Melaminium bis­(hydrogen oxalate)

The crystal structure of melaminium bis­(hydrogen oxalate), C₃H₈N₆²⁺·2C₂HO₄^-, contains hydrogen oxalate anions that are linked by hydrogen bonds into a linear chain; adjacent chains are linked through the dication (which has crystallographic twofold symmetry), forming a layer structure.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.041
• wR factor = 0.116
• Data-to-parameter ratio = 10.8

checkCIF/PLATON results

No syntax errors found



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 ....       2.15
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.38
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C3     -   C4     ...       1.53 Ang.
PLAT432_ALERT_2_C Short Inter X...Y Contact  O4     ..  C4      ..       3.01 Ang.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 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
   4 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.

Melaminium(2+) di(hydrogen oxalate)

Crystal data

C3H8N6^2+·2C2HO4^−	F(000) = 632
Mr = 306.21	Dx = 1.785 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1045 reflections
a = 20.829 (2) Å	θ = 3.3–27.3°
b = 8.428 (1) Å	µ = 0.16 mm^−1
c = 6.8415 (8) Å	T = 295 K
β = 108.402 (2)°	Block, colorless
V = 1139.6 (2) Å^3	0.20 × 0.16 × 0.15 mm
Z = 4

Data collection

Bruker APEX area-detector diffractometer	1068 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.019
Graphite monochromator	θmax = 27.5°, θmin = 2.6°
φ and ω scans	h = −25→26
3287 measured reflections	k = −10→9
1269 independent reflections	l = −4→8

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.116	All H-atom parameters refined
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0711P)^2 + 0.2079P] where P = (Fo^2 + 2Fc^2)/3
1269 reflections	(Δ/σ)max = 0.001
117 parameters	Δρmax = 0.26 e Å^−3
5 restraints	Δρmin = −0.22 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.39408 (6)	0.3304 (1)	0.5019 (2)	0.0351 (3)
O2	0.33277 (6)	0.5529 (1)	0.4576 (2)	0.0347 (4)
O3	0.28898 (6)	0.1879 (1)	0.2248 (2)	0.0325 (3)
O4	0.22063 (5)	0.3629 (1)	0.3048 (2)	0.0359 (3)
N1	0.5000	0.5051 (2)	0.7500	0.0294 (5)
N2	0.4468 (1)	0.7417 (2)	0.6298 (2)	0.0248 (3)
N3	0.3942 (1)	0.9795 (2)	0.5160 (2)	0.0272 (3)
N4	0.5000	0.9864 (2)	0.7500	0.0241 (4)
C1	0.5000	0.6586 (2)	0.7500	0.0230 (5)
C2	0.44746 (7)	0.9047 (2)	0.6330 (2)	0.0219 (3)
C3	0.3406 (1)	0.4069 (2)	0.4346 (2)	0.0256 (4)
C4	0.2765 (1)	0.3165 (2)	0.3126 (2)	0.0253 (4)
H3o	0.251 (1)	0.141 (2)	0.164 (3)	0.062 (7)*
H1	0.465 (1)	0.458 (2)	0.672 (3)	0.034 (5)*
H2	0.412 (1)	0.688 (2)	0.567 (3)	0.034 (5)*
H3a	0.393 (1)	1.080 (1)	0.517 (3)	0.032 (5)*
H3b	0.360 (1)	0.930 (2)	0.437 (3)	0.040 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0217 (6)	0.0237 (6)	0.0496 (8)	0.0022 (4)	−0.0036 (5)	−0.0034 (5)
O2	0.0281 (6)	0.0198 (6)	0.0458 (8)	0.0013 (5)	−0.0032 (5)	−0.0047 (5)
O3	0.0269 (7)	0.0224 (6)	0.0417 (7)	−0.0029 (5)	0.0016 (5)	−0.0070 (5)
O4	0.0215 (6)	0.0305 (7)	0.0482 (8)	0.0036 (5)	0.0002 (5)	−0.0008 (5)
N1	0.023 (1)	0.021 (1)	0.035 (1)	0.000	−0.004 (1)	0.000
N2	0.017 (1)	0.021 (1)	0.030 (1)	−0.003 (1)	−0.002 (1)	0.000 (1)
N3	0.019 (1)	0.024 (1)	0.032 (1)	0.001 (1)	−0.003 (1)	0.002 (1)
N4	0.018 (1)	0.021 (1)	0.029 (1)	0.000	0.001 (1)	0.000
C1	0.020 (1)	0.022 (1)	0.024 (1)	0.000	0.004 (1)	0.000
C2	0.018 (1)	0.024 (1)	0.023 (1)	0.000 (1)	0.005 (1)	0.001 (1)
C3	0.023 (1)	0.021 (1)	0.029 (1)	0.000 (1)	0.003 (1)	0.002 (1)
C4	0.024 (1)	0.018 (1)	0.028 (1)	0.003 (1)	0.000 (1)	0.005 (1)

Geometric parameters (Å, º)

O1—C3	1.242 (2)	C2—N4	1.326 (2)
O2—C3	1.257 (2)	N4—C2^i	1.326 (2)
O3—C4	1.305 (2)	C3—C4	1.535 (2)
O4—C4	1.214 (2)	O3—H3o	0.86 (1)
C1—N1	1.294 (3)	N1—H1	0.85 (1)
C1—N2	1.349 (2)	N2—H2	0.86 (1)
C1—N2^i	1.349 (2)	N3—H3a	0.85 (1)
C2—N2	1.374 (2)	N3—H3b	0.86 (1)
C2—N3	1.308 (2)
C1—N2—C2	120.5 (1)	O3—C4—O4	125.1 (2)
C2^i—N4—C2	117.5 (2)	O3—C4—C3	113.4 (1)
N1—C1—N2	121.3 (1)	O4—C4—C3	121.5 (1)
N1—C1—N2^i	121.3 (1)	C4—O3—H3o	109 (2)
N2—C1—N2^i	117.4 (2)	C1—N1—H1	118 (1)
N2—C2—N3	118.0 (1)	C1—N2—H2	116 (1)
N2—C2—N4	122.0 (1)	C2—N2—H2	123 (1)
N3—C2—N4	119.9 (1)	C2—N3—H3a	120 (1)
O1—C3—O2	126.8 (1)	C2—N3—H3b	122 (1)
O1—C3—C4	117.9 (1)	H3a—N3—H3b	118 (2)
O2—C3—C4	115.4 (1)
N1—C1—N2—C2	179.5 (1)	N2—C2—N4—C2^i	−0.5 (1)
N2^i—C1—N2—C2	−0.5 (1)	O1—C3—C4—O4	153.4 (2)
N3—C2—N2—C1	−178.9 (1)	O2—C3—C4—O4	−25.8 (2)
N4—C2—N2—C1	1.1 (2)	O1—C3—C4—O3	−25.6 (2)
N3—C2—N4—C2^i	179.4 (2)	O2—C3—C4—O3	155.3 (1)

Symmetry code: (i) −x+1, y, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3o···O2^ii	0.86 (1)	1.84 (1)	2.699 (2)	176 (2)
N1—H1···O1	0.85 (1)	1.90 (1)	2.748 (2)	173 (2)
N2—H2···O2	0.86 (1)	1.94 (1)	2.792 (2)	173 (2)
N3—H3a···O1^iii	0.85 (1)	2.11 (1)	2.959 (2)	175 (2)
N3—H3b···O4^iv	0.86 (1)	2.03 (1)	2.861 (2)	164 (2)

Symmetry codes: (ii) −x+1/2, y−1/2, −z+1/2; (iii) x, y+1, z; (iv) −x+1/2, y+1/2, −z+1/2.