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Crystal structure and Hirshfeld surface analysis of bis­­[hydrazinium(1+)] hexa­fluorido­silicate: (N2H5)2SiF6

aLaboratoire de Physico-chimie des Matériaux Inorganiques, Université Ibn Tofail, Faculté des Sciences, BP 133, 14000 Kenitra, Morocco, bCentre Régional des Métiers de l'Education et de la Formation, Madinat Al Irfane, Souissi, BP 6210 Rabat, Morocco, and cLaboratoire de Chimie Appliquée des Matériaux, Centre des Sciences des Matériaux, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Batouta, BP 1014, Rabat, Morocco
*Correspondence e-mail: a_ouasri@yahoo.com

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 20 August 2019; accepted 11 September 2019; online 20 September 2019)

In the title inorganic mol­ecular salt, (N2H5)2SiF6, the silicon atom at the centre of the slightly distorted SiF6 octa­hedron [range of Si—F distances = 1.6777 (4)–1.7101 (4) Å] lies on a crystallographic inversion centre. In the crystal, the ions are connected by N—H⋯N and N—H⋯F hydrogen bonds; the former link the cations into [010] chains and the latter (some of which are bifurcated or trifurcated) link the ions into a three-dimensional network. The two-dimensional fingerprint plots show that F⋯H/H⋯F inter­actions dominate the Hirshfeld surface (75.5%) followed by H⋯H (13.6%) and N⋯H/H⋯N (8.4%) whereas F⋯F (1.9%) and F⋯N/N⋯F (0.6%) have negligible percentages. The title compound is isostructural with its germanium-containing analogue.

1. Chemical context

Hydrazinium hexa­fluorido­metalate compounds have been studied by X-ray diffraction, vibrational spectroscopy and thermal analyses: they have been found to exist with two different formulae: N2H6MF6 (Kojić-Prodić et al., 1971a[Kojić-Prodić, B., Matković, B. & Šćavničar, S. (1971a). Acta Cryst. B27, 635-637.],b[Kojić-Prodić, B., Šćavničar, S. & Matković, B. (1971b). Acta Cryst. B27, 638-644.]; Frlec et al., 1980[Frlec, B., Gantar, D., Golič, L. & Leban, I. (1980). Acta Cryst. B36, 1917-1918.]; Golič et al., 1980[Golič, L., Kaučič, V. & Kojić-Prodić, B. (1980). Acta Cryst. B36, 659-661.]; Cameron et al., 1983[Cameron, T. S., Knop, O. & MacDonald, L. A. (1983). Can. J. Chem. 61, 184-188.]; Knop et al., 1983[Knop, O., Cameron, T. S., James, M. A. & Falk, M. (1983). Can. J. Chem. 61, 1620-1646.]; Ouasri et al., 2002[Ouasri, A., Rhandour, A., Dhamelincourt, M.-C., Dhamelincourt, P. & Mazzah, A. (2002). J. Raman Spectrosc. 33, 726-729.]) and (N2H5)2MF6 (Gantar & Rahten, 1988[Gantar, D., Rahten, A. & Volavsek, B. (1988). J. Fluor. Chem. 41, 335-344.]; Leban et al., 1994[Leban, I., Jesih, A. & Rahten, A. (1994). Acta Cryst. C50, 842-843.]) where M = Ga, Si, Ti, Zr and Hf. The name `hydrazinium hexa­fluorido­silicate' has been applied to both compounds: N2H6SiF6 and (N2H5)2SiF6.

[Scheme 1]

The crystal structure of N2H6SiF6 is well described by Frlec et al. (1980[Frlec, B., Gantar, D., Golič, L. & Leban, I. (1980). Acta Cryst. B36, 1917-1918.]) and by Cameron et al. (1983[Cameron, T. S., Knop, O. & MacDonald, L. A. (1983). Can. J. Chem. 61, 184-188.]), whereas that of (N2H5)2SiF6 has not previously been reported to our best knowledge. However, this compound was characterized by chemical analysis, vibrational spectroscopy and X-ray powder photography by Gantar & Rahten (1986[Gantar, D. & Rahten, A. (1986). Thermochim. Acta, 108, 149-155.]), who determined the unit-cell parameters and the space group. We now describe the synthesis, single crystal structure and Hirshfeld surface analysis of the title compound, (I)[link], at room temperature.

2. Structural commentary

Compound (I)[link] is an inorganic mol­ecular salt built up from N2H5+ cations and SiF62− anions, as shown in Fig. 1[link]. In this structure, all atoms are in general positions except for the silicon atom, which is located at the Wyckoff position 2d on the inversion centre [\overline{1}] of the space group P21/n. Thus, the silicon atom is connected to three unique fluorine atoms and their symmetry equivalents, forming a slightly elongated octa­hedron with Si—F distances in the range of 1.6777 (4) to 1.7101 (4) Å. The minimum and maximum cis F—S—F angles are 89.26 (2) and 90.74 (2)°, respectively. The N—N separation in the cation is 1.4416 (8) Å.

[Figure 1]
Figure 1
Mol­ecular structure of (I)[link] with displacement ellipsoids drawn at the 50% probability level.

3. Supra­molecular features and Hirshfeld surface analysis

In the extended structure of (I)[link], the hydrazinium cations are linked by strong N—H⋯N hydrogen bonds (Table 1[link]), building an infinite zigzag chain propagating along the [010] direction as shown in Fig. 2[link]. The [SiF6]2− anion inter­acts with the (N2H5)+ cations through electrostatic attraction and accepts no fewer than ten simple, bifurcated or trifurcated N—H⋯F hydrogen bonds (Fig. 3[link], Table 1[link]). This results in a three-dimensional network in which the hydrazinium cations build zigzag chains parallel to the b-axis direction and the [SiF6]2− anions are stacked along the [100] direction (Fig. 4[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1A⋯F1i 0.89 2.36 2.8436 (7) 114
N1—H1A⋯F3ii 0.89 2.04 2.9174 (7) 170
N1—H1B⋯N2iii 0.89 2.03 2.8963 (8) 165
N1—H1C⋯F3iv 0.89 2.02 2.9025 (7) 170
N1—H1C⋯F2v 0.89 2.49 2.9078 (7) 109
N2—H2A⋯F1vi 0.83 2.52 3.0952 (7) 127
N2—H2A⋯F2vi 0.83 2.64 3.0725 (7) 114
N2—H2A⋯F3vi 0.83 2.43 3.2373 (7) 167
N2—H2B⋯F3vii 0.86 2.49 3.2683 (7) 150
N2—H2B⋯F2v 0.86 2.51 3.1036 (7) 127
N2—H2B⋯F1iv 0.86 2.60 3.0124 (7) 110
Symmetry codes: (i) x, y+1, z; (ii) -x+1, -y+1, -z+1; (iii) [-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]; (iv) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]; (v) [-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]; (vi) [-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]; (vii) [x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z+{\script{1\over 2}}].
[Figure 2]
Figure 2
A view of the hydrazinium (1+) cations building an [010] chain through N—H⋯F hydrogen bonds (dashed blue lines).
[Figure 3]
Figure 3
Details of the hydrogen bonds between the hydrazinium (1+) cations and (SiF6)2− anions in (I)[link].
[Figure 4]
Figure 4
The crystal structure of (I)[link] with the anions shown as polyhedra.

The packing of (I)[link] was further investigated and qu­anti­fied with a Hirshfeld surface analysis (McKinnon et al., 2004[McKinnon, J. J., Spackman, M. A. & Mitchell, A. S. (2004). Acta Cryst. B60, 627-668.]; Spackman & Jayatilaka, 2009[Spackman, M. A. & Jayatilaka, D. (2009). CrystEngComm, 11, 19-32.]) and two-dimensional fingerprint plots generated using the CrystalExplorer package (Turner et al., 2017[Turner, M. J., McKinnon, J. J., Wolff, S. K., Grimwood, D. J., Spackman, P. R., Jayatilaka, D. & Spackman, M. A. (2017). CrystalExplorer17. The University of Western Australia.]).

The acceptor atoms in the inter­actions are shown with negative electrostatic potentials (red regions), and donor atoms are shown with positive electrostatic potentials (blue regions). The N—H⋯F inter­actions in the structure are apparent from the relatively bright red-spots on the Hirshfeld surface of (I)[link] mapped over dnorm (Fig. S1 in the supporting information). In order to provide qu­anti­tative information on the contribution of the inter­molecular inter­actions to the crystal packing, the three-dimensional dnorm surface is resolved into two-dimensional fingerprint plots, generated based on de and di distance scales and illustrated in Fig. 5[link](a)–(f) The F⋯H/H⋯F inter­actions appear as distinct spikes in the fingerprint plot, and occupy the majority of the total Hirshfeld surface (75.5%) as illustrated in Fig. 5[link](a); the characteristic `wingtip' features indicate the N—H⋯F hydrogen bonds. The H⋯F inter­action are represented by a spike (di = 0.8, de = 1.1 Å) at the bottom left (donor), whereas the F⋯H inter­actions are represented by a spike (di = 1.1, de = 0.8 Å) at the bottom right (acceptor) of the fingerprint plot. The H⋯H contacts appear in the middle of the scattered points; these contacts comprise 13.6% of the total Hirshfeld surface [Fig. 5[link](c)]. The N⋯H contacts cover 8.4% of the total surface, as the third important contributor in the crystal packing, Fig. 5[link](d) while the F⋯F and F⋯N/N⋯F contacts make negligible contributions of 1.9% [Fig. 5[link](e)] and 0.6% [Fig. 5[link](f)], respectively.

[Figure 5]
Figure 5
Fingerprint plots for the inter­actions present in the crystal packing of (I)[link] showing (a) all contacts and those delineated into (b) F⋯H, (c) H⋯H, (d) N⋯H, (e) F⋯F and (f) F⋯N. The outline of the full fingerprint is shown in grey.

4. Database survey

Hydrazinium (2+) hexa­fluorido­silicate, N2H6SiF6, at room temperature, crystallizes in a pseudo-tetra­gonal ortho­rhom­bic space group (Pbca, Z = 4), with a = 7.605 (1) Å, b = 7.586 (2) Å and c = 8.543 (1) Å (Frlec et al., 1980[Frlec, B., Gantar, D., Golič, L. & Leban, I. (1980). Acta Cryst. B36, 1917-1918.]; Cameron et al., 1983[Cameron, T. S., Knop, O. & MacDonald, L. A. (1983). Can. J. Chem. 61, 184-188.]). Its structure consists of centrosymmetric N2H62+ and SiF62− ions arranged in a NaC1-type packing and connected by N—H⋯F hydrogen bonds, forming layers of cations and anions lying parallel to (001) plane.

Hydrazinium (1+) hexa­halogenometallates were studied by Gantar and co-workers (Gantar et al., 1985[Gantar, D., Golic, L., Leban, I. & Rahten, A. (1985). J. Fluor. Chem. 30, 19-28.]; Gantar & Rahten, 1986[Gantar, D. & Rahten, A. (1986). Thermochim. Acta, 108, 149-155.]) who showed that (N2H5)2GeF6 crystallizes in the monoclinic system, space group P21/n (Z = 2), with cell parameters a = 6.015 (2) Å, b = 5.249 (1) Å, c = 11.181 (2)Å and β = 100.15 (2)° and is clearly isostructural with (I)[link].

Fluoride complexes of titanium (IV) with ammonium cation derivatives include two hydrazinium hexa­fluorido­titanates (IV), (N2H5)2TiF6 (Leban et al., 1994[Leban, I., Jesih, A. & Rahten, A. (1994). Acta Cryst. C50, 842-843.]) and N2H6TiF6 (Kojić-Prodić et al.,1971a[Kojić-Prodić, B., Matković, B. & Šćavničar, S. (1971a). Acta Cryst. B27, 635-637.],b[Kojić-Prodić, B., Šćavničar, S. & Matković, B. (1971b). Acta Cryst. B27, 638-644.]). The monoclinic crystals of (N2H5)2TiF6 [P21; Z = 4; a = 7.815 (1) Å, b = 10.019 (1) Å, c = 9.338 (1) Å; β = 93.58 (1)°] exhibit racemic twinning but are not isostructural with (I)[link]. The crystal structure of (N2H5)2TiF6 consists of N2H5+ cations and two types of slightly distorted octa­hedral (TiF6)2− anions. The N2H5+ cations and (TiF6)2− anions are linked via N—H⋯F and N—H⋯N hydrogen bonds, building a three-dimensional network. Two other isostructural hydrazinium (l+) hexa­fluorido complexes, (N2H5)2ZrF6 and (N2H5)2HfF6, were prepared and characterized by chemical analysis, vibrational spectroscopy and X-ray powder diffraction (Gantar & Rahten, 1988[Gantar, D., Rahten, A. & Volavsek, B. (1988). J. Fluor. Chem. 41, 335-344.]). The infrared spectrum analysis of the title compound at room temperature confirms the obtained results by Gantar & Rahten with the exception of the assignments of two infrared bands (see supporting information).

5. Synthesis and Infrared measurement technique.

Hydrazinium (1+) hexa­fluorido­silicate (N2H5)2SiF6 crystals in the form of colourless blocks were obtained by slow evaporation, at room temperature, of an aqueous solution containing stoichiometric amounts of hydrazine NH2NH2 and H2SiF6. The infrared spectrum was recorded in the range 450–4000 cm−1 with a Vertex 70 FTIR spectrometer.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. H atoms were located in a difference-Fourier map and refined using a riding model with N—H = 0.86 Å and Uiso(H) = 1.2Ueq(N). The highest peak and the deepest hole in the final Fourier map are at 0.67 Å from F3 and 0.0 Å from Si1.

Table 2
Experimental details

Crystal data
Chemical formula F6H10N4Si
Mr 208.21
Crystal system, space group Monoclinic, P21/n
Temperature (K) 296
a, b, c (Å) 5.9496 (3), 5.2484 (2), 11.0029 (5)
β (°) 100.245 (1)
V3) 338.10 (3)
Z 2
Radiation type Mo Kα
μ (mm−1) 0.42
Crystal size (mm) 0.31 × 0.24 × 0.16
 
Data collection
Diffractometer Bruker D8 VENTURE Super DUO
Absorption correction Multi-scan (SADABS; Krause et al., 2015[Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3-10.])
Tmin, Tmax 0.638, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 19683, 1488, 1379
Rint 0.027
(sin θ/λ)max−1) 0.806
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.021, 0.059, 1.06
No. of reflections 1488
No. of parameters 54
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.27, −0.22
Computer programs: APEX3 and SAINT-Plus (Bruker, 2016[Bruker (2016). APEX3 and SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT2014/7 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2014/7 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]), Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.])and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT-Plus (Bruker, 2016); data reduction: SAINT-Plus (Bruker, 2016); program(s) used to solve structure: SHELXT2014/7 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: Mercury (Macrae et al., 2008)and publCIF (Westrip, 2010).

Bis[hydrazinium(1+)] hexafluoridosilicate top
Crystal data top
F6H10N4SiF(000) = 212
Mr = 208.21Dx = 2.045 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 5.9496 (3) ÅCell parameters from 1488 reflections
b = 5.2484 (2) Åθ = 3.7–35.0°
c = 11.0029 (5) ŵ = 0.42 mm1
β = 100.245 (1)°T = 296 K
V = 338.10 (3) Å3Block, colourless
Z = 20.31 × 0.24 × 0.16 mm
Data collection top
Bruker D8 VENTURE Super DUO
diffractometer
1488 independent reflections
Radiation source: INCOATEC IµS micro-focus source1379 reflections with I > 2σ(I)
HELIOS mirror optics monochromatorRint = 0.027
Detector resolution: 10.4167 pixels mm-1θmax = 35.0°, θmin = 3.7°
φ and ω scansh = 99
Absorption correction: multi-scan
(SADABS; Krause et al., 2015)
k = 88
Tmin = 0.638, Tmax = 0.746l = 1717
19683 measured reflections
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.021 w = 1/[σ2(Fo2) + (0.0348P)2 + 0.036P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.059(Δ/σ)max = 0.001
S = 1.06Δρmax = 0.27 e Å3
1488 reflectionsΔρmin = 0.22 e Å3
54 parametersExtinction correction: SHELXL-2018/3 (Sheldrick 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.093 (10)
Special details top

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) top
xyzUiso*/Ueq
Si10.5000000.0000000.5000000.01562 (7)
F10.28419 (6)0.13785 (8)0.55514 (4)0.02516 (10)
F30.31234 (7)0.21784 (8)0.42375 (4)0.02473 (10)
F20.55101 (7)0.18926 (8)0.62475 (4)0.02576 (10)
N10.46840 (9)0.60149 (11)0.77712 (5)0.02307 (11)
H1A0.5308930.6390800.7116120.035*
H1B0.3341220.5259160.7524450.035*
H1C0.5604070.4970030.8267360.035*
N20.43562 (9)0.83227 (11)0.84285 (5)0.02447 (11)
H2A0.3907250.7857870.9062430.037*
H2B0.5679060.8985650.8692960.037*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Si10.01429 (10)0.01983 (11)0.01242 (10)0.00065 (6)0.00149 (6)0.00092 (6)
F10.02032 (17)0.0332 (2)0.02288 (17)0.00450 (14)0.00636 (13)0.00188 (14)
F30.02217 (17)0.02512 (18)0.02510 (18)0.00506 (13)0.00071 (13)0.00348 (13)
F20.02585 (18)0.0309 (2)0.01981 (17)0.00025 (14)0.00210 (13)0.01005 (14)
N10.0199 (2)0.0245 (2)0.0237 (2)0.00006 (16)0.00101 (16)0.00587 (18)
N20.0222 (2)0.0289 (2)0.0220 (2)0.00171 (18)0.00320 (17)0.00167 (18)
Geometric parameters (Å, º) top
Si1—F2i1.6777 (4)N1—N21.4416 (8)
Si1—F21.6777 (4)N1—H1A0.8900
Si1—F1i1.6785 (4)N1—H1B0.8900
Si1—F11.6785 (4)N1—H1C0.8900
Si1—F3i1.7101 (4)N2—H2A0.8268
Si1—F31.7101 (4)N2—H2B0.8624
F2i—Si1—F2180.0F1i—Si1—F390.52 (2)
F2i—Si1—F1i89.90 (2)F1—Si1—F389.48 (2)
F2—Si1—F1i90.10 (2)F3i—Si1—F3180.0
F2i—Si1—F190.10 (2)N2—N1—H1A109.5
F2—Si1—F189.90 (2)N2—N1—H1B109.5
F1i—Si1—F1180.0H1A—N1—H1B109.5
F2i—Si1—F3i90.74 (2)N2—N1—H1C109.5
F2—Si1—F3i89.26 (2)H1A—N1—H1C109.5
F1i—Si1—F3i89.48 (2)H1B—N1—H1C109.5
F1—Si1—F3i90.52 (2)N1—N2—H2A105.6
F2i—Si1—F389.26 (2)N1—N2—H2B108.1
F2—Si1—F390.74 (2)H2A—N2—H2B104.3
Symmetry code: (i) x+1, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···F1ii0.892.362.8436 (7)114
N1—H1A···F3iii0.892.042.9174 (7)170
N1—H1B···N2iv0.892.032.8963 (8)165
N1—H1C···F3v0.892.022.9025 (7)170
N1—H1C···F2vi0.892.492.9078 (7)109
N2—H2A···F1vii0.832.523.0952 (7)127
N2—H2A···F2vii0.832.643.0725 (7)114
N2—H2A···F3vii0.832.433.2373 (7)167
N2—H2B···F3viii0.862.493.2683 (7)150
N2—H2B···F2vi0.862.513.1036 (7)127
N2—H2B···F1v0.862.603.0124 (7)110
Symmetry codes: (ii) x, y+1, z; (iii) x+1, y+1, z+1; (iv) x+1/2, y1/2, z+3/2; (v) x+1/2, y+1/2, z+1/2; (vi) x+3/2, y+1/2, z+3/2; (vii) x+1/2, y+1/2, z+3/2; (viii) x+1/2, y+3/2, z+1/2.
 

Acknowledgements

The authors thank the Faculty of Science, Mohammed V University in Rabat, Morocco, for the X-ray measurements.

References

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