Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109030509/fg3107sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270109030509/fg3107Isup2.hkl |
CCDC reference: 749692
For related literature, see: Abu-Youssef, Dey, Gohar, Massoud, Öhrström & Langer (2007); Abu-Youssef, Langer & Öhrström (2006a, 2006b); Bernstein et al. (1995); Bowmaker et al. (2005); Fun et al. (2008); Janiak (2000); Lin et al. (2008); Massoud & Langer (2009).
To an aqueous solution (4 ml) of AgNO3 (0.169 g, 1 mmol), an ethanol solution (4 ml) of 4-(dimethylamino)pyridine (0.367 g, 1 mmol) was added. Drops of 0.1 N HNO3 were added and a brown precipitate formed, which was dissolved by stirring and heating. The final clear solution was allowed to stand for a couple of days, after which colorless crystals of different morphologies (needles, prisms, plates and cubes) suitable for X-ray measurements were collected and dried in air, with a yield of 50% with respect to the metal. Note that all the crystals have the same structure as confirmed by X-ray single-crystal analysis.
Aromatic H atoms were refined isotropically with Uiso(H) set at 1.2Ueq(C) and their positions were constrained to an ideal geometry using an appropriate riding model (C—H = 0.95 Å). For methyl groups, N—C—H angles (109.5°) were kept fixed, while the torsion angle was allowed to refine with the starting positions based on the circular Fourier synthesis averaged using the local threefold axis. A common Uiso(H) was refined for the methyl H atoms [final value 0.059 (4) Å2; C—H = 0.98 Å]. Water H atoms were restrained to have O—H distances of 0.88 (s.u. value?) Å with a common Uiso(H) refined [final value 0.070 (10) Å2].
Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003) and SADABS (Sheldrick, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
[Ag(C7H10N2)2]NO3·2H2O | F(000) = 920 |
Mr = 450.25 | Dx = 1.646 Mg m−3 |
Orthorhombic, Cmc21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: C 2c -2 | Cell parameters from 3205 reflections |
a = 20.3572 (10) Å | θ = 3.3–22.9° |
b = 11.3133 (5) Å | µ = 1.14 mm−1 |
c = 7.8904 (4) Å | T = 153 K |
V = 1817.22 (15) Å3 | Prism, colourless |
Z = 4 | 0.32 × 0.17 × 0.14 mm |
Bruker SMART CCD area-detector diffractometer | 2856 independent reflections |
Radiation source: fine-focus sealed tube | 2268 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.062 |
Detector resolution: 120 pixels mm-1 | θmax = 30.6°, θmin = 2.1° |
ω scans | h = −29→29 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −16→16 |
Tmin = 0.711, Tmax = 0.856 | l = −11→11 |
14780 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.033 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.064 | w = 1/[σ2(Fo2) + (0.0266P)2 + 0.1432P] where P = (Fo2 + 2Fc2)/3 |
S = 1.00 | (Δ/σ)max = 0.001 |
2856 reflections | Δρmax = 0.74 e Å−3 |
137 parameters | Δρmin = −0.36 e Å−3 |
5 restraints | Absolute structure: Flack (1983), 1330 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.06 (3) |
[Ag(C7H10N2)2]NO3·2H2O | V = 1817.22 (15) Å3 |
Mr = 450.25 | Z = 4 |
Orthorhombic, Cmc21 | Mo Kα radiation |
a = 20.3572 (10) Å | µ = 1.14 mm−1 |
b = 11.3133 (5) Å | T = 153 K |
c = 7.8904 (4) Å | 0.32 × 0.17 × 0.14 mm |
Bruker SMART CCD area-detector diffractometer | 2856 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2268 reflections with I > 2σ(I) |
Tmin = 0.711, Tmax = 0.856 | Rint = 0.062 |
14780 measured reflections |
R[F2 > 2σ(F2)] = 0.033 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.064 | Δρmax = 0.74 e Å−3 |
S = 1.00 | Δρmin = −0.36 e Å−3 |
2856 reflections | Absolute structure: Flack (1983), 1330 Friedel pairs |
137 parameters | Absolute structure parameter: −0.06 (3) |
5 restraints |
Experimental. Data were collected at 153 K using a Siemens SMART CCD diffractometer equipped with LT-2 A cooling device. A full sphere of reciprocal space was scanned by 0.3° steps in ω with a crystal–to–detector distance of 3.97 cm, 1 second per frame. Preliminary orientation matrix was obtained from the first 100 frames using SMART (Bruker, 2003). The collected frames were integrated using the preliminary orientation matrix which was updated every 100 frames. Final cell parameters were obtained by refinement on the position of 3205 reflections with I>10σ(I) after integration of all the frames data using SAINT (Bruker, 2003). |
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. |
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. |
x | y | z | Uiso*/Ueq | ||
Ag1 | 1.0000 | 0.89370 (2) | 0.11483 (3) | 0.03393 (10) | |
N1 | 0.89430 (9) | 0.87828 (15) | 0.1171 (8) | 0.0299 (4) | |
C2 | 0.86131 (13) | 0.7975 (2) | 0.0259 (4) | 0.0305 (6) | |
H2 | 0.8862 | 0.7410 | −0.0357 | 0.037* | |
C3 | 0.79423 (13) | 0.7911 (2) | 0.0156 (4) | 0.0297 (6) | |
H3 | 0.7741 | 0.7306 | −0.0499 | 0.036* | |
C4 | 0.75502 (11) | 0.87433 (18) | 0.1024 (8) | 0.0266 (6) | |
C5 | 0.78948 (13) | 0.9585 (2) | 0.2002 (4) | 0.0302 (6) | |
H5 | 0.7662 | 1.0161 | 0.2638 | 0.036* | |
C6 | 0.85697 (15) | 0.9565 (2) | 0.2028 (4) | 0.0324 (6) | |
H6 | 0.8788 | 1.0142 | 0.2695 | 0.039* | |
N2 | 0.68857 (11) | 0.87351 (18) | 0.0938 (6) | 0.0324 (7) | |
C7 | 0.65486 (13) | 0.7824 (3) | −0.0028 (4) | 0.0417 (8) | |
H7A | 0.6720 | 0.7810 | −0.1189 | 0.059 (4)* | |
H7B | 0.6077 | 0.7994 | −0.0051 | 0.059 (4)* | |
H7C | 0.6622 | 0.7053 | 0.0506 | 0.059 (4)* | |
C8 | 0.64910 (14) | 0.9596 (3) | 0.1855 (4) | 0.0386 (7) | |
H8A | 0.6553 | 0.9486 | 0.3077 | 0.059 (4)* | |
H8B | 0.6027 | 0.9486 | 0.1570 | 0.059 (4)* | |
H8C | 0.6628 | 1.0396 | 0.1537 | 0.059 (4)* | |
N3 | 1.0000 | 0.8214 (3) | 0.6454 (5) | 0.0318 (11) | |
O1 | 1.0000 | 0.8566 (4) | 0.4980 (6) | 0.0536 (13) | |
O2 | 1.0000 | 0.8931 (3) | 0.7638 (6) | 0.0497 (13) | |
O3 | 1.0000 | 0.7134 (3) | 0.6755 (4) | 0.0561 (10) | |
O4 | 1.0000 | 0.5989 (4) | 0.9823 (5) | 0.0634 (14) | |
O5 | 1.0000 | 0.6141 (4) | 0.3225 (6) | 0.0729 (17) | |
H41 | 1.0000 | 0.645 (6) | 0.893 (7) | 0.070 (10)* | |
H42 | 1.0000 | 0.527 (2) | 0.948 (8) | 0.070 (10)* | |
H51 | 1.0000 | 0.622 (6) | 0.214 (3) | 0.070 (10)* | |
H52 | 1.0000 | 0.683 (3) | 0.374 (7) | 0.070 (10)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ag1 | 0.03155 (14) | 0.03464 (15) | 0.03561 (16) | 0.000 | 0.000 | 0.0026 (3) |
N1 | 0.0321 (9) | 0.0299 (9) | 0.0277 (9) | −0.0018 (7) | 0.001 (3) | 0.005 (2) |
C2 | 0.0353 (15) | 0.0272 (14) | 0.0288 (14) | 0.0044 (12) | 0.0049 (13) | −0.0016 (12) |
C3 | 0.0383 (15) | 0.0255 (13) | 0.0252 (14) | 0.0019 (12) | −0.0047 (12) | −0.0019 (11) |
C4 | 0.0331 (11) | 0.0281 (12) | 0.0185 (15) | 0.0031 (9) | −0.0022 (19) | 0.0032 (16) |
C5 | 0.0389 (16) | 0.0256 (14) | 0.0262 (13) | 0.0015 (12) | 0.0024 (13) | −0.0026 (12) |
C6 | 0.0469 (17) | 0.0257 (14) | 0.0245 (14) | −0.0036 (12) | 0.0011 (14) | −0.0026 (12) |
N2 | 0.0323 (10) | 0.0325 (10) | 0.032 (2) | 0.0043 (8) | −0.0004 (14) | −0.0068 (13) |
C7 | 0.0355 (17) | 0.0451 (18) | 0.0446 (19) | −0.0006 (14) | −0.0058 (14) | −0.0069 (15) |
C8 | 0.0385 (17) | 0.0381 (17) | 0.0393 (17) | 0.0071 (13) | 0.0054 (14) | −0.0026 (13) |
N3 | 0.0318 (15) | 0.0289 (16) | 0.035 (4) | 0.000 | 0.000 | −0.0004 (17) |
O1 | 0.088 (3) | 0.048 (3) | 0.025 (2) | 0.000 | 0.000 | 0.004 (2) |
O2 | 0.081 (3) | 0.042 (3) | 0.026 (2) | 0.000 | 0.000 | −0.0071 (16) |
O3 | 0.078 (2) | 0.0289 (16) | 0.062 (3) | 0.000 | 0.000 | 0.0089 (14) |
O4 | 0.113 (4) | 0.046 (2) | 0.032 (2) | 0.000 | 0.000 | −0.003 (2) |
O5 | 0.152 (5) | 0.035 (2) | 0.032 (2) | 0.000 | 0.000 | −0.001 (2) |
Ag1—N1 | 2.1589 (18) | N2—C7 | 1.454 (4) |
Ag1—N1i | 2.1590 (18) | C7—H7A | 0.9800 |
N1—C2 | 1.343 (5) | C7—H7B | 0.9800 |
N1—C6 | 1.348 (5) | C7—H7C | 0.9800 |
C2—C3 | 1.370 (4) | C8—H8A | 0.9800 |
C2—H2 | 0.9500 | C8—H8B | 0.9800 |
C3—C4 | 1.412 (4) | C8—H8C | 0.9800 |
C3—H3 | 0.9500 | N3—O1 | 1.229 (6) |
C4—N2 | 1.355 (3) | N3—O2 | 1.238 (5) |
C4—C5 | 1.412 (5) | N3—O3 | 1.245 (4) |
C5—C6 | 1.374 (4) | O4—H41 | 0.88 (2) |
C5—H5 | 0.9500 | O4—H42 | 0.85 (2) |
C6—H6 | 0.9500 | O5—H51 | 0.86 (2) |
N2—C8 | 1.455 (4) | O5—H52 | 0.88 (2) |
N1—Ag1—N1i | 170.68 (10) | C4—N2—C7 | 120.2 (3) |
C2—N1—C6 | 115.7 (2) | C8—N2—C7 | 118.3 (2) |
C2—N1—Ag1 | 123.3 (3) | N2—C7—H7A | 109.5 |
C6—N1—Ag1 | 120.9 (2) | N2—C7—H7B | 109.5 |
N1—C2—C3 | 124.5 (3) | H7A—C7—H7B | 109.5 |
N1—C2—H2 | 117.7 | N2—C7—H7C | 109.5 |
C3—C2—H2 | 117.7 | H7A—C7—H7C | 109.5 |
C2—C3—C4 | 119.9 (3) | H7B—C7—H7C | 109.5 |
C2—C3—H3 | 120.0 | N2—C8—H8A | 109.5 |
C4—C3—H3 | 120.0 | N2—C8—H8B | 109.5 |
N2—C4—C5 | 121.9 (3) | H8A—C8—H8B | 109.5 |
N2—C4—C3 | 122.4 (3) | N2—C8—H8C | 109.5 |
C5—C4—C3 | 115.7 (2) | H8A—C8—H8C | 109.5 |
C6—C5—C4 | 119.6 (3) | H8B—C8—H8C | 109.5 |
C6—C5—H5 | 120.2 | O1—N3—O2 | 120.1 (4) |
C4—C5—H5 | 120.2 | O1—N3—O3 | 119.9 (4) |
N1—C6—C5 | 124.5 (3) | O2—N3—O3 | 120.0 (4) |
N1—C6—H6 | 117.7 | H41—O4—H42 | 108 (8) |
C5—C6—H6 | 117.7 | H51—O5—H52 | 112 (6) |
C4—N2—C8 | 121.5 (3) | ||
N1i—Ag1—N1—C2 | −46 (2) | C3—C4—C5—C6 | 1.3 (6) |
N1i—Ag1—N1—C6 | 138.7 (17) | C2—N1—C6—C5 | −0.7 (6) |
C6—N1—C2—C3 | 0.2 (6) | Ag1—N1—C6—C5 | 174.8 (3) |
Ag1—N1—C2—C3 | −175.2 (3) | C4—C5—C6—N1 | −0.1 (5) |
N1—C2—C3—C4 | 1.1 (5) | C5—C4—N2—C8 | −0.1 (7) |
C2—C3—C4—N2 | 178.6 (4) | C3—C4—N2—C8 | 179.5 (4) |
C2—C3—C4—C5 | −1.8 (6) | C5—C4—N2—C7 | −177.5 (4) |
N2—C4—C5—C6 | −179.1 (4) | C3—C4—N2—C7 | 2.1 (7) |
Symmetry code: (i) −x+2, y, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H41···O3 | 0.88 (2) | 1.88 (3) | 2.746 (6) | 168 (8) |
O4—H42···O5ii | 0.85 (2) | 1.88 (2) | 2.719 (6) | 167 (6) |
O5—H51···O4iii | 0.86 (2) | 1.84 (2) | 2.690 (8) | 166 (6) |
O5—H52···O1 | 0.88 (2) | 2.19 (2) | 3.074 (6) | 179 (6) |
O5—H52···O3 | 0.88 (2) | 2.41 (5) | 3.003 (6) | 125 (5) |
C7—H7B···O3iv | 0.98 | 2.62 | 3.452 (3) | 143 |
Symmetry codes: (ii) −x+2, −y+1, z+1/2; (iii) x, y, z−1; (iv) −x+3/2, −y+3/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | [Ag(C7H10N2)2]NO3·2H2O |
Mr | 450.25 |
Crystal system, space group | Orthorhombic, Cmc21 |
Temperature (K) | 153 |
a, b, c (Å) | 20.3572 (10), 11.3133 (5), 7.8904 (4) |
V (Å3) | 1817.22 (15) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.14 |
Crystal size (mm) | 0.32 × 0.17 × 0.14 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.711, 0.856 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 14780, 2856, 2268 |
Rint | 0.062 |
(sin θ/λ)max (Å−1) | 0.715 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.033, 0.064, 1.00 |
No. of reflections | 2856 |
No. of parameters | 137 |
No. of restraints | 5 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.74, −0.36 |
Absolute structure | Flack (1983), 1330 Friedel pairs |
Absolute structure parameter | −0.06 (3) |
Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003) and SADABS (Sheldrick, 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H41···O3 | 0.88 (2) | 1.88 (3) | 2.746 (6) | 168 (8) |
O4—H42···O5i | 0.853 (19) | 1.88 (2) | 2.719 (6) | 167 (6) |
O5—H51···O4ii | 0.86 (2) | 1.84 (2) | 2.690 (8) | 166 (6) |
O5—H52···O1 | 0.882 (19) | 2.19 (2) | 3.074 (6) | 179 (6) |
O5—H52···O3 | 0.882 (19) | 2.41 (5) | 3.003 (6) | 125 (5) |
C7—H7B···O3iii | 0.98 | 2.62 | 3.452 (3) | 143 |
Symmetry codes: (i) −x+2, −y+1, z+1/2; (ii) x, y, z−1; (iii) −x+3/2, −y+3/2, z−1/2. |
Compound | Ag—N | N—Ag—N | Ag···O |
[Ag(dmap)2]NO3.2H2O, (I) | 2.1589 (18), 2.1590 (18) | 170.681 (6) | 2.638 (4), 2.770 (5) |
[Ag(dmap)2]PF6a | 2.119 (3) | 180 | - |
[Ag(4-ampy)2]NO3b | 2.125 (6) | 173.07 (2) | 2.889 (6) |
[Ag4(3-ampy)4(NO3)4]nc | 2.216 (2)/2.228 (2)/2.297 (2)/2.340 (2)/2.317 (2)/2.369 (3)/2.207 (2) | 124.98 (10)/126.32 (10)/140.07 (8) | 2.445 (3)/2.562 (3)/2.643 (2)/2.463 (2)/2.456 (3)/2.570 (2)/2.582 (2) |
[Ag3(2-ampy)4(NO3)2]NO3d | 2.198 (3)/2.186 (3)/2.384 (3)/2.419 (3) | 154.122 (11)/82.617 (12) | 2.539 (3)/2.786 (3) |
[Ag(2-ampy)3]NO3d | 2.222 (17)/2.232 (19)/2.396 (2) | 105.05 (7)/113.18 (7)/140.64 (6) | 2.696 (2) |
[Ag(2-ampy)2]NO3e | 2.1406 (14)/2.1413 (14)/2.1115 (14) | 175.97 (6)/180 | 2.849 (3) |
References: (a) Lin et al. (2008); (b) Abu-Youssef et al. (2006a); (c) Abu-Youssef et al. (2006b); (d) Bowmaker et al. (2005); (e) Fun et al. (2008). |
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Aminopyridines are water-soluble ligands which attract an intense interest owing to their versatile coordination modes, especially with AgI ions (Bowmaker et al., 2005). These type of ligands can coordinate to the metal center either via the ring N atom alone (as a monodentate ligand) or via both the ring N atom and the amine group N atom (as bridging and/or bidentate ligand). When 2-aminopyridine reacts with AgNO3 in water/ethanol solution, three compounds are formed with different stoichometric ratios, namely [Ag(2-ampy)2]NO3 (Fun et al., 2008), [Ag(2-ampy)3]NO3 and [Ag3(2-ampy)4(NO3)2]NO3 (Bowmaker et al., 2005). In the case of 3- and 4-aminopyridines, only one compound is known for each, {[Ag4(3-ampy)4(NO3)4]}n and [Ag(4-ampy)2]NO3 (Abu-Youssef et al., 2006a,b). In all the previously mentioned compounds, hydrogen bonds of the type N—H···O are formed between the amine groups of the ligands and nitrate O atoms. We have prepared the title silver(I) compound, (I), with 4-(dimethylamino)pyridine (dmap) as a continuation of our previous work on AgI compounds with pyridine-type ligands and especially aminopyridines (Abu-Youssef et al., 2006a,b; 2007).
The molecular stucture of (I) is shown in Fig. 1. The AgI ion is bonded to two dmap moieties via their pyridine N atoms, with distorted linear coordination geometry, which is the most preferred coordination geometry for AgI ions (Abu-Youssef et al., 2007; Massoud & Langer, 2009). Table 2 shows a comparison between (I) and some related aminopyridine AgI compounds. Shorter Ag—N bond distances, larger N—Ag—N bond angles and hence weaker Ag···O interactions are reported for related the linear compounds [Ag(dmap)2](PF6) (Lin et al., 2008), [Ag(4-ampy)2]NO3 (Abu-Youssef et al., 2006a) and [Ag(2-ampy)2]NO3 (Fun et al., 2008) compared with those found in (I), while for the trigonal-planar and tetrahedral compounds [Ag3(2-ampy)4(NO3)2]NO3 (Bowmaker et al., 2005) and {[Ag4(3-ampy)4(NO3)4]}n (Abu-Youssef et al., 2006b), longer Ag—N bond distances and smaller N—Ag—N bond angles are found. In the case of [Ag(dmap)2](PF6) (Lin et al., 2008), no interaction could be considered between (PF6)- and the AgI ion, where the shortest Ag···F distances are 3.007 (3) and 3.528 (6) Å.
A novel system of strong water/nitrate hydrogen bonds in (I) is shown in Fig. 2 with data in Table 1. The water/nitrate hydrogen bonds form rings [with graph-set symbol R45(12) (Bernstein et al., 1995)], forming strands propagating in the c direction. The [Ag(dmap)2]+ units are arranged in an alternating zigzag pattern between these hydrogen-bonded strands. The water/nitrate strands are also arranged in an alternating pattern above each other, with no interaction found between the successive strands. The packing scheme for (I) is shown in Fig. 3. A weak C—H···O hydrogen bond (Table 1) is found between one of the methyl groups of the dmap ligand and one of the nitrate O atoms.
No π–π interaction was found in (I), following the requirement stated by Janiak (2000).
Introducing the two methyl groups as a substituents in the amine N atom of the 4-aminopyridine ligand has greatly affected the structural features of the resulting compound (I). The bulky terminal groups of the ligand in (I) force both the nitrate and the water molecules to be arranged around the metal centres and not to be packed in between the [Ag(dmap)2]+ units as in the case of [Ag(4-ampy)2]NO3 (Abu-Youssef et al., 2006a). The nitrate anions are known for their ability to form strong hydrogen bonds, being better acceptors than the hexafluorophosphate anions in the case of [Ag(dmap)2](PF6) (Lin et al., 2008). In addition to the steric effect of the dmap ligand and the presence of nitrate groups as counter-ions, the high water content increases the possibility of formation of hydrogen bonds with the nitrate groups forming novel water/nitrate hydrogen bonded strands. This structure is very stable since different crystal morphologies were formed, which in all cases afforded the same internal order.