Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103010047/na1613sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103010047/na1613Isup2.hkl |
CCDC reference: 214415
Melamine was added to a solution of (DL)-malic acid (10%) and the resulting solution was slowly evaporated. After several days, colourless crystals of (I) appeared.
Data collection: KM-4 Software (Kuma, 2000); cell refinement: KM-4 Software; data reduction: KM-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1990); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
2C3H7N6+·C4H4O52−·4H2O | F(000) = 1936 |
Mr = 458.43 | Dx = 1.519 Mg m−3 Dm = 1.52 Mg m−3 Dm measured by floatation |
Monoclinic, C2/c | Melting point: decomposition K |
Hall symbol: -C 2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 26.533 (5) Å | Cell parameters from 3878 reflections |
b = 12.297 (2) Å | θ = 3.2–28.4° |
c = 13.079 (3) Å | µ = 0.13 mm−1 |
β = 110.00 (3)° | T = 293 K |
V = 4010.0 (16) Å3 | Parallelepiped, colourless |
Z = 8 | 0.28 × 0.24 × 0.16 mm |
KUMA KM-4 with area CCD detector diffractometer | 4986 independent reflections |
Radiation source: fine-focus sealed tube | 3878 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.034 |
Detector resolution: 1024x1024 with blocks 2x2 pixels mm-1 | θmax = 28.4°, θmin = 3.2° |
ω scan | h = −24→35 |
Absorption correction: analytical face-indexed, SHEXLTL (Sheldrick, 1990) | k = −16→16 |
Tmin = 0.961, Tmax = 0.968 | l = −17→17 |
15560 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.040 | H-atom parameters constrained |
wR(F2) = 0.041 | w = 1/[σ2(Fo2) + (0.0061P)2 + 0.0402P] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | (Δ/σ)max = 0.009 |
4986 reflections | Δρmax = 0.36 e Å−3 |
305 parameters | Δρmin = −0.28 e Å−3 |
12 restraints | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.000227 (7) |
2C3H7N6+·C4H4O52−·4H2O | V = 4010.0 (16) Å3 |
Mr = 458.43 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 26.533 (5) Å | µ = 0.13 mm−1 |
b = 12.297 (2) Å | T = 293 K |
c = 13.079 (3) Å | 0.28 × 0.24 × 0.16 mm |
β = 110.00 (3)° |
KUMA KM-4 with area CCD detector diffractometer | 4986 independent reflections |
Absorption correction: analytical face-indexed, SHEXLTL (Sheldrick, 1990) | 3878 reflections with I > 2σ(I) |
Tmin = 0.961, Tmax = 0.968 | Rint = 0.034 |
15560 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 12 restraints |
wR(F2) = 0.041 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.36 e Å−3 |
4986 reflections | Δρmin = −0.28 e Å−3 |
305 parameters |
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 | ||
N11 | 0.46949 (9) | 0.79460 (18) | 0.11303 (15) | 0.0465 (6) | |
N12 | 0.54955 (7) | 0.8903 (2) | 0.14109 (14) | 0.0506 (6) | |
H12 | 0.5833 | 0.8888 | 0.1513 | 0.061* | |
N13 | 0.47021 (9) | 0.99027 (18) | 0.11278 (16) | 0.0516 (6) | |
C11 | 0.44537 (11) | 0.8942 (3) | 0.1040 (2) | 0.0548 (8) | |
C12 | 0.52339 (12) | 0.9864 (3) | 0.1336 (2) | 0.0529 (8) | |
C13 | 0.52136 (12) | 0.7964 (3) | 0.13210 (19) | 0.0524 (8) | |
N14 | 0.54929 (7) | 0.70549 (16) | 0.14191 (14) | 0.0556 (6) | |
H14A | 0.5335 | 0.6436 | 0.1358 | 0.067* | |
H14B | 0.5833 | 0.7083 | 0.1544 | 0.067* | |
N15 | 0.39330 (7) | 0.89640 (15) | 0.08354 (14) | 0.0610 (6) | |
H15A | 0.3768 | 0.9577 | 0.0765 | 0.073* | |
H15B | 0.3757 | 0.8366 | 0.0772 | 0.073* | |
N16 | 0.55240 (7) | 1.07418 (16) | 0.14903 (15) | 0.0610 (7) | |
H16A | 0.5376 | 1.1369 | 0.1460 | 0.073* | |
H16B | 0.5864 | 1.0695 | 0.1622 | 0.073* | |
N21 | 0.49878 (9) | 1.29636 (17) | 0.12272 (15) | 0.0475 (6) | |
N22 | 0.41808 (7) | 1.3887 (2) | 0.09778 (15) | 0.0567 (6) | |
H22 | 0.3842 | 1.3868 | 0.0862 | 0.068* | |
N23 | 0.49610 (9) | 1.49190 (17) | 0.12158 (15) | 0.0488 (6) | |
C21 | 0.44599 (12) | 1.2963 (3) | 0.1055 (2) | 0.0493 (8) | |
C22 | 0.44388 (13) | 1.4845 (3) | 0.1084 (2) | 0.0534 (8) | |
C23 | 0.52030 (10) | 1.3943 (3) | 0.12682 (19) | 0.0485 (7) | |
N24 | 0.42017 (7) | 1.20374 (17) | 0.09932 (14) | 0.0666 (7) | |
H24A | 0.4372 | 1.1431 | 0.1063 | 0.080* | |
H24B | 0.3863 | 1.2039 | 0.0883 | 0.080* | |
N25 | 0.41570 (7) | 1.57432 (16) | 0.10462 (15) | 0.0679 (7) | |
H25A | 0.4310 | 1.6368 | 0.1106 | 0.082* | |
H25B | 0.3822 | 1.5701 | 0.0962 | 0.082* | |
N26 | 0.57250 (7) | 1.39923 (15) | 0.14086 (14) | 0.0601 (6) | |
H26A | 0.5907 | 1.3403 | 0.1468 | 0.072* | |
H26B | 0.5879 | 1.4613 | 0.1439 | 0.072* | |
O1 | 0.64947 (6) | 0.87657 (15) | 0.14596 (14) | 0.0750 (6) | |
O2 | 0.66539 (6) | 1.04170 (14) | 0.21407 (14) | 0.0685 (5) | |
C1 | 0.67678 (10) | 0.9611 (3) | 0.1664 (2) | 0.0627 (9) | |
C2 | 0.72465 (8) | 0.97206 (18) | 0.12886 (19) | 0.0574 (7) | |
H2A | 0.7572 | 0.9615 | 0.1909 | 0.069* | |
H2B | 0.7254 | 1.0454 | 0.1022 | 0.069* | |
C3 | 0.72458 (8) | 0.8922 (2) | 0.0400 (2) | 0.0529 (7) | |
H3 | 0.7193 | 0.8188 | 0.0638 | 0.063* | |
O5 | 0.68117 (5) | 0.91631 (12) | −0.05737 (13) | 0.0636 (5) | |
H5 | 0.6929 | 0.9302 | −0.1063 | 0.095* | |
C4 | 0.77711 (11) | 0.8947 (2) | 0.0204 (3) | 0.0621 (8) | |
O3 | 0.81856 (6) | 0.86354 (14) | 0.09722 (14) | 0.0718 (6) | |
O4 | 0.77891 (6) | 0.92749 (14) | −0.06762 (15) | 0.0780 (6) | |
O1W | 0.76915 (9) | 1.15316 (16) | −0.0965 (2) | 0.0964 (6) | |
H11W | 0.77224 | 1.08484 | −0.10230 | 0.147* | |
H21W | 0.78503 | 1.18391 | −0.13519 | 0.147* | |
O2W | 0.64867 (5) | 0.58852 (18) | 0.18184 (15) | 0.0760 (6) | |
H12W | 0.67063 | 0.57537 | 0.14892 | 0.114* | |
H22W | 0.66633 | 0.61574 | 0.24344 | 0.114* | |
O3W | 0.66949 (9) | 1.26100 (15) | 0.20657 (15) | 0.0809 (6) | |
H13W | 0.66678 | 1.19223 | 0.20072 | 0.119* | |
H23W | 0.67305 | 1.27745 | 0.27180 | 0.119* | |
O4W | 0.82101 (8) | 1.21342 (19) | 0.11737 (18) | 0.1097 (7) | |
H14W | 0.79422 | 1.20748 | 0.058980 | 0.166* | |
H24W | 0.81560 | 1.26820 | 0.151880 | 0.166* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N11 | 0.0438 (14) | 0.0396 (17) | 0.0646 (16) | 0.0039 (13) | 0.0294 (13) | 0.0037 (12) |
N12 | 0.0383 (13) | 0.0460 (16) | 0.0757 (15) | −0.0043 (15) | 0.0303 (12) | −0.0057 (14) |
N13 | 0.0452 (15) | 0.0478 (18) | 0.0664 (16) | 0.0016 (13) | 0.0249 (13) | 0.0034 (12) |
C11 | 0.0492 (19) | 0.057 (2) | 0.068 (2) | 0.003 (2) | 0.0323 (17) | 0.0048 (19) |
C12 | 0.059 (2) | 0.040 (2) | 0.070 (2) | −0.0006 (19) | 0.036 (2) | −0.0029 (17) |
C13 | 0.058 (2) | 0.036 (2) | 0.068 (2) | −0.001 (2) | 0.0275 (19) | 0.0024 (17) |
N14 | 0.0541 (14) | 0.0363 (15) | 0.0816 (16) | −0.0008 (12) | 0.0301 (12) | 0.0011 (13) |
N15 | 0.0412 (12) | 0.0422 (14) | 0.0930 (17) | 0.0004 (13) | 0.0144 (13) | 0.0036 (12) |
N16 | 0.0495 (14) | 0.0473 (16) | 0.0966 (18) | −0.0001 (13) | 0.0385 (13) | 0.0004 (14) |
N21 | 0.0421 (14) | 0.0403 (16) | 0.0596 (16) | −0.0038 (13) | 0.0167 (12) | 0.0023 (12) |
N22 | 0.0437 (13) | 0.0455 (15) | 0.0811 (17) | 0.0071 (16) | 0.0218 (13) | 0.0018 (15) |
N23 | 0.0365 (14) | 0.0526 (19) | 0.0623 (16) | 0.0038 (13) | 0.0235 (13) | 0.0043 (12) |
C21 | 0.045 (2) | 0.042 (2) | 0.060 (2) | 0.0003 (18) | 0.0169 (17) | −0.0009 (16) |
C22 | 0.063 (2) | 0.046 (2) | 0.056 (2) | 0.0082 (19) | 0.0255 (18) | 0.0059 (16) |
C23 | 0.0369 (17) | 0.046 (2) | 0.0647 (19) | 0.003 (2) | 0.0200 (16) | 0.0048 (18) |
N24 | 0.0607 (15) | 0.0488 (16) | 0.0951 (19) | −0.0003 (13) | 0.0327 (14) | −0.0001 (14) |
N25 | 0.0585 (15) | 0.0441 (16) | 0.1035 (19) | 0.0040 (13) | 0.0307 (14) | 0.0037 (14) |
N26 | 0.0552 (14) | 0.0364 (14) | 0.0905 (16) | −0.0041 (12) | 0.0271 (13) | −0.0087 (12) |
O1 | 0.0628 (13) | 0.0622 (15) | 0.1129 (16) | −0.0080 (11) | 0.0465 (12) | −0.0150 (12) |
O2 | 0.0633 (12) | 0.0612 (13) | 0.0910 (14) | 0.0058 (10) | 0.0395 (11) | −0.0110 (11) |
C1 | 0.0451 (19) | 0.067 (2) | 0.077 (2) | 0.0063 (18) | 0.0227 (18) | −0.001 (2) |
C2 | 0.0514 (16) | 0.0487 (17) | 0.068 (2) | 0.0053 (15) | 0.0144 (15) | −0.0010 (17) |
C3 | 0.0373 (15) | 0.0522 (18) | 0.072 (2) | 0.0027 (16) | 0.0217 (16) | 0.0095 (17) |
O5 | 0.0454 (10) | 0.0773 (14) | 0.0734 (12) | −0.0044 (10) | 0.0272 (10) | −0.0034 (11) |
C4 | 0.067 (2) | 0.0494 (19) | 0.086 (3) | −0.0051 (19) | 0.047 (2) | −0.006 (2) |
O3 | 0.0469 (11) | 0.0835 (16) | 0.0860 (14) | 0.0065 (11) | 0.0242 (10) | 0.0143 (12) |
O4 | 0.0629 (12) | 0.0928 (16) | 0.0954 (16) | 0.0094 (10) | 0.0490 (12) | 0.0126 (12) |
O1W | 0.1077 (16) | 0.0800 (13) | 0.1187 (17) | −0.0054 (15) | 0.0610 (14) | −0.0135 (16) |
O2W | 0.0554 (12) | 0.0910 (15) | 0.0857 (14) | 0.0027 (12) | 0.0292 (11) | 0.0006 (15) |
O3W | 0.0823 (13) | 0.0660 (15) | 0.0931 (16) | 0.0110 (13) | 0.0286 (15) | −0.0055 (13) |
O4W | 0.0873 (15) | 0.0985 (19) | 0.153 (2) | 0.0055 (12) | 0.0537 (17) | 0.0147 (17) |
N11—C13 | 1.312 (3) | N24—H24A | 0.8600 |
N11—C11 | 1.368 (3) | N24—H24B | 0.8600 |
N12—C12 | 1.357 (3) | N25—H25A | 0.8600 |
N12—C13 | 1.359 (3) | N25—H25B | 0.8600 |
N12—H12 | 0.8600 | N26—H26A | 0.8600 |
N13—C11 | 1.339 (3) | N26—H26B | 0.8600 |
N13—C12 | 1.343 (3) | O1—C1 | 1.243 (3) |
C11—N15 | 1.315 (2) | O2—C1 | 1.261 (3) |
C12—N16 | 1.301 (3) | C1—C2 | 1.516 (3) |
C13—N14 | 1.323 (3) | C2—C3 | 1.521 (3) |
N14—H14A | 0.8600 | C2—H2A | 0.9700 |
N14—H14B | 0.8600 | C2—H2B | 0.9700 |
N15—H15A | 0.8600 | C3—O5 | 1.426 (2) |
N15—H15B | 0.8600 | C3—C4 | 1.501 (3) |
N16—H16A | 0.8600 | C3—H3 | 0.9800 |
N16—H16B | 0.8600 | O5—H5 | 0.8200 |
N21—C23 | 1.326 (3) | C4—O4 | 1.236 (3) |
N21—C21 | 1.341 (3) | C4—O3 | 1.269 (3) |
N22—C21 | 1.341 (3) | O1W—H11W | 0.85 |
N22—C22 | 1.345 (3) | O1W—H21W | 0.85 |
N22—H22 | 0.8600 | O2W—H12W | 0.85 |
N23—C22 | 1.340 (3) | O2W—H22W | 0.85 |
N23—C23 | 1.351 (3) | O3W—H13W | 0.85 |
C21—N24 | 1.316 (2) | O3W—H23W | 0.85 |
C22—N25 | 1.326 (3) | O4W—H14W | 0.85 |
C23—N26 | 1.335 (2) | O4W—H24W | 0.85 |
C13—N11—C11 | 115.5 (2) | N21—C23—N23 | 127.9 (2) |
C12—N12—C13 | 118.8 (2) | N26—C23—N23 | 114.8 (3) |
C12—N12—H12 | 120.6 | C21—N24—H24A | 120.0 |
C13—N12—H12 | 120.6 | C21—N24—H24B | 120.0 |
C11—N13—C12 | 116.0 (2) | H24A—N24—H24B | 120.0 |
N15—C11—N13 | 116.8 (3) | C22—N25—H25A | 120.0 |
N15—C11—N11 | 117.7 (3) | C22—N25—H25B | 120.0 |
N13—C11—N11 | 125.5 (2) | H25A—N25—H25B | 120.0 |
N16—C12—N13 | 121.8 (3) | C23—N26—H26A | 120.0 |
N16—C12—N12 | 116.8 (3) | C23—N26—H26B | 120.0 |
N13—C12—N12 | 121.4 (3) | H26A—N26—H26B | 120.0 |
N11—C13—N14 | 121.4 (3) | O1—C1—O2 | 122.9 (3) |
N11—C13—N12 | 122.8 (3) | O1—C1—C2 | 119.7 (3) |
N14—C13—N12 | 115.9 (3) | O2—C1—C2 | 117.4 (3) |
C13—N14—H14A | 120.0 | C1—C2—C3 | 114.1 (2) |
C13—N14—H14B | 120.0 | C1—C2—H2A | 108.7 |
H14A—N14—H14B | 120.0 | C3—C2—H2A | 108.7 |
C11—N15—H15A | 120.0 | C1—C2—H2B | 108.7 |
C11—N15—H15B | 120.0 | C3—C2—H2B | 108.7 |
H15A—N15—H15B | 120.0 | H2A—C2—H2B | 107.6 |
C12—N16—H16A | 120.0 | O5—C3—C4 | 110.9 (2) |
C12—N16—H16B | 120.0 | O5—C3—C2 | 109.7 (2) |
H16A—N16—H16B | 120.0 | C4—C3—C2 | 111.1 (2) |
C23—N21—C21 | 114.7 (2) | O5—C3—H3 | 108.4 |
C21—N22—C22 | 119.1 (2) | C4—C3—H3 | 108.4 |
C21—N22—H22 | 120.5 | C2—C3—H3 | 108.4 |
C22—N22—H22 | 120.5 | C3—O5—H5 | 109.5 |
C22—N23—C23 | 113.5 (2) | O4—C4—O3 | 122.5 (3) |
N24—C21—N21 | 120.2 (3) | O4—C4—C3 | 120.0 (3) |
N24—C21—N22 | 117.8 (3) | O3—C4—C3 | 117.5 (3) |
N21—C21—N22 | 122.0 (3) | H11W—O1W—H21W | 107.7 |
N25—C22—N23 | 119.5 (3) | H12W—O2W—H22W | 107.4 |
N25—C22—N22 | 117.7 (3) | H13W—O3W—H23W | 107.7 |
N23—C22—N22 | 122.7 (3) | H14W—O4W—H24W | 107.7 |
N21—C23—N26 | 117.3 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N12—H12···O1 | 0.86 | 1.79 | 2.635 (3) | 169 |
N14—H14A···N23i | 0.86 | 2.09 | 2.950 (3) | 179 |
N14—H14B···O2W | 0.86 | 2.21 | 2.890 (3) | 136 |
N15—H15A···O5ii | 0.86 | 2.14 | 2.977 (3) | 165 |
N15—H15B···O4Wiii | 0.86 | 2.28 | 3.085 (3) | 156 |
N16—H16A···N21 | 0.86 | 2.19 | 3.045 (3) | 175 |
N16—H16B···O2 | 0.86 | 2.00 | 2.851 (3) | 170 |
N22—H22···O3iv | 0.86 | 1.82 | 2.656 (3) | 164 |
N24—H24A···N13 | 0.86 | 2.06 | 2.920 (3) | 174 |
N24—H24B···O5ii | 0.86 | 2.25 | 2.950 (3) | 139 |
N25—H25A···N11v | 0.86 | 2.19 | 3.046 (3) | 176 |
N25—H25B···O4Wiv | 0.86 | 2.47 | 3.091 (3) | 129 |
N26—H26A···O3W | 0.86 | 2.19 | 2.956 (3) | 148 |
N26—H26B···O2Wv | 0.86 | 2.18 | 3.008 (3) | 162 |
O5—H5···O4 | 0.82 | 2.16 | 2.646 (3) | 118 |
O5—H5···O2vi | 0.82 | 2.24 | 2.919 (3) | 141 |
O1W—H11W···O4 | 0.85 | 1.98 | 2.801 (3) | 162 |
O1W—H21W···O3Wvii | 0.85 | 1.89 | 2.728 (3) | 170 |
O2W—H12W···O4viii | 0.85 | 1.97 | 2.815 (3) | 170 |
O2W—H22W···O4Wix | 0.85 | 2.11 | 2.908 (3) | 156 |
O3W—H13W···O2 | 0.85 | 1.86 | 2.702 (3) | 170 |
O3W—H23W···O3x | 0.85 | 1.96 | 2.778 (3) | 161 |
O4W—H14W···O1W | 0.85 | 2.02 | 2.763 (3) | 145 |
O4W—H24W···O1Wvii | 0.85 | 2.32 | 2.836 (3) | 119 |
Symmetry codes: (i) x, y−1, z; (ii) −x+1, −y+2, −z; (iii) x−1/2, y−1/2, z; (iv) x−1/2, y+1/2, z; (v) x, y+1, z; (vi) x, −y+2, z−1/2; (vii) −x+3/2, −y+5/2, −z; (viii) −x+3/2, −y+3/2, −z; (ix) −x+3/2, y−1/2, −z+1/2; (x) −x+3/2, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | 2C3H7N6+·C4H4O52−·4H2O |
Mr | 458.43 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 26.533 (5), 12.297 (2), 13.079 (3) |
β (°) | 110.00 (3) |
V (Å3) | 4010.0 (16) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.13 |
Crystal size (mm) | 0.28 × 0.24 × 0.16 |
Data collection | |
Diffractometer | KUMA KM-4 with area CCD detector diffractometer |
Absorption correction | Analytical face-indexed, SHEXLTL (Sheldrick, 1990) |
Tmin, Tmax | 0.961, 0.968 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 15560, 4986, 3878 |
Rint | 0.034 |
(sin θ/λ)max (Å−1) | 0.669 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.041, 1.07 |
No. of reflections | 4986 |
No. of parameters | 305 |
No. of restraints | 12 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.36, −0.28 |
Computer programs: KM-4 Software (Kuma, 2000), KM-4 Software, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL (Sheldrick, 1990).
N11—C13 | 1.312 (3) | N23—C22 | 1.340 (3) |
N11—C11 | 1.368 (3) | N23—C23 | 1.351 (3) |
N12—C12 | 1.357 (3) | O1—C1 | 1.243 (3) |
N12—C13 | 1.359 (3) | O2—C1 | 1.261 (3) |
N13—C11 | 1.339 (3) | C1—C2 | 1.516 (3) |
N13—C12 | 1.343 (3) | C2—C3 | 1.521 (3) |
N21—C23 | 1.326 (3) | C3—O5 | 1.426 (2) |
N21—C21 | 1.341 (3) | C3—C4 | 1.501 (3) |
N22—C21 | 1.341 (3) | C4—O4 | 1.236 (3) |
N22—C22 | 1.345 (3) | C4—O3 | 1.269 (3) |
C13—N11—C11 | 115.5 (2) | N21—C23—N23 | 127.9 (2) |
C12—N12—C13 | 118.8 (2) | O1—C1—O2 | 122.9 (3) |
C11—N13—C12 | 116.0 (2) | O1—C1—C2 | 119.7 (3) |
N13—C11—N11 | 125.5 (2) | O2—C1—C2 | 117.4 (3) |
N13—C12—N12 | 121.4 (3) | C1—C2—C3 | 114.1 (2) |
N11—C13—N12 | 122.8 (3) | O5—C3—C4 | 110.9 (2) |
C23—N21—C21 | 114.7 (2) | O5—C3—C2 | 109.7 (2) |
C21—N22—C22 | 119.1 (2) | C4—C3—C2 | 111.1 (2) |
C22—N23—C23 | 113.5 (2) | O4—C4—O3 | 122.5 (3) |
N21—C21—N22 | 122.0 (3) | O4—C4—C3 | 120.0 (3) |
N23—C22—N22 | 122.7 (3) | O3—C4—C3 | 117.5 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N12—H12···O1 | 0.86 | 1.79 | 2.635 (3) | 169 |
N14—H14A···N23i | 0.86 | 2.09 | 2.950 (3) | 179 |
N14—H14B···O2W | 0.86 | 2.21 | 2.890 (3) | 136 |
N15—H15A···O5ii | 0.86 | 2.14 | 2.977 (3) | 165 |
N15—H15B···O4Wiii | 0.86 | 2.28 | 3.085 (3) | 156 |
N16—H16A···N21 | 0.86 | 2.19 | 3.045 (3) | 175 |
N16—H16B···O2 | 0.86 | 2.00 | 2.851 (3) | 170 |
N22—H22···O3iv | 0.86 | 1.82 | 2.656 (3) | 164 |
N24—H24A···N13 | 0.86 | 2.06 | 2.920 (3) | 174 |
N24—H24B···O5ii | 0.86 | 2.25 | 2.950 (3) | 139 |
N25—H25A···N11v | 0.86 | 2.19 | 3.046 (3) | 176 |
N25—H25B···O4Wiv | 0.86 | 2.47 | 3.091 (3) | 129 |
N26—H26A···O3W | 0.86 | 2.19 | 2.956 (3) | 148 |
N26—H26B···O2Wv | 0.86 | 2.18 | 3.008 (3) | 162 |
O5—H5···O4 | 0.82 | 2.16 | 2.646 (3) | 118 |
O5—H5···O2vi | 0.82 | 2.24 | 2.919 (3) | 141 |
O1W—H11W···O4 | 0.85 | 1.98 | 2.801 (3) | 162 |
O1W—H21W···O3Wvii | 0.85 | 1.89 | 2.728 (3) | 170 |
O2W—H12W···O4viii | 0.85 | 1.97 | 2.815 (3) | 170 |
O2W—H22W···O4Wix | 0.85 | 2.11 | 2.908 (3) | 156 |
O3W—H13W···O2 | 0.85 | 1.86 | 2.702 (3) | 170 |
O3W—H23W···O3x | 0.85 | 1.96 | 2.778 (3) | 161 |
O4W—H14W···O1W | 0.85 | 2.02 | 2.763 (3) | 145 |
O4W—H24W···O1Wvii | 0.85 | 2.32 | 2.836 (3) | 119 |
Symmetry codes: (i) x, y−1, z; (ii) −x+1, −y+2, −z; (iii) x−1/2, y−1/2, z; (iv) x−1/2, y+1/2, z; (v) x, y+1, z; (vi) x, −y+2, z−1/2; (vii) −x+3/2, −y+5/2, −z; (viii) −x+3/2, −y+3/2, −z; (ix) −x+3/2, y−1/2, −z+1/2; (x) −x+3/2, y+1/2, −z+1/2. |
This study is a continuation of our investigations characterizing the hydrogen bonds formed by triazine derivatives in the solid state (Janczak & Kubiak, 1999; Janczak & Perpétuo, 2001a,b,c,d; Perpétuo & Janczak, 2002a,b; Janczak & Perpétuo, 2002a,b). Melamine and its organic and inorganic complexes or salts can develop well defined supramolecular structures via multiple hydrogen bonds by self-assembly of components that contain complementary arrays of hydrogen-bonding sites (Desiraju, 1990; MacDonald & Whitesides, 1994; Row, 1999; Krische & Lehn, 2000; Sherrington & Taskinen, 2001). To expand the understanding of the solid-state physical-organic chemistry of compounds containing multiple hydrogen-bonding systems, we present here the solid-state structure of the title compound, (I). Additionally, the geometries of both oppositely charged parts, i.e. the singly protonated melaminium cation and the DL-malate dianion, are compared with ab initio fully optimized parameters calculated at the HF/6–31 G(d,p) level (Frisch et al. 1995). The ab initio molecular orbital calculations were carried out on isolated ions, and the results are illustrated in Fig. 1.
The asymmetric unit of (I) consists of two melaminium cations, singly protonated at one of the ring N atoms, a DL-malate dianion and four water molecules (Fig. 2). The six-membered rings of the singly protonated melaminium residues exhibit significant distortions from the ideal hexagonal form. The internal C—N—C angle at the protonated N atom in both independent melaminium cations is greater than the other two C—N—C angles within the ring. This increase is a result of the steric effect of a lone-pair electron, predicted by the valence-shell electron-pair repulsion theory (VSEPR; Gillespie, 1963, 1992). As a result of the protonation of the melamine ring at one of the three ring N atoms, the internal N—C—N angle involving only the non-protonated N atoms is significantly greater than the N—C—N angles involving both protonated and non-protonated N atoms. The ab initio optimized geometry calculated for the singly protonated melaminium residue shows a correlation between the C—N—C and N—C—N angles within the ring similar to that seen in the crystal. Thus, the ring distortion of the singly protonated malaminium residue results mainly from the protonation and, to a lesser degree, from the hydrogen-bonding system and the crystal packing. The C—N bond lengths in the optimized melaminium residue are slightly shorter than those in the crystal. The lengthening of the C—N bonds of the melaminium rings in the crystal is likely to be due to the interaction of the π—π clouds between the rings in the stacks and the hydrogen-bonding system. A similar correlation between the internal C—N—C and N—C—N angles within the melaminium ring is reported for crystals of barbituric acid with melamine (Zerkowski et al. 1994), melaminium phthalate (Janczak & Perpétuo, 2001a), melaminium chloride hemihydrate (Janczak & Perpétuo, 2001c), bis(melaminium) sulfate dihydrate (Janczak & Perpétuo, 2001 d), melaminium acetate (Perpétuo & Janczak, 2002a), melaminium glutarate monohydrate (Janczak & Perpétuo, 2002a) and melaminium phosphate (Janczak & Perpétuo, 2002b), i.e. those singly protonated melaminium salts that have been previously structurally characterized.
Each melaminium residue is involved in nine hydrogen bonds; in seven of them it acts as a donor and in the remaining two it acts as an acceptor. The two pairs of almost linear N—H···N hydrogen bonds link the melaminium moieties to form chains, which in turn form stacks along the [001] direction. Within one stack, the melaminium residues are separated by 3.196 (3) Å. This distance is shorter than that between the π-aromatic ring systems (3.4 Å; Pauling, 1960) and indicates a π–π interactions between the melaminium rings within the stack. The remaining five N—H···O hydrogen bonds (see Table 2), which are more bent, link the chains of melaminium residues with DL-malate ions and water molecules (see Fig. 3). These N—H···O hydrogen bonds stabilize the stacking structure. One of the melaminium moieties forms three hydrogen bonds with two malate ions (with atoms O1 and O2 of one malate ion and with atom O5 of the other malate ion), while the other melaminium residue forms only two hydrogen bonds with two malate ions (with atom O3 of one malate ion and with atom O5 of the second). Atom H12 at the protonated N atom of one melamine residue is involved in a hydrogen bond with atom O1 of the COO− group, while atom H22 on the protonated N atom of the second melaminium residue forms a hydrogen bond with atom O3 of the other COO− group. Additionally, the first melaminium residue is involved in hydrogen bonds with two water molecules (O2W and O4W), and the other melaminium cation is involved in hydrogen bonds with three water molecules (O2W, O3W and O4W).
The conformation of the carbon skeleton of the malate anion is extended [ψ = −170.5 (3)°], with the C3-carboxyl group almost planar with atoms C3 and O5 [ϕ2 = 7.3 (4)°] because of the intramolecular O5—H5···O4 hydrogen bonding interaction, with a relatively short O5···O4 distance. The conformation of the C2-carboxyl group (COO−) around the C—C bond is clinal [χ = 17.3 (4)°]. The C1—C2—C3—C4 (ψ), O4—C4—C3—O5 (ϕ2) and C3—C2—C1—O1 (χ) torsion angles describe well the conformation of the malate ion and the conformation of malic acid (Sluis & Kron, 1985; 1989). In the optimized malate dianion, the values of ψ, ϕ2 and χ are −166.3, 4.2 and 36.9°, respectively. The greatest difference between the angles in the optimized ion and in the crystal malate ion is found for angle χ, which describes the orientation of the COO− group at atom C2 as a result of the formation of the relatively strong O···H—N hydrogen bonds with the melaminium moiety. The optimized O—C—O angles in both dissociated carboxyl groups are greater than those in the crystal, probably because of the diminishing steric effect of lone pairs of electrons on the O atoms, resulting from the O···H—-N and O···H—O hydrogen-bonding interactions. The C—O bonds in both COO− groups are intermediate between single Csp2—O (1.308–1.320 Å) and double Csp2═O (1.214–1.224 Å; Allen et al., 1987; Allen, 2002) indicating delocalization of the charge on both O atoms of the COO− groups. The slight difference between the C1—O1 and C1—O2 bonds in one COO− group and between the C4—O3 and C4—O4 bonds in the other COO− group correlates well with the strength of the hydrogen bonds in which the O atoms are involved (Table 2). The C3—O5 bond length is slightly longer in the crystal than in the ab initio calculation, since, in the crystal, the hydroxyl group is involved in four hydrogen bonds, viz. in two as a donor and in two as an acceptor. Thus, hydroxyl atom H5 of the malate ion forms bifurcated hydrogen bond. The malate ions form hydrogen-bonded chains via O5—H5···O2vi interactions and, together with hydrogen-bonded water molecules, form a two-dimensional layer parallel to the (100) plane.
Two pairs of water molecules (O1W and O4W) related by an inversion centre form a hydrogen-bonded cyclic tetramer in which atom O4W is a donor and atom O1W is an acceptor. Additionally, water molecule O3W interacts as an acceptor with atom H21W, and water molecule O2W interacts via atom H22W to form an O2W—H22W···O4Wix hydrogen bond.