supplementary materials


hb7141 scheme

Acta Cryst. (2013). E69, m567    [ doi:10.1107/S1600536813026135 ]

Pyridinium trans-diaquabis[oxalato(2-)-[kappa]2O1,O2]chromate(III) urea monosolvate

G. Bebga, M. Signé, J. Nenwa, M. Mbarki and B. P. T. Fokwa

Abstract top

The asymmetric unit of the title solvated molecular salt, (C5H6N)[Cr(C2O4)2(H2O)2]·CO(NH2)2, contains half a formula unit. Each component is completed by crystallographic twofold symmetry: in the cation, one C and the N atom lie on the rotation axis; in the anion, the CrIII ion lies on the axis; in the solvent molecule, the C and the O atom lie on the axis. The aqua ligands are in a trans disposition in the resulting CrO6 octahedron. In the crystal, the components are linked by O-H...O, N-H...O and N-H...(O,O) hydrogen bonds, generating a three-dimensional network.

Comment top

Recently, the crystal structures of some salts involving organic cations and the complex anion [Cr(C2O4)2(H2O)2]-, have been reported (Bélombé et al.,2009; Nenwa et al., 2010; Chérif, Zidet al., 2012; Chérif, Abdelhak et al., 2012; Nenwa, Gouet et al. 2012). We now report the structure of the title compound, with the organic cation, pyridinium, the trans-diaquabis(oxalate)chromate(III) complex anion and the urea molecule which replaces the fraction of water molecule of crystallization in the previously described structures (Chérif et al., 2011; Chérif, Abdelhak et al.,2012; Dridi et al., 2013).

The constituents of the title compound are shown in Fig.1. It appears to be the first member of salts with general formula Am[M(C2O4)2(H2O)2].xOC(NH2)2; where A = organic cation, M = metal(II) or metal(III), m = 1 or 2 and x 0. The asymmetric unit is formed by a pyridinium cation, a [Cr(C2O4)2(H2O)2] anionic complex in trans-aqua configuration and one urea molecule. The chromium (III) ion lies on a twofold axis and is six-coordinated in a distorted octahedral geometry defined by four O atoms from two chelating bidendate oxalate anions in the equatorial plane and by two O atoms from two apical aqua ligands. The equatorial Cr–O(oxalate) distances, 1.9435 (13) Å and 1.9762 (13) Å, are slightly shorter than the axial Cr–O(water) one [1.9955 (15) Å]. These bond distances are similar to those observed in homologous complex salts (Bélombé et al., 2009; Nenwa et al., 2010; Chérif et al., 2011; Chérif, Abdelhak et al., 2012; Chérif, Abdelhak et al., 2012; Nenwa et al., 2012; Dridi et al., 2013).

The crystal structure can be described by a characteristic layered arrangement of the pyridinium cation, (C5H6N)+, the complex anion, [Cr(C2O4)2(H2O)2]-, and the urea molecule (Fig. 2). O–H···O and N–H···O hydrogen bonding interactions link the components (Fig.3).

Related literature top

For molecular salts containing the [Cr(C2O4)2(H2O)2]- anion, see: Bélombé et al. (2009); Nenwa et al. (2010, 2012); Chérif et al. (2011); Chérif, Zid et al. (2012); Chérif, Abdelhak et al. (2012); Dridi et al. (2013).

Experimental top

1 mmol (267 mg) of CrCl3·6H2O was dissolved in 50 ml of water. The green filtered solution was stirred at 323 K, 2 mmol (253 mg) of oxalic acid, 1 mmol (79.1 mg) of pyridine and 2 mmol (121 mg) of urea were added in successive small portions and stirred for 2 h. The resulting violet solution was left at room temperature; violet prisms were obtained after one week of slow evaporation.

Refinement top

The H atoms of the pyridimium cation were positioned geometrically, with C—H, N—H distances of 0.93 and 0.86 Å respectively, and constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C, N). The urea H atoms were located in a difference Fourier map and freely 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, 2012).

Figures top
[Figure 1] Fig. 1. Molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level.
[Figure 2] Fig. 2. Packing diagram of the title compound, viewed along the a axis, showing its layered structure.
[Figure 3] Fig. 3. Interconnection of the constituents of the title compound into a three-dimensional network. Hydrogen bonds are highlighted with dashed lines.
Pyridinium trans-diaquabis[oxalato(2-)-κ2O1,O2]chromate(III) urea monosolvate top
Crystal data top
(C5H6N)[Cr(C2O4)2(H2O)2]·CH4N2OZ = 4
Mr = 404.24F(000) = 828
Monoclinic, I2/aDx = 1.712 Mg m3
Hall symbol: -I 2yaMo Kα radiation, λ = 0.71073 Å
a = 7.6456 (7) ŵ = 0.80 mm1
b = 21.4096 (18) ÅT = 293 K
c = 9.7404 (12) ÅPrism, violet
β = 100.278 (1)°0.20 × 0.16 × 0.13 mm
V = 1568.8 (3) Å3
Data collection top
Bruker APEX CCD
diffractometer
2343 independent reflections
Radiation source: fine-focus sealed tube1980 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.032
ω scansθmax = 30.9°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
h = 1010
Tmin = 0.851, Tmax = 0.935k = 3030
11770 measured reflectionsl = 1314
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)] = 0.041Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.111H atoms treated by a mixture of independent and constrained refinement
S = 1.10 w = 1/[σ2(Fo2) + (0.0515P)2 + 1.3542P]
where P = (Fo2 + 2Fc2)/3
2343 reflections(Δ/σ)max < 0.001
132 parametersΔρmax = 0.30 e Å3
5 restraintsΔρmin = 0.56 e Å3
Crystal data top
(C5H6N)[Cr(C2O4)2(H2O)2]·CH4N2OV = 1568.8 (3) Å3
Mr = 404.24Z = 4
Monoclinic, I2/aMo Kα radiation
a = 7.6456 (7) ŵ = 0.80 mm1
b = 21.4096 (18) ÅT = 293 K
c = 9.7404 (12) Å0.20 × 0.16 × 0.13 mm
β = 100.278 (1)°
Data collection top
Bruker APEX CCD
diffractometer
2343 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
1980 reflections with I > 2σ(I)
Tmin = 0.851, Tmax = 0.935Rint = 0.032
11770 measured reflectionsθmax = 30.9°
Refinement top
R[F2 > 2σ(F2)] = 0.041H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.111Δρmax = 0.30 e Å3
S = 1.10Δρmin = 0.56 e Å3
2343 reflectionsAbsolute structure: ?
132 parametersAbsolute structure parameter: ?
5 restraintsRogers parameter: ?
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
Cr40.25000.223340 (17)0.00000.02410 (13)
O10.45417 (19)0.22672 (6)0.10198 (14)0.0315 (3)
O20.35892 (18)0.15558 (6)0.11799 (13)0.0324 (3)
O30.14209 (17)0.29281 (6)0.11952 (12)0.0288 (3)
O40.1309 (2)0.39675 (7)0.12681 (15)0.0436 (4)
O50.3604 (2)0.05182 (7)0.13176 (16)0.0498 (4)
C10.1842 (2)0.34777 (8)0.07105 (17)0.0285 (3)
C20.3134 (3)0.10049 (8)0.07197 (18)0.0319 (4)
N10.75000.48039 (15)0.00000.0622 (8)
H10.75000.52060.00000.075*
C30.8444 (3)0.38759 (15)0.1108 (3)0.0576 (7)
H30.90990.36680.18680.069*
C40.75000.35421 (17)0.00000.0527 (8)
H40.75000.31080.00000.063*
C50.8402 (4)0.45021 (15)0.1071 (3)0.0594 (7)
H50.90230.47270.18190.071*
O60.75000.17120 (9)0.00000.0388 (4)
N20.6418 (3)0.08022 (9)0.0971 (2)0.0447 (4)
C60.75000.11234 (13)0.00000.0326 (5)
H2A0.584 (3)0.0960 (12)0.168 (2)0.055 (8)*
H2B0.649 (4)0.0435 (8)0.092 (3)0.061 (9)*
H1B0.434 (3)0.2215 (11)0.1855 (17)0.049 (8)*
H1A0.544 (3)0.2077 (11)0.071 (2)0.053 (8)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cr40.0280 (2)0.0240 (2)0.01765 (18)0.0000.00312 (13)0.000
O10.0307 (7)0.0389 (7)0.0229 (6)0.0050 (5)0.0004 (5)0.0009 (5)
O20.0385 (7)0.0280 (6)0.0259 (6)0.0010 (5)0.0071 (5)0.0020 (5)
O30.0334 (6)0.0290 (6)0.0213 (5)0.0013 (5)0.0020 (5)0.0010 (4)
O40.0565 (9)0.0310 (7)0.0391 (8)0.0071 (6)0.0026 (7)0.0067 (6)
O50.0713 (11)0.0278 (7)0.0433 (8)0.0053 (7)0.0084 (8)0.0046 (6)
C10.0313 (9)0.0293 (8)0.0245 (8)0.0015 (6)0.0043 (6)0.0013 (6)
C20.0358 (9)0.0303 (8)0.0272 (8)0.0024 (7)0.0014 (7)0.0024 (6)
N10.069 (2)0.0486 (17)0.071 (2)0.0000.0156 (17)0.000
C30.0445 (13)0.0814 (19)0.0409 (12)0.0074 (12)0.0084 (10)0.0166 (12)
C40.0477 (19)0.0471 (18)0.062 (2)0.0000.0057 (16)0.000
C50.0567 (15)0.0726 (18)0.0456 (13)0.0166 (13)0.0001 (11)0.0139 (12)
O60.0303 (9)0.0295 (9)0.0514 (12)0.0000.0067 (8)0.000
N20.0520 (11)0.0336 (9)0.0434 (10)0.0022 (8)0.0052 (8)0.0043 (8)
C60.0291 (12)0.0338 (12)0.0346 (12)0.0000.0052 (10)0.000
Geometric parameters (Å, º) top
Cr4—O2i1.9436 (12)N1—C5ii1.313 (3)
Cr4—O21.9436 (12)N1—C51.313 (3)
Cr4—O3i1.9762 (12)N1—H10.8600
Cr4—O31.9762 (12)C3—C51.341 (4)
Cr4—O11.9955 (14)C3—C41.385 (3)
Cr4—O1i1.9955 (14)C3—H30.9300
O1—H1B0.808 (16)C4—C3ii1.385 (3)
O1—H1A0.808 (16)C4—H40.9300
O2—C21.287 (2)C5—H50.9300
O3—C11.287 (2)O6—C61.260 (3)
O4—C11.217 (2)N2—C61.331 (2)
O5—C21.216 (2)N2—H2A0.821 (17)
C1—C1i1.559 (3)N2—H2B0.788 (17)
C2—C2i1.556 (3)C6—N2ii1.331 (2)
O2i—Cr4—O283.43 (7)O3—C1—C1i113.91 (9)
O2i—Cr4—O3i179.29 (5)O5—C2—O2125.43 (17)
O2—Cr4—O3i97.10 (5)O5—C2—C2i120.99 (11)
O2i—Cr4—O397.10 (5)O2—C2—C2i113.59 (9)
O2—Cr4—O3179.29 (5)C5ii—N1—C5121.0 (4)
O3i—Cr4—O382.36 (7)C5ii—N1—H1119.5
O2i—Cr4—O191.34 (6)C5—N1—H1119.5
O2—Cr4—O191.76 (6)C5—C3—C4119.2 (2)
O3i—Cr4—O189.11 (5)C5—C3—H3120.4
O3—Cr4—O187.76 (5)C4—C3—H3120.4
O2i—Cr4—O1i91.76 (6)C3—C4—C3ii117.9 (4)
O2—Cr4—O1i91.34 (6)C3—C4—H4121.1
O3i—Cr4—O1i87.76 (5)C3ii—C4—H4121.1
O3—Cr4—O1i89.11 (5)N1—C5—C3121.3 (3)
O1—Cr4—O1i175.84 (8)N1—C5—H5119.3
Cr4—O1—H1B117.8 (19)C3—C5—H5119.3
Cr4—O1—H1A119.1 (19)C6—N2—H2A124 (2)
H1B—O1—H1A108 (2)C6—N2—H2B116 (2)
C2—O2—Cr4114.66 (11)H2A—N2—H2B119 (3)
C1—O3—Cr4114.90 (10)O6—C6—N2121.10 (13)
O4—C1—O3125.58 (16)O6—C6—N2ii121.10 (13)
O4—C1—C1i120.51 (11)N2—C6—N2ii117.8 (3)
Symmetry codes: (i) x+1/2, y, z; (ii) x+3/2, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O4iii0.862.262.979 (3)142
N1—H1···O4iv0.862.262.979 (3)142
N2—H2A···O4v0.82 (2)2.36 (2)3.134 (2)158 (3)
N2—H2B···O5vi0.79 (2)2.08 (2)2.847 (2)166 (3)
O1—H1B···O3v0.81 (2)1.91 (2)2.7135 (18)174 (3)
O1—H1A···O60.81 (2)1.79 (2)2.5910 (16)176 (3)
Symmetry codes: (iii) x+1, y+1, z; (iv) x+1/2, y+1, z; (v) x+1/2, y+1/2, z1/2; (vi) x+1, y, z.
Selected bond lengths (Å) top
Cr4—O21.9436 (12)Cr4—O11.9955 (14)
Cr4—O31.9762 (12)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O4i0.862.262.979 (3)142
N1—H1···O4ii0.862.262.979 (3)142
N2—H2A···O4iii0.821 (17)2.357 (19)3.134 (2)158 (3)
N2—H2B···O5iv0.788 (17)2.077 (19)2.847 (2)166 (3)
O1—H1B···O3iii0.808 (16)1.909 (16)2.7135 (18)174 (3)
O1—H1A···O60.808 (16)1.785 (16)2.5910 (16)176 (3)
Symmetry codes: (i) x+1, y+1, z; (ii) x+1/2, y+1, z; (iii) x+1/2, y+1/2, z1/2; (iv) x+1, y, z.
Acknowledgements top

The authors thank Tobias Storp (RWTH Aachen) for his technical support during the X-ray experiments.

references
References top

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