Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109013110/dn3109sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270109013110/dn3109Isup2.hkl |
CCDC reference: 735109
To an aqueous solution (Volume?) of AgNO3 (0.34 g, 2 mmol) was added a methanolic solution (Volume?) of the melamine ligand (0.5 g, 4 mmol). When a white gelatinous precipitate had formed, drops of 0.1 N HNO3 were added. The mixture was then heated and stirred to dissolve most of the precipitate. The turbid solution was filtered and allowed to stand for a couple of days. Colourless needles of (I) suitable for X-ray diffraction measurements were collected and dried in air (yield ~60% relative to the metal). 1H NMR in dimethyl sulfoxide gave only one peak at δ(6H) = 6.34 p.p.m.
H atoms were located at a difference Fourier map and refined freely in an isotropic approximation.
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(C3H6N6)2]NO3 | Z = 2 |
Mr = 422.16 | F(000) = 420 |
Triclinic, P1 | Dx = 2.127 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.9908 (5) Å | Cell parameters from 5531 reflections |
b = 9.8312 (6) Å | θ = 2.3–33.0° |
c = 10.0569 (6) Å | µ = 1.58 mm−1 |
α = 64.296 (1)° | T = 153 K |
β = 77.915 (1)° | Prism, colourless |
γ = 67.998 (1)° | 0.14 × 0.06 × 0.05 mm |
V = 659.00 (7) Å3 |
Bruker SMART CCD area-detector diffractometer | 4651 independent reflections |
Radiation source: fine-focus sealed tube | 3957 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.027 |
Detector resolution: 120 pixels mm-1 | θmax = 33.0°, θmin = 2.3° |
ω scans | h = −12→11 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −14→14 |
Tmin = 0.810, Tmax = 0.925 | l = −15→15 |
11902 measured reflections |
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)] = 0.029 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.071 | All H-atom parameters refined |
S = 1.00 | w = 1/[σ2(Fo2) + (0.0407P)2 + 0.1354P] where P = (Fo2 + 2Fc2)/3 |
4651 reflections | (Δ/σ)max = 0.001 |
256 parameters | Δρmax = 0.99 e Å−3 |
0 restraints | Δρmin = −0.94 e Å−3 |
[Ag(C3H6N6)2]NO3 | γ = 67.998 (1)° |
Mr = 422.16 | V = 659.00 (7) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.9908 (5) Å | Mo Kα radiation |
b = 9.8312 (6) Å | µ = 1.58 mm−1 |
c = 10.0569 (6) Å | T = 153 K |
α = 64.296 (1)° | 0.14 × 0.06 × 0.05 mm |
β = 77.915 (1)° |
Bruker SMART CCD area-detector diffractometer | 4651 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 3957 reflections with I > 2σ(I) |
Tmin = 0.810, Tmax = 0.925 | Rint = 0.027 |
11902 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.071 | All H-atom parameters refined |
S = 1.00 | Δρmax = 0.99 e Å−3 |
4651 reflections | Δρmin = −0.94 e Å−3 |
256 parameters |
Experimental. Data were collected at 153 K using a Bruker SMART CCD diffractometer equipped with an 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, 20 s per frame. A 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 5531 reflections with I>10σ(I) after integration of all the frames data using SAINT (Bruker, 2003). |
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. |
x | y | z | Uiso*/Ueq | ||
Ag1 | 0.860262 (19) | −0.143123 (17) | 0.544375 (16) | 0.01604 (5) | |
N1 | 0.7382 (2) | 0.2679 (2) | 0.23828 (18) | 0.0162 (3) | |
O1 | 0.7570 (2) | 0.40304 (17) | 0.16829 (17) | 0.0219 (3) | |
O2 | 0.8343 (2) | 0.16766 (18) | 0.34405 (16) | 0.0204 (3) | |
O3 | 0.6226 (2) | 0.23227 (19) | 0.20292 (18) | 0.0219 (3) | |
N11 | 1.0179 (2) | −0.26619 (19) | 0.39907 (17) | 0.0130 (3) | |
C12 | 1.1505 (2) | −0.4095 (2) | 0.4494 (2) | 0.0131 (3) | |
N12 | 1.2024 (3) | −0.4658 (2) | 0.5857 (2) | 0.0192 (4) | |
H12A | 1.282 (4) | −0.553 (3) | 0.619 (3) | 0.021 (7)* | |
H12B | 1.164 (4) | −0.415 (3) | 0.638 (3) | 0.025 (7)* | |
N13 | 1.2328 (2) | −0.50137 (19) | 0.37182 (18) | 0.0138 (3) | |
C14 | 1.1724 (3) | −0.4430 (2) | 0.2369 (2) | 0.0134 (3) | |
N14 | 1.2433 (3) | −0.5366 (2) | 0.1591 (2) | 0.0182 (4) | |
H14A | 1.232 (4) | −0.498 (4) | 0.083 (3) | 0.027 (8)* | |
H14B | 1.338 (4) | −0.595 (4) | 0.185 (4) | 0.037 (9)* | |
N15 | 1.0455 (2) | −0.30305 (19) | 0.17381 (18) | 0.0135 (3) | |
N16 | 0.8485 (2) | −0.0768 (2) | 0.1987 (2) | 0.0176 (3) | |
H16A | 0.814 (4) | −0.049 (3) | 0.118 (3) | 0.025 (7)* | |
H16B | 0.798 (4) | −0.017 (3) | 0.245 (3) | 0.020 (7)* | |
C16 | 0.9731 (2) | −0.2181 (2) | 0.2579 (2) | 0.0123 (3) | |
N21 | 0.6983 (2) | −0.02386 (19) | 0.69357 (17) | 0.0130 (3) | |
C22 | 0.5652 (2) | 0.1192 (2) | 0.6455 (2) | 0.0128 (3) | |
N22 | 0.4853 (2) | 0.1615 (2) | 0.52075 (19) | 0.0156 (3) | |
H22A | 0.422 (4) | 0.262 (3) | 0.482 (3) | 0.020 (7)* | |
H22B | 0.548 (4) | 0.120 (3) | 0.461 (3) | 0.015 (6)* | |
N23 | 0.5014 (2) | 0.22040 (19) | 0.71291 (18) | 0.0138 (3) | |
C24 | 0.5786 (2) | 0.1711 (2) | 0.8403 (2) | 0.0131 (3) | |
N24 | 0.5254 (3) | 0.2717 (2) | 0.9085 (2) | 0.0175 (3) | |
H24A | 0.571 (4) | 0.257 (4) | 0.975 (4) | 0.037 (9)* | |
H24B | 0.462 (3) | 0.362 (3) | 0.867 (3) | 0.016 (6)* | |
N25 | 0.7019 (2) | 0.02883 (19) | 0.90456 (17) | 0.0135 (3) | |
N26 | 0.8707 (2) | −0.2109 (2) | 0.8935 (2) | 0.0170 (3) | |
H26A | 0.911 (4) | −0.272 (3) | 0.852 (3) | 0.019 (7)* | |
H26B | 0.911 (4) | −0.231 (3) | 0.972 (3) | 0.019 (6)* | |
C26 | 0.7554 (2) | −0.0656 (2) | 0.8292 (2) | 0.0125 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ag1 | 0.01693 (8) | 0.01584 (8) | 0.01453 (7) | 0.00107 (5) | −0.00147 (5) | −0.01028 (6) |
N1 | 0.0165 (8) | 0.0151 (7) | 0.0156 (7) | 0.0008 (6) | −0.0013 (6) | −0.0094 (6) |
O1 | 0.0311 (8) | 0.0135 (7) | 0.0169 (7) | −0.0011 (6) | −0.0015 (6) | −0.0072 (6) |
O2 | 0.0190 (7) | 0.0194 (7) | 0.0181 (7) | −0.0029 (6) | −0.0072 (6) | −0.0032 (6) |
O3 | 0.0179 (7) | 0.0260 (8) | 0.0263 (8) | −0.0003 (6) | −0.0061 (6) | −0.0177 (7) |
N11 | 0.0141 (7) | 0.0120 (7) | 0.0108 (7) | 0.0012 (6) | −0.0033 (5) | −0.0061 (6) |
C12 | 0.0130 (8) | 0.0136 (8) | 0.0112 (8) | −0.0010 (6) | −0.0012 (6) | −0.0061 (7) |
N12 | 0.0222 (9) | 0.0166 (8) | 0.0149 (8) | 0.0046 (7) | −0.0079 (7) | −0.0088 (7) |
N13 | 0.0158 (7) | 0.0111 (7) | 0.0132 (7) | 0.0014 (6) | −0.0037 (6) | −0.0071 (6) |
C14 | 0.0149 (8) | 0.0114 (8) | 0.0130 (8) | −0.0010 (7) | −0.0016 (6) | −0.0064 (7) |
N14 | 0.0222 (9) | 0.0158 (8) | 0.0133 (8) | 0.0052 (7) | −0.0070 (7) | −0.0097 (7) |
N15 | 0.0158 (7) | 0.0113 (7) | 0.0119 (7) | 0.0013 (6) | −0.0033 (6) | −0.0067 (6) |
N16 | 0.0206 (8) | 0.0139 (8) | 0.0144 (8) | 0.0040 (6) | −0.0066 (6) | −0.0076 (6) |
C16 | 0.0137 (8) | 0.0120 (8) | 0.0105 (8) | −0.0018 (6) | −0.0020 (6) | −0.0052 (6) |
N21 | 0.0134 (7) | 0.0125 (7) | 0.0111 (7) | 0.0012 (6) | −0.0025 (5) | −0.0065 (6) |
C22 | 0.0118 (8) | 0.0127 (8) | 0.0127 (8) | −0.0009 (6) | −0.0016 (6) | −0.0061 (7) |
N22 | 0.0160 (8) | 0.0151 (8) | 0.0143 (8) | 0.0031 (6) | −0.0050 (6) | −0.0094 (6) |
N23 | 0.0139 (7) | 0.0130 (7) | 0.0124 (7) | 0.0016 (6) | −0.0041 (6) | −0.0066 (6) |
C24 | 0.0129 (8) | 0.0138 (8) | 0.0128 (8) | −0.0021 (6) | −0.0012 (6) | −0.0071 (7) |
N24 | 0.0203 (8) | 0.0142 (8) | 0.0177 (8) | 0.0029 (6) | −0.0070 (7) | −0.0103 (7) |
N25 | 0.0139 (7) | 0.0128 (7) | 0.0124 (7) | 0.0009 (6) | −0.0033 (6) | −0.0069 (6) |
N26 | 0.0192 (8) | 0.0143 (8) | 0.0149 (8) | 0.0038 (6) | −0.0065 (6) | −0.0087 (6) |
C26 | 0.0113 (8) | 0.0131 (8) | 0.0116 (8) | −0.0012 (6) | −0.0008 (6) | −0.0057 (7) |
Ag1—N11 | 2.1925 (16) | N16—H16A | 0.81 (3) |
Ag1—N21 | 2.2083 (16) | N16—H16B | 0.84 (3) |
N1—O2 | 1.248 (2) | N21—C22 | 1.360 (2) |
N1—O1 | 1.256 (2) | N21—C26 | 1.368 (2) |
N1—O3 | 1.262 (2) | C22—N23 | 1.330 (2) |
N11—C12 | 1.361 (2) | C22—N22 | 1.356 (2) |
N11—C16 | 1.368 (2) | N22—H22A | 0.87 (3) |
C12—N12 | 1.329 (2) | N22—H22B | 0.84 (3) |
C12—N13 | 1.345 (2) | N23—C24 | 1.351 (2) |
N12—H12A | 0.83 (3) | C24—N24 | 1.334 (2) |
N12—H12B | 0.82 (3) | C24—N25 | 1.340 (2) |
N13—C14 | 1.340 (2) | N24—H24A | 0.75 (3) |
C14—N15 | 1.338 (2) | N24—H24B | 0.81 (3) |
C14—N14 | 1.352 (2) | N25—C26 | 1.340 (2) |
N14—H14A | 0.70 (3) | N26—C26 | 1.331 (2) |
N14—H14B | 0.77 (3) | N26—H26A | 0.81 (3) |
N15—C16 | 1.339 (2) | N26—H26B | 0.83 (3) |
N16—C16 | 1.330 (2) | ||
N11—Ag1—N21 | 178.58 (6) | N16—C16—N11 | 118.15 (17) |
O2—N1—O1 | 119.95 (17) | N15—C16—N11 | 124.79 (16) |
O2—N1—O3 | 119.43 (17) | C22—N21—C26 | 113.75 (16) |
O1—N1—O3 | 120.62 (17) | C22—N21—Ag1 | 122.61 (12) |
C12—N11—C16 | 114.40 (15) | C26—N21—Ag1 | 121.44 (12) |
C12—N11—Ag1 | 122.23 (12) | N23—C22—N22 | 116.51 (16) |
C16—N11—Ag1 | 122.65 (12) | N23—C22—N21 | 125.66 (17) |
N12—C12—N13 | 116.66 (17) | N22—C22—N21 | 117.79 (17) |
N12—C12—N11 | 118.55 (17) | C22—N22—H22A | 114.3 (18) |
N13—C12—N11 | 124.78 (16) | C22—N22—H22B | 116.0 (17) |
C12—N12—H12A | 120.4 (19) | H22A—N22—H22B | 116 (2) |
C12—N12—H12B | 123 (2) | C22—N23—C24 | 114.87 (16) |
H12A—N12—H12B | 117 (3) | N24—C24—N25 | 117.54 (17) |
C14—N13—C12 | 114.85 (15) | N24—C24—N23 | 117.16 (17) |
N15—C14—N13 | 126.15 (17) | N25—C24—N23 | 125.30 (17) |
N15—C14—N14 | 117.15 (17) | C24—N24—H24A | 123 (2) |
N13—C14—N14 | 116.68 (17) | C24—N24—H24B | 119.8 (18) |
C14—N14—H14A | 116 (2) | H24A—N24—H24B | 115 (3) |
C14—N14—H14B | 111 (2) | C24—N25—C26 | 115.19 (16) |
H14A—N14—H14B | 118 (3) | C26—N26—H26A | 121.3 (19) |
C14—N15—C16 | 114.97 (16) | C26—N26—H26B | 117.3 (19) |
C16—N16—H16A | 120 (2) | H26A—N26—H26B | 121 (3) |
C16—N16—H16B | 122.1 (19) | N26—C26—N25 | 116.71 (17) |
H16A—N16—H16B | 118 (3) | N26—C26—N21 | 118.45 (17) |
N16—C16—N15 | 117.06 (17) | N25—C26—N21 | 124.84 (17) |
N21—Ag1—N11—C12 | −68 (2) | N11—Ag1—N21—C22 | −113 (2) |
N21—Ag1—N11—C16 | 101 (2) | N11—Ag1—N21—C26 | 85 (2) |
C16—N11—C12—N12 | −179.85 (18) | C26—N21—C22—N23 | 5.4 (3) |
Ag1—N11—C12—N12 | −9.4 (3) | Ag1—N21—C22—N23 | −157.88 (15) |
C16—N11—C12—N13 | −0.9 (3) | C26—N21—C22—N22 | −172.27 (17) |
Ag1—N11—C12—N13 | 169.62 (15) | Ag1—N21—C22—N22 | 24.4 (2) |
N12—C12—N13—C14 | 177.84 (18) | N22—C22—N23—C24 | 177.18 (18) |
N11—C12—N13—C14 | −1.2 (3) | N21—C22—N23—C24 | −0.6 (3) |
C12—N13—C14—N15 | 2.3 (3) | C22—N23—C24—N24 | 176.93 (18) |
C12—N13—C14—N14 | −175.80 (18) | C22—N23—C24—N25 | −4.2 (3) |
N13—C14—N15—C16 | −1.2 (3) | N24—C24—N25—C26 | −177.83 (18) |
N14—C14—N15—C16 | 176.88 (18) | N23—C24—N25—C26 | 3.3 (3) |
C14—N15—C16—N16 | 178.89 (18) | C24—N25—C26—N26 | −176.66 (18) |
C14—N15—C16—N11 | −1.2 (3) | C24—N25—C26—N21 | 2.4 (3) |
C12—N11—C16—N16 | −177.93 (18) | C22—N21—C26—N26 | 172.65 (18) |
Ag1—N11—C16—N16 | 11.6 (2) | Ag1—N21—C26—N26 | −23.8 (2) |
C12—N11—C16—N15 | 2.1 (3) | C22—N21—C26—N25 | −6.4 (3) |
Ag1—N11—C16—N15 | −168.32 (15) | Ag1—N21—C26—N25 | 157.10 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
N12—H12A···N23i | 0.83 (3) | 2.21 (3) | 3.032 (2) | 177 (3) |
N12—H12B···O1ii | 0.82 (3) | 2.23 (3) | 2.901 (2) | 139 (3) |
N12—H12B···O2ii | 0.82 (3) | 2.52 (3) | 3.201 (2) | 141 (3) |
N14—H14A···O1iii | 0.70 (3) | 2.27 (3) | 2.969 (2) | 170 (3) |
N14—H14B···O3i | 0.77 (3) | 2.26 (3) | 3.012 (2) | 165 (3) |
N16—H16A···N25iv | 0.81 (3) | 2.20 (3) | 3.013 (2) | 176 (3) |
N16—H16B···O3 | 0.84 (3) | 2.22 (3) | 2.909 (2) | 139 (2) |
N16—H16B···O2 | 0.84 (3) | 2.54 (3) | 3.271 (2) | 146 (2) |
N22—H22A···N13v | 0.87 (3) | 2.18 (3) | 3.041 (2) | 170 (2) |
N22—H22B···O3 | 0.84 (3) | 2.38 (3) | 3.013 (2) | 132 (2) |
N22—H22B···O2 | 0.84 (3) | 2.46 (3) | 2.982 (2) | 121 (2) |
N24—H24A···O3vi | 0.75 (3) | 2.31 (3) | 3.044 (2) | 163 (3) |
N24—H24B···O1vii | 0.81 (3) | 2.25 (3) | 3.016 (2) | 160 (2) |
N26—H26A···O1ii | 0.81 (3) | 2.48 (3) | 2.972 (2) | 120 (2) |
N26—H26B···N15vi | 0.83 (3) | 2.21 (3) | 3.034 (2) | 174 (3) |
Symmetry codes: (i) x+1, y−1, z; (ii) −x+2, −y, −z+1; (iii) −x+2, −y, −z; (iv) x, y, z−1; (v) x−1, y+1, z; (vi) x, y, z+1; (vii) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | [Ag(C3H6N6)2]NO3 |
Mr | 422.16 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 153 |
a, b, c (Å) | 7.9908 (5), 9.8312 (6), 10.0569 (6) |
α, β, γ (°) | 64.296 (1), 77.915 (1), 67.998 (1) |
V (Å3) | 659.00 (7) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 1.58 |
Crystal size (mm) | 0.14 × 0.06 × 0.05 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.810, 0.925 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11902, 4651, 3957 |
Rint | 0.027 |
(sin θ/λ)max (Å−1) | 0.767 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.071, 1.00 |
No. of reflections | 4651 |
No. of parameters | 256 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.99, −0.94 |
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 |
N12—H12A···N23i | 0.83 (3) | 2.21 (3) | 3.032 (2) | 177 (3) |
N12—H12B···O1ii | 0.82 (3) | 2.23 (3) | 2.901 (2) | 139 (3) |
N12—H12B···O2ii | 0.82 (3) | 2.52 (3) | 3.201 (2) | 141 (3) |
N14—H14A···O1iii | 0.70 (3) | 2.27 (3) | 2.969 (2) | 170 (3) |
N14—H14B···O3i | 0.77 (3) | 2.26 (3) | 3.012 (2) | 165 (3) |
N16—H16A···N25iv | 0.81 (3) | 2.20 (3) | 3.013 (2) | 176 (3) |
N16—H16B···O3 | 0.84 (3) | 2.22 (3) | 2.909 (2) | 139 (2) |
N16—H16B···O2 | 0.84 (3) | 2.54 (3) | 3.271 (2) | 146 (2) |
N22—H22A···N13v | 0.87 (3) | 2.18 (3) | 3.041 (2) | 170 (2) |
N22—H22B···O3 | 0.84 (3) | 2.38 (3) | 3.013 (2) | 132 (2) |
N22—H22B···O2 | 0.84 (3) | 2.46 (3) | 2.982 (2) | 121 (2) |
N24—H24A···O3vi | 0.75 (3) | 2.31 (3) | 3.044 (2) | 163 (3) |
N24—H24B···O1vii | 0.81 (3) | 2.25 (3) | 3.016 (2) | 160 (2) |
N26—H26A···O1ii | 0.81 (3) | 2.48 (3) | 2.972 (2) | 120 (2) |
N26—H26B···N15vi | 0.83 (3) | 2.21 (3) | 3.034 (2) | 174 (3) |
Symmetry codes: (i) x+1, y−1, z; (ii) −x+2, −y, −z+1; (iii) −x+2, −y, −z; (iv) x, y, z−1; (v) x−1, y+1, z; (vi) x, y, z+1; (vii) −x+1, −y+1, −z+1. |
Compound | Ag—N | Ag—N | N—Ag—N | Ag···O |
[Ag(melamine)2](NO3), (I) | 2.1925 (16) | 2.2083 (16) | 178.58 (6) | 2.7924 (16) |
[Ag(melamine)2](ClO4)a | 2.162 (4) | 2.179 (4) | 167.7 (2) | 2.776 (4)/2.785 (6) |
[Ag(melamine)(NO3)]nb | 2.289 (2) | 2.260 (2) | 127.2 (6) | 2.569 (2) |
References: (a) Zhu et al. (1999); (b) Sivashankar et al. (2001). |
Silver(I) is able to form linear (Greenwood & Earnshaw, 1997), trigonal-planar or tetrahedral coordination geometries, due to the presence of vacant s and π orbitals. Our ongoing research concerns the synthesis, structure and biological activity of different silver(I) compounds with pyridine-type ligands (Abu-Youssef et al., 2007) and especially aminopyridines (Abu-Youssef et al., 2006a,b). Melamine is considered an interesting ligand from a supramolecular chemistry point of view, due to the presence of three donor and three acceptor N atoms. This makes the probability of achieving three-dimensional network structures via melamine–metal coordination bonds and melamine–melamine hydrogen bonds much higher than with pyridines and pyrazines. Melamine is also used as a co-ligand to extend the dimensionality of a structure when poor coordinating ligands are used (Zhang et al., 2004). Although melamine–melamine hydrogen bonds facilitate the solubility of the ligand in water, coordination of the ligand to metals is not easy, and once the compound is formed the solubility decreases. Against this background, we have prepared the title silver(I)–melamine complex, (I), and present its structure here.
The silver(I) centre of (I) is coordinated to two monodentate melamine ligands, each through one of its triazine ring N atoms, forming a linear coordination geometry around the silver(I) ion (Fig. 1). The Ag—N bond distances are slightly longer than those reported for [Ag(melamine)2] (Zhu et al., 1999) and shorter than those reported for [Ag(melamine)(NO3)]n (Sivashankar et al., 2001), while the N—Ag—N bond angle is larger than those found in above-mentioned compounds (Table 2). Only a weak interaction between the AgI ion and the nitrate group is found, with geometric values almost identical to those observed for [Ag(melamine)2](ClO4) (Zhu et al., 1999) (Table 2). A similar interaction was also found in [Ag(melamine)(NO3)]n, where Ag—O1 is 2.569 (2) Å (Table 2) with a distorted trigonal-planar coordination geometry around the AgI ion.
Strong N—H···N hydrogen bonds (Table 1) connect the cationic [Ag(melamine)2]+ units of (I) to form two-dimensional honeycomb sheets (Fig. 2a). This two-dimensional honeycomb sheet is best described as a chain of N—H···N hydrogen-bonded melamine ligands connected by AgI ions. The N—H···N hydrogen bonds in (I) [D···A distances in the range 3.011–3.039 Å and D—H···A angles in the range 165–176°] are much stronger than those found in [Ag(melamine)(NO3)]n (D···A = 3.077 Å and D—H···A = 159°).
A similar double-layer honeycomb structure was found for the compound of AgI with isocyanurate, [Ag4(C3N3H2O3)4(bpy)] (bpy = 4,4'-bipyridine; Zhang et al., 2007) (Fig. 2b), in which the bilayer sheets are connected via bpy ligands to form a three-dimensional network structure. The two-dimensional honeycomb sheets in this isocyanourate compound are formed through shorter N—H···O hydrogen bonds [2.836 (4)–2.891 (4) Å]. Both this compound and (I) exhibit the same type of hydrogen-bonded ring, a small one with graph-set symbol R22(8) (Bernstein et al., 1995), formed through direct hydrogen bonding between melamine moieties in (I) and between isocyanourate moieties in [Ag4(C3N3H2O3)4(bpy)].
Although compound (I) and [Ag(melamine)2](ClO4) have a common cation, they pack differently, and only a ladder structure is formed via N—H···N hydrogen bonds for the latter. This can be attributed to the difference in size between nitrate and perchlorate counterions. The smaller nitrate anions in (I) are firmly sandwiched between the above-mentioned hydrogen-bonded sheets via N—H···O hydrogen bonds, resulting in the formation of another bilayered hydrogen-bonded two-dimensional sheet of molecules. The thickness of this bilayer sheet is larger than the sum of van der Waals radii for two silver(I) ions (3.40 Å; Reference?), with an Ag···Ag distance of 3.924 (3) Å, in contrast with [Ag4(C3N3H2O3)4(bpy)], where the Ag···Ag distance is 3.004 Å, which confirms a higher interaction within the sheet.
There are ten different N—H···O interactions observed in (I) (Table 1). Only those with D···A distances in the range 2.97–3.27 Å and D—H···A angles in the range 145–164° are considered strong hydrogen bonds, but they are still weaker than those found in [Ag(melamine)(NO3)]n (D···A distances 3.177 and 3.198 Å and D—H···A angles 169 and 178°). Fig. 3 shows two cationic sheets of [Ag(melamine)2]+ and illustrates how the nitrates are packed between them mainly through atoms O1, connected to the upper sheet, and O3, connected to the lower sheet, via hydrogen bonds to the NH2 groups of the melamine ligands. The N—H···O hydrogen bonds in (I) are weaker than the N—H···N hydrogen bonds. Melamine acts as a bridging ligand in the case of [Ag(melamine)(NO3)]n, giving rise to a one-dimensional zigzag structure which is extended to a three-dimensional structure via both N—H···N and N—H···O hydrogen bonds.
The angle between the mean planes of the triazine rings of (I) is 8.4 (1)°. The triazine rings show some distortion due to hydrogen bonding and π–π interactions. Normally, π–π stacking takes place only when the rings are parallel displaced (offset or slipped stacking), and the angle between the centroid-to-centroid vector and the normal of the ring should be around 20° and centroid-to-centroid distances up to 3.8 Å (Janiak, 2000). In compound (I), the centroid-to-centroid distance is 3.821 (2) Å, the perpendicular distance from the centroid to the plane [Plane of what?] is 3.6 Å and the angle between the centroid-to-centroid vector and the normal of the ring is 17.8°, close to normal π–π stacking values. Such π-system aggregates are stabilized by the polar solvents effect (Janiak, 2000). This can acount for the insolubility observed for compound (I) in water.