The crystal structure of the triclinic form of the title compound, NH4+·C2HO4−·C2H2O4·2H2O, has been redetermined, providing a significant increase in the precision of the derived geometric parameters. The asymmetric unit comprises an ammonium cation, an oxalate anion, half each of two oxalic acid molecules, each disposed about a centre of inversion, and two water molecules of crystallization.
Supporting information
CCDC reference: 625001
Key indicators
- Single-crystal X-ray study
- T = 298 K
- Mean (C-C) = 0.001 Å
- R factor = 0.043
- wR factor = 0.132
- Data-to-parameter ratio = 34.9
checkCIF/PLATON results
No syntax errors found
Alert level A
PLAT772_ALERT_2_A Suspect O-H Bond in CIF: O9 -H6 .. 1.46 Ang.
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See text's comment on this point
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Alert level B
PLAT029_ALERT_3_B _diffrn_measured_fraction_theta_full Low ....... 0.96
PLAT417_ALERT_2_B Short Inter D-H..H-D H1 .. H6 .. 1.97 Ang.
PLAT417_ALERT_2_B Short Inter D-H..H-D H2 .. H6 .. 1.94 Ang.
PLAT417_ALERT_2_B Short Inter D-H..H-D H4 .. H5 .. 2.05 Ang.
PLAT432_ALERT_2_B Short Inter X...Y Contact O1 .. C2 .. 2.91 Ang.
Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ?
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor .... 3.11
PLAT355_ALERT_3_C Long O-H Bond (0.82A) O3 - H7 ... 1.04 Ang.
PLAT355_ALERT_3_C Long O-H Bond (0.82A) O2 - H6 ... 1.01 Ang.
PLAT369_ALERT_2_C Long C(sp2)-C(sp2) Bond C1 - C1_a ... 1.55 Ang.
PLAT369_ALERT_2_C Long C(sp2)-C(sp2) Bond C2 - C2_b ... 1.54 Ang.
PLAT369_ALERT_2_C Long C(sp2)-C(sp2) Bond C3 - C4 ... 1.55 Ang.
PLAT432_ALERT_2_C Short Inter X...Y Contact O1 .. C2 .. 2.98 Ang.
1 ALERT level A = In general: serious problem
5 ALERT level B = Potentially serious problem
8 ALERT level C = Check and explain
0 ALERT level G = General alerts; check
1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
10 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
0 ALERT type 4 Improvement, methodology, query or suggestion
0 ALERT type 5 Informative message, check
Data collection: XCS (Colapietro et al., 1992); cell refinement: XCS; data reduction: XCS; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.
ammonium oxalate oxalic acid dihydrate
top
Crystal data top
NH4+·C2HO4−·C2H2O4·2H2O | Z = 2 |
Mr = 233.14 | F(000) = 244 |
Triclinic, P1 | Dx = 1.652 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.710689 Å |
a = 6.3387 (8) Å | Cell parameters from 121 reflections |
b = 7.2227 (9) Å | θ = 20–24° |
c = 10.5527 (11) Å | µ = 0.17 mm−1 |
α = 94.172 (10)° | T = 298 K |
β = 100.274 (10)° | Block, colourless |
γ = 97.704 (10)° | 0.30 × 0.20 × 0.20 mm |
V = 468.77 (10) Å3 | |
Data collection top
Huber CS four-circle diffractometer | Rint = 0.021 |
Radiation source: X-ray tube | θmax = 42.0°, θmin = 2.9° |
Graphite monochromator | h = 0→11 |
ω scans | k = −13→13 |
6934 measured reflections | l = −19→19 |
6283 independent reflections | 3 standard reflections every 97 reflections |
5265 reflections with I > 2σ(I) | intensity decay: 1% |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.043 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.132 | All H-atom parameters refined |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0705P)2 + 0.0474P] where P = (Fo2 + 2Fc2)/3 |
6283 reflections | (Δ/σ)max < 0.001 |
180 parameters | Δρmax = 0.44 e Å−3 |
0 restraints | Δρmin = −0.31 e Å−3 |
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 | x | y | z | Uiso*/Ueq | |
O1 | 0.66148 (9) | 0.66530 (8) | 0.43215 (5) | 0.03350 (10) | |
O2 | 0.49852 (9) | 0.07707 (9) | 0.34789 (5) | 0.03568 (11) | |
O3 | 0.34181 (10) | 0.49021 (8) | 0.34594 (5) | 0.03643 (12) | |
O4 | 0.23800 (9) | −0.09787 (8) | 0.42365 (5) | 0.03535 (11) | |
O5 | 0.81598 (13) | 0.43035 (7) | 0.18644 (5) | 0.04050 (14) | |
O6 | 0.72643 (11) | 0.15335 (7) | 0.06757 (5) | 0.03674 (12) | |
O7 | 0.66656 (11) | 0.33721 (7) | −0.14887 (5) | 0.03692 (12) | |
O8 | 0.76210 (11) | 0.60954 (7) | −0.02241 (5) | 0.03831 (13) | |
O9 | 0.23164 (10) | 0.07154 (8) | 0.14523 (5) | 0.03311 (10) | |
O10 | 0.94415 (10) | 0.25231 (11) | 0.37405 (6) | 0.04401 (15) | |
N1 | 0.84141 (11) | 0.84410 (8) | 0.22442 (6) | 0.03114 (10) | |
C1 | 0.50660 (10) | 0.54737 (7) | 0.43714 (5) | 0.02526 (9) | |
C2 | 0.41858 (10) | −0.00905 (8) | 0.43560 (5) | 0.02634 (9) | |
C3 | 0.75572 (10) | 0.32392 (8) | 0.07806 (5) | 0.02591 (9) | |
C4 | 0.72488 (10) | 0.43596 (8) | −0.04184 (5) | 0.02586 (9) | |
H1 | 0.239 (3) | 0.186 (3) | 0.1174 (18) | 0.074 (5)* | |
H2 | 0.255 (2) | 0.003 (2) | 0.0830 (15) | 0.053 (4)* | |
H3 | 0.862 (4) | 0.218 (3) | 0.437 (2) | 0.093 (6)* | |
H4 | 1.070 (3) | 0.304 (2) | 0.4216 (19) | 0.070 (5)* | |
H5 | 0.866 (3) | 0.357 (2) | 0.2592 (15) | 0.055 (4)* | |
H6 | 0.393 (3) | 0.071 (2) | 0.2627 (17) | 0.069 (5)* | |
H7 | 0.347 (3) | 0.554 (3) | 0.2609 (19) | 0.075 (5)* | |
H8 | 0.760 (3) | 0.800 (3) | 0.2804 (18) | 0.073 (5)* | |
H9 | 0.973 (3) | 0.867 (2) | 0.2685 (16) | 0.058 (4)* | |
H10 | 0.795 (4) | 0.943 (3) | 0.188 (2) | 0.095 (6)* | |
H11 | 0.815 (2) | 0.750 (2) | 0.1599 (15) | 0.052 (4)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0368 (2) | 0.0350 (2) | 0.02636 (18) | −0.00582 (17) | 0.00462 (16) | 0.01145 (16) |
O2 | 0.0339 (2) | 0.0455 (3) | 0.02599 (19) | −0.00090 (19) | 0.00202 (16) | 0.01405 (18) |
O3 | 0.0426 (3) | 0.0356 (2) | 0.02447 (18) | −0.00835 (19) | −0.00450 (17) | 0.01198 (16) |
O4 | 0.0306 (2) | 0.0423 (3) | 0.0290 (2) | −0.00429 (17) | −0.00101 (16) | 0.01066 (18) |
O5 | 0.0714 (4) | 0.0268 (2) | 0.02048 (17) | 0.0063 (2) | 0.0011 (2) | 0.00472 (14) |
O6 | 0.0594 (3) | 0.02220 (17) | 0.02691 (19) | 0.00290 (18) | 0.0036 (2) | 0.00826 (14) |
O7 | 0.0583 (3) | 0.0279 (2) | 0.02035 (16) | 0.00007 (19) | −0.00063 (18) | 0.00594 (14) |
O8 | 0.0653 (4) | 0.02177 (17) | 0.0267 (2) | 0.0053 (2) | 0.0044 (2) | 0.00816 (15) |
O9 | 0.0437 (3) | 0.0316 (2) | 0.02445 (18) | 0.00745 (18) | 0.00410 (17) | 0.00880 (15) |
O10 | 0.0366 (3) | 0.0581 (4) | 0.0332 (2) | −0.0065 (2) | −0.00142 (19) | 0.0222 (2) |
N1 | 0.0374 (3) | 0.0266 (2) | 0.0281 (2) | −0.00018 (17) | 0.00499 (18) | 0.00645 (16) |
C1 | 0.0323 (2) | 0.02228 (18) | 0.02043 (18) | 0.00096 (16) | 0.00349 (15) | 0.00656 (14) |
C2 | 0.0286 (2) | 0.0266 (2) | 0.02299 (19) | 0.00306 (16) | 0.00198 (16) | 0.00588 (15) |
C3 | 0.0342 (2) | 0.02283 (19) | 0.02089 (18) | 0.00418 (16) | 0.00387 (16) | 0.00705 (14) |
C4 | 0.0335 (2) | 0.02303 (19) | 0.02084 (18) | 0.00365 (16) | 0.00293 (16) | 0.00756 (14) |
Geometric parameters (Å, º) top
O1—C1 | 1.2219 (7) | O9—H2 | 0.838 (16) |
O2—C2 | 1.2912 (8) | O9—H6 | 1.459 (18) |
O2—H6 | 1.016 (18) | O10—H3 | 0.94 (2) |
O3—C1 | 1.2867 (8) | O10—H4 | 0.879 (19) |
O3—H7 | 1.042 (19) | N1—H8 | 0.90 (2) |
O4—C2 | 1.2155 (8) | N1—H9 | 0.866 (18) |
O5—C3 | 1.2970 (8) | N1—H10 | 0.89 (2) |
O5—H5 | 0.995 (16) | N1—H11 | 0.903 (16) |
O6—C3 | 1.2150 (7) | C1—C1i | 1.5464 (10) |
O7—C4 | 1.2586 (8) | C2—C2ii | 1.5386 (11) |
O8—C4 | 1.2392 (7) | C3—C4 | 1.5483 (7) |
O9—H1 | 0.89 (2) | | |
| | | |
C2—O2—H6 | 113.9 (9) | O1—C1—O3 | 126.54 (5) |
C1—O3—H7 | 114.2 (10) | O1—C1—C1i | 120.29 (7) |
C3—O5—H5 | 111.3 (9) | O3—C1—C1i | 113.16 (6) |
H1—O9—H2 | 103.7 (15) | O4—C2—O2 | 126.72 (6) |
H1—O9—H6 | 110.8 (14) | O4—C2—C2ii | 120.98 (7) |
H2—O9—H6 | 112.2 (12) | O2—C2—C2ii | 112.30 (6) |
H3—O10—H4 | 102.3 (17) | O6—C3—O5 | 125.20 (5) |
H8—N1—H9 | 104.9 (15) | O6—C3—C4 | 121.59 (5) |
H8—N1—H10 | 112.7 (18) | O5—C3—C4 | 113.21 (5) |
H9—N1—H10 | 114.3 (16) | O8—C4—O7 | 127.69 (5) |
H8—N1—H11 | 103.1 (14) | O8—C4—C3 | 117.30 (5) |
H9—N1—H11 | 115.9 (14) | O7—C4—C3 | 115.00 (5) |
H10—N1—H11 | 105.6 (17) | | |
| | | |
O6—C3—C4—O8 | −178.70 (7) | O6—C3—C4—O7 | 0.48 (10) |
O5—C3—C4—O8 | 0.76 (9) | O5—C3—C4—O7 | 179.94 (7) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, −y, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H6···O9 | 1.016 (18) | 1.459 (18) | 2.4731 (8) | 175.7 (17) |
O3—H7···O7iii | 1.042 (19) | 1.463 (19) | 2.4974 (7) | 171.3 (18) |
O5—H5···O10 | 0.995 (16) | 1.517 (16) | 2.5120 (8) | 177.4 (14) |
O9—H2···O6iv | 0.838 (16) | 1.913 (17) | 2.7476 (9) | 173.4 (15) |
O9—H1···O8iii | 0.89 (2) | 1.85 (2) | 2.7231 (8) | 166.7 (18) |
O10—H4···O1v | 0.879 (19) | 2.06 (2) | 2.8959 (9) | 158.3 (16) |
O10—H3···O4ii | 0.94 (2) | 1.92 (2) | 2.8311 (8) | 162 (2) |
N1—H8···O1 | 0.90 (2) | 2.079 (19) | 2.9466 (8) | 162.0 (17) |
N1—H9···O4vi | 0.866 (18) | 2.101 (18) | 2.9359 (9) | 161.6 (15) |
N1—H10···O6vii | 0.89 (2) | 2.09 (2) | 2.9671 (8) | 166 (2) |
N1—H11···O8 | 0.903 (16) | 2.058 (16) | 2.9275 (9) | 161.2 (14) |
Symmetry codes: (ii) −x+1, −y, −z+1; (iii) −x+1, −y+1, −z; (iv) −x+1, −y, −z; (v) −x+2, −y+1, −z+1; (vi) x+1, y+1, z; (vii) x, y+1, z. |