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The crystal structure of NaCl·CH4N2O·H2O has been determined at 117 K and redetermined at room temperature. It can be described as consisting of alternating `organic' and `inorganic' planar layers. While at room temperature the structure belongs to the space group I2, the low-temperature structure belongs to the space group Pn21m. All water O atoms are located on positions with crystallographic symmetry 2 (m) in the room-temperature (low-temperature) structure, which means that the water mol­ecules belong, in both cases, to point group mm2. During the phase transition, half of the urea mol­ecules per unit cell perform a 90° rotation about their respective C-O axes. The other half and the inorganic parts of the structure remain unaltered. The relationship between the two phases is remarkable, inasmuch as no obvious reason for the transition to occur could be found; the internal structures of all components of the two phases remain unaltered and even the inter­actions between the different parts seem to be the same before and after the transition (at least when looked at from an energetic point of view).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270108022427/gd3223sup1.cif
Contains datablocks I_293K, I_117K, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270108022427/gd3223I_293Ksup2.hkl
Contains datablock I_293K

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270108022427/gd3223I_117Ksup3.hkl
Contains datablock I_117K

CCDC references: 700016; 700017

Comment top

In the Georg-Kerschensteiner-Gymnasium Müllheim there is a 30 year tradition of growing crystals by pupils (Georg-Kerschensteiner-Gymnasium Müllheim, 2008). In searching for more crystal growth experiments performable by grammar school students – and being aware of the existence of rock salt–glucose–water (1/2/1) crystals (Ferguson et al., 1991) – we have tried to grow crystals from aqueous solutions containing rock salt and urea. The growth experiments led to large single-crystal plates of which we determined the structure at ambient temperature and at 117 K. Structure analysis showed the crystals to be composed of rock salt, urea and water in the molar relation 1:1:1. Actually, NaCl.CH4N2O.H2O, (I) (or NCUREA), crystals have been known for a long time (see Kleber et al., 1950); their three-dimensional structure at ambient conditions was determined by Palm & MacGillavry (1963) from two Weissenberg zero-level photographs. Our own X-ray experiments confirm and refine the results of Palm & MacGillavry (1963) but show that the structure at 117 K is different from that at room temperature.

While in principle our room-temperature structure of (I) is equal to the I2 structure described by Palm and MacGillavry (1963) there are, not surprisingly, some differences in detail. For example, the short Cl—N distance of 3.05 Å mentioned by Palm & MacGillavry (1963) is replaced by the more reasonable distance of 3.35 Å in our investigation. Furthermore, the quality of our data allowed us to localize all H atoms in the difference Fourier maps (but see the Experimental section) and to determine the correct absolute configuration.

Palm & MacGillavry (1963) have already described the structure and its relationship to the structures of urea and NaCl. In addition to their view we would like to picture the structure (Fig. 1a) as a stacking of toothed alternating `inorganic' and `organic' (001) layers (Fig. 2). The former consist of Na+ ions, Cl- ions and H2O molecules, forming infinite –Na(µ2-OH2)Na([µ2-Cl]22-OH2)Na– chains parallel to [100] with vicinal chains connected by O—H···Cl hydrogen bonds (Fig. 3). The Cl atoms form the `teeth' of these layers. The organic layers simply contain the urea molecules with the O3 atoms acting as `teeth'. The interface between the two different layers is stabilized by Na—O3 bonds, by four different N—H···Cl hydrogen bonds and by O—H···O hydrogen bonds. As already mentioned by Palm & MacGillavry (1963), the Na+ ions are octahedrally coordinated by two Cl- ions, two water O atoms and two carbonyl O atoms (Tables 1 and 3). The Cl- ions are twofold coordinated by two Na+ ions in a nonlinear manner. If hydrogen bonds to Cl (Tables 2 and 4) are included, an irregular sevenfold coordination results.

Within one organic layer, the orientation of the planar urea molecules alternates in the 110 directions by a form of local 4 operation, i.e. one molecule is transformed into the vicinal one (approximately) by mirroring at, for example, (x, y, 3/4) and a subsequent rotation by 90° about a [001] axis roughly located at (0, 1/2, z) or (1/2, 0, z). When going from one organic layer to the vicinal one in the [001] direction, there is a similar relation between two vicinal urea molecules. Here, the mirror plane is, for example, (x, y, 1/2) and the rotation axis is defined by the (approximately) coinciding axes of the two carbonyl groups [close to (0, 0, z) or (1/2, 1/2, z)].

The 117 K Pn21m structure of (I) (Fig. 1b) differs from the room-temperature I2 structure exclusively by the fact that this latter operation (and only this one) is replaced by a real mirror m, i.e. the rotation by 90° about the [001] axis drops out. This means that in the transition from room temperature to 117 K the inorganic layers and one of the two organic layers remain essentially the same, while in the second organic layer all urea molecules perform a synchronized 90° flip about a [001] axis defined (approximately) by their respective carbonyl groups. While a superposition of the projections of the two structures parallel [100] hardly shows any positional differences, small, but significant, differences can be seen in the second organic layers when viewed parallel to the [010] direction (Fig. 4).

The coordination polyhedra of Na and of two of the four Cl atoms remain unaltered by the transition. For the other two Cl atoms, the absolute configuration of the coordination polyhedron (including H atoms) changes; furthermore, two of the H atoms (H11 and H21) are `donated' to a given Cl atom by two different urea molecules after the transition as compared with the situation before the transition (which obviously is reversible, see the Experimental section).

Thus, hydrogen bonds are broken and reformed. There is, on the other hand, no group–subgroup relation between the two space groups I2 (room temperature) and Pn21m (117 K), the multiplicity of the general position being 4 in both cases. Instead, the relationship between the two structures is reflected in the fact that both space groups are maximal non-isomorphic subgroups to Im2m. As the different components of the structure do not change significantly during the transition and as even the interactions between these different parts seem to be unaffected in principle (at least when seen from an energetical point of view), we could find no obvious reason for the transition to occur.

Another question is how easily alkali halides, purely organic molecules and water form crystalline structures as a `joint venture' as in (I). As an answer to this, a search in the 2008 release of the Cambridge Structural Database (CSD; Allen, 2002) yielded some 50 structures fulfilling this condition. However, we found only nine structures [including (I)] with a 1:1:1 composition (Table 5). In most of these, the alkali ion is `captured' (i.e. multiply coordinated) by a cyclic part of the organic molecule. Only two structures [CSD refcodes CMHTRB (Fodor et al., 1971 or 1973??) and KESGUL (Fan et al., 2007)] do not show this feature and are as such comparable to (I). In contrast to the latter, in KESGUL the inorganic part consists of isolated NaI `molecules' and isolated water molecules. Details of the CMHTRB structure are not available. Finally, it should be noted that thiourea (CH4N2S) forms structures with CsX (X = F and Cl) and water, but the compositions are 1:4:2 and 1:4:1 in these cases (Boeyens 1968a,b).

Related literature top

For related literature, see: Fan et al. (2007); Georg-Kerschensteiner-Gymnasium (2008); Palm & MacGillavry (1963).

Experimental top

Urea (40.0 g, 0.666 mol), NaCl (15.5 g, 0.265 mol) and H2O (40 ml) were stirred at 303 K by a magnetic stirrer until a clear solution had formed. After slow evaporation of the water at 285 K (in a refrigerator), large crystal plates formed. The experiment was repeated. The separated solution was cooled to room temperature. A seed crystal cut from one of the crystal plates obtained in the previous experiment was added and the solution was put into the refrigerator. Large crystal plates formed comparatively rapidly in the solution. The solution was removed and the plates were dried with paper. Two small roughly isometric fragments were cut from the large crystal plates and measured in sealed capillaries. The first fragment was measured first at 117 K and then at room temperature. The second fragment was measured first at room temperature and then at 117 K.

Refinement top

After solution and/or refinement, the two room-temperature (and the two low-temperature) structures turned out to be essentially the same (Figs. 5 and 6). The two structures yielding the best reliability factors (the room-temperature structure of crystal 1 and the low-temperature structure of crystal 2) are referred to in the tables and figures. All H atoms were located in difference maps, but free refinement did not lead to positions of sufficient quality. Therefore, in both structures, the H atoms bonded to N atoms were treated as riding atoms, with N—H distances of 0.88 Å and with Uiso(H) values of 1.2Ueq(N). Restraints were applied to the water molecules [specify values of restraints]. The correct absolute configuration for the ambient-temperature structure, and the correct orientation of the low-temperature structure with respect to the polar-axis direction, were established by means of the Flack ( 1983) parameters, although these have no chemical significance.

Computing details top

For both compounds, data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SCHAKAL99 (Keller, 2004); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The room-temperature I2 (a) and low-temperature Pn21m (b) structures of (I) (view parallel to [100]). All x values of corresponding atoms differ by approximately 0.25 (before and after the transition, see Fig. 4). The two structures differ significantly only in the shaded range (location of one-half of the amide groups). In (b), atom Na2 is positioned exactly behind Na1.
[Figure 2] Fig. 2. A ball-and-stick model and a space-filling model of the room-temperature structure of (I) superimposed, as seen parallel to [010]. In the space-filling model, the atoms of the inorganic layers have been shaded grey.
[Figure 3] Fig. 3. An inorganic layer of (I), as seen parallel to [101], with O3 atoms and O—H···O hydrogen bonds added.
[Figure 4] Fig. 4. : A superimposition of the room-temperature structure (red solid lines) and the low temperature structure (blue dashed lines) of (I) as seen parallel to [0–10]. After aligning both a vectors vertically, prior to superimposition the room temperature structure has been rotated by 0.076° counterclockwise to account for the difference of 0.152° between the monoclinic angle and 90°. The point of coincidence in the center is marked by "*".
[Figure 5] Fig. 5. : The molecular structure of (I) at room temperature. Displacement ellipsoids are shown at the ??% probability level.
[Figure 6] Fig. 6. : The molecular structure of (I) at 115 K. Displacement ellipsoids are shown at the ??% probability level.
(I_293K) Rock salt–urea–water (1/1/1) (NaCl.CH4N2O.H2O) top
Crystal data top
NaCl·CH4N2O·H2OF(000) = 280
Mr = 136.52Dx = 1.539 Mg m3
Monoclinic, I2Mo Kα radiation, λ = 0.71073 Å
Hall symbol: I 2yCell parameters from 5993 reflections
a = 6.4845 (2) Åθ = 3.1–35.2°
b = 5.2362 (2) ŵ = 0.62 mm1
c = 17.3497 (5) ÅT = 293 K
β = 90.152 (2)°Distorted cube, colourless
V = 589.09 (3) Å30.4 × 0.4 × 0.4 mm
Z = 4
Data collection top
Bruker SMART CCD area-detector
diffractometer
1728 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.057
Graphite monochromatorθmax = 30.3°, θmin = 2.4°
phi and ω scansh = 99
7728 measured reflectionsk = 77
1752 independent reflectionsl = 2424
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.031H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.085 w = 1/[σ2(Fo2) + (0.0443P)2 + 0.0989P]
where P = (Fo2 + 2Fc2)/3
S = 1.25(Δ/σ)max = 0.006
1752 reflectionsΔρmax = 0.36 e Å3
71 parametersΔρmin = 0.31 e Å3
5 restraintsAbsolute structure: Flack (1983), 783 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.00 (7)
Crystal data top
NaCl·CH4N2O·H2OV = 589.09 (3) Å3
Mr = 136.52Z = 4
Monoclinic, I2Mo Kα radiation
a = 6.4845 (2) ŵ = 0.62 mm1
b = 5.2362 (2) ÅT = 293 K
c = 17.3497 (5) Å0.4 × 0.4 × 0.4 mm
β = 90.152 (2)°
Data collection top
Bruker SMART CCD area-detector
diffractometer
1728 reflections with I > 2σ(I)
7728 measured reflectionsRint = 0.057
1752 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.031H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.085Δρmax = 0.36 e Å3
S = 1.25Δρmin = 0.31 e Å3
1752 reflectionsAbsolute structure: Flack (1983), 783 Friedel pairs
71 parametersAbsolute structure parameter: 0.00 (7)
5 restraints
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
xyzUiso*/Ueq
Cl10.50588 (6)0.41569 (9)0.61655 (2)0.03345 (12)
Na10.24084 (9)0.19015 (15)0.49905 (4)0.02959 (16)
O10.50000.1216 (3)0.50000.0336 (4)
H10.482 (4)0.215 (5)0.5372 (9)0.050*
O20.00000.5314 (3)0.50000.0334 (4)
H20.005 (4)0.629 (5)0.5372 (9)0.050*
O30.4972 (2)0.4896 (3)0.91172 (7)0.0336 (3)
N10.3855 (3)0.6191 (5)0.79495 (11)0.0564 (6)
H110.30020.72540.81520.068*
H120.39370.60570.74570.068*
N20.6330 (3)0.3147 (5)0.80417 (11)0.0561 (6)
H210.71290.21780.83090.067*
H220.63570.30800.75470.067*
C10.5041 (2)0.4763 (3)0.83970 (9)0.0291 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0389 (2)0.0384 (2)0.02304 (17)0.00727 (17)0.00164 (13)0.00221 (16)
Na10.0232 (3)0.0338 (3)0.0318 (3)0.0006 (2)0.0000 (2)0.0007 (3)
O10.0398 (8)0.0244 (9)0.0365 (9)0.0000.0020 (7)0.000
O20.0418 (9)0.0247 (8)0.0339 (9)0.0000.0026 (7)0.000
O30.0371 (6)0.0431 (7)0.0206 (5)0.0038 (5)0.0004 (4)0.0025 (4)
N10.0666 (11)0.0731 (14)0.0294 (8)0.0388 (11)0.0009 (8)0.0016 (8)
N20.0612 (11)0.0750 (14)0.0320 (9)0.0392 (10)0.0006 (8)0.0049 (8)
C10.0316 (7)0.0336 (9)0.0220 (7)0.0034 (6)0.0003 (5)0.0009 (5)
Geometric parameters (Å, º) top
Cl1—Na1i2.8516 (8)Na1—O3iv2.4281 (15)
Cl1—Na12.9130 (8)O3—C11.252 (2)
Na1—Na1ii3.1237 (12)N1—C11.323 (2)
Na1—Na1i3.3612 (12)N2—C11.341 (2)
Na1—O12.3430 (13)O1—H10.819 (15)
Na1—O22.3732 (15)O2—H20.825 (16)
Na1—O3iii2.4251 (15)
Cl1i—Na1—Cl189.11 (2)O2—Na1—Cl194.41 (3)
Na1i—Cl1—Na171.32 (2)O3iii—Na1—Cl1174.21 (4)
O1—Na1—O2175.26 (5)O3iv—Na1—Cl195.97 (4)
O1—Na1—O3iii99.71 (5)Na1—O1—Na1i91.66 (7)
O2—Na1—O3iii84.43 (4)Na1ii—O2—Na182.31 (6)
O1—Na1—O3iv98.70 (5)C1—O3—Na1v128.51 (12)
O2—Na1—O3iv84.36 (4)C1—O3—Na1vi133.19 (12)
O3iii—Na1—O3iv78.28 (6)Na1v—O3—Na1vi80.12 (5)
O1—Na1—Cl1i83.05 (3)O3—C1—N1122.16 (16)
O2—Na1—Cl1i94.21 (3)O3—C1—N2121.16 (16)
O3iii—Na1—Cl1i96.63 (4)N1—C1—N2116.68 (17)
O3iv—Na1—Cl1i174.81 (4)H1—O1—H1i106 (3)
O1—Na1—Cl181.70 (3)H2—O2—H2ii103 (3)
Symmetry codes: (i) x+1, y, z+1; (ii) x, y, z+1; (iii) x1/2, y1/2, z1/2; (iv) x+1/2, y1/2, z+3/2; (v) x+1/2, y+1/2, z+1/2; (vi) x+1/2, y+1/2, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H12···Cl10.862.563.3671 (19)157
N1—H11···Cl1vi0.862.523.3512 (19)163
N2—H22···Cl10.862.603.397 (2)155
N2—H21···Cl1vii0.862.583.4242 (19)168
O1—H1···Cl1viii0.82 (2)2.38 (2)3.1559 (14)159 (2)
O2—H2···O3vi0.83 (2)2.08 (2)2.846 (2)154 (2)
Symmetry codes: (vi) x+1/2, y+1/2, z+3/2; (vii) x+3/2, y1/2, z+3/2; (viii) x, y1, z.
(I_117K) Rock salt–urea–water (1/1/1) (NaCl.CH4N2O.H2O) top
Crystal data top
NaCl·CH4N2O·H2OF(000) = 280
Mr = 136.52Dx = 1.574 Mg m3
Orthorhombic, Pn21mMo Kα radiation, λ = 0.71073 Å
Hall symbol: P -2 -2bcCell parameters from 4386 reflections
a = 6.4374 (2) Åθ = 2.4–34.9°
b = 5.1744 (2) ŵ = 0.63 mm1
c = 17.2998 (5) ÅT = 117 K
V = 576.25 (3) Å3Distorted cube, colourless
Z = 40.3 × 0.3 × 0.3 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
2022 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.079
Graphite monochromatorθmax = 35.6°, θmin = 2.4°
phi and ω scansh = 1010
15591 measured reflectionsk = 88
2688 independent reflectionsl = 2728
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.034H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.086 w = 1/[σ2(Fo2) + (0.0424P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.95(Δ/σ)max = 0.002
2688 reflectionsΔρmax = 0.66 e Å3
76 parametersΔρmin = 0.36 e Å3
5 restraintsAbsolute structure: Flack (1983), 1109 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.02 (6)
Crystal data top
NaCl·CH4N2O·H2OV = 576.25 (3) Å3
Mr = 136.52Z = 4
Orthorhombic, Pn21mMo Kα radiation
a = 6.4374 (2) ŵ = 0.63 mm1
b = 5.1744 (2) ÅT = 117 K
c = 17.2998 (5) Å0.3 × 0.3 × 0.3 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
2022 reflections with I > 2σ(I)
15591 measured reflectionsRint = 0.079
2688 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.034H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.086Δρmax = 0.66 e Å3
S = 0.95Δρmin = 0.36 e Å3
2688 reflectionsAbsolute structure: Flack (1983), 1109 Friedel pairs
76 parametersAbsolute structure parameter: 0.02 (6)
5 restraints
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
xyzUiso*/Ueq
Cl10.26051 (4)0.41551 (8)0.616725 (17)0.01411 (8)
Na10.51476 (11)0.19051 (16)0.50000.01254 (17)
Na20.00615 (11)0.19552 (16)0.50000.01291 (17)
O10.25054 (19)0.1198 (3)0.50000.0148 (3)
H10.236 (2)0.215 (4)0.5380 (8)0.030*
O20.2449 (2)0.5368 (3)0.50000.0142 (3)
H20.234 (2)0.631 (4)0.5389 (8)0.028*
O30.24513 (15)0.4920 (2)0.91144 (6)0.0143 (2)
N10.1363 (2)0.6310 (4)0.79429 (7)0.0261 (3)
H110.04900.74090.81550.031*
H120.14540.62010.74360.031*
N20.3852 (2)0.3192 (4)0.80336 (7)0.0265 (3)
H210.46660.21780.83070.032*
H220.38970.31410.75250.032*
C10.2549 (2)0.4807 (3)0.83891 (8)0.0131 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.01587 (13)0.01720 (14)0.00927 (11)0.0034 (2)0.00045 (11)0.00067 (13)
Na10.0095 (3)0.0144 (4)0.0136 (4)0.0007 (3)0.0000.000
Na20.0102 (3)0.0155 (4)0.0130 (4)0.0004 (3)0.0000.000
O10.0162 (6)0.0129 (8)0.0152 (6)0.0008 (7)0.0000.000
O20.0170 (7)0.0122 (7)0.0133 (6)0.0004 (6)0.0000.000
O30.0165 (4)0.0187 (5)0.0076 (4)0.0013 (4)0.0006 (4)0.0008 (4)
N10.0280 (7)0.0370 (8)0.0134 (6)0.0173 (7)0.0002 (5)0.0000 (6)
N20.0283 (7)0.0371 (8)0.0141 (6)0.0160 (6)0.0009 (5)0.0023 (6)
C10.0131 (6)0.0159 (6)0.0102 (5)0.0012 (5)0.0000 (5)0.0007 (5)
Geometric parameters (Å, º) top
Cl1—Na12.8481 (7)Na2—O22.3411 (17)
Cl1—Na22.8845 (7)Na2—O3iii2.4131 (12)
Na1—Na2i3.0842 (11)O3—C11.2577 (17)
Na1—Na23.3534 (11)N1—C11.336 (2)
Na1—O12.3392 (16)N2—C11.334 (2)
Na1—O2i2.3674 (17)O1—H10.827 (15)
Na1—O3ii2.4066 (12)O2—H20.833 (15)
Na2—O12.3223 (16)
Cl1iv—Na1—Cl190.31 (3)O3iii—Na2—O3vi78.83 (6)
Cl1—Na2—Cl1iv88.86 (3)O1—Na2—Cl181.59 (3)
Na1—Cl1—Na271.60 (2)O2—Na2—Cl195.34 (3)
O1—Na1—O2i174.16 (6)O3iii—Na2—Cl1174.94 (4)
O1—Na1—O3ii100.02 (4)O3vi—Na2—Cl196.15 (3)
O2i—Na1—O3ii84.45 (4)Na2—O1—Na192.01 (6)
O3ii—Na1—O3v79.08 (6)Na2—O2—Na1vii81.84 (6)
O1—Na1—Cl1iv82.11 (3)C1—O3—Na1viii128.53 (10)
O2i—Na1—Cl1iv93.79 (3)C1—O3—Na2ix133.28 (10)
O3ii—Na1—Cl1iv174.23 (3)Na1viii—O3—Na2ix79.57 (4)
O3v—Na1—Cl1iv95.29 (3)O3—C1—N2121.36 (14)
O2i—Na1—Cl193.79 (3)O3—C1—N1121.40 (14)
O1—Na2—O2175.67 (6)N2—C1—N1117.24 (13)
O1—Na2—O3iii98.45 (5)H1—O1—H1iv105 (3)
O2—Na2—O3iii84.88 (4)H2—O2—H2iv108 (3)
Symmetry codes: (i) x+1, y, z; (ii) x+1, y1/2, z+3/2; (iii) x, y1/2, z1/2; (iv) x, y, z+1; (v) x+1, y1/2, z1/2; (vi) x, y1/2, z+3/2; (vii) x1, y, z; (viii) x+1, y+1/2, z+3/2; (ix) x, y+1/2, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H12···Cl10.882.553.3643 (14)155
N1—H11···Cl1ix0.882.483.3260 (14)161
N2—H22···Cl10.882.553.3641 (13)155
N2—H21···Cl1ii0.882.523.3877 (15)168
O1—H1···Cl1x0.83 (2)2.35 (2)3.1405 (12)160 (2)
O2—H2···O3ix0.83 (2)2.06 (2)2.8097 (18)150 (2)
Symmetry codes: (ii) x+1, y1/2, z+3/2; (ix) x, y+1/2, z+3/2; (x) x, y1, z.

Experimental details

(I_293K)(I_117K)
Crystal data
Chemical formulaNaCl·CH4N2O·H2ONaCl·CH4N2O·H2O
Mr136.52136.52
Crystal system, space groupMonoclinic, I2Orthorhombic, Pn21m
Temperature (K)293117
a, b, c (Å)6.4845 (2), 5.2362 (2), 17.3497 (5)6.4374 (2), 5.1744 (2), 17.2998 (5)
α, β, γ (°)90, 90.152 (2), 9090, 90, 90
V3)589.09 (3)576.25 (3)
Z44
Radiation typeMo KαMo Kα
µ (mm1)0.620.63
Crystal size (mm)0.4 × 0.4 × 0.40.3 × 0.3 × 0.3
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Bruker SMART CCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
7728, 1752, 1728 15591, 2688, 2022
Rint0.0570.079
(sin θ/λ)max1)0.7100.819
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.031, 0.085, 1.25 0.034, 0.086, 0.95
No. of reflections17522688
No. of parameters7176
No. of restraints55
H-atom treatmentH atoms treated by a mixture of independent and constrained refinementH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.36, 0.310.66, 0.36
Absolute structureFlack (1983), 783 Friedel pairsFlack (1983), 1109 Friedel pairs
Absolute structure parameter0.00 (7)0.02 (6)

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXTL (Sheldrick, 2008), SCHAKAL99 (Keller, 2004).

Selected bond lengths (Å) for (I_293K) top
Cl1—Na1i2.8516 (8)Na1—O3iii2.4251 (15)
Cl1—Na12.9130 (8)Na1—O3iv2.4281 (15)
Na1—Na1ii3.1237 (12)O3—C11.252 (2)
Na1—Na1i3.3612 (12)N1—C11.323 (2)
Na1—O12.3430 (13)N2—C11.341 (2)
Na1—O22.3732 (15)
Symmetry codes: (i) x+1, y, z+1; (ii) x, y, z+1; (iii) x1/2, y1/2, z1/2; (iv) x+1/2, y1/2, z+3/2.
Hydrogen-bond geometry (Å, º) for (I_293K) top
D—H···AD—HH···AD···AD—H···A
N1—H12···Cl10.862.563.3671 (19)157.1
N1—H11···Cl1v0.862.523.3512 (19)162.9
N2—H22···Cl10.862.603.397 (2)154.7
N2—H21···Cl1vi0.862.583.4242 (19)167.7
O1—H1···Cl1vii0.819 (15)2.38 (2)3.1559 (14)159 (2)
O2—H2···O3v0.825 (16)2.08 (2)2.846 (2)154 (2)
Symmetry codes: (v) x+1/2, y+1/2, z+3/2; (vi) x+3/2, y1/2, z+3/2; (vii) x, y1, z.
Selected bond lengths (Å) for (I_117K) top
Cl1—Na12.8481 (7)Na2—O12.3223 (16)
Cl1—Na22.8845 (7)Na2—O22.3411 (17)
Na1—Na2i3.0842 (11)Na2—O3iii2.4131 (12)
Na1—Na23.3534 (11)O3—C11.2577 (17)
Na1—O12.3392 (16)N1—C11.336 (2)
Na1—O2i2.3674 (17)N2—C11.334 (2)
Na1—O3ii2.4066 (12)
Symmetry codes: (i) x+1, y, z; (ii) x+1, y1/2, z+3/2; (iii) x, y1/2, z1/2.
Hydrogen-bond geometry (Å, º) for (I_117K) top
D—H···AD—HH···AD···AD—H···A
N1—H12···Cl10.882.553.3643 (14)154.7
N1—H11···Cl1iv0.882.483.3260 (14)161.0
N2—H22···Cl10.882.553.3641 (13)154.8
N2—H21···Cl1ii0.882.523.3877 (15)168.2
O1—H1···Cl1v0.827 (15)2.352 (18)3.1405 (12)159.5 (19)
O2—H2···O3iv0.833 (15)2.06 (2)2.8097 (18)150 (2)
Symmetry codes: (ii) x+1, y1/2, z+3/2; (iv) x, y+1/2, z+3/2; (v) x, y1, z.
Alkali halide (AX)–organic molecule–water structures with a 1:1:1 composition top
AXOrganic moleculeCSD-CodeCaRef.
NaClCH4N2O(I)noPalm et al., 1963; this work
NaClC27H35N2O4UHARUQyesGawley et al., 2002
NaBrC10H17NO3CMHTRBbnoFodor et al., 1973
NaBrC32H38N4O6ZEXCAGyesSuwinska, 1995
NaIC18H23N2O6FIRYAGyesArnold et al., 1987
NaIC22H31NO3KESGULnoFan et al., 2007
NaIC26H38N2O4VIHFUNbyesMeadows et al., 2000
KIC26H38N2O4VIHGICbyesMeadows et al., 2000
KIC20H40N2O7VOWVEIyesDalley et al., 1992
Notes: (a) alkali atom multiply coordinated by organic ring structure; (b) no atomic coordinates available.
 

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