metal-organic compounds
Diaquabis[5-(2-pyrazin-2-yl)tetrazolato]copper(II)–pyrazine-2-carbonitrile (1/2)
aUnité de Recherche de Chimie de l'Environnement et Moléculaire Structurale, Université Constantine 1, Algeria, and bCRM2, UMR-CNRS 7036, Jean Barriol Institut, Lorraine University, BP 230, 54506 Vandoeuvre-lés-Nancy Cedex, France
*Correspondence e-mail: bm_abdel@yahoo.fr
The title compound, [Cu(C5H3N6)2(H2O)2]·2C5H3N3, is a 1:2 between the mononuclear complex diaquabis[5-(pyrazin-2-yl)tetrazolato]copper(II) and the reagent pyrazine-2-carbonitrile which was used in the synthesis. The CuII atom is located on an inversion centre and has a distorted octahedral [4 + 2]-coordination environment formed by four N atoms of two chelating bidentate 5-(pyrazin-2-yl)tetrazolate ligands at shorter distances and two water O atoms at longer distances. The CuII complex molecules are held together by O—H⋯N hydrogen bonds and π–π stacking interactions [centroid–centroid distance 3.6139 (8) Å], forming layers parallel to (100). These layers alternate with layers of pyrazine-2-carbonitrile molecules and both are held together via C—H⋯N hydrogen bonds and further π–π stacking interactions.
CCDC reference: 984463
Related literature
For related CuII complexes, see: Liu et al. (2007); Abu-Youssef et al. (2007). For hydrogen-bonding networks and IR spectroscopy of related complexes, see: Abu-Youssef et al. (2007). For the synthesis of the title compound, see: Zhao et al. (2008).
Experimental
Crystal data
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Data collection: CrysAlis PRO (Oxford Diffraction, 2008); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2009).
Supporting information
CCDC reference: 984463
10.1107/S1600536814002293/qk2063sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814002293/qk2063Isup2.hkl
In continuation of related research (Abu-Youssef et al., 2007; Liu et al., 2007), we set out to investigate a new copper compound with the aim to study its molecular and
including hydrogen bonding and network topology. The title compound, [Cu(Pyztz)2(H2O)2].(CPy)2 (Fig. 1), crystallizes in the monoclinic P21/c, and the contains an anionic 5-(pyrazin-2-yl)tetrazolato ligand (Pyztz), one coordinated water molecule, one central Cu2+ ion which is located on an inversion centre, and one pyrazine-2-carbonitrile molecule (CPy). In the complex [Cu(Pyztz)2(H2O)2] the copper ion adopts a Jahn-Teller-distorted octahedral coordination by four N atoms of two chelating bidentate Pyztz ligands and by two water O atoms at distinctly longer distances (Table 1). The two Pyztz ligands of the complex are essentially coplanar and the complex is reinforced by two intramolecular hydrogen bonds C3—H3···N4 (Table 2). Identical Cu complexes with bond lengths similar to the title compound were reported from [Cu(Pyztz)2(H2O)2] (Abu-Youssef et al., 2007) and from [Cu(Pyztz)2(H2O)2].H2O (Liu et al., 2007; Abu-Youssef et al., 2007).The [Cu(Pyztz)2(H2O)2] complexes in the title compound are arranged in layers parallel (100) and form two-dimensional infinite networks parallel this plane (Fig. 2). They are held together by O—H···N hydrogen bonds between the water molecules as donors and tetrazole nitrogen atoms N5 and N6 as acceptors (Table 2) and by π-π stacking interactions between pairs of tetrazole rings (Fig. 3; Cg3···Cg3). Inserted between the layers of the [Cu(Pyztz)2(H2O)2] complexes are layers of CPy molecules, which are held together by π-π stacking (Fig. 3, Cg5···Cg5) and by weak intermolecular C—H···N hydrogen bonds to N4 and N9 as acceptors (Fig. 2, Table 2).
From the topological viewpoint the structure of [Cu(Pyztz)2(H2O)2].(CPy)2 may be considered as tetragonal plane net, the Cu complex could be regarded as node. Each complex is bound to four other complexes and acting as 4-connected node and each cyanopyrazine fragment is between two tetragonal planes net. In this way the structure could be reduced to an uninodal 4 - c net, of sql topological type, and the Point (Schlafli) symbol for the net is 44 62 (Fig. 2 b).
The compound was prepared under solvothermal conditions, by a mixture of 0.065 g (1 mmol) of sodium azide, 2 ml of pyrazine-2-carbonitrile and 0.255 g (1 mmol) of copper fluoborate hydrate according to a literature procedure.(Zhao et al., 2008). The mixture was kept indisturbed for a few days at room temperature and furnished blue crystals suitable for X-ray diffraction.
Carbon bonded H atoms were placed at calculated positions and were treated as riding on the parent C atoms with C—H = 0.95 Å, Uiso(H) = 1.2Ueq(C). The two H atoms of the water molecule were refined with distance restraints of O—H = 0.82 (1) Å and H–H = 1.40 (2) Å, whereas their Uiso(H) were refined freely.
Data collection: CrysAlis PRO (Oxford Diffraction, 2008); cell
CrysAlis PRO (Oxford Diffraction, 2008); data reduction: CrysAlis PRO (Oxford Diffraction, 2008); program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2009).Fig. 1. Molecular structure of the title compound [Cu(Pyztz)2(H2O)2].(CPy)2 with displacement ellipsoids drawn at the 50% probability level. | |
Fig. 2. (a) The crystal structure of [Cu(Pyztz)2(H2O)2].(CPy)2 viewed along [001] showing hydrogen bonds as red lines. (b) The 4-connected sql net topology of the O—H···N hydrogen bonds in [Cu(Pyztz)2(H2O)2].(CPy)2. | |
Fig. 3. π-π stacking interactions in [Cu(Pyztz)2(H2O)2].(CPy)2 with Cg···Cg distances in Å. |
[Cu(C5H3N6)2(H2O)2]·2C5H3N3 | F(000) = 614 |
Mr = 604.06 | Dx = 1.656 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 70 reflections |
a = 13.591 (2) Å | θ = 2.2–30.6° |
b = 12.784 (3) Å | µ = 0.96 mm−1 |
c = 7.216 (2) Å | T = 100 K |
β = 104.93 (2)° | Prism, blue |
V = 1211.4 (5) Å3 | 0.1 × 0.08 × 0.06 mm |
Z = 2 |
Agilent SuperNova CCD diffractometer | 3265 reflections with I > 2σ(I) |
Radiation source: micro-source | Rint = 0.036 |
Multi-layer monochromator | θmax = 30.6°, θmin = 2.2° |
φ and ω scans | h = −19→19 |
72054 measured reflections | k = −16→18 |
3711 independent reflections | l = −10→10 |
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)] = 0.027 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.075 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0387P)2 + 0.609P] where P = (Fo2 + 2Fc2)/3 |
3711 reflections | (Δ/σ)max = 0.001 |
195 parameters | Δρmax = 0.62 e Å−3 |
2 restraints | Δρmin = −0.24 e Å−3 |
[Cu(C5H3N6)2(H2O)2]·2C5H3N3 | V = 1211.4 (5) Å3 |
Mr = 604.06 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 13.591 (2) Å | µ = 0.96 mm−1 |
b = 12.784 (3) Å | T = 100 K |
c = 7.216 (2) Å | 0.1 × 0.08 × 0.06 mm |
β = 104.93 (2)° |
Agilent SuperNova CCD diffractometer | 3265 reflections with I > 2σ(I) |
72054 measured reflections | Rint = 0.036 |
3711 independent reflections |
R[F2 > 2σ(F2)] = 0.027 | 2 restraints |
wR(F2) = 0.075 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.08 | Δρmax = 0.62 e Å−3 |
3711 reflections | Δρmin = −0.24 e Å−3 |
195 parameters |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
Cu1 | 1.0000 | 0.0000 | 1.0000 | 0.01027 (6) | |
O1 | 0.89916 (7) | −0.01043 (7) | 1.21907 (13) | 0.01521 (17) | |
H1W | 0.9008 (14) | 0.0452 (12) | 1.271 (3) | 0.022 (4)* | |
H2W | 0.9197 (14) | −0.0577 (11) | 1.294 (2) | 0.028 (5)* | |
N1 | 0.71720 (8) | −0.15880 (9) | 0.54002 (16) | 0.0195 (2) | |
N2 | 0.87742 (8) | −0.05530 (7) | 0.79219 (14) | 0.01180 (18) | |
N3 | 0.97170 (8) | 0.15216 (7) | 0.96694 (14) | 0.01155 (18) | |
N4 | 0.90083 (8) | 0.21867 (8) | 0.86795 (14) | 0.01393 (19) | |
N5 | 0.93288 (8) | 0.31435 (8) | 0.91544 (15) | 0.01499 (19) | |
N6 | 1.02487 (8) | 0.31291 (8) | 1.04561 (15) | 0.01458 (19) | |
N7 | 0.64661 (9) | 0.29939 (9) | 0.97445 (17) | 0.0217 (2) | |
N8 | 0.51739 (8) | 0.13314 (9) | 0.80887 (16) | 0.0188 (2) | |
N9 | 0.66710 (10) | −0.07623 (10) | 0.97158 (19) | 0.0269 (3) | |
C1 | 0.78740 (9) | −0.21147 (9) | 0.67013 (17) | 0.0155 (2) | |
H1 | 0.7816 | −0.2853 | 0.6786 | 0.019* | |
C2 | 0.86881 (9) | −0.16041 (8) | 0.79360 (16) | 0.0115 (2) | |
C3 | 0.80715 (10) | −0.00197 (9) | 0.66417 (17) | 0.0148 (2) | |
H3 | 0.8108 | 0.0722 | 0.6597 | 0.018* | |
C4 | 0.72809 (10) | −0.05505 (10) | 0.53648 (18) | 0.0186 (2) | |
H4 | 0.6802 | −0.0157 | 0.4434 | 0.022* | |
C5 | 1.04598 (9) | 0.21169 (8) | 1.07398 (16) | 0.0116 (2) | |
C7 | 0.64409 (10) | 0.01012 (10) | 0.9505 (2) | 0.0195 (2) | |
C8 | 0.61209 (9) | 0.11813 (10) | 0.91986 (17) | 0.0165 (2) | |
C9 | 0.67664 (10) | 0.19991 (10) | 1.00151 (18) | 0.0191 (2) | |
H9 | 0.7432 | 0.1845 | 1.0778 | 0.023* | |
C10 | 0.55197 (10) | 0.31480 (11) | 0.86613 (19) | 0.0214 (3) | |
H10 | 0.5274 | 0.3845 | 0.8444 | 0.026* | |
C11 | 0.48782 (10) | 0.23276 (11) | 0.78358 (19) | 0.0210 (2) | |
H11 | 0.4213 | 0.2483 | 0.7073 | 0.025* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cu1 | 0.01191 (10) | 0.00595 (9) | 0.01099 (10) | −0.00037 (6) | −0.00058 (7) | −0.00041 (6) |
O1 | 0.0205 (4) | 0.0105 (4) | 0.0139 (4) | −0.0007 (3) | 0.0032 (3) | −0.0003 (3) |
N1 | 0.0178 (5) | 0.0192 (5) | 0.0187 (5) | −0.0033 (4) | 0.0000 (4) | −0.0030 (4) |
N2 | 0.0139 (4) | 0.0097 (4) | 0.0116 (4) | −0.0010 (3) | 0.0028 (3) | −0.0009 (3) |
N3 | 0.0138 (4) | 0.0090 (4) | 0.0110 (4) | 0.0004 (3) | 0.0016 (3) | 0.0002 (3) |
N4 | 0.0170 (5) | 0.0104 (4) | 0.0142 (4) | 0.0030 (3) | 0.0035 (4) | 0.0020 (3) |
N5 | 0.0197 (5) | 0.0104 (4) | 0.0155 (5) | 0.0016 (4) | 0.0057 (4) | 0.0009 (3) |
N6 | 0.0202 (5) | 0.0089 (4) | 0.0158 (4) | −0.0004 (4) | 0.0068 (4) | −0.0004 (3) |
N7 | 0.0188 (5) | 0.0222 (5) | 0.0225 (5) | −0.0026 (4) | 0.0024 (4) | −0.0030 (4) |
N8 | 0.0151 (5) | 0.0225 (5) | 0.0176 (5) | −0.0017 (4) | 0.0020 (4) | −0.0032 (4) |
N9 | 0.0231 (6) | 0.0247 (6) | 0.0316 (6) | −0.0003 (5) | 0.0044 (5) | 0.0031 (5) |
C1 | 0.0168 (5) | 0.0135 (5) | 0.0154 (5) | −0.0044 (4) | 0.0026 (4) | −0.0028 (4) |
C2 | 0.0141 (5) | 0.0103 (5) | 0.0107 (5) | −0.0020 (4) | 0.0042 (4) | −0.0015 (4) |
C3 | 0.0159 (5) | 0.0133 (5) | 0.0139 (5) | 0.0002 (4) | 0.0014 (4) | 0.0005 (4) |
C4 | 0.0171 (6) | 0.0186 (6) | 0.0164 (6) | −0.0002 (4) | −0.0023 (4) | −0.0004 (4) |
C5 | 0.0155 (5) | 0.0087 (5) | 0.0117 (5) | −0.0013 (4) | 0.0051 (4) | −0.0004 (4) |
C7 | 0.0153 (6) | 0.0248 (6) | 0.0178 (6) | −0.0019 (4) | 0.0032 (4) | 0.0007 (5) |
C8 | 0.0154 (5) | 0.0199 (6) | 0.0141 (5) | −0.0015 (4) | 0.0038 (4) | −0.0002 (4) |
C9 | 0.0144 (5) | 0.0228 (6) | 0.0184 (6) | −0.0025 (4) | 0.0012 (4) | −0.0009 (5) |
C10 | 0.0196 (6) | 0.0209 (6) | 0.0225 (6) | 0.0011 (5) | 0.0033 (5) | −0.0019 (5) |
C11 | 0.0153 (6) | 0.0246 (6) | 0.0207 (6) | 0.0010 (5) | 0.0005 (5) | −0.0030 (5) |
Cu1—N3 | 1.9853 (9) | N7—C10 | 1.3365 (17) |
Cu1—N3i | 1.9853 (9) | N8—C11 | 1.3338 (17) |
Cu1—N2 | 2.0583 (10) | N8—C8 | 1.3431 (16) |
Cu1—N2i | 2.0583 (10) | N9—C7 | 1.1467 (17) |
Cu1—O1 | 2.3477 (9) | C1—C2 | 1.3915 (15) |
Cu1—O1i | 2.3477 (9) | C1—H1 | 0.9500 |
O1—H1W | 0.801 (17) | C2—C5i | 1.4538 (16) |
O1—H2W | 0.810 (13) | C3—C4 | 1.3978 (17) |
N1—C4 | 1.3355 (16) | C3—H3 | 0.9500 |
N1—C1 | 1.3355 (16) | C4—H4 | 0.9500 |
N2—C3 | 1.3325 (15) | C5—C2i | 1.4538 (16) |
N2—C2 | 1.3491 (14) | C7—C8 | 1.4475 (18) |
N3—C5 | 1.3390 (15) | C8—C9 | 1.3940 (17) |
N3—N4 | 1.3441 (13) | C9—H9 | 0.9500 |
N4—N5 | 1.3139 (14) | C10—C11 | 1.3955 (19) |
N5—N6 | 1.3567 (15) | C10—H10 | 0.9500 |
N6—C5 | 1.3299 (14) | C11—H11 | 0.9500 |
N7—C9 | 1.3346 (18) | ||
N3—Cu1—N3i | 180.0 | C11—N8—C8 | 115.26 (11) |
N3—Cu1—N2i | 81.16 (4) | N1—C1—C2 | 121.32 (11) |
N3i—Cu1—N2i | 98.84 (4) | N1—C1—H1 | 119.3 |
N3—Cu1—N2 | 98.84 (4) | C2—C1—H1 | 119.3 |
N3i—Cu1—N2 | 81.16 (4) | N2—C2—C1 | 121.24 (11) |
N2i—Cu1—N2 | 180.0 | N2—C2—C5i | 113.46 (10) |
N3—Cu1—O1 | 90.45 (4) | C1—C2—C5i | 125.21 (10) |
N3i—Cu1—O1 | 89.55 (4) | N2—C3—C4 | 120.04 (11) |
N2i—Cu1—O1 | 91.85 (4) | N2—C3—H3 | 120.0 |
N2—Cu1—O1 | 88.15 (4) | C4—C3—H3 | 120.0 |
N3—Cu1—O1i | 89.55 (4) | N1—C4—C3 | 122.66 (11) |
N3i—Cu1—O1i | 90.45 (4) | N1—C4—H4 | 118.7 |
N2i—Cu1—O1i | 88.15 (4) | C3—C4—H4 | 118.7 |
N2—Cu1—O1i | 91.85 (4) | N6—C5—N3 | 111.32 (10) |
O1—Cu1—O1i | 180.0 | N6—C5—C2i | 130.06 (10) |
Cu1—O1—H1W | 108.3 (13) | N3—C5—C2i | 118.51 (10) |
Cu1—O1—H2W | 109.2 (13) | N9—C7—C8 | 178.22 (15) |
H1W—O1—H2W | 112.8 (17) | N8—C8—C9 | 123.16 (12) |
C4—N1—C1 | 116.84 (11) | N8—C8—C7 | 115.56 (11) |
C3—N2—C2 | 117.82 (10) | C9—C8—C7 | 121.28 (11) |
C3—N2—Cu1 | 129.08 (8) | N7—C9—C8 | 121.16 (12) |
C2—N2—Cu1 | 113.08 (8) | N7—C9—H9 | 119.4 |
C5—N3—N4 | 106.12 (9) | C8—C9—H9 | 119.4 |
C5—N3—Cu1 | 113.18 (8) | N7—C10—C11 | 122.70 (13) |
N4—N3—Cu1 | 140.70 (8) | N7—C10—H10 | 118.6 |
N5—N4—N3 | 107.83 (10) | C11—C10—H10 | 118.6 |
N4—N5—N6 | 110.64 (9) | N8—C11—C10 | 121.74 (12) |
C5—N6—N5 | 104.10 (9) | N8—C11—H11 | 119.1 |
C9—N7—C10 | 115.97 (12) | C10—C11—H11 | 119.1 |
N3—Cu1—N2—C3 | 5.57 (11) | C3—N2—C2—C5i | 174.67 (10) |
N3i—Cu1—N2—C3 | −174.43 (11) | Cu1—N2—C2—C5i | −6.64 (12) |
O1—Cu1—N2—C3 | 95.74 (11) | N1—C1—C2—N2 | 2.97 (18) |
O1i—Cu1—N2—C3 | −84.25 (11) | N1—C1—C2—C5i | −173.49 (11) |
N3—Cu1—N2—C2 | −172.94 (8) | C2—N2—C3—C4 | −0.28 (17) |
N3i—Cu1—N2—C2 | 7.06 (8) | Cu1—N2—C3—C4 | −178.73 (9) |
O1—Cu1—N2—C2 | −82.77 (8) | C1—N1—C4—C3 | −1.44 (19) |
O1i—Cu1—N2—C2 | 97.24 (8) | N2—C3—C4—N1 | 2.2 (2) |
N2i—Cu1—N3—C5 | 6.01 (8) | N5—N6—C5—N3 | 0.31 (13) |
N2—Cu1—N3—C5 | −173.99 (8) | N5—N6—C5—C2i | −175.83 (11) |
O1—Cu1—N3—C5 | 97.81 (8) | N4—N3—C5—N6 | −0.29 (13) |
O1i—Cu1—N3—C5 | −82.19 (8) | Cu1—N3—C5—N6 | 179.06 (7) |
N2i—Cu1—N3—N4 | −174.98 (13) | N4—N3—C5—C2i | 176.35 (10) |
N2—Cu1—N3—N4 | 5.01 (13) | Cu1—N3—C5—C2i | −4.31 (13) |
O1—Cu1—N3—N4 | −83.19 (12) | C11—N8—C8—C9 | −1.01 (18) |
O1i—Cu1—N3—N4 | 96.82 (12) | C11—N8—C8—C7 | 179.02 (12) |
C5—N3—N4—N5 | 0.14 (12) | C10—N7—C9—C8 | 0.21 (19) |
Cu1—N3—N4—N5 | −178.91 (9) | N8—C8—C9—N7 | 0.7 (2) |
N3—N4—N5—N6 | 0.05 (13) | C7—C8—C9—N7 | −179.38 (12) |
N4—N5—N6—C5 | −0.22 (13) | C9—N7—C10—C11 | −0.7 (2) |
C4—N1—C1—C2 | −1.06 (18) | C8—N8—C11—C10 | 0.56 (19) |
C3—N2—C2—C1 | −2.18 (17) | N7—C10—C11—N8 | 0.3 (2) |
Cu1—N2—C2—C1 | 176.51 (9) |
Symmetry code: (i) −x+2, −y, −z+2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1W···N5ii | 0.80 (2) | 2.07 (2) | 2.8577 (13) | 170 (2) |
O1—H2W···N6iii | 0.81 (1) | 2.05 (1) | 2.8543 (14) | 173 (2) |
C1—H1···N9iv | 0.95 | 2.57 | 3.2993 (17) | 134 |
C3—H3···N4 | 0.95 | 2.51 | 3.2825 (15) | 138 |
C11—H11···N1v | 0.95 | 2.51 | 3.2800 (17) | 138 |
Symmetry codes: (ii) x, −y+1/2, z+1/2; (iii) −x+2, y−1/2, −z+5/2; (iv) x, −y−1/2, z−1/2; (v) −x+1, −y, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1W···N5i | 0.801 (17) | 2.065 (17) | 2.8577 (13) | 169.8 (18) |
O1—H2W···N6ii | 0.810 (13) | 2.048 (14) | 2.8543 (14) | 172.9 (18) |
C1—H1···N9iii | 0.95 | 2.57 | 3.2993 (17) | 134.1 |
C3—H3···N4 | 0.95 | 2.51 | 3.2825 (15) | 138.1 |
C11—H11···N1iv | 0.95 | 2.51 | 3.2800 (17) | 138.0 |
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+2, y−1/2, −z+5/2; (iii) x, −y−1/2, z−1/2; (iv) −x+1, −y, −z+1. |
Acknowledgements
Technical support (X-ray measurements) from CRM2 UMR-CNRS 7036 Jean Barriol Institut, Lorraine University, is gratefully acknowledged.
References
Abu-Youssef, M. A. M., Mautner, F. A., Massoud, A. A. & Ohrstrom, L. (2007). Polyhedron, 26, 1531–1540. CAS Google Scholar
Burla, M. C., Camalli, M., Carrozzini, B., Cascarano, G. L., Giacovazzo, C., Polidori, G. & Spagna, R. (2003). J. Appl. Cryst. 36, 1103. CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Liu, J.-T., Fan, S.-D. & Ng, S. W. (2007). Acta Cryst. E63, m1651. Web of Science CSD CrossRef IUCr Journals Google Scholar
Oxford Diffraction, (2008). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zhao, H., Qu, Z.-R., Ye, H.-Y. & Xiong, R.-G. (2008). Chem. Soc. Rev. 37, 84–100. Web of Science CrossRef PubMed Google Scholar
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