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The title compound, (C3H12N2)[Cr2O7], consists of a discrete dichromate anion with an eclipsed conformation and a propane-1,3-diammonium cation. Both kinds of ions have a mirror plane passing through the bridging O atom and the central methyl­ene C atom of the Cr2O72− and C3H12N22+ moieties, respectively. Anions and cations are alternately stacked to form columns parallel to the b axis. Ions are linked by intra- and inter-column hydrogen bonds of types N—H...O and C—H...O, involving O atoms of the dichromate anions as acceptors, and ammonium or methyl­ene groups as donors.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536812031042/bh2445sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536812031042/bh2445Isup2.hkl
Contains datablock I

CCDC reference: 896521

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.032
  • wR factor = 0.096
  • Data-to-parameter ratio = 35.2

checkCIF/PLATON results

No syntax errors found



Alert level B PLAT934_ALERT_3_B Number of (Iobs-Icalc)/SigmaW .gt. 10 Outliers . 1
Alert level C PLAT906_ALERT_3_C Large K value in the Analysis of Variance ...... 2.050 PLAT918_ALERT_3_C Reflection(s) # with I(obs) much smaller I(calc) 1
Alert level G PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF .... ? PLAT007_ALERT_5_G Note: Number of Unrefined D-H Atoms ............ 3 PLAT153_ALERT_1_G The su's on the Cell Axes are Equal .......... 0.00200 Ang. PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature 293 K PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature 293 K PLAT764_ALERT_4_G Overcomplete CIF Bond List Detected (Rep/Expd) . 1.33 Ratio
0 ALERT level A = Most likely a serious problem - resolve or explain 1 ALERT level B = A potentially serious problem, consider carefully 2 ALERT level C = Check. Ensure it is not caused by an omission or oversight 6 ALERT level G = General information/check it is not something unexpected 3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 3 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion 2 ALERT type 5 Informative message, check

Comment top

Hexavalent chromium is a predominant waste product of several metal finishing, petroleum refining and steel industries (Wani et al., 2007). It exists as chromate in basic and neutral medium and as dichromate in acidic environment.

In presence of 1,3-diaminopropane in water, the chromic acid is condensed into dichromate to form the hybrid title compound, (C3H12N2)Cr2O7. The observed molecular structure is depicted in Fig. 1. To counter-balance the electric charge of Cr2O72-, the used 1,3-diaminopropane has been doubly protonated. The title compound crystallizes in the orthorhombic Pnma space group, so that the dichromate anion and 1,3-diammoniumpropane should be symmetrical with respect to the symmetry plane (m). Owing of the passage of the latter through the bridging atoms O1 and C2 of Cr2O7 and C3H12N2 respectively, the asymmetric unit is built by one independent CrO4 group and the half of a 1,3-diammoniumpropane cation. The main geometrical features of Cr2O72- agree with those previously observed for this group in other compounds (Akriche & Rzaigui, 2009; Sieroń, 2007; Khadhrani et al., 2006).

The bond lengths and the angles within the cation are comparable with those observed in other 1,3-diammoniumpropane salts such as [C3H12N2]ZnCl4 (Kallel et al., 1980) and [C3H12N2](ClO4)2 (Pritchard et al., 1992). In this structure, the cations and anions are alternately stacked to form columns parallel to the axis b (Fig. 2). The electrostatic interactions and H-bonds intra and inter columns keep up the three-dimensional network cohesion. The established weak H-bonds (Brown, 1976; Blessing, 1986) of types N—H···O and C—H···O involve oxygen atoms of the dichromate anions as acceptors, and the protonated nitrogen atoms and carbon atoms of 1,3-diammoniumpropane as donors.

Related literature top

For related structures, see: Akriche & Rzaigui (2009); Sieroń (2007); Khadhrani et al. (2006); Kallel et al. (1980); Pritchard et al. (1992). For a discussion on hydrogen bonding, see: Brown (1976); Blessing (1986). For background on CrVI species as industrial waste, see: Wani et al. (2007).

Experimental top

Single crystals of the title compound were prepared at room temperature by dissolving CrO3 (0.10 g, 1 mmol) and 1,3-diaminopropane (0.07 g, 1 mmol) in distilled water (20 ml). The resulting solution was stirred during 30 min. and then evaporated slowly at room temperature until the formation of orange prismatic single crystals.

Refinement top

All H atoms attached to C and N atoms were fixed geometrically and treated as riding with C—H = 0.97 Å (methylene) and N—H = 0.89 Å. Isotropic displacement parameters for H atoms were calculated as Uiso(H) = 1.2Ueq(C) for CH2 groups and Uiso(H) = 1.5Ueq(N1) for the ammonium group.

Structure description top

Hexavalent chromium is a predominant waste product of several metal finishing, petroleum refining and steel industries (Wani et al., 2007). It exists as chromate in basic and neutral medium and as dichromate in acidic environment.

In presence of 1,3-diaminopropane in water, the chromic acid is condensed into dichromate to form the hybrid title compound, (C3H12N2)Cr2O7. The observed molecular structure is depicted in Fig. 1. To counter-balance the electric charge of Cr2O72-, the used 1,3-diaminopropane has been doubly protonated. The title compound crystallizes in the orthorhombic Pnma space group, so that the dichromate anion and 1,3-diammoniumpropane should be symmetrical with respect to the symmetry plane (m). Owing of the passage of the latter through the bridging atoms O1 and C2 of Cr2O7 and C3H12N2 respectively, the asymmetric unit is built by one independent CrO4 group and the half of a 1,3-diammoniumpropane cation. The main geometrical features of Cr2O72- agree with those previously observed for this group in other compounds (Akriche & Rzaigui, 2009; Sieroń, 2007; Khadhrani et al., 2006).

The bond lengths and the angles within the cation are comparable with those observed in other 1,3-diammoniumpropane salts such as [C3H12N2]ZnCl4 (Kallel et al., 1980) and [C3H12N2](ClO4)2 (Pritchard et al., 1992). In this structure, the cations and anions are alternately stacked to form columns parallel to the axis b (Fig. 2). The electrostatic interactions and H-bonds intra and inter columns keep up the three-dimensional network cohesion. The established weak H-bonds (Brown, 1976; Blessing, 1986) of types N—H···O and C—H···O involve oxygen atoms of the dichromate anions as acceptors, and the protonated nitrogen atoms and carbon atoms of 1,3-diammoniumpropane as donors.

For related structures, see: Akriche & Rzaigui (2009); Sieroń (2007); Khadhrani et al. (2006); Kallel et al. (1980); Pritchard et al. (1992). For a discussion on hydrogen bonding, see: Brown (1976); Blessing (1986). For background on CrVI species as industrial waste, see: Wani et al. (2007).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. An ORTEP view of the title compound with displacement ellipsoids at the 30% probability level. H atoms are represented as small spheres of arbitrary radii. Symmetry code: (i) x, y-1, z
[Figure 2] Fig. 2. Projection of the crystal structure along the c axis.
Propane-1,3-diammonium dichromate(VI) top
Crystal data top
(C3H12N2)[Cr2O7]F(000) = 592
Mr = 292.15Dx = 2.019 Mg m3
Orthorhombic, PnmaAg Kα radiation, λ = 0.56083 Å
Hall symbol: -P 2ac 2nCell parameters from 25 reflections
a = 8.818 (2) Åθ = 9–11°
b = 13.764 (2) ŵ = 1.18 mm1
c = 7.918 (2) ÅT = 293 K
V = 961.1 (4) Å3Prism, orange
Z = 40.30 × 0.15 × 0.10 mm
Data collection top
Enraf–Nonius CAD4
diffractometer
Rint = 0.020
Radiation source: fine-focus sealed tubeθmax = 28.0°, θmin = 2.3°
Graphite monochromatorh = 143
non–profiled ω scansk = 233
4877 measured reflectionsl = 313
2430 independent reflections2 standard reflections every 120 min
1811 reflections with I > 2σ(I) intensity decay: 3%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.032H-atom parameters constrained
wR(F2) = 0.096 w = 1/[σ2(Fo2) + (0.0502P)2 + 0.243P]
where P = (Fo2 + 2Fc2)/3
S = 1.10(Δ/σ)max = 0.001
2430 reflectionsΔρmax = 0.79 e Å3
69 parametersΔρmin = 0.61 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 constraintsExtinction coefficient: 0.024 (2)
Primary atom site location: structure-invariant direct methods
Crystal data top
(C3H12N2)[Cr2O7]V = 961.1 (4) Å3
Mr = 292.15Z = 4
Orthorhombic, PnmaAg Kα radiation, λ = 0.56083 Å
a = 8.818 (2) ŵ = 1.18 mm1
b = 13.764 (2) ÅT = 293 K
c = 7.918 (2) Å0.30 × 0.15 × 0.10 mm
Data collection top
Enraf–Nonius CAD4
diffractometer
Rint = 0.020
4877 measured reflections2 standard reflections every 120 min
2430 independent reflections intensity decay: 3%
1811 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0320 restraints
wR(F2) = 0.096H-atom parameters constrained
S = 1.10Δρmax = 0.79 e Å3
2430 reflectionsΔρmin = 0.61 e Å3
69 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cr0.58026 (3)0.131997 (16)0.65346 (3)0.01952 (8)
O20.59121 (13)0.05330 (8)0.80635 (15)0.0271 (2)
O40.72115 (14)0.11753 (9)0.52532 (16)0.0324 (3)
O30.42366 (14)0.11686 (10)0.55239 (19)0.0388 (3)
O10.5853 (2)0.25000.7434 (2)0.0322 (4)
N10.66136 (15)0.07105 (9)0.16706 (17)0.0263 (2)
H1A0.72770.07160.08240.039*
H1B0.60160.01920.15780.039*
H1C0.71090.06870.26490.039*
C20.6661 (2)0.25000.1633 (3)0.0237 (3)
H2A0.73270.25000.06580.028*
H2B0.72850.25000.26420.028*
C10.56785 (16)0.16037 (11)0.16067 (19)0.0231 (2)
H1D0.49950.16150.25670.028*
H1E0.50700.16010.05860.028*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cr0.02104 (11)0.01893 (11)0.01860 (11)0.00012 (7)0.00096 (8)0.00048 (7)
O20.0335 (5)0.0232 (4)0.0245 (4)0.0013 (4)0.0003 (4)0.0043 (4)
O40.0308 (6)0.0386 (6)0.0277 (5)0.0028 (4)0.0079 (5)0.0010 (5)
O30.0285 (6)0.0481 (7)0.0398 (7)0.0008 (5)0.0122 (5)0.0022 (6)
O10.0481 (10)0.0202 (6)0.0282 (7)0.0000.0002 (7)0.000
N10.0279 (6)0.0220 (5)0.0289 (6)0.0000 (5)0.0022 (5)0.0018 (5)
C20.0207 (8)0.0216 (7)0.0287 (9)0.0000.0028 (7)0.000
C10.0206 (6)0.0235 (6)0.0252 (6)0.0010 (4)0.0002 (5)0.0005 (5)
Geometric parameters (Å, º) top
Cr—O31.6096 (13)N1—H1C0.8900
Cr—O41.6165 (13)C2—C11.5077 (19)
Cr—O21.6274 (12)C2—C1i1.5077 (19)
Cr—O11.7740 (8)C2—H2A0.9700
O1—Cri1.7740 (8)C2—H2B0.9700
N1—C11.481 (2)C1—H1D0.9700
N1—H1A0.8900C1—H1E0.9700
N1—H1B0.8900
O3—Cr—O4109.35 (8)C1—C2—C1i109.83 (17)
O3—Cr—O2109.55 (7)C1—C2—H2A109.7
O4—Cr—O2109.84 (6)C1i—C2—H2A109.7
O3—Cr—O1109.85 (8)C1—C2—H2B109.7
O4—Cr—O1110.21 (8)C1i—C2—H2B109.7
O2—Cr—O1108.02 (7)H2A—C2—H2B108.2
Cr—O1—Cri132.57 (11)N1—C1—C2111.03 (13)
C1—N1—H1A109.5N1—C1—H1D109.4
C1—N1—H1B109.5C2—C1—H1D109.4
H1A—N1—H1B109.5N1—C1—H1E109.4
C1—N1—H1C109.5C2—C1—H1E109.4
H1A—N1—H1C109.5H1D—C1—H1E108.0
H1B—N1—H1C109.5
Symmetry code: (i) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O2ii0.892.512.9326 (19)110
N1—H1A···O3iii0.892.122.9609 (19)156
N1—H1B···O2iv0.891.992.8168 (19)154
N1—H1C···O40.892.172.955 (2)147
N1—H1C···O2v0.892.442.9844 (19)120
C1—H1D···O30.972.513.405 (2)153
C1—H1E···O2ii0.972.593.176 (2)119
Symmetry codes: (ii) x, y, z1; (iii) x+1/2, y, z+1/2; (iv) x+1, y, z+1; (v) x+3/2, y, z1/2.

Experimental details

Crystal data
Chemical formula(C3H12N2)[Cr2O7]
Mr292.15
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)293
a, b, c (Å)8.818 (2), 13.764 (2), 7.918 (2)
V3)961.1 (4)
Z4
Radiation typeAg Kα, λ = 0.56083 Å
µ (mm1)1.18
Crystal size (mm)0.30 × 0.15 × 0.10
Data collection
DiffractometerEnraf–Nonius CAD4
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
4877, 2430, 1811
Rint0.020
(sin θ/λ)max1)0.836
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.096, 1.10
No. of reflections2430
No. of parameters69
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.79, 0.61

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg & Putz, 2005), WinGX publication routines (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O3i0.892.122.9609 (19)156.3
N1—H1B···O2ii0.891.992.8168 (19)153.5
N1—H1C···O40.892.172.955 (2)146.7
N1—H1C···O2iii0.892.442.9844 (19)119.5
C1—H1D···O30.972.513.405 (2)153.1
C1—H1E···O2iv0.972.593.176 (2)119.1
Symmetry codes: (i) x+1/2, y, z+1/2; (ii) x+1, y, z+1; (iii) x+3/2, y, z1/2; (iv) x, y, z1.
 

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