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In the title compound, NH4+·C4HO4-·2\over 3H2O, the hydrogen squarate anions and water molecules are arranged to form planes almost parallel to bc. The ammonium cations are located between these planes and cross-link them in the a direction by means of an extensive network of hydrogen bonds. There are two symmetry-independent sets of cations and anions. One of the hydrogen squarate anions and one of the ammonium cations are situated on a twofold axis and the H atoms of these moieties are disordered over the symmetry-related sites.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199009415/ln1082sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270199009415/ln1082Isup2.hkl
Contains datablock I

CCDC reference: 140971

Comment top

The structure determination of ammonium hydrogen squarate–water (3/2), (I), was carried out as part of a project investigating scheme the non-linear optical properties of new classes of organic compounds. The crystal structures of L-argininium hydrogen squarate (Angelova, Velikova et al., 1996), R-(-)-1-phenylglycinium hydrogen squarate (Angelova, Petrova et al., 1996), guanidinium hydrogen squarate (Kolev, Preut et al., 1997), 1-phenylethylammonium hydrogen squarate monohydrate (Kolev, Stahl et al., 1997), bis[(L)-(-)-asparaginum hydrogen squarate] monohydrate (Kolev, Stahl, Preut, Koniczek et al., 1998) and L-(+)-serinium hydrogen squarate (Kolev, Stahl, Preut, Bleckmann & Radomirska et al., 1998) have already been published. A search of the chemical literature (Chemical Abstracts and Beilstein) has shown no entry for (I). The crystal structures of hydrogen squarates of [H2NMe2]+ (Wang & Stucky, 1974), some alkali metals (Bull et al., 1973; Semmingsen, 1976) and 3 d metals such as Co and Ni (Brach et al., 1987) are already known.

The title compound exhibits a structure in which hydrogen squarate anions and water molecules are hydrogen-bonded and arranged to form planes almost parallel to the bc plane. The ammonium ions are located between these planes and connect them by an extensive network of hydrogen bonds. The structures of the individual moieties and the atomic numbering scheme are shown in Fig. 1, while the packing of the structure along the a axis is shown in Fig. 2.

There are two symmetry-independent squarate anions in the asymmetric unit. One of them has C2 symmetry and is situated on the twofold axis at (0, y, 1/4). The set of symmetrically equivalent anions of this type are hydrogen-bonded to each other and build zigzag chains which run parallel to the c axis. These chains are arranged to form squarate planes (S) which are virtually coincident with the (100) plane. The hydrogen squarate anions of the second type do not possess crystallographic C2 symmetry, but still form similar hydrogen-bonded chains which are, in addition, hydrogen-bonded to the water molecules. The water molecules thereby cross-link this latter type of anionic chains and the thus-constituted squarate–water planes (S/W) lie parallel to (100) but are located at approximately 1/4 and 3/4 along the a axis. The two ammonium ions have different structural roles. The cation involving N1 is in a general position and the ammonium ions of this type cross-link one S plane to its neighbouring S/W planes situated on either side along the a direction. In addition, these cations cross-link adjacent anionic chains within each S plane. The cation involving N2 is situated on a twofold axis at (1/2, y, 1/4). The ammonium ions of this type couple adjacent S/W planes via N—H···O hydrogen bonds and, together with the water molecules, also help to cross-link adjacent anionic chains within each S/W plane. Thus, the structure can be described as a set of alternating layers of anions and cations arranged in the sequence S N1 S/W N2 S/W N1 S··· along the a axis.

In most of the reported structures of organic compounds containing hydrogen squarate moieties, the anions are hydrogen-bonded to each other to create similar chains. The only known exception is the structure of L-argininium hydrogen squarate, where the squarate anions are dimerized through double cyclic O—H···O bonds (Angelova, Velikova et al., 1996).

Full details of the hydrogen-bonding geometry are given in Table 2. The O···O contacts within the hydrogen squarate chains of 2.4510 (13) and 2.464 (2) Å indicate very strong hydrogen bonding (Emsley, 1980). The hydrogen bonds formed between hydrogen squarate chains and water molecules within the S/W plane can be described as normal, with O···O distances of 2.7534 (18) and 2.7840 (18) Å. Significantly weaker are the N—H···O hydrogen bonds, which connect the ammonium cations to the squarate anions and the water molecules. The N···O distances vary between 2.8312 (14) and 3.109 (2) Å.

Experimental top

The title compound was prepared by addition of an aqueous solution of ammonium carbonate to a water solution of squaric acid in a 2:1 molar ratio with continuous stirring for 30 min. The product was purified by multiple recrystallization from double-distilled water. Colourless crystals of (I) suitable for X-ray analysis were grown by slow evaporation from an aqueous solution at room temperature.

Refinement top

All H atoms were placed in positions found from difference Fourier syntheses and allowed to refine freely. Due to the local C2 symmetry of one of the hydrogen squarate anions, the position of the H atom of this anion has been refined with a site occupancy of 0.5. Positional disorder of this type is known in L-(+)-serinium hydrogen squarate. Atom N2 of one ammonium group is situated on a twofold axis. Four non-equivalent H atoms were located around this N atom and their positions were similarly refined with site occupancies of 0.5.

Computing details top

Data collection: CAD-4 Manual (Enraf-Nonius, 1988); data reduction: SDP/PDP (Enraf-Nonius, 1985); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The independent entities in the structure of (I), with atom labels and 50% probability ellipsoids for non-H atoms. The disordered H atoms are indicated by dotted lines.
[Figure 2] Fig. 2. The packing of the molecules in (I) down the a axis. The hydrogen bonds are indicated by dotted lines and the disordered H atoms are indicated by dashed lines.
Ammonium hydrogen squarate–water (3/2) top
Crystal data top
H4N+·C4HO4·2/3H2OF(000) = 448
Mr = 143.10Dx = 1.586 Mg m3
Monoclinic, P2/cMo Kα radiation, λ = 0.71073 Å
a = 10.031 (3) ÅCell parameters from 22 reflections
b = 8.2799 (17) Åθ = 20.0–21.7°
c = 10.968 (2) ŵ = 0.15 mm1
β = 99.274 (2)°T = 293 K
V = 899.02 (16) Å3Prismatic, colourless
Z = 60.40 × 0.33 × 0.26 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.106
Radiation source: fine-focus sealed tubeθmax = 27.9°, θmin = 2.1°
Graphite monochromatorh = 013
ω–2θ scansk = 1010
4406 measured reflectionsl = 1414
2166 independent reflections3 standard reflections every 500 reflections
1343 reflections with I > 2σ(I) intensity decay: 0.7%
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)] = 0.053All H-atom parameters refined
wR(F2) = 0.146Calculated w = 1/[σ2(Fo2) + (0.0811P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max < 0.001
2166 reflectionsΔρmax = 0.51 e Å3
181 parametersΔρmin = 0.33 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.014 (3)
Crystal data top
H4N+·C4HO4·2/3H2OV = 899.02 (16) Å3
Mr = 143.10Z = 6
Monoclinic, P2/cMo Kα radiation
a = 10.031 (3) ŵ = 0.15 mm1
b = 8.2799 (17) ÅT = 293 K
c = 10.968 (2) Å0.40 × 0.33 × 0.26 mm
β = 99.274 (2)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.106
4406 measured reflections3 standard reflections every 500 reflections
2166 independent reflections intensity decay: 0.7%
1343 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0530 restraints
wR(F2) = 0.146All H-atom parameters refined
S = 1.01Δρmax = 0.51 e Å3
2166 reflectionsΔρmin = 0.33 e Å3
181 parameters
Special details top

Experimental. none

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
C120.00262 (16)0.43584 (17)0.18491 (12)0.0311 (4)
C110.00284 (17)0.25896 (18)0.18118 (12)0.0330 (4)
C210.30642 (17)0.26129 (18)0.00869 (12)0.0327 (4)
C220.32240 (17)0.43500 (18)0.00426 (12)0.0330 (4)
C230.32758 (16)0.43854 (18)0.12603 (11)0.0318 (4)
C240.31840 (17)0.26017 (18)0.12985 (12)0.0325 (4)
O110.00637 (15)0.15556 (14)0.10095 (10)0.0478 (4)
O120.00473 (13)0.54942 (14)0.10518 (9)0.0400 (3)
H10.014 (8)0.508 (12)0.023 (7)0.10 (2)*0.50
O210.28971 (14)0.15910 (13)0.09197 (9)0.0435 (4)
O220.32956 (15)0.54604 (14)0.08491 (9)0.0468 (4)
O230.33528 (14)0.55179 (14)0.20507 (8)0.0429 (4)
O240.31969 (14)0.15811 (14)0.21039 (9)0.0452 (4)
H20.330 (3)0.498 (5)0.181 (3)0.126 (12)*
N10.13389 (18)0.8576 (2)0.15585 (13)0.0420 (4)
H110.088 (2)0.954 (3)0.1419 (19)0.061 (6)*
H120.174 (2)0.850 (2)0.236 (2)0.052 (6)*
H130.201 (3)0.860 (3)0.098 (2)0.084 (9)*
H140.080 (3)0.774 (3)0.1339 (18)0.057 (6)*
N20.50000.8703 (3)0.25000.0416 (5)
H210.445 (4)0.980 (6)0.227 (4)0.060 (13)*0.50
H220.532 (5)0.875 (5)0.334 (4)0.041 (10)*0.50
H230.462 (5)0.776 (6)0.226 (5)0.070 (16)*0.50
H240.566 (6)0.879 (6)0.200 (5)0.064 (14)*0.50
OW0.34403 (17)0.14189 (17)0.01083 (11)0.0499 (4)
HW10.337 (3)0.214 (3)0.038 (2)0.064 (7)*
HW20.325 (3)0.059 (3)0.035 (2)0.076 (8)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C120.0406 (8)0.0299 (7)0.0230 (6)0.0000 (7)0.0060 (6)0.0011 (5)
C110.0409 (8)0.0300 (7)0.0269 (7)0.0020 (7)0.0016 (6)0.0001 (5)
C210.0460 (9)0.0295 (7)0.0232 (6)0.0009 (7)0.0073 (6)0.0007 (5)
C220.0488 (9)0.0283 (7)0.0227 (6)0.0000 (7)0.0085 (6)0.0007 (5)
C230.0433 (8)0.0312 (7)0.0217 (6)0.0011 (7)0.0077 (6)0.0007 (5)
C240.0430 (8)0.0308 (7)0.0241 (6)0.0006 (7)0.0069 (6)0.0005 (5)
O110.0710 (9)0.0358 (7)0.0340 (6)0.0057 (6)0.0004 (6)0.0092 (4)
O120.0658 (8)0.0312 (6)0.0234 (5)0.0029 (6)0.0082 (5)0.0036 (4)
O210.0720 (9)0.0318 (6)0.0268 (5)0.0016 (6)0.0086 (5)0.0041 (4)
O220.0899 (10)0.0302 (6)0.0223 (5)0.0058 (6)0.0156 (6)0.0010 (4)
O230.0760 (9)0.0322 (6)0.0216 (5)0.0053 (6)0.0113 (5)0.0035 (4)
O240.0730 (9)0.0344 (7)0.0294 (6)0.0028 (6)0.0115 (6)0.0083 (4)
N10.0558 (10)0.0359 (8)0.0325 (7)0.0021 (8)0.0013 (7)0.0023 (6)
N20.0492 (13)0.0432 (13)0.0327 (11)0.0000.0072 (10)0.000
OW0.0795 (11)0.0350 (7)0.0335 (6)0.0008 (7)0.0038 (6)0.0024 (5)
Geometric parameters (Å, º) top
C12—O121.2820 (17)O12—H10.96 (8)
C12—C12i1.420 (2)O22—H21.12 (3)
C12—C111.465 (2)N1—H110.92 (2)
C11—O111.2241 (17)N1—H120.91 (2)
C11—C11i1.501 (3)N1—H131.00 (3)
C21—O211.2365 (18)N1—H140.89 (3)
C21—C221.447 (2)N2—H211.07 (5)
C21—C241.5048 (17)N2—H220.92 (4)
C22—O221.2859 (17)N2—H230.89 (5)
C22—C231.4217 (17)N2—H240.92 (6)
C23—O231.2710 (17)OW—HW10.79 (3)
C23—C241.481 (2)OW—HW20.86 (3)
C24—O241.2210 (17)
O12—C12—C12i132.81 (8)C23—C24—C2187.74 (11)
O12—C12—C11135.60 (12)C12—O12—H1112 (6)
C12i—C12—C1191.59 (7)C22—O22—H2114 (2)
O11—C11—C12135.97 (13)H11—N1—H12110.8 (17)
O11—C11—C11i135.62 (9)H11—N1—H13104 (2)
C12—C11—C11i88.41 (7)H12—N1—H13112 (2)
O21—C21—C22134.91 (12)H11—N1—H14111 (2)
O21—C21—C24136.13 (14)H12—N1—H14111.4 (18)
C22—C21—C2488.96 (11)H13—N1—H14106 (2)
O22—C22—C23132.81 (14)H21—N2—H22107 (4)
O22—C22—C21134.88 (12)H21—N2—H23120 (4)
C23—C22—C2192.30 (11)H22—N2—H23113 (5)
O23—C23—C22133.56 (14)H21—N2—H24101 (4)
O23—C23—C24135.55 (12)H22—N2—H24115 (3)
C22—C23—C2490.89 (11)H23—N2—H24102 (5)
O24—C24—C23135.83 (13)HW1—OW—HW2103 (2)
O24—C24—C21136.43 (14)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O12—H1···O12ii0.96 (8)1.52 (7)2.464 (2)167 (8)
O22—H2···O23iii1.12 (3)1.33 (3)2.4510 (13)177 (4)
N1—H11···O11iv0.92 (2)1.93 (3)2.856 (2)176.0 (18)
N1—H12···O21v0.91 (2)2.05 (2)2.953 (2)172.2 (19)
N1—H13···OWiv1.00 (3)1.84 (3)2.838 (2)171 (2)
N1—H14···O120.89 (3)2.05 (3)2.916 (2)166 (2)
N2—H21···O24iv1.07 (5)1.93 (5)2.981 (2)167 (4)
N2—H22···OWvi0.92 (4)1.95 (4)2.8312 (14)160 (4)
N2—H23···O230.89 (5)2.24 (5)3.109 (2)165 (5)
N2—H24···O21vii0.92 (6)2.04 (6)2.9481 (13)167 (4)
OW—HW1···O22viii0.79 (3)2.05 (3)2.7840 (18)153 (2)
OW—HW2···O210.86 (3)1.92 (3)2.7534 (18)163 (2)
Symmetry codes: (ii) x, y+1, z; (iii) x, y+1, z1/2; (iv) x, y+1, z; (v) x, y+1, z+1/2; (vi) x+1, y+1, z+1/2; (vii) x+1, y+1, z; (viii) x, y1, z.

Experimental details

Crystal data
Chemical formulaH4N+·C4HO4·2/3H2O
Mr143.10
Crystal system, space groupMonoclinic, P2/c
Temperature (K)293
a, b, c (Å)10.031 (3), 8.2799 (17), 10.968 (2)
β (°) 99.274 (2)
V3)899.02 (16)
Z6
Radiation typeMo Kα
µ (mm1)0.15
Crystal size (mm)0.40 × 0.33 × 0.26
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
4406, 2166, 1343
Rint0.106
(sin θ/λ)max1)0.659
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.053, 0.146, 1.01
No. of reflections2166
No. of parameters181
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.51, 0.33

Computer programs: CAD-4 Manual (Enraf-Nonius, 1988), SDP/PDP (Enraf-Nonius, 1985), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976), SHELXL97.

Selected bond lengths (Å) top
C12—O121.2820 (17)C21—C241.5048 (17)
C12—C12i1.420 (2)C22—O221.2859 (17)
C12—C111.465 (2)C22—C231.4217 (17)
C11—O111.2241 (17)C23—O231.2710 (17)
C11—C11i1.501 (3)C23—C241.481 (2)
C21—O211.2365 (18)C24—O241.2210 (17)
C21—C221.447 (2)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O12—H1···O12ii0.96 (8)1.52 (7)2.464 (2)167 (8)
O22—H2···O23iii1.12 (3)1.33 (3)2.4510 (13)177 (4)
N1—H11···O11iv0.92 (2)1.93 (3)2.856 (2)176.0 (18)
N1—H12···O21v0.91 (2)2.05 (2)2.953 (2)172.2 (19)
N1—H13···OWiv1.00 (3)1.84 (3)2.838 (2)171 (2)
N1—H14···O120.89 (3)2.05 (3)2.916 (2)166 (2)
N2—H21···O24iv1.07 (5)1.93 (5)2.981 (2)167 (4)
N2—H22···OWvi0.92 (4)1.95 (4)2.8312 (14)160 (4)
N2—H23···O230.89 (5)2.24 (5)3.109 (2)165 (5)
N2—H24···O21vii0.92 (6)2.04 (6)2.9481 (13)167 (4)
OW—HW1···O22viii0.79 (3)2.05 (3)2.7840 (18)153 (2)
OW—HW2···O210.86 (3)1.92 (3)2.7534 (18)163 (2)
Symmetry codes: (ii) x, y+1, z; (iii) x, y+1, z1/2; (iv) x, y+1, z; (v) x, y+1, z+1/2; (vi) x+1, y+1, z+1/2; (vii) x+1, y+1, z; (viii) x, y1, z.
 

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