In the title bimetallic metal–organic framework, {Fe(Brpz)2[Cu(CN)2]2}n, where Brpz is 2-bromopyrazine, the FeII cation is located on an inversion centre and has a slightly elongated octahedral FeN6 coordination environment. The CuI center has a fourfold CuC3N coordination environment with an almost perfect trigonal–pyramidal geometry. Copper(I) centers related by a twofold rotation axis are bridged by two carbon atoms from a pair of μ-CN groups, resulting in Cu2(CN)2 units that build up the coordination framework.
Keywords: crystal structure, bromopyrazine, dicyanocuprate, iron(II), copper(I), bimetallic, metal-organic framework, MOF
Abstract
In the title metal-organic framework, [Fe(C4H3BrN2)2{Cu(CN)2}2]n, the FeII cation is located on an inversion center and has a slightly elongated octahedral coordination environment [FeN6], ligated by two pyrazine N atoms of symmetry-related bridging 2-bromopyrazine molecules in the axial positions and by four N atoms of pairs of symmetry-related cyanido groups in the equatorial positions. The CuI center has a fourfold coordination environment [CuC3N], with an almost perfect trigonal–pyramidal geometry, formed by three cyanido C atoms and an N atom of a bridging 2-bromopyrazine molecule. Copper(I) centers related by a twofold rotation axis are bridged by two carbon atoms from a pair of μ-CN groups, resulting in Cu2(CN)2 units. Each Cu2(CN)2 unit is linked to six FeII cations via a pair of linear CN units, the pair of μ-CN groups and two bridging 2-bromopyrazine ligands, resulting in the formation of a metal–organic framework, which is additionally stabilized by the short Cu⋯Cu contacts of 2.4450 (7) Å.
Chemical context
The rational design and synthesis of cyanide-based coordination materials is of key interest today. By using different approaches for their design and tunable structures, composition and porosity, various exciting properties of these compounds, such as catalytic, photoluminescent, magnetic, electrical and other can be achieved (Zhang et al., 2015 ▸; Catala & Mallah, 2017 ▸). The cyanide anion is an important ligand in coordination chemistry as it can be used for stabilization of coordination materials formed by diverse transition metals. Cyanide-containing coordination materials of very different topologies have been proposed, although attention is frequently paid to heterometallic complexes.
The first class of cyanide-based metallic complexes emerged in the 18th century with the discovery of Prussian blue. Later its analogues containing two types of metals were synthesized. The inclusion of different metals instead of iron resulted in the occurrence of various attractive physical properties of these materials, which allowed their use as molecular sieves, for nanoscale devices, for hydrogen storage, etc. (Newton et al., 2011 ▸). Prussian blue analogues form networks with general formula AM A[MB(CN)6] (A = alkali metal ion, MA and MB = transition metal ions) (Keggin & Miles, 1936 ▸). These complexes have a cubic structure in which the metallic centers are bridged in an MA—C≡N—MB fashion, forming three-dimensional frameworks.
Another class of heterometallic cyanide coordination compounds that has attracted much attention is represented by f–d complexes composed of lanthanide(III) ions and d-block cyanometallates. This type of materials has been shown to have exceptional photoluminescent properties (Chorazy et al., 2017 ▸). In addition, polynuclear octacyanides form a different family of cyanide-based heterometallic complexes. Compounds of this class can adopt very different geometries creating 0, 1, 2 or 3D assemblies. These materials are known for photomagnetism, molecular magnetism, and the ability to create chiral networks (Sieklucka et al., 2011 ▸).
The Hofmann clathrate analogues of the general formula [MA(L)x{MB(CN)y}] constitute another prominent example of bimetallic cyanometallates (Hofmann & Küspert, 1897 ▸), which are famous for their switchable magnetic properties (Muñoz & Real, 2011 ▸). Here we describe the crystal structure of a new Hofmann clathrate analogue of general formula [Fe(Brpz)2{Cu(CN)2}2]n.
Structural commentary
A fragment of the structure of the title compound, illustrating the sixfold coordination environment of atom Fe1, is shown in Fig. 1 ▸. Selected geometrical parameters are given in Table 1 ▸. The FeII ion is located on an inversion centre and has a slightly elongated FeN6 octahedral coordination environment. It is ligated by two N atoms of symmetry-related 2-bromopyrazine molecules in axial positions [Fe1—N3 = 1.980 (2) Å] and by four N atoms of symmetry related cyanido groups in the equatorial positions [Fe1—N1 = 1.958 (2) and Fe1—N2 = 1.952 (2) Å]. The Fe—N bond lengths clearly indicate that the FeII center is in the low-spin state at the temperature of the experiment, i.e. 296 K. The deviation from an ideal octahedron of the FeII center can be described by the octahedral distortion parameter Σ|90 − θ| = 23.36°, where θ is a cis-N—Fe—N angle. Notably, this sum is higher than that expected for a low-spin FeII ion. It is important to note, and should always be taken into account, that the octahedral distortion value cannot always be used to judge the spin state of a metallic center, it is rather a characteristic of the order level in the structure, the measurement temperature, etc.
Figure 1.
A fragment of the crystal structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at 50% probability level [symmetry codes: (i) −x + 
, −y + 
, −z + 1; (ii) −x + 1, −y, −z + 1; (iii) −x + 1, y, −z + ; (iv) x, −y, z + ].
Table 1. Selected geometric parameters (Å, °).
| Cu1—Cu1i | 2.4450 (7) | Cu1—C2iv | 2.181 (3) |
| Cu1—N4ii | 2.152 (2) | Fe1—N1 | 1.958 (2) |
| Cu1—C1 | 1.924 (3) | Fe1—N2 | 1.952 (2) |
| Cu1—C2iii | 2.049 (3) | Fe1—N3 | 1.980 (2) |
| N4ii—Cu1—C2iv | 99.77 (10) | N3—Fe1—N3v | 180 |
| C2iii—Cu1—N4ii | 94.29 (10) | N2v—Fe1—N3 | 87.27 (9) |
| C2iii—Cu1—C2iv | 104.00 (10) | N2—Fe1—N3 | 92.73 (9) |
| C1—Cu1—N4ii | 109.09 (10) | N2v—Fe1—N1 | 92.19 (9) |
| C1—Cu1—C2iv | 116.07 (11) | N2—Fe1—N1 | 87.81 (9) |
| C1—Cu1—C2iii | 128.08 (11) | N1—Fe1—N3 | 90.92 (9) |
| N1—Fe1—N1v | 180 | N1v—Fe1—N3 | 89.08 (9) |
| N2—Fe1—N2v | 180 |
Symmetry codes: (i) 
; (ii) 
; (iii) 
; (iv) 
; (v) 
.
Atom Cu1 has a fourfold CuC3N coordination environment (Fig. 2 ▸, Table 1 ▸) with a τ4 descriptor of 0.82, close to that for a perfect trigonal–pyramidal geometry (τ4 = 0.00 for square-planar, 1.00 for tetrahedral and 0.85 for trigonal–pyramidal; Yang et al., 2007 ▸). It is ligated by three C atoms of the cyanido groups and an N atom of a bridging 2-bromopyrazine molecule [Cu1—C1 = 1.924 (3), Cu1—C2iv = 2.181 (3), Cu1—C2iii = 2.049 (3), Cu1—N4ii = 2.152 (2) Å]. Notably, the coordination to atom Fe1 occurs only via the more sterically accessible atom N3 of the pyrazine ring, while atom Cu1 binds to atom N4 of the pyrazine ring.
Figure 2.
A view of the coordination environment of the Cu atoms in the title compound, with atom labelling [symmetry codes: (i) −x + 1, −y, −z + 1; (iii) x, −y, z + ; (iv) x, −y, z + ].
Supramolecular features
The crystal packing of the title compound is shown in Fig. 3 ▸. The coordination framework is made up of bridging 2-bromopyrazine ligands and Cu2(CN)2 moieties (Fig. 2 ▸). The latter are formed by a pair of copper atoms, centered about a twofold rotation axis, being bridged by two carbon atoms from a pair of μ-CN groups. Each Cu2(CN)2 unit is linked to six FeII cations via a pair of linear CN units, the pair of μ-CN groups and two bridging 2-bromopyrazine ligands, resulting in the formation of a metal–organic framework (Fig. 3 ▸). The framework is additionally stabilized by the short Cu1⋯Cu1i contact of 2.4550 (7) Å, which is significantly shorter than the sum of the corresponding van der Waals radii, viz. 2.8 Å. Additionally, within the framework there are weak Br⋯π contacts of 3.8298 (6) Å, that are of lone-pair⋯π origin.
Figure 3.
A view normal to plane (110) of the crystal structure of the title compound, showing the Cu⋯Cu contacts as dashed lines. H atoms have been omitted for clarity. Colour code: Fe dark red, Cu light blue, C grey, N blue, Br orange.
Database survey
A search of the Cambridge Structural Database (CSD, version 5.39, last update August 2018; Groom et al., 2016 ▸) gave 15 hits for Fe—N≡C—Cu bimetallic structures supported mainly by substituted pyridines and pyrimidines. These include a number of variable temperature measurements of certain compounds in order to study their spin-crossover behaviour; for example, the two-dimensional coordination polymer catena-[bis[(μ3-cyano-C,C,N)(μ2-cyano-C,N)]tetrakis(3-cyanopyridyl)dicopper(I)iron(II)] (VEHHOG, VEHHOG01; Galet et al., 2006 ▸), and the framework structures catena-[tetrakis(μ2-cyano-C,N)bis(μ2-pyrimidine-N,N′)dicopper(I)iron(II)] (EHOQOH01, EHOQOH03; Agustí et al., 2008 ▸) and catena-[octakis(μ2-cyano)octakis(3-chloropyridine)tetracopper(I)diiron(II)] (YUBRET, YUBRET03; Agustí et al., 2009 ▸).
A search of the CSD for the bridging Cu2(CN)2 unit gave 27 hits. The majority of these are monometallic copper(I) metal–organic frameworks (MOFs). The Cu⋯Cu distances vary from ca 2.31 Å in the two-dimensional network structure catena-[bis(μ3-cyano)tetrakis(μ2-cyano)tris(N,N,N′,N′-tetramethylethylenediamine)hexacopper(I)] (HIWHUQ; Stocker et al., 1999 ▸) to ca 2.72 Å in the MOF catena-[tris(μ-cyano)tris(μ-cyano)diamminepentacopper] (OPODAA; Grifasi et al., 2016 ▸). Two particular compounds resemble the title MOF, namely catena-[bis(μ3-cyano-C,C,N)(μ2-cyano-C,N)(μ2-2,3-dimethylpyrazine-N,N′)tricopper(I)] (FERWUV; Greve & Nather, 2004 ▸), which involves a bridging 2,3-dimethylpyrazine ligand, and catena-[(μ3-cyano)(μ2-4,4′-bipyridine)tris(μ2-cyano)hexamethyldicopper(I)ditin(IV)] (NUMRUI; Ibrahim et al., 1998 ▸), which is a bimetallic MOF with a bridging 4,4′-bipyridine ligand. The respective Cu⋯Cu distances are ca 2.49 and 2.62 Å, compared to 2.4550 (7) Å in the title MOF.
Synthesis and crystallization
Crystals of the title compound were obtained by slow diffusion within three layers in a 3 ml glass tube. The first layer was a solution of K[Cu(CN)2] (7.8 mg, 0.05 mmol) in 1 ml of water; the second layer was a water/ethanol mixture (1:1, 1 ml); the third layer was a solution of Fe(ClO4)2·6H2O (9.1 mg, 0.025 mmol) and 2-bromopyrazine (8.0 mg, 0.05 mmol) in 0.5 ml of ethanol. After two weeks, brown crystals were formed in the middle layer. The crystals were kept under the mother solution prior to measurement.
Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. All the hydrogen atoms were placed geometrically and refined as riding: C—H = 0.93 Å with Uiso(H) = 1.2Ueq(C).
Table 2. Experimental details.
| Crystal data | |
| Chemical formula | [Cu2Fe(CN)4(C4H3BrN2)2] |
| M r | 605.00 |
| Crystal system, space group | Monoclinic, C2/c |
| Temperature (K) | 296 |
| a, b, c (Å) | 13.6143 (17), 9.3067 (11), 13.2101 (15) |
| β (°) | 92.369 (4) |
| V (Å3) | 1672.3 (3) |
| Z | 4 |
| Radiation type | Mo Kα |
| μ (mm−1) | 8.17 |
| Crystal size (mm) | 0.2 × 0.1 × 0.05 |
| Data collection | |
| Diffractometer | Bruker SMART |
| Absorption correction | Multi-scan (SADABS; Bruker, 2013 ▸) |
| T min, T max | 0.487, 0.746 |
| No. of measured, independent and observed [I > 2σ(I)] reflections | 8711, 2023, 1799 |
| R int | 0.029 |
| (sin θ/λ)max (Å−1) | 0.661 |
| Refinement | |
| R[F 2 > 2σ(F 2)], wR(F 2), S | 0.026, 0.063, 1.04 |
| No. of reflections | 2023 |
| No. of parameters | 115 |
| H-atom treatment | H-atom parameters constrained |
| Δρmax, Δρmin (e Å−3) | 1.08, −0.76 |
Supplementary Material
Crystal structure: contains datablock(s) I, Global. DOI: 10.1107/S2056989018016638/su5461sup1.cif
Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989018016638/su5461Isup2.hkl
CCDC reference: 1880717
Additional supporting information: crystallographic information; 3D view; checkCIF report
Acknowledgments
We are grateful to the Ministry of Education and Science of Ukraine and H2020 Marie Skłodowska-Curie Actions for financial support.
supplementary crystallographic information
Crystal data
| [Cu2Fe(CN)4(C4H3BrN2)2] | F(000) = 1152 |
| Mr = 605.00 | Dx = 2.403 Mg m−3 |
| Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
| a = 13.6143 (17) Å | Cell parameters from 3458 reflections |
| b = 9.3067 (11) Å | θ = 2.7–28.0° |
| c = 13.2101 (15) Å | µ = 8.17 mm−1 |
| β = 92.369 (4)° | T = 296 K |
| V = 1672.3 (3) Å3 | Plate, brown |
| Z = 4 | 0.2 × 0.1 × 0.05 mm |
Data collection
| Bruker SMART diffractometer | 1799 reflections with I > 2σ(I) |
| φ and ω scans | Rint = 0.029 |
| Absorption correction: multi-scan (SADABS; Bruker, 2013) | θmax = 28.0°, θmin = 2.7° |
| Tmin = 0.487, Tmax = 0.746 | h = −17→17 |
| 8711 measured reflections | k = −12→12 |
| 2023 independent reflections | l = −17→17 |
Refinement
| Refinement on F2 | Primary atom site location: structure-invariant direct methods |
| Least-squares matrix: full | Secondary atom site location: difference Fourier map |
| R[F2 > 2σ(F2)] = 0.026 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.063 | H-atom parameters constrained |
| S = 1.04 | w = 1/[σ2(Fo2) + (0.0308P)2 + 4.9236P] where P = (Fo2 + 2Fc2)/3 |
| 2023 reflections | (Δ/σ)max = 0.001 |
| 115 parameters | Δρmax = 1.08 e Å−3 |
| 0 restraints | Δρmin = −0.76 e Å−3 |
Special details
| 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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
| x | y | z | Uiso*/Ueq | ||
| Br1 | 0.58637 (3) | 0.80466 (3) | 0.43290 (2) | 0.02782 (10) | |
| Cu1 | 0.56339 (2) | −0.11583 (4) | 0.68710 (2) | 0.01446 (10) | |
| Fe1 | 0.750000 | 0.250000 | 0.500000 | 0.00911 (12) | |
| N2 | 0.64165 (17) | 0.2082 (2) | 0.40313 (17) | 0.0125 (4) | |
| N4 | 0.61897 (18) | 0.6878 (3) | 0.62526 (18) | 0.0167 (5) | |
| N3 | 0.68414 (17) | 0.4233 (2) | 0.55166 (16) | 0.0131 (4) | |
| N1 | 0.68406 (17) | 0.1288 (2) | 0.59751 (17) | 0.0133 (4) | |
| C6 | 0.6791 (2) | 0.4482 (3) | 0.6517 (2) | 0.0179 (6) | |
| H6 | 0.697279 | 0.376181 | 0.697551 | 0.022* | |
| C2 | 0.5807 (2) | 0.1643 (3) | 0.3484 (2) | 0.0144 (5) | |
| C3 | 0.6541 (2) | 0.5292 (3) | 0.4890 (2) | 0.0167 (5) | |
| H3 | 0.654572 | 0.515097 | 0.419324 | 0.020* | |
| C5 | 0.6474 (2) | 0.5785 (3) | 0.6873 (2) | 0.0205 (6) | |
| H5 | 0.645476 | 0.591957 | 0.756995 | 0.025* | |
| C1 | 0.6393 (2) | 0.0431 (3) | 0.63961 (19) | 0.0129 (5) | |
| C4 | 0.6224 (2) | 0.6594 (3) | 0.5265 (2) | 0.0164 (5) |
Atomic displacement parameters (Å2)
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Br1 | 0.0441 (2) | 0.02245 (17) | 0.01682 (15) | 0.01597 (14) | 0.00049 (13) | 0.00483 (11) |
| Cu1 | 0.01237 (17) | 0.01466 (17) | 0.01645 (17) | −0.00143 (13) | 0.00172 (13) | 0.00342 (13) |
| Fe1 | 0.0097 (3) | 0.0095 (2) | 0.0081 (2) | −0.00185 (19) | −0.00025 (19) | 0.00029 (18) |
| N2 | 0.0139 (12) | 0.0124 (10) | 0.0114 (10) | 0.0000 (9) | 0.0031 (9) | 0.0019 (8) |
| N4 | 0.0199 (13) | 0.0148 (11) | 0.0154 (11) | 0.0042 (9) | 0.0019 (10) | 0.0007 (9) |
| N3 | 0.0124 (11) | 0.0152 (11) | 0.0118 (10) | −0.0003 (9) | 0.0006 (9) | −0.0006 (9) |
| N1 | 0.0133 (11) | 0.0142 (11) | 0.0122 (10) | 0.0002 (9) | −0.0011 (9) | −0.0018 (9) |
| C6 | 0.0245 (16) | 0.0162 (13) | 0.0130 (12) | 0.0054 (11) | −0.0003 (11) | 0.0026 (10) |
| C2 | 0.0162 (14) | 0.0109 (11) | 0.0158 (12) | 0.0015 (10) | −0.0011 (10) | 0.0019 (10) |
| C3 | 0.0193 (14) | 0.0181 (13) | 0.0126 (12) | 0.0047 (11) | 0.0005 (10) | −0.0022 (10) |
| C5 | 0.0302 (17) | 0.0198 (14) | 0.0115 (12) | 0.0071 (12) | 0.0019 (11) | 0.0004 (11) |
| C1 | 0.0142 (13) | 0.0144 (13) | 0.0101 (11) | 0.0008 (10) | −0.0001 (10) | 0.0014 (9) |
| C4 | 0.0166 (14) | 0.0173 (13) | 0.0151 (13) | 0.0054 (11) | −0.0003 (10) | 0.0041 (10) |
Geometric parameters (Å, º)
| Br1—C4 | 1.884 (3) | N2—C2 | 1.153 (4) |
| Cu1—Cu1i | 2.4450 (7) | N4—C5 | 1.353 (4) |
| Cu1—N4ii | 2.152 (2) | N4—C4 | 1.334 (4) |
| Cu1—C1 | 1.924 (3) | N3—C6 | 1.347 (3) |
| Cu1—C2iii | 2.049 (3) | N3—C3 | 1.340 (4) |
| Cu1—C2iv | 2.181 (3) | N1—C1 | 1.160 (4) |
| Fe1—N1 | 1.958 (2) | C6—H6 | 0.9300 |
| Fe1—N2v | 1.952 (2) | C6—C5 | 1.376 (4) |
| Fe1—N2 | 1.952 (2) | C3—H3 | 0.9300 |
| Fe1—N3 | 1.980 (2) | C3—C4 | 1.385 (4) |
| Fe1—N3v | 1.980 (2) | C5—H5 | 0.9300 |
| Fe1—N1v | 1.958 (2) | ||
| N4ii—Cu1—Cu1i | 121.81 (7) | C2—N2—Fe1 | 170.7 (2) |
| N4ii—Cu1—C2iv | 99.77 (10) | C5—N4—Cu1vi | 120.31 (19) |
| C2iii—Cu1—Cu1i | 57.25 (8) | C4—N4—Cu1vi | 124.53 (19) |
| C2iv—Cu1—Cu1i | 52.20 (8) | C4—N4—C5 | 115.0 (2) |
| C2iii—Cu1—N4ii | 94.29 (10) | C6—N3—Fe1 | 121.39 (19) |
| C2iii—Cu1—C2iv | 104.00 (10) | C3—N3—Fe1 | 121.14 (18) |
| C1—Cu1—Cu1i | 128.71 (8) | C3—N3—C6 | 116.9 (2) |
| C1—Cu1—N4ii | 109.09 (10) | C1—N1—Fe1 | 167.4 (2) |
| C1—Cu1—C2iv | 116.07 (11) | N3—C6—H6 | 119.4 |
| C1—Cu1—C2iii | 128.08 (11) | N3—C6—C5 | 121.1 (3) |
| N1—Fe1—N1v | 180 | C5—C6—H6 | 119.4 |
| N2—Fe1—N2v | 180 | Cu1iii—C2—Cu1vii | 70.56 (9) |
| N3—Fe1—N3v | 180 | N2—C2—Cu1iii | 151.5 (2) |
| N2v—Fe1—N3 | 87.27 (9) | N2—C2—Cu1vii | 137.1 (2) |
| N2v—Fe1—N3v | 92.73 (9) | N3—C3—H3 | 119.5 |
| N2—Fe1—N3 | 92.73 (9) | N3—C3—C4 | 120.9 (3) |
| N2—Fe1—N3v | 87.27 (9) | C4—C3—H3 | 119.5 |
| N2v—Fe1—N1 | 92.19 (9) | N4—C5—C6 | 122.7 (3) |
| N2—Fe1—N1 | 87.81 (9) | N4—C5—H5 | 118.6 |
| N2—Fe1—N1v | 92.19 (9) | C6—C5—H5 | 118.6 |
| N2v—Fe1—N1v | 87.81 (9) | N1—C1—Cu1 | 170.1 (2) |
| N1—Fe1—N3 | 90.92 (9) | N4—C4—Br1 | 118.8 (2) |
| N1v—Fe1—N3v | 90.92 (9) | N4—C4—C3 | 123.2 (3) |
| N1v—Fe1—N3 | 89.08 (9) | C3—C4—Br1 | 118.0 (2) |
| N1—Fe1—N3v | 89.08 (9) | ||
| Cu1vi—N4—C5—C6 | 176.8 (2) | N3—C3—C4—N4 | −0.5 (5) |
| Cu1vi—N4—C4—Br1 | 5.2 (3) | C6—N3—C3—C4 | 2.0 (4) |
| Cu1vi—N4—C4—C3 | −176.7 (2) | C3—N3—C6—C5 | −2.0 (4) |
| Fe1—N3—C6—C5 | 169.6 (2) | C5—N4—C4—Br1 | −179.1 (2) |
| Fe1—N3—C3—C4 | −169.7 (2) | C5—N4—C4—C3 | −1.0 (4) |
| N3—C6—C5—N4 | 0.6 (5) | C4—N4—C5—C6 | 1.0 (5) |
| N3—C3—C4—Br1 | 177.6 (2) |
Symmetry codes: (i) −x+1, y, −z+3/2; (ii) x, y−1, z; (iii) −x+1, −y, −z+1; (iv) x, −y, z+1/2; (v) −x+3/2, −y+1/2, −z+1; (vi) x, y+1, z; (vii) x, −y, z−1/2.
Funding Statement
This work was funded by Ministry of Education and Science of Ukraine grant DZ/55-2018. H2020 Marie Skłodowska-Curie Actions grant 734322.
References
- Agustí, G., Muñoz, M. C., Gaspar, A. B. & Real, J. A. (2009). Inorg. Chem. 48, 3371–3381. [DOI] [PubMed]
- Agustí, G., Thompson, A. L., Gaspar, A. B., Muñoz, M. C., Goeta, A. E., Rodríguez-Velamazán, J. A., Castro, M., Burriel, R. & Real, J. A. (2008). Dalton Trans. pp. 642–649. [DOI] [PubMed]
- Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.
- Bruker (2013). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
- Catala, L. & Mallah, T. (2017). Coord. Chem. Rev. 346, 32–61.
- Chorazy, S., Wyczesany, M. & Sieklucka, B. (2017). Molecules, 22, 1902. [DOI] [PMC free article] [PubMed]
- Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341.
- Galet, A., Muñoz, M. C. & Real, J. A. (2006). Inorg. Chem. 45, 4583–4585. [DOI] [PubMed]
- Greve, J. & Nather, C. (2004). Z. Naturforsch. Teil B, 59, 1325–1331.
- Grifasi, F., Priola, E., Chierotti, M. R., Diana, E., Garino, C. & Gobetto, R. (2016). Eur. J. Inorg. Chem. pp. 2975–2983.
- Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. [DOI] [PMC free article] [PubMed]
- Hofmann, K. A. & Küspert, F. (1897). Z. Anorg. Chem. 15, 204–207.
- Ibrahim, A. M. A., Siebel, E. & Fischer, R. D. (1998). Inorg. Chem. 37, 3521–3525. [DOI] [PubMed]
- Keggin, J. F. & Miles, F. D. (1936). Nature, 137, 577–578.
- Muñoz, M. C. & Real, J. A. (2011). Coord. Chem. Rev. 255, 2068–2093.
- Newton, G. N., Nihei, M. & Oshio, H. (2011). Eur. J. Inorg. Chem. pp. 3031–3042.
- Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [DOI] [PubMed]
- Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8.
- Sieklucka, B., Podgajny, R., Korzeniak, T., Nowicka, B., Pinkowicz, D. & Kozieł, M. (2011). Eur. J. Inorg. Chem. pp. 305–326.
- Stocker, F. B., Staeva, T. B., Rienstra, C. M. & Britton, D. (1999). Inorg. Chem. 38, 984–991. [DOI] [PubMed]
- Yang, L., Powell, D. R. & Houser, R. P. (2007). Dalton Trans. pp. 955–964. [DOI] [PubMed]
- Zhang, X., Dong, G. Y., Yu, B., Van Hecke, K. & Cui, G. H. (2015). Transition Met. Chem. 40, 907–916.
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) I, Global. DOI: 10.1107/S2056989018016638/su5461sup1.cif
Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989018016638/su5461Isup2.hkl
CCDC reference: 1880717
Additional supporting information: crystallographic information; 3D view; checkCIF report