compound_12. DOI: 10.1107/S2053229624004534/jx3083compound_12sup13.hkl
Acknowledgments
This research was undertaken in part using the MX1 and MX2 beamlines at the Australian Synchrotron (Aragão et al., 2018 ▸; Cowieson et al., 2015 ▸; McPhillips et al., 2002 ▸), part of ANSTO, and made use of the Australian Cancer Research Foundation (ACRF) detector. Open access publishing facilitated by The University of Melbourne, as part of the Wiley–The University of Melbourne agreement via the Council of Australian University Librarians.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Crystal structure: contains datablock(s) compound_1, compound_2, compound_3, compound_4, compound_5, compound_6, compound_7, compound_8, compound_9, compound_10, compound_11, compound_12, global. DOI: 10.1107/S2053229624004534/jx3083sup1.cif
Structure factors: contains datablock(s) compound_1. DOI: 10.1107/S2053229624004534/jx3083compound_1sup2.hkl
Structure factors: contains datablock(s) compound_2. DOI: 10.1107/S2053229624004534/jx3083compound_2sup3.hkl
Structure factors: contains datablock(s) compound_3. DOI: 10.1107/S2053229624004534/jx3083compound_3sup4.hkl
Structure factors: contains datablock(s) compound_4. DOI: 10.1107/S2053229624004534/jx3083compound_4sup5.hkl
Structure factors: contains datablock(s) compound_5. DOI: 10.1107/S2053229624004534/jx3083compound_5sup6.hkl
Structure factors: contains datablock(s) compound_6. DOI: 10.1107/S2053229624004534/jx3083compound_6sup7.hkl
Structure factors: contains datablock(s) compound_7. DOI: 10.1107/S2053229624004534/jx3083compound_7sup8.hkl
Structure factors: contains datablock(s) compound_8. DOI: 10.1107/S2053229624004534/jx3083compound_8sup9.hkl
Structure factors: contains datablock(s) compound_9. DOI: 10.1107/S2053229624004534/jx3083compound_9sup10.hkl
Structure factors: contains datablock(s) compound_10. DOI: 10.1107/S2053229624004534/jx3083compound_10sup11.hkl
Structure factors: contains datablock(s) compound_11. DOI: 10.1107/S2053229624004534/jx3083compound_11sup12.hkl
Structure factors: contains datablock(s) compound_12. DOI: 10.1107/S2053229624004534/jx3083compound_12sup13.hkl