metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

Pyridinium cis-di­aqua­bis­­(oxalato-κ2O,O′)chromate(III)

aDepartment of Inorganic Chemistry, University of Yaounde I, POB 812 Yaounde, Cameroon, bHigher Teacher Training College, POB 47, University of Yaounde 1, Cameroon, and cInstitut für Anorganische Chemie, RWTH Aachen, D-52056 Aachen, Germany
*Correspondence e-mail: jnenwa@yahoo.fr

(Received 5 October 2012; accepted 25 October 2012; online 31 October 2012)

The title compound, (C5H6N)[Cr(C2O4)2(H2O)2], contains one protonated pyridine mol­ecule and one [Cr(C2O4)2(H2O)2] complex anion in the asymmetric unit. The CrIII in the complex anion is coordinated in a distorted octa­hedral environment by two O atoms from two cis water mol­ecules and four O atoms from two chelating oxalate dianions. The crystal packing is stabilized by inter­molecular N—H⋯O(oxalate) and O—H⋯O(oxalate) hydrogen bonds and by ππ stacking inter­actions (centroid–centroid distance = 3.602 Å) between pyridine rings, thereby building up a three-dimensional network.

Related literature

For the structural characterization of organic–inorganic salts containing the [Cr(C2O4)2(H2O)2] anion, see: Bélombé et al. (2009[Bélombé, M. M., Nenwa, J. & Emmerling, F. (2009). Z. Kristallogr. New Cryst. Struct. 224, 239-240.]); Nenwa et al. (2010[Nenwa, J., Belombe, M. M., Ngoune, J. & Fokwa, B. P. T. (2010). Acta Cryst. E66, m1410.], 2012[Nenwa, J., Bebga, G., Martin, S., Bélombé, M. M., Mbarki, M. & Fokwa, B. P. T. (2012). Acta Cryst. E68, m1325-m1326.]); Chérif et al. (2011[Chérif, I., Abdelhak, J., Zid, M. F. & Driss, A. (2011). Acta Cryst. E67, m1648-m1649.]); Chérif, Abdelhak et al. (2012[Chérif, I., Abdelhak, J., Zid, M. F. & Driss, A. (2012). Acta Cryst. E68, m824-m825.]); Chérif, Zid et al. (2012[Chérif, I., Zid, M. F., El-Ghozzi, M. & Avignant, D. (2012). Acta Cryst. E68, m900- m901.]).

[Scheme 1]

Experimental

Crystal data
  • (C5H6N)[Cr(C2O4)2(H2O)2]

  • Mr = 344.18

  • Monoclinic, P 21 /c

  • a = 7.479 (2) Å

  • b = 24.700 (8) Å

  • c = 7.056 (2) Å

  • β = 107.744 (6)°

  • V = 1241.4 (6) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.98 mm−1

  • T = 100 K

  • 0.15 × 0.04 × 0.04 mm

Data collection
  • Bruker SMART APEX CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2004[Bruker (2004). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.862, Tmax = 0.961

  • 18649 measured reflections

  • 3703 independent reflections

  • 2580 reflections with I > 2σ(I)

  • Rint = 0.106

Refinement
  • R[F2 > 2σ(F2)] = 0.061

  • wR(F2) = 0.160

  • S = 1.13

  • 3703 reflections

  • 206 parameters

  • 5 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.59 e Å−3

  • Δρmin = −0.69 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1⋯O24 0.86 2.10 2.783 (4) 136
N1—H1⋯O23 0.86 2.17 2.901 (4) 143
OW1—H1B⋯O12i 0.81 (2) 1.94 (2) 2.720 (4) 162 (5)
OW1—H1A⋯O23ii 0.86 (5) 1.84 (5) 2.680 (4) 168 (5)
OW2—H2A⋯O13iii 0.81 (2) 1.98 (3) 2.732 (4) 154 (4)
OW2—H2B⋯O14iv 0.82 (2) 1.83 (2) 2.639 (4) 173 (5)
Symmetry codes: (i) [x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]; (ii) x, y, z+1; (iii) [x+1, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]; (iv) x+1, y, z.

Data collection: SMART (Bruker, 2004[Bruker (2004). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2004[Bruker (2004). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND (Brandenburg, 2010[Brandenburg, K. (2010). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


Comment top

Recently, we have reported the structure of a few organic-inorganic hybrid salts involving various aromatic iminium cations and the complex anion, [Cr(C2O4)2(H2O)2]- in trans-geometry (Bélombé et al., 2009; Nenwa et al., 2010, 2012). In the present investigation, we wish to report the structure of a homologous salt, containing the complex anion adopting the cis-geometry and protonated pyridinium as a counter cation. This cis-anion which is somewhat less common has been observed in a similar organic-inorganic hybrid salt, with 2-amino-5-chloropyridinium as the organic cation (Chérif, Abdelhak et al., 2012).

The asymmetric unit of the title compound, (C5H6N)[Cr(C2O4)2(H2O)2] which crstallizes in space group P21/c, is shown in Fig. 1. The CrIII site in the complex anion has a distorted octahedral coordination environment build up by two O atoms (OW1, OW2) from two cis water molecules and four O atoms (O11, O12, O21, O22) from two chelating oxalate dianions. The main geometric parameters of the (C5H6N)+ cation are in agreement with those found in salts with similar cationic entities (Bélombé et al., 2009; Nenwa et al., 2010; Nenwa et al., 2012; Chérif et al., 2011; Chérif, Abdelhak et al., 2012; Chérif, Zid et al., 2012). The bond distances in the complex anion (Table 1) are comparable with those reported in the 2-amino-5-chloropyridinium compound (Chérif, Abdelhak et al., 2012). The crystal packing is stabilized by intermolecular N—H···O (oxalate) and O—H···O (oxalate) hydrogen bonds and by ππ stacking interactions [centroid-centroid distance = 3.602 Å] between pyridine rings, thereby building up a three-dimensional network (Table 2, Fig. 2).

Related literature top

For the structural characterization of organic–inorganic salts containing the [Cr(C2O4)2(H2O)2]- anion, see: Bélombé et al. (2009); Nenwa et al. (2010, 2012); Chérif et al. (2011); Chérif, Abdelhak et al. (2012); Chérif, Zid et al. (2012).

Experimental top

Pyridine (1 mmol, 79.1 mg) and oxalic acid (2 mmol, 260 mg) were added in successive small portions in an aqueous solution (50 ml) of CrCl3.6H2O (1 mmol, 266.5 mg). The mixture was stirred for 4 h continuously. The final blue-violet solution obtained was left at room temperature and violet crystals suitable for X-ray diffraction were obtained after a few days.

Refinement top

The H atoms were positioned geometrically, with C—H, N—H distances of 0.95 and 0.86 Å respectively, and constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C,N). The water H atoms were initially located in a difference Fourier map and refined with distance restraints of d(O–H1) = 0.83 (2) with all Uiso(H) values refined.

Computing details top

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2010); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound with displacement ellipsoids drawn at the 50% probability level.
[Figure 2] Fig. 2. Crystal packing of the title compound, showing the components linked via N–H···O and O–H···O hydrogen bonds (dashed lines) forming a three-dimensional network. ππ stacking between the protonated pyridine rings is also observed.
Pyridinium cis-diaquabis(oxalato-κ2O,O')chromate(III) top
Crystal data top
(C5H6N)[Cr(C2O4)2(H2O)2]F(000) = 700
Mr = 344.18Dx = 1.842 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P_2ybcCell parameters from 3703 reflections
a = 7.479 (2) Åθ = 1.7–30.9°
b = 24.700 (8) ŵ = 0.98 mm1
c = 7.056 (2) ÅT = 100 K
β = 107.744 (6)°Needle, violet
V = 1241.4 (6) Å30.15 × 0.04 × 0.04 mm
Z = 4
Data collection top
Bruker SMART APEX CCD
diffractometer
3703 independent reflections
Radiation source: fine-focus sealed tube2580 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.106
ϕ and ω scansθmax = 30.9°, θmin = 1.7°
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
h = 1010
Tmin = 0.862, Tmax = 0.961k = 3433
18649 measured reflectionsl = 910
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.061Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.160H atoms treated by a mixture of independent and constrained refinement
S = 1.13 w = 1/[σ2(Fo2) + (0.0636P)2]
where P = (Fo2 + 2Fc2)/3
3703 reflections(Δ/σ)max = 0.001
206 parametersΔρmax = 0.59 e Å3
5 restraintsΔρmin = 0.69 e Å3
Crystal data top
(C5H6N)[Cr(C2O4)2(H2O)2]V = 1241.4 (6) Å3
Mr = 344.18Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.479 (2) ŵ = 0.98 mm1
b = 24.700 (8) ÅT = 100 K
c = 7.056 (2) Å0.15 × 0.04 × 0.04 mm
β = 107.744 (6)°
Data collection top
Bruker SMART APEX CCD
diffractometer
3703 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
2580 reflections with I > 2σ(I)
Tmin = 0.862, Tmax = 0.961Rint = 0.106
18649 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0615 restraints
wR(F2) = 0.160H atoms treated by a mixture of independent and constrained refinement
S = 1.13Δρmax = 0.59 e Å3
3703 reflectionsΔρmin = 0.69 e Å3
206 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cr10.00150 (8)0.67285 (2)0.06297 (8)0.00840 (15)
C110.3839 (5)0.67581 (15)0.0409 (5)0.0119 (7)
C120.3217 (5)0.73552 (14)0.0479 (5)0.0099 (7)
C210.0773 (5)0.61425 (14)0.2335 (5)0.0110 (7)
C220.1456 (5)0.57906 (15)0.0428 (5)0.0120 (7)
O110.2502 (3)0.64143 (10)0.0020 (4)0.0113 (5)
O120.1425 (3)0.74032 (10)0.0051 (4)0.0105 (5)
O130.4367 (4)0.77229 (11)0.0905 (4)0.0177 (6)
O140.5518 (4)0.66425 (11)0.0766 (4)0.0170 (6)
O210.0065 (3)0.65975 (10)0.2098 (4)0.0113 (5)
O220.1238 (4)0.60185 (10)0.1125 (4)0.0118 (5)
O230.0948 (4)0.59673 (10)0.3912 (4)0.0137 (5)
O240.2113 (4)0.53428 (11)0.0504 (4)0.0186 (6)
OW10.0262 (4)0.67909 (11)0.3493 (4)0.0139 (5)
OW20.2371 (4)0.71532 (11)0.1053 (4)0.0139 (5)
N10.2547 (4)0.48994 (13)0.3963 (5)0.0148 (6)
H10.20810.51520.34190.018*
C20.3312 (6)0.44697 (16)0.2871 (6)0.0177 (8)
H20.33200.44460.15530.021*
C30.2476 (5)0.49522 (15)0.5870 (6)0.0147 (7)
H30.19270.52560.65900.018*
C40.3220 (6)0.45543 (16)0.6751 (6)0.0172 (8)
H40.31640.45830.80820.021*
C50.4083 (5)0.40652 (15)0.3686 (6)0.0180 (8)
H50.46180.37650.29300.022*
C60.4059 (5)0.41073 (16)0.5641 (6)0.0161 (8)
H60.45990.38390.62120.019*
H1B0.019 (6)0.6988 (17)0.415 (6)0.032 (15)*
H2A0.310 (5)0.721 (2)0.214 (4)0.033 (15)*
H1A0.051 (8)0.6501 (17)0.419 (9)0.06 (2)*
H2B0.296 (6)0.700 (2)0.040 (6)0.06 (2)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cr10.0108 (3)0.0067 (3)0.0083 (3)0.0012 (2)0.0037 (2)0.0006 (2)
C110.0116 (16)0.0135 (17)0.0112 (17)0.0003 (13)0.0043 (13)0.0004 (14)
C120.0122 (16)0.0114 (16)0.0052 (16)0.0005 (13)0.0015 (13)0.0007 (12)
C210.0141 (17)0.0108 (17)0.0102 (17)0.0011 (13)0.0065 (14)0.0005 (13)
C220.0157 (17)0.0120 (17)0.0095 (17)0.0011 (13)0.0056 (14)0.0046 (14)
O110.0123 (12)0.0093 (12)0.0129 (13)0.0006 (9)0.0048 (10)0.0011 (9)
O120.0116 (12)0.0086 (12)0.0110 (13)0.0004 (9)0.0031 (10)0.0003 (9)
O130.0148 (13)0.0116 (13)0.0250 (16)0.0046 (10)0.0035 (11)0.0026 (11)
O140.0128 (12)0.0175 (14)0.0222 (15)0.0043 (10)0.0073 (11)0.0070 (11)
O210.0132 (12)0.0094 (12)0.0123 (13)0.0012 (9)0.0053 (10)0.0014 (9)
O220.0187 (13)0.0109 (13)0.0074 (12)0.0035 (10)0.0061 (10)0.0021 (10)
O230.0205 (13)0.0112 (13)0.0109 (13)0.0017 (10)0.0069 (10)0.0004 (10)
O240.0351 (16)0.0092 (13)0.0144 (14)0.0103 (11)0.0119 (12)0.0024 (10)
OW10.0217 (14)0.0106 (13)0.0106 (13)0.0050 (11)0.0069 (11)0.0003 (10)
OW20.0108 (12)0.0163 (14)0.0150 (14)0.0020 (10)0.0044 (11)0.0048 (11)
N10.0198 (16)0.0104 (15)0.0167 (16)0.0004 (12)0.0090 (13)0.0021 (12)
C20.028 (2)0.0151 (19)0.0117 (18)0.0035 (16)0.0091 (16)0.0003 (14)
C30.0166 (18)0.0114 (17)0.0139 (18)0.0028 (13)0.0013 (14)0.0026 (14)
C40.024 (2)0.0173 (19)0.0100 (18)0.0015 (15)0.0040 (15)0.0013 (14)
C50.024 (2)0.0083 (17)0.019 (2)0.0024 (14)0.0037 (16)0.0042 (14)
C60.0199 (19)0.0129 (18)0.017 (2)0.0007 (14)0.0068 (15)0.0062 (14)
Geometric parameters (Å, º) top
Cr1—O111.959 (3)OW1—H1B0.814 (19)
Cr1—O221.960 (3)OW1—H1A0.86 (5)
Cr1—O121.963 (3)OW2—H2A0.806 (19)
Cr1—O211.963 (3)OW2—H2B0.818 (19)
Cr1—OW11.978 (3)N1—C21.334 (5)
Cr1—OW21.993 (3)N1—C31.337 (5)
C11—O141.237 (4)N1—H10.8600
C11—O111.276 (4)C2—C51.365 (5)
C11—C121.552 (5)C2—H20.9300
C12—O131.224 (4)C3—C41.369 (5)
C12—O121.286 (4)C3—H30.9300
C21—O231.238 (4)C4—C61.388 (5)
C21—O211.275 (4)C4—H40.9300
C21—C221.552 (5)C5—C61.378 (6)
C22—O241.218 (4)C5—H50.9300
C22—O221.285 (4)C6—H60.9300
O11—Cr1—O2292.85 (11)C12—O12—Cr1115.7 (2)
O11—Cr1—O1282.18 (10)C21—O21—Cr1114.0 (2)
O22—Cr1—O12174.30 (11)C22—O22—Cr1114.4 (2)
O11—Cr1—O2191.36 (11)Cr1—OW1—H1B135 (3)
O22—Cr1—O2183.09 (11)Cr1—OW1—H1A117 (4)
O12—Cr1—O2194.19 (11)H1B—OW1—H1A103 (4)
O11—Cr1—OW192.26 (11)Cr1—OW2—H2A123 (4)
O22—Cr1—OW189.69 (11)Cr1—OW2—H2B106 (4)
O12—Cr1—OW193.28 (11)H2A—OW2—H2B107 (3)
O21—Cr1—OW1172.08 (11)C2—N1—C3122.5 (3)
O11—Cr1—OW2171.04 (11)C2—N1—H1118.8
O22—Cr1—OW295.79 (11)C3—N1—H1118.8
O12—Cr1—OW289.07 (11)N1—C2—C5120.1 (4)
O21—Cr1—OW287.33 (11)N1—C2—H2120.0
OW1—Cr1—OW290.17 (12)C5—C2—H2120.0
O14—C11—O11124.7 (3)N1—C3—C4119.4 (3)
O14—C11—C12120.6 (3)N1—C3—H3120.3
O11—C11—C12114.8 (3)C4—C3—H3120.3
O13—C12—O12126.4 (3)C3—C4—C6119.4 (4)
O13—C12—C11121.2 (3)C3—C4—H4120.3
O12—C12—C11112.4 (3)C6—C4—H4120.3
O23—C21—O21126.0 (3)C2—C5—C6119.2 (4)
O23—C21—C22119.1 (3)C2—C5—H5120.4
O21—C21—C22114.9 (3)C6—C5—H5120.4
O24—C22—O22126.3 (3)C5—C6—C4119.4 (4)
O24—C22—C21120.1 (3)C5—C6—H6120.3
O22—C22—C21113.6 (3)C4—C6—H6120.3
C11—O11—Cr1114.8 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O240.862.102.783 (4)136
N1—H1···O230.862.172.901 (4)143
OW1—H1B···O12i0.81 (2)1.94 (2)2.720 (4)162 (5)
OW1—H1A···O23ii0.86 (5)1.84 (5)2.680 (4)168 (5)
OW2—H2A···O13iii0.81 (2)1.98 (3)2.732 (4)154 (4)
OW2—H2B···O14iv0.82 (2)1.83 (2)2.639 (4)173 (5)
Symmetry codes: (i) x, y+3/2, z+1/2; (ii) x, y, z+1; (iii) x+1, y+3/2, z+1/2; (iv) x+1, y, z.

Experimental details

Crystal data
Chemical formula(C5H6N)[Cr(C2O4)2(H2O)2]
Mr344.18
Crystal system, space groupMonoclinic, P21/c
Temperature (K)100
a, b, c (Å)7.479 (2), 24.700 (8), 7.056 (2)
β (°) 107.744 (6)
V3)1241.4 (6)
Z4
Radiation typeMo Kα
µ (mm1)0.98
Crystal size (mm)0.15 × 0.04 × 0.04
Data collection
DiffractometerBruker SMART APEX CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2004)
Tmin, Tmax0.862, 0.961
No. of measured, independent and
observed [I > 2σ(I)] reflections
18649, 3703, 2580
Rint0.106
(sin θ/λ)max1)0.723
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.061, 0.160, 1.13
No. of reflections3703
No. of parameters206
No. of restraints5
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.59, 0.69

Computer programs: SMART (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2010), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O240.862.102.783 (4)135.5
N1—H1···O230.862.172.901 (4)142.5
OW1—H1B···O12i0.814 (19)1.94 (2)2.720 (4)162 (5)
OW1—H1A···O23ii0.86 (5)1.84 (5)2.680 (4)168 (5)
OW2—H2A···O13iii0.806 (19)1.98 (3)2.732 (4)154 (4)
OW2—H2B···O14iv0.818 (19)1.83 (2)2.639 (4)173 (5)
Symmetry codes: (i) x, y+3/2, z+1/2; (ii) x, y, z+1; (iii) x+1, y+3/2, z+1/2; (iv) x+1, y, z.
 

Acknowledgements

The authors thank Prof. Barthelemy Nyasse (Organic Chemistry Department, University of Yaounde I) for the donation of pyridine and Tobias Storp (RWTH Aachen) for his technical support during X-ray experiments.

References

First citationBélombé, M. M., Nenwa, J. & Emmerling, F. (2009). Z. Kristallogr. New Cryst. Struct. 224, 239–240.  Google Scholar
First citationBrandenburg, K. (2010). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBruker (2004). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationChérif, I., Abdelhak, J., Zid, M. F. & Driss, A. (2011). Acta Cryst. E67, m1648–m1649.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationChérif, I., Abdelhak, J., Zid, M. F. & Driss, A. (2012). Acta Cryst. E68, m824–m825.  CSD CrossRef IUCr Journals Google Scholar
First citationChérif, I., Zid, M. F., El-Ghozzi, M. & Avignant, D. (2012). Acta Cryst. E68, m900– m901.  CSD CrossRef IUCr Journals Google Scholar
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
First citationNenwa, J., Bebga, G., Martin, S., Bélombé, M. M., Mbarki, M. & Fokwa, B. P. T. (2012). Acta Cryst. E68, m1325–m1326.  CSD CrossRef CAS IUCr Journals Google Scholar
First citationNenwa, J., Belombe, M. M., Ngoune, J. & Fokwa, B. P. T. (2010). Acta Cryst. E66, m1410.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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