supplementary materials


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Acta Cryst. (2012). E68, m389    [ doi:10.1107/S1600536812009506 ]

Ammonium imidazolium dichromate

R.-Q. Zhu

Abstract top

In the crystal structure of the title compound, (C3H5N2)(NH4)[Cr2O7], the anions and cations are linked through N-H...O hydrogen bonds, resulting in a three-dimensional structure which contains three kinds of layers parallel to (001). One layer contains imidazole cations, the other two layers the ammonium cations and dichromate anions. The dichromate anion has an eclipsed conformation with a dihedral angle of 14.65 (18)° between the mean planes of the O-P-O-P-O backbone.

Comment top

We synthesized the title compound to find ferroelectric material by dielectric measurements of compound as a function of temperature(Fu et al., 2009; Ye et al., 2006; Zhang et al., 2008; Zhang et al., 2010). In the range from 190 K to near its melting point (m.p. >370 K), no dielectric anomaly was observed.

A view of the title compound is shown in Fig.1. The structure is consolidated by multiple intermolecular and intramolecular hydrogen bonds between N and O. This hydrogen bondings (table 1, Fig.2) produces a three-dimensional net work. The N···O distances of the hydrogen bonding are in the range of 2.827 (4) – 3.011 (4) for table 1. Hydrogen bonding is the most reliable desigen element in the non-covalent assembly of molecules with donor and accept functionalities, and as such it is the most important interaction in crystal engineering (Bernstein et al., 1995).

Related literature top

The title compound was synthesized as part of a search for ferroelectric materials. For general background to ferroelectric metal-organic frameworks, see: Fu et al. (2009); Ye et al. (2006); Zhang et al. (2008, 2010). For graph-set motifs, see: Bernstein et al. (1995).

Experimental top

A mixture of imidazole (0.68 g, 10 mmol), ammonium dichromate (2.5 g, 10 mmol) in water was stirred for several days at ambient temperature, red sheet crystals were obtained.

Refinement top

Hydrogen atom positions were calculated and allowed to ride on their parent atoms with aromtic C–H = 0.93 Å and N–H = 0.86 Å, and with Uĩso(H)=1.2Ueq(C or N).The H atoms on N1 were freely refined.

Computing details top

Data collection: CrystalClear (Rigaku,2005); cell refinement: CrystalClear (Rigaku,2005); data reduction: CrystalClear (Rigaku,2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, with the displacement ellipsoids drawn at the 30% probability level.
[Figure 2] Fig. 2. Packing diagram of the title compound, showing the structure along the a axis. Hydrogen bonds are shown as dashed lines.
Ammonium imidazolium dichromate top
Crystal data top
(C3H5N2)(NH4)[Cr2O7]F(000) = 608
Mr = 303.13Dx = 2.004 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 2297 reflections
a = 5.6260 (11) Åθ = 3.1–27.5°
b = 8.2749 (17) ŵ = 2.18 mm1
c = 21.593 (4) ÅT = 293 K
β = 91.90 (3)°Plane, red
V = 1004.7 (3) Å30.32 × 0.27 × 0.22 mm
Z = 4
Data collection top
Rigaku SCXmini
diffractometer
2297 independent reflections
Radiation source: fine-focus sealed tube1907 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.047
CCD Profile fitting scansθmax = 27.5°, θmin = 3.1°
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2005)
h = 77
Tmin = 0.502, Tmax = 0.618k = 1010
10091 measured reflectionsl = 2827
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)] = 0.037Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.085H atoms treated by a mixture of independent and constrained refinement
S = 1.09 w = 1/[σ2(Fo2) + (0.0321P)2 + 0.944P]
where P = (Fo2 + 2Fc2)/3
2297 reflections(Δ/σ)max < 0.001
152 parametersΔρmax = 0.34 e Å3
0 restraintsΔρmin = 0.52 e Å3
Crystal data top
(C3H5N2)(NH4)[Cr2O7]V = 1004.7 (3) Å3
Mr = 303.13Z = 4
Monoclinic, P21/cMo Kα radiation
a = 5.6260 (11) ŵ = 2.18 mm1
b = 8.2749 (17) ÅT = 293 K
c = 21.593 (4) Å0.32 × 0.27 × 0.22 mm
β = 91.90 (3)°
Data collection top
Rigaku SCXmini
diffractometer
1907 reflections with I > 2σ(I)
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2005)
Rint = 0.047
Tmin = 0.502, Tmax = 0.618θmax = 27.5°
10091 measured reflectionsStandard reflections: ?
2297 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.037H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.085Δρmax = 0.34 e Å3
S = 1.09Δρmin = 0.52 e Å3
2297 reflectionsAbsolute structure: ?
152 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > σ(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
C10.3469 (6)0.7554 (4)0.06526 (17)0.0396 (8)
H1A0.23450.74470.09560.048*
C20.6599 (6)0.8268 (4)0.01522 (17)0.0390 (8)
H2A0.80340.87570.00600.047*
C30.5350 (7)0.7289 (5)0.02122 (18)0.0473 (9)
H3A0.57250.69650.06100.057*
N10.5234 (6)0.7387 (4)0.24161 (17)0.0325 (6)
N20.5405 (5)0.8437 (4)0.06922 (14)0.0437 (7)
H2B0.58510.90230.10040.052*
N30.3399 (5)0.6843 (3)0.01056 (15)0.0449 (8)
H3B0.22990.62000.00300.054*
O10.0282 (4)0.9810 (3)0.42701 (10)0.0378 (5)
O20.0350 (5)1.1228 (3)0.31828 (11)0.0422 (6)
O30.3641 (4)0.9650 (3)0.34399 (12)0.0429 (6)
O40.0528 (4)0.7910 (2)0.32273 (11)0.0375 (5)
O50.0001 (5)0.5720 (3)0.41884 (11)0.0458 (6)
O60.2197 (4)0.4834 (3)0.31508 (12)0.0425 (6)
O70.2496 (4)0.5232 (3)0.32071 (11)0.0415 (6)
Cr10.08035 (8)0.97044 (5)0.35383 (2)0.02452 (14)
Cr20.00312 (8)0.58625 (5)0.34477 (2)0.02334 (14)
H1B0.439 (8)0.692 (6)0.264 (2)0.066 (16)*
H1C0.644 (9)0.783 (6)0.256 (2)0.081 (18)*
H1D0.556 (8)0.677 (6)0.221 (2)0.051 (15)*
H1E0.439 (8)0.796 (6)0.226 (2)0.059 (15)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0366 (18)0.0382 (19)0.044 (2)0.0071 (15)0.0056 (15)0.0040 (16)
C20.0287 (16)0.0377 (18)0.051 (2)0.0066 (14)0.0055 (15)0.0081 (16)
C30.051 (2)0.051 (2)0.040 (2)0.0087 (18)0.0061 (17)0.0013 (18)
N10.0337 (17)0.0280 (16)0.0357 (17)0.0060 (14)0.0008 (14)0.0038 (14)
N20.0505 (18)0.0362 (16)0.0438 (18)0.0065 (14)0.0080 (14)0.0024 (13)
N30.0370 (16)0.0365 (16)0.060 (2)0.0108 (13)0.0108 (14)0.0028 (15)
O10.0463 (13)0.0415 (13)0.0256 (11)0.0090 (11)0.0029 (10)0.0019 (10)
O20.0659 (16)0.0254 (11)0.0352 (13)0.0112 (11)0.0000 (11)0.0048 (10)
O30.0323 (12)0.0482 (14)0.0485 (15)0.0032 (11)0.0072 (11)0.0030 (12)
O40.0465 (13)0.0199 (10)0.0452 (14)0.0002 (9)0.0130 (11)0.0003 (9)
O50.0538 (15)0.0505 (15)0.0334 (13)0.0077 (12)0.0042 (11)0.0057 (11)
O60.0324 (12)0.0254 (11)0.0686 (17)0.0075 (9)0.0132 (11)0.0037 (11)
O70.0290 (12)0.0459 (14)0.0501 (15)0.0066 (10)0.0109 (11)0.0050 (11)
Cr10.0307 (3)0.0190 (2)0.0239 (3)0.00146 (18)0.00126 (19)0.00066 (18)
Cr20.0199 (2)0.0209 (2)0.0292 (3)0.00099 (17)0.00006 (18)0.00220 (18)
Geometric parameters (Å, º) top
C1—N21.312 (4)N1—H1E0.74 (5)
C1—N31.319 (5)N2—H2B0.8600
C1—H1A0.9300N3—H3B0.8600
C2—C31.316 (5)O1—Cr11.619 (2)
C2—N21.372 (5)O2—Cr11.602 (2)
C2—H2A0.9300O3—Cr11.618 (2)
C3—N31.364 (5)O4—Cr21.779 (2)
C3—H3A0.9300O4—Cr11.784 (2)
N1—H1B0.79 (5)O5—Cr21.603 (2)
N1—H1C0.83 (5)O6—Cr21.602 (2)
N1—H1D0.71 (5)O7—Cr21.616 (2)
N2—C1—N3107.8 (3)C2—N2—H2B125.8
N2—C1—H1A126.1C1—N3—C3109.2 (3)
N3—C1—H1A126.1C1—N3—H3B125.4
C3—C2—N2107.7 (3)C3—N3—H3B125.4
C3—C2—H2A126.1Cr2—O4—Cr1129.15 (13)
N2—C2—H2A126.1O2—Cr1—O3110.17 (13)
C2—C3—N3106.8 (3)O2—Cr1—O1109.98 (12)
C2—C3—H3A126.6O3—Cr1—O1109.94 (13)
N3—C3—H3A126.6O2—Cr1—O4108.44 (11)
H1B—N1—H1C119 (5)O3—Cr1—O4109.34 (12)
H1B—N1—H1D102 (5)O1—Cr1—O4108.94 (12)
H1C—N1—H1D110 (5)O6—Cr2—O5110.06 (14)
H1B—N1—H1E102 (4)O6—Cr2—O7111.42 (13)
H1C—N1—H1E113 (5)O5—Cr2—O7108.47 (13)
H1D—N1—H1E110 (5)O6—Cr2—O4106.74 (11)
C1—N2—C2108.5 (3)O5—Cr2—O4109.46 (12)
C1—N2—H2B125.8O7—Cr2—O4110.69 (12)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2B···O7i0.862.163.011 (4)170
N3—H3B···O1ii0.862.042.827 (4)152
N1—H1B···O70.79 (5)2.16 (5)2.940 (4)169 (5)
N1—H1C···O4iii0.83 (5)2.19 (5)2.943 (4)151 (5)
N1—H1D···O3iv0.71 (5)2.29 (5)3.004 (5)176 (5)
N1—H1E···O6v0.74 (5)2.15 (5)2.895 (4)174 (5)
Symmetry codes: (i) x+1, y+1/2, z+1/2; (ii) x, y+3/2, z1/2; (iii) x+1, y, z; (iv) x+1, y1/2, z+1/2; (v) x, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2B···O7i0.862.163.011 (4)170
N3—H3B···O1ii0.862.042.827 (4)152
N1—H1B···O70.79 (5)2.16 (5)2.940 (4)169 (5)
N1—H1C···O4iii0.83 (5)2.19 (5)2.943 (4)151 (5)
N1—H1D···O3iv0.71 (5)2.29 (5)3.004 (5)176 (5)
N1—H1E···O6v0.74 (5)2.15 (5)2.895 (4)174 (5)
Symmetry codes: (i) x+1, y+1/2, z+1/2; (ii) x, y+3/2, z1/2; (iii) x+1, y, z; (iv) x+1, y1/2, z+1/2; (v) x, y+1/2, z+1/2.
Acknowledgements top

This work was supported by Southeast University.

references
References top

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