Crystal structure of di­methyl­ammonium hydrogen oxalate hemi(oxalic acid)

The title salt consists of a di­methyl­ammonium cation (Me₂NH₂⁺), an hydrogenoxalate anion (HC₂O₄⁻), and half a mol­ecule of oxalic acid (H₂C₂O₄) situated about an inversion center. They are linked together through inter­molecular hydrogen bonds, forming a two-dimensional bilayer-like self-assembly.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.001 Å
• R factor = 0.028
• wR factor = 0.075
• Data-to-parameter ratio = 16.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....        2.3 Note
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          5 Report

Alert level G
PLAT007_ALERT_5_G Number of Unrefined Donor-H Atoms ..............          4 Report
PLAT154_ALERT_1_G The su's on the Cell Angles are Equal ..........    0.00200 Degree
PLAT432_ALERT_2_G Short Inter X...Y Contact  O1     ..  C2      ..       2.97 Ang.
PLAT910_ALERT_3_G Missing # of FCF Reflection(s) Below Th(Min) ...          1 Report
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600         14 Note

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   2 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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Computing details

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: Olex2 (Dolomanov et al., 2009) and Mercury (Macrae et al., 2008; software used to prepare material for publication: Olex2 (Dolomanov et al., 2009).

Dimethylammonium hydrogen oxalate hemi(oxalic acid)

Crystal data

C2H8N^+·C2HO4^−·0.5C2H2O4	Z = 2
Mr = 180.14	F(000) = 190.1598
Triclinic, P1	Dx = 1.497 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.6519 (3) Å	Cell parameters from 7049 reflections
b = 7.5809 (4) Å	θ = 3.0–27.6°
c = 10.3100 (6) Å	µ = 0.14 mm^−1
α = 75.467 (2)°	T = 100 K
β = 88.120 (2)°	Prism, colourless
γ = 69.487 (2)°	0.5 × 0.3 × 0.1 mm
V = 399.76 (4) Å^3

Data collection

Bruker D8 Venture triumph Mo diffractometer	1840 independent reflections
Radiation source: X-ray tube, Siemens KFF Mo 2K-90C	1655 reflections with I ≥ 2σ(I)
TRIUMPH curved crystal monochromator	Rint = 0.023
φ and ω scans	θmax = 27.6°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −7→7
Tmin = 0.693, Tmax = 0.746	k = −9→9
10413 measured reflections	l = −13→13

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.028	H-atom parameters not refined
wR(F^2) = 0.075	w = 1/[σ^2(Fo^2) + (0.0375P)^2 + 0.1325P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max = 0.001
1840 reflections	Δρmax = 0.38 e Å^−3
113 parameters	Δρmin = −0.26 e Å^−3

Special details

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.

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

	x	y	z	Uiso*/Ueq
O1	0.75407 (12)	0.32103 (10)	0.47166 (7)	0.01407 (16)
O2	0.57685 (12)	0.40754 (10)	0.26360 (7)	0.01329 (16)
O3	0.14369 (12)	0.38767 (11)	0.36954 (7)	0.01625 (17)
H3	0.0215	0.3632	0.4083	0.024*
O4	0.36051 (14)	0.20987 (11)	0.56626 (7)	0.02010 (17)
O5	0.29036 (13)	0.37192 (10)	0.09144 (7)	0.01471 (16)
H5	0.3683	0.3944	0.1497	0.022*
O6	0.01961 (13)	0.67729 (10)	0.07499 (7)	0.01568 (16)
C1	0.57857 (16)	0.34999 (13)	0.38821 (9)	0.01061 (18)
C2	0.34558 (17)	0.30728 (13)	0.45205 (9)	0.01216 (19)
C3	0.08336 (17)	0.52128 (13)	0.04793 (9)	0.01171 (19)
N1	0.22327 (15)	0.83866 (11)	0.24521 (8)	0.01223 (17)
H1A	0.3034	0.7852	0.3284	0.015*
H1B	0.1697	0.7490	0.2236	0.015*
C4	0.40571 (19)	0.88277 (15)	0.14735 (10)	0.0182 (2)
H4A	0.3224	0.9359	0.0569	0.027*
H4B	0.5500	0.7630	0.1500	0.027*
H4C	0.4653	0.9785	0.1705	0.027*
C5	−0.00007 (19)	1.01362 (14)	0.24892 (11)	0.0177 (2)
H5A	−0.0886	1.0711	0.1598	0.027*
H5B	0.0557	1.1091	0.2751	0.027*
H5C	−0.1149	0.9761	0.3143	0.027*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0100 (3)	0.0212 (4)	0.0119 (3)	−0.0072 (3)	−0.0008 (2)	−0.0031 (3)
O2	0.0113 (3)	0.0178 (3)	0.0107 (3)	−0.0060 (3)	−0.0004 (2)	−0.0024 (3)
O3	0.0089 (3)	0.0274 (4)	0.0131 (3)	−0.0087 (3)	0.0002 (3)	−0.0030 (3)
O4	0.0162 (4)	0.0286 (4)	0.0148 (3)	−0.0123 (3)	−0.0008 (3)	0.0022 (3)
O5	0.0134 (3)	0.0149 (3)	0.0150 (3)	−0.0021 (3)	−0.0044 (3)	−0.0059 (3)
O6	0.0178 (3)	0.0130 (3)	0.0166 (3)	−0.0046 (3)	−0.0040 (3)	−0.0051 (3)
C1	0.0087 (4)	0.0105 (4)	0.0127 (4)	−0.0028 (3)	0.0003 (3)	−0.0039 (3)
C2	0.0103 (4)	0.0154 (4)	0.0126 (4)	−0.0057 (3)	0.0004 (3)	−0.0050 (3)
C3	0.0127 (4)	0.0138 (4)	0.0091 (4)	−0.0059 (3)	−0.0003 (3)	−0.0018 (3)
N1	0.0145 (4)	0.0118 (4)	0.0107 (4)	−0.0050 (3)	−0.0005 (3)	−0.0028 (3)
C4	0.0166 (5)	0.0202 (5)	0.0186 (5)	−0.0074 (4)	0.0050 (4)	−0.0055 (4)
C5	0.0152 (5)	0.0148 (4)	0.0211 (5)	−0.0037 (4)	0.0033 (4)	−0.0034 (4)

Geometric parameters (Å, º)

O1—C1	1.2573 (11)	N1—H1A	0.9100
O2—C1	1.2480 (11)	N1—H1B	0.9100
O3—H3	0.8400	N1—C4	1.4822 (12)
O3—C2	1.3089 (11)	N1—C5	1.4842 (12)
O4—C2	1.2105 (12)	C4—H4A	0.9800
O5—H5	0.8400	C4—H4B	0.9800
O5—C3	1.3051 (11)	C4—H4C	0.9800
O6—C3	1.2111 (12)	C5—H5A	0.9800
C1—C2	1.5515 (13)	C5—H5B	0.9800
C3—C3^i	1.5501 (17)	C5—H5C	0.9800
C2—O3—H3	109.5	C5—N1—H1A	109.0
C3—O5—H5	109.5	C5—N1—H1B	109.0
O1—C1—C2	114.27 (8)	N1—C4—H4A	109.5
O2—C1—O1	126.60 (8)	N1—C4—H4B	109.5
O2—C1—C2	119.13 (8)	N1—C4—H4C	109.5
O3—C2—C1	112.45 (8)	H4A—C4—H4B	109.5
O4—C2—O3	126.54 (9)	H4A—C4—H4C	109.5
O4—C2—C1	121.01 (8)	H4B—C4—H4C	109.5
O5—C3—C3^i	111.64 (10)	N1—C5—H5A	109.5
O6—C3—O5	126.87 (8)	N1—C5—H5B	109.5
O6—C3—C3^i	121.48 (10)	N1—C5—H5C	109.5
H1A—N1—H1B	107.8	H5A—C5—H5B	109.5
C4—N1—H1A	109.0	H5A—C5—H5C	109.5
C4—N1—H1B	109.0	H5B—C5—H5C	109.5
C4—N1—C5	112.87 (8)
O1—C1—C2—O3	162.31 (8)	O2—C1—C2—O3	−17.79 (12)
O1—C1—C2—O4	−17.45 (13)	O2—C1—C2—O4	162.45 (9)

Symmetry code: (i) −x, −y+1, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O1^ii	0.84	1.73	2.564 (1)	174
O5—H5···O2	0.84	1.73	2.565 (1)	170
N1—H1A···O1^iii	0.91	2.08	2.854 (1)	143
N1—H1A···O4^iii	0.91	2.23	2.964 (1)	137
N1—H1B···O6	0.91	2.05	2.846 (1)	146
C5—H5C···O4^iv	0.98	2.41	3.346 (1)	159

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