Buy article online - an online subscription or single-article purchase is required to access this article.
In the crystal structure of the title compound, [O(CH
2CH
2)
2NH
2][C
6H
7O
7]·H
2O, the cation interacts with the negatively charged carboxylato group of adjacent anions [N
O 2.847 (3) and 2.942 (3) Å], forming a linear chain running along the
b axis of the crystal. Adjacent chains are linked through the carboxylic —CO
2H groups and the water molecule into a layer structure.
Supporting information
CCDC reference: 217608
Key indicators
- Single-crystal X-ray study
- T = 298 K
- Mean (C-C) = 0.003 Å
- R factor = 0.055
- wR factor = 0.143
- Data-to-parameter ratio = 11.0
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Alert Level C:
PLAT_731 Alert C Bond Calc 0.85(3), Rep 0.850(10) ...... 3.00 su-Rat
O1W -H1W2 1.555 1.555
PLAT_735 Alert C D-H Calc 0.86(4), Rep 0.850(10) ...... 4.00 su-Rat
O3 -H3O 1.555 1.555
PLAT_735 Alert C D-H Calc 0.85(3), Rep 0.850(10) ...... 3.00 su-Rat
O1W -H1W2 1.555 1.555
PLAT_736 Alert C H...A Calc 1.76(4), Rep 1.760(10) ...... 4.00 su-Rat
H3O -O2 1.555 2.665
PLAT_736 Alert C H...A Calc 1.93(3), Rep 1.930(10) ...... 3.00 su-Rat
H1W2 -O7 1.555 8.755
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
5 Alert Level C = Please check
Morpholine (0.87 g, 10 mmol) and citric acid monohydrate (0.21 g, 10 mol) were heated in a small volume of ethanol (25 ml); a few drops of water were added to dissolve the acid completely. Slow evaporation of the solvent yielded the mono(morpholinium) dihydrate citrate as a a monohydrate. The use of twice the quantity of the amine gave the identical compound. Elemental analysis. Found/Calc. for C10H19O9N: 40.8 (40.4); H 6.5 (6.4); N 4.5% (4.7%). IR (KBr pellet): νCOOH 1717, νas(COO) 1414, νs(COO) 1414, 1396; νC=N 1107 cm−1.
The water, hydroxyl and ammonium H atoms were located and refined. The aliphatic H atoms were positioned geometrically (C—H 0.97 Å), and were included in the refinement in the riding model approximation; the temperature factors were set to 1.5 (methyl) or 1.2 (other H atoms) times Ueq of the parent atom.
The diffraction measurements were performed up to a 2θ angle of 56°; however, as the inclusion of reflections above 50° led to an R factor greater than 7%, these were excluded from the refinement.
Data collection: SMART (Bruker, 2001); cell refinement: SAINT; data reduction: SAINT (Bruker, 2001); 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.
Morpholinium dihydrogen citrate dihydrate
top
Crystal data top
C4H10NO·C6H7O7·H2O | Dx = 1.508 Mg m−3 |
Mr = 297.26 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbca | Cell parameters from 4726 reflections |
a = 11.3774 (6) Å | θ = 2.4–27.3° |
b = 12.4823 (7) Å | µ = 0.13 mm−1 |
c = 18.437 (1) Å | T = 298 K |
V = 2618.3 (2) Å3 | Block, colorless |
Z = 8 | 0.28 × 0.18 × 0.18 mm |
F(000) = 1264 | |
Data collection top
Bruker AXS area-detector diffractometer | 2103 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.028 |
Graphite monochromator | θmax = 25.0°, θmin = 2.2° |
ϕ and ω scan | h = −13→13 |
12407 measured reflections | k = −14→10 |
2305 independent reflections | l = −20→21 |
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)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.143 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.15 | w = 1/[σ2(Fo2) + (0.0711P)2 + 1.4573P] where P = (Fo2 + 2Fc2)/3 |
2305 reflections | (Δ/σ)max = 0.001 |
209 parameters | Δρmax = 0.29 e Å−3 |
7 restraints | Δρmin = −0.19 e Å−3 |
Crystal data top
C4H10NO·C6H7O7·H2O | V = 2618.3 (2) Å3 |
Mr = 297.26 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 11.3774 (6) Å | µ = 0.13 mm−1 |
b = 12.4823 (7) Å | T = 298 K |
c = 18.437 (1) Å | 0.28 × 0.18 × 0.18 mm |
Data collection top
Bruker AXS area-detector diffractometer | 2103 reflections with I > 2σ(I) |
12407 measured reflections | Rint = 0.028 |
2305 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.055 | 7 restraints |
wR(F2) = 0.143 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.15 | Δρmax = 0.29 e Å−3 |
2305 reflections | Δρmin = −0.19 e Å−3 |
209 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.7018 (2) | 0.4461 (2) | 0.3243 (1) | 0.0458 (5) | |
O2 | 0.8506 (2) | 0.5350 (2) | 0.2768 (1) | 0.0370 (4) | |
O3 | 0.7367 (2) | 0.5590 (2) | 0.6623 (1) | 0.0451 (5) | |
O4 | 0.6867 (2) | 0.4115 (2) | 0.6037 (1) | 0.0516 (6) | |
O5 | 0.9106 (2) | 0.3694 (1) | 0.4891 (1) | 0.0424 (5) | |
O6 | 0.7354 (2) | 0.3010 (1) | 0.4610 (1) | 0.0379 (5) | |
O7 | 0.6357 (1) | 0.4984 (1) | 0.4561 (1) | 0.0290 (4) | |
O8 | 0.3538 (2) | 0.2267 (2) | 0.2404 (1) | 0.0481 (5) | |
O1w | 0.9859 (2) | 0.1797 (2) | 0.5015 (1) | 0.0497 (6) | |
N1 | 0.5971 (2) | 0.2640 (2) | 0.2574 (1) | 0.0371 (5) | |
C1 | 0.7892 (2) | 0.5054 (2) | 0.3295 (1) | 0.0266 (5) | |
C2 | 0.8230 (2) | 0.5481 (2) | 0.4041 (1) | 0.0273 (5) | |
C3 | 0.7591 (2) | 0.4941 (2) | 0.4678 (1) | 0.0244 (5) | |
C4 | 0.7850 (2) | 0.5521 (2) | 0.5388 (1) | 0.0269 (5) | |
C5 | 0.7300 (2) | 0.4999 (2) | 0.6041 (1) | 0.0280 (5) | |
C6 | 0.7983 (2) | 0.3765 (2) | 0.4727 (1) | 0.0258 (5) | |
C7 | 0.5131 (2) | 0.2781 (2) | 0.3181 (1) | 0.0420 (6) | |
C8 | 0.4100 (2) | 0.2064 (2) | 0.3076 (2) | 0.0479 (7) | |
C9 | 0.4334 (2) | 0.2074 (2) | 0.1824 (2) | 0.0464 (7) | |
C10 | 0.5379 (2) | 0.2798 (2) | 0.1865 (1) | 0.0409 (6) | |
H3o | 0.708 (3) | 0.526 (3) | 0.699 (2) | 0.09 (1)* | |
H5o | 0.930 (3) | 0.303 (1) | 0.491 (2) | 0.06 (1)* | |
H7o | 0.626 (3) | 0.476 (3) | 0.413 (1) | 0.06 (1)* | |
H1w1 | 1.059 (1) | 0.168 (3) | 0.502 (2) | 0.06 (1)* | |
H1w2 | 0.950 (3) | 0.125 (2) | 0.485 (2) | 0.08 (1)* | |
H1n1 | 0.628 (3) | 0.202 (1) | 0.260 (2) | 0.06 (1)* | |
H1n2 | 0.653 (2) | 0.307 (2) | 0.265 (2) | 0.06 (1)* | |
H2a | 0.8068 | 0.6243 | 0.4056 | 0.033* | |
H2b | 0.9070 | 0.5388 | 0.4107 | 0.033* | |
H4a | 0.8694 | 0.5551 | 0.5457 | 0.032* | |
H4b | 0.7564 | 0.6251 | 0.5352 | 0.032* | |
H7a | 0.4871 | 0.3521 | 0.3200 | 0.050* | |
H7b | 0.5515 | 0.2613 | 0.3637 | 0.050* | |
H8a | 0.4357 | 0.1323 | 0.3092 | 0.058* | |
H8b | 0.3544 | 0.2173 | 0.3468 | 0.058* | |
H9a | 0.3933 | 0.2185 | 0.1366 | 0.056* | |
H9b | 0.4593 | 0.1334 | 0.1841 | 0.056* | |
H10a | 0.5920 | 0.2636 | 0.1474 | 0.049* | |
H10b | 0.5132 | 0.3538 | 0.1817 | 0.049* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.053 (1) | 0.056 (1) | 0.028 (1) | −0.027 (1) | 0.002 (1) | −0.009 (1) |
O2 | 0.045 (1) | 0.044 (1) | 0.022 (1) | −0.010 (1) | 0.004 (1) | −0.001 (1) |
O3 | 0.071 (1) | 0.043 (1) | 0.021 (1) | −0.016 (1) | 0.006 (1) | −0.002 (1) |
O4 | 0.082 (2) | 0.042 (1) | 0.031 (1) | −0.023 (1) | 0.007 (1) | 0.001 (1) |
O5 | 0.033 (1) | 0.027 (1) | 0.067 (1) | 0.003 (1) | −0.009 (1) | 0.001 (9) |
O6 | 0.039 (1) | 0.023 (1) | 0.051 (1) | −0.003 (1) | −0.004 (1) | −0.001 (1) |
O7 | 0.027 (1) | 0.032 (1) | 0.029 (1) | 0.002 (1) | −0.001 (1) | 0.000 (1) |
O8 | 0.026 (1) | 0.060 (1) | 0.059 (1) | −0.002 (1) | −0.005 (1) | 0.002 (1) |
O1w | 0.035 (1) | 0.035 (1) | 0.079 (2) | 0.009 (1) | −0.014 (1) | −0.006 (1) |
N1 | 0.025 (1) | 0.034 (1) | 0.053 (1) | −0.001 (1) | −0.005 (1) | −0.003 (1) |
C1 | 0.033 (1) | 0.023 (1) | 0.024 (1) | 0.000 (1) | −0.001 (1) | −0.001 (1) |
C2 | 0.030 (1) | 0.025 (1) | 0.026 (1) | −0.003 (1) | 0.001 (1) | −0.001 (1) |
C3 | 0.027 (1) | 0.024 (1) | 0.022 (1) | −0.003 (1) | 0.000 (1) | −0.001 (1) |
C4 | 0.032 (1) | 0.025 (1) | 0.024 (1) | −0.001 (1) | 0.001 (1) | −0.001 (1) |
C5 | 0.028 (1) | 0.031 (1) | 0.025 (1) | −0.001 (1) | −0.001 (1) | 0.002 (1) |
C6 | 0.029 (1) | 0.027 (1) | 0.022 (1) | −0.003 (1) | 0.002 (1) | −0.001 (1) |
C7 | 0.039 (2) | 0.050 (2) | 0.037 (2) | 0.004 (1) | −0.004 (1) | −0.003 (1) |
C8 | 0.038 (2) | 0.054 (2) | 0.052 (2) | −0.002 (1) | 0.006 (1) | 0.008 (1) |
C9 | 0.042 (2) | 0.054 (2) | 0.044 (2) | −0.004 (1) | −0.010 (1) | −0.005 (1) |
C10 | 0.040 (2) | 0.044 (2) | 0.039 (1) | 0.001 (1) | 0.002 (1) | 0.003 (1) |
Geometric parameters (Å, º) top
O1—C1 | 1.243 (3) | O5—H5o | 0.86 (1) |
O2—C1 | 1.253 (3) | O7—H7o | 0.85 (1) |
O3—C5 | 1.304 (3) | O1w—H1w1 | 0.85 (1) |
O4—C5 | 1.207 (3) | O1w—H1w2 | 0.85 (1) |
O5—C6 | 1.316 (3) | N1—H1n1 | 0.85 (1) |
O6—C6 | 1.203 (3) | N1—H1n2 | 0.85 (1) |
O7—C3 | 1.421 (3) | C2—H2a | 0.97 |
O8—C8 | 1.418 (3) | C2—H2b | 0.97 |
O8—C9 | 1.421 (3) | C4—H4a | 0.97 |
N1—C7 | 1.482 (3) | C4—H4b | 0.97 |
N1—C10 | 1.484 (3) | C7—H7a | 0.97 |
C1—C2 | 1.524 (3) | C7—H7b | 0.97 |
C2—C3 | 1.536 (3) | C8—H8a | 0.97 |
C3—C4 | 1.525 (3) | C8—H8b | 0.97 |
C3—C6 | 1.536 (3) | C9—H9a | 0.97 |
C4—C5 | 1.505 (3) | C9—H9b | 0.97 |
C7—C8 | 1.489 (4) | C10—H10a | 0.97 |
C9—C10 | 1.496 (4) | C10—H10b | 0.97 |
O3—H3o | 0.85 (1) | | |
| | | |
C8—O8—C9 | 109.9 (2) | C1—C2—H2a | 108.6 |
O1—C1—O2 | 124.2 (2) | C3—C2—H2a | 108.6 |
O1—C1—C2 | 118.7 (2) | C1—C2—H2b | 108.6 |
O2—C1—C2 | 117.2 (2) | C3—C2—H2b | 108.6 |
C1—C2—C3 | 114.6 (2) | H2a—C2—H2b | 107.6 |
O7—C3—C2 | 109.6 (2) | C5—C4—H4a | 108.8 |
O7—C3—C4 | 107.7 (2) | C3—C4—H4a | 108.8 |
C2—C3—C4 | 110.9 (2) | C5—C4—H4b | 108.8 |
O7—C3—C6 | 109.4 (2) | C3—C4—H4b | 108.8 |
C2—C3—C6 | 109.0 (2) | H4a—C4—H4b | 107.7 |
C4—C3—C6 | 110.3 (2) | N1—C7—H7a | 109.7 |
C3—C4—C5 | 113.6 (2) | C8—C7—H7a | 109.7 |
O3—C5—O4 | 123.1 (2) | N1—C7—H7b | 109.7 |
O3—C5—C4 | 112.8 (2) | C8—C7—H7b | 109.7 |
O4—C5—C4 | 124.1 (2) | H7a—C7—H7b | 108.2 |
O5—C6—O6 | 124.4 (2) | O8—C8—H8a | 109.4 |
O5—C6—C3 | 111.1 (2) | C7—C8—H8a | 109.4 |
O6—C6—C3 | 124.4 (2) | O8—C8—H8b | 109.4 |
N1—C7—C8 | 109.8 (2) | C7—C8—H8b | 109.4 |
O8—C8—C7 | 111.1 (2) | H8a—C8—H8b | 108.0 |
O8—C9—C10 | 111.4 (2) | O8—C9—H9a | 109.3 |
N1—C10—C9 | 109.0 (2) | C10—C9—H9a | 109.3 |
C5—O3—H3o | 110 (3) | O8—C9—H9b | 109.3 |
C6—O5—H5o | 109 (2) | C10—C9—H9b | 109.3 |
C3—O7—H7o | 105 (2) | H9a—C9—H9b | 108.0 |
H1w1—O1w—H1w2 | 109 (4) | N1—C10—H10a | 109.9 |
C7—N1—H1n1 | 109 (2) | C9—C10—H10a | 109.9 |
C10—N1—H1n1 | 111 (2) | N1—C10—H10b | 109.9 |
C7—N1—H1n2 | 107 (2) | C9—C10—H10b | 109.9 |
C10—N1—H1n2 | 113 (2) | H10a—C10—H10b | 108.3 |
H1n1—N1—H1n2 | 106 (3) | | |
| | | |
O1—C1—C2—C3 | 11.9 (3) | C4—C3—C6—O6 | 125.1 (2) |
O2—C1—C2—C3 | −169.8 (2) | C2—C3—C6—O6 | −113.0 (2) |
C1—C2—C3—O7 | −53.2 (2) | O7—C3—C6—O5 | −175.1 (2) |
C1—C2—C3—C4 | −171.9 (2) | C4—C3—C6—O5 | −56.9 (2) |
C1—C2—C3—C6 | 66.5 (2) | C2—C3—C6—O5 | 65.1 (2) |
O7—C3—C4—C5 | 63.2 (2) | C10—N1—C7—C8 | 54.3 (3) |
C2—C3—C4—C5 | −177.0 (2) | C9—O8—C8—C7 | 61.1 (3) |
C6—C3—C4—C5 | −56.1 (3) | N1—C7—C8—O8 | −57.6 (3) |
C3—C4—C5—O4 | 12.2 (3) | C8—O8—C9—C10 | −61.4 (3) |
C3—C4—C5—O3 | −169.6 (2) | C7—N1—C10—C9 | −54.1 (3) |
O7—C3—C6—O6 | 6.8 (3) | O8—C9—C10—N1 | 57.7 (3) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3o···O2i | 0.85 (1) | 1.76 (1) | 2.612 (2) | 176 (4) |
O5—H5o···O1w | 0.86 (1) | 1.68 (1) | 2.529 (3) | 172 (4) |
O7—H7o···O1 | 0.85 (1) | 1.89 (2) | 2.625 (2) | 144 (3) |
N1—H1n2···O1 | 0.85 (1) | 2.13 (2) | 2.847 (3) | 143 (3) |
N1—H1n1···O2ii | 0.85 (1) | 2.12 (2) | 2.942 (3) | 162 (3) |
O1w—H1w1···O6iii | 0.85 (1) | 2.16 (2) | 2.932 (3) | 152 (3) |
O1w—H1w2···O7ii | 0.85 (1) | 1.93 (1) | 2.782 (3) | 175 (4) |
Symmetry codes: (i) −x+3/2, −y+1, z+1/2; (ii) −x+3/2, y−1/2, z; (iii) x+1/2, −y+1/2, −z+1. |
Experimental details
Crystal data |
Chemical formula | C4H10NO·C6H7O7·H2O |
Mr | 297.26 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 298 |
a, b, c (Å) | 11.3774 (6), 12.4823 (7), 18.437 (1) |
V (Å3) | 2618.3 (2) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.13 |
Crystal size (mm) | 0.28 × 0.18 × 0.18 |
|
Data collection |
Diffractometer | Bruker AXS area-detector diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12407, 2305, 2103 |
Rint | 0.028 |
(sin θ/λ)max (Å−1) | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.143, 1.15 |
No. of reflections | 2305 |
No. of parameters | 209 |
No. of restraints | 7 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.29, −0.19 |
Selected geometric parameters (Å, º) topO1—C1 | 1.243 (3) | N1—C7 | 1.482 (3) |
O2—C1 | 1.253 (3) | N1—C10 | 1.484 (3) |
O3—C5 | 1.304 (3) | C1—C2 | 1.524 (3) |
O4—C5 | 1.207 (3) | C2—C3 | 1.536 (3) |
O5—C6 | 1.316 (3) | C3—C4 | 1.525 (3) |
O6—C6 | 1.203 (3) | C3—C6 | 1.536 (3) |
O7—C3 | 1.421 (3) | C4—C5 | 1.505 (3) |
O8—C8 | 1.418 (3) | C7—C8 | 1.489 (4) |
O8—C9 | 1.421 (3) | C9—C10 | 1.496 (4) |
| | | |
C8—O8—C9 | 109.9 (2) | C3—C4—C5 | 113.6 (2) |
O1—C1—O2 | 124.2 (2) | O3—C5—O4 | 123.1 (2) |
O1—C1—C2 | 118.7 (2) | O3—C5—C4 | 112.8 (2) |
O2—C1—C2 | 117.2 (2) | O4—C5—C4 | 124.1 (2) |
C1—C2—C3 | 114.6 (2) | O5—C6—O6 | 124.4 (2) |
O7—C3—C2 | 109.6 (2) | O5—C6—C3 | 111.1 (2) |
O7—C3—C4 | 107.7 (2) | O6—C6—C3 | 124.4 (2) |
C2—C3—C4 | 110.9 (2) | N1—C7—C8 | 109.8 (2) |
O7—C3—C6 | 109.4 (2) | O8—C8—C7 | 111.1 (2) |
C2—C3—C6 | 109.0 (2) | O8—C9—C10 | 111.4 (2) |
C4—C3—C6 | 110.3 (2) | N1—C10—C9 | 109.0 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3o···O2i | 0.85 (1) | 1.76 (1) | 2.612 (2) | 176 (4) |
O5—H5o···O1w | 0.86 (1) | 1.68 (1) | 2.529 (3) | 172 (4) |
O7—H7o···O1 | 0.85 (1) | 1.89 (2) | 2.625 (2) | 144 (3) |
N1—H1n2···O1 | 0.85 (1) | 2.13 (2) | 2.847 (3) | 143 (3) |
N1—H1n1···O2ii | 0.85 (1) | 2.12 (2) | 2.942 (3) | 162 (3) |
O1w—H1w1···O6iii | 0.85 (1) | 2.16 (2) | 2.932 (3) | 152 (3) |
O1w—H1w2···O7ii | 0.85 (1) | 1.93 (1) | 2.782 (3) | 175 (4) |
Symmetry codes: (i) −x+3/2, −y+1, z+1/2; (ii) −x+3/2, y−1/2, z; (iii) x+1/2, −y+1/2, −z+1. |
Subscribe to Acta Crystallographica Section E: Crystallographic Communications
The full text of this article is available to subscribers to the journal.
If you have already registered and are using a computer listed in your registration details, please email
support@iucr.org for assistance.
A previous report described the dicyclohexylammonium salts of monocarboxylic and dicarboxylic acids (Ng, 2003). For some of the acids, their reaction with dicyclohexylamine afforded ammonium carboxylate as a hydrate (Ng, 1992; Yang et al., 2000). On the other hand, others reacted with an excess of this secondary amine to yield only the mono(ammonium) salt, e.g., dicyclohexylammonium hydrogen oxalate (Ng, 1994). The reaction with the tribasic acid, citric acid, gave a compound that rapidly turned opaque when the crystals were removed from its solution in ethanol; on the other hand, the use of diisopropylamine in place of dicyclohexylamine led to a syrupy material after the solvent had evaported. A check on the sec-ammonium derivatives of carboxylic acids suggested the use of morpholine as this amine furnishes a large number of isolable carboxylates, such as chloronitrobenzoates (Ishida et al., 2001a; 2001b, 2001c) and morpholinoformate (Brown & Gray, 1982). Citric has also been characterized as an N-substituted morpholinium derivative (Peeters et al., 1979). In the present study, the reaction of citric acid with either one or two molar equivalents of morpholine gave the air-stable title compound, (I) (Fig. 1).
In the crystal structure of (I), the cation interacts with the carboxyl O atoms of two citrato anions [N···O 2.847 (3) and 2.942 (3) Å] resulting in the formation of a linear chain running along the b axis of the crystal. Such a hydrogen-bonded motif has previously been noted in dicyclohexylammonium trifluoroacetate (Ng et al., 1999). Adjacent chains are linked through the carboxylic —CO2H groups and water molecule into a layer structure (Fig. 2, Table 2).