Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107017817/jz3060sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270107017817/jz3060Isup2.hkl |
CCDC reference: 652506
Sulfapyridine (1 g) was melted at 468 K in a boiling tube under nitrogen, kept at that temperature for 5 min to destroy any remnant clusters of the stable polymorph, and poured carefully into 30 ml of boiling toluene. This caused considerable turbulance and resulted in a few solidified globules of sulphapyridine plus some crystal flakes. The formation of these crystals was probably due to crystallization from solution under the influence of the many seeds arising from the solidification and dispersion. The reasons why this procedure gives the imide/amide polymorph, the structure of which is reported here, has been discussed by Threlfall (2003). This polymorph can be identified with polymorph III of the pharmaceutical literature described by Burger et al. (1980) and others. Polymorph III of the the CSD is the stable sulfapyridine polymorph I of the pharmaceutical literature, which has been so described for almost 70 years. Only small and imperfectly formed crystals could be obtained, and the high merging R of the collected data set may be ascribed to the large number of weak reflections and the generally high anisotropic mosaicity.
All H atoms were located in difference maps. The positions of the H atoms attached to nitrogen were refined using a DFIX command [N—H = 0.88 (3) Å]. All other H atoms were treated as riding, with C—H distances of 0.95 Å. The Uiso(H) values were set to 1.2 times Ueq of the parent atom, except those for imide and amide H atoms H2N and H1N', which were refined freely.
Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Bruker, 1998) and Mercury (Bruno et al., 2002); software used to prepare material for publication: SHELXL97.
C11H11N3O2S | F(000) = 1040 |
Mr = 249.29 | Dx = 1.408 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 10.827 (2) Å | Cell parameters from 3016 reflections |
b = 14.932 (3) Å | θ = 3.1–25.2° |
c = 15.486 (3) Å | µ = 0.27 mm−1 |
β = 110.07 (3)° | T = 120 K |
V = 2351.6 (9) Å3 | Block, colourless |
Z = 8 | 0.25 × 0.20 × 0.15 mm |
Bruker–Nonius KappaCCD diffractometer | 4717 independent reflections |
Radiation source: Bruker–Nonius FR591 rotating anode | 2572 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.140 |
Detector resolution: 9.091 pixels mm-1 | θmax = 26.5°, θmin = 2.4° |
ϕ and ω scans | h = −13→13 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −18→18 |
Tmin = 0.903, Tmax = 0.956 | l = −19→19 |
23782 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)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.130 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.90 | w = 1/[σ2(Fo2) + (0.0611P)2] where P = (Fo2 + 2Fc2)/3 |
4717 reflections | (Δ/σ)max < 0.001 |
327 parameters | Δρmax = 0.26 e Å−3 |
4 restraints | Δρmin = −0.35 e Å−3 |
C11H11N3O2S | V = 2351.6 (9) Å3 |
Mr = 249.29 | Z = 8 |
Monoclinic, P21/n | Mo Kα radiation |
a = 10.827 (2) Å | µ = 0.27 mm−1 |
b = 14.932 (3) Å | T = 120 K |
c = 15.486 (3) Å | 0.25 × 0.20 × 0.15 mm |
β = 110.07 (3)° |
Bruker–Nonius KappaCCD diffractometer | 4717 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2572 reflections with I > 2σ(I) |
Tmin = 0.903, Tmax = 0.956 | Rint = 0.140 |
23782 measured reflections |
R[F2 > 2σ(F2)] = 0.055 | 4 restraints |
wR(F2) = 0.130 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.90 | Δρmax = 0.26 e Å−3 |
4717 reflections | Δρmin = −0.35 e Å−3 |
327 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 | ||
S1 | 0.79165 (7) | 0.91158 (5) | 0.08072 (6) | 0.0335 (2) | |
O1 | 0.6676 (2) | 0.88850 (14) | 0.01075 (15) | 0.0459 (6) | |
O2 | 0.7930 (2) | 0.99467 (13) | 0.12980 (16) | 0.0454 (6) | |
N1 | 0.9068 (2) | 0.92362 (15) | 0.03914 (16) | 0.0282 (6) | |
N2 | 1.0107 (2) | 0.88849 (18) | −0.06154 (17) | 0.0302 (6) | |
H2N | 1.035 (3) | 0.942 (2) | −0.0539 (19) | 0.030 (9)* | |
N3 | 0.9092 (3) | 0.6324 (2) | 0.3679 (2) | 0.0434 (7) | |
H3N | 0.856 (3) | 0.5896 (19) | 0.365 (2) | 0.052* | |
H4N | 0.990 (2) | 0.631 (2) | 0.411 (2) | 0.052* | |
C1 | 0.9283 (3) | 0.86111 (19) | −0.01806 (19) | 0.0275 (7) | |
C2 | 0.8777 (3) | 0.7740 (2) | −0.0374 (2) | 0.0375 (8) | |
H2 | 0.8169 | 0.7523 | −0.0104 | 0.045* | |
C3 | 0.9161 (3) | 0.7205 (2) | −0.0953 (2) | 0.0444 (9) | |
H3 | 0.8825 | 0.6613 | −0.1075 | 0.053* | |
C4 | 1.0032 (3) | 0.7513 (2) | −0.1365 (2) | 0.0493 (10) | |
H4 | 1.0300 | 0.7136 | −0.1763 | 0.059* | |
C5 | 1.0491 (3) | 0.8358 (2) | −0.1190 (2) | 0.0418 (9) | |
H5 | 1.1084 | 0.8583 | −0.1469 | 0.050* | |
C6 | 0.8303 (3) | 0.82519 (18) | 0.1616 (2) | 0.0271 (7) | |
C7 | 0.9451 (3) | 0.82911 (19) | 0.2377 (2) | 0.0308 (7) | |
H7 | 1.0054 | 0.8768 | 0.2433 | 0.037* | |
C8 | 0.9722 (3) | 0.7644 (2) | 0.3051 (2) | 0.0342 (8) | |
H8 | 1.0517 | 0.7677 | 0.3562 | 0.041* | |
C9 | 0.8846 (3) | 0.69404 (19) | 0.2995 (2) | 0.0318 (7) | |
C10 | 0.7695 (3) | 0.6906 (2) | 0.2231 (2) | 0.0359 (8) | |
H10 | 0.7084 | 0.6436 | 0.2183 | 0.043* | |
C11 | 0.7422 (3) | 0.75446 (19) | 0.1542 (2) | 0.0336 (7) | |
H11 | 0.6640 | 0.7503 | 0.1021 | 0.040* | |
S1' | 0.31604 (8) | 0.54048 (5) | 0.14125 (6) | 0.0382 (2) | |
O1' | 0.4361 (2) | 0.51171 (14) | 0.13030 (16) | 0.0461 (6) | |
O2' | 0.2876 (2) | 0.51284 (14) | 0.22137 (15) | 0.0455 (6) | |
N1' | 0.1930 (3) | 0.50047 (17) | 0.05485 (18) | 0.0363 (7) | |
H1N' | 0.118 (4) | 0.498 (2) | 0.063 (2) | 0.070 (13)* | |
N2' | 0.0522 (2) | 0.51033 (15) | −0.09503 (17) | 0.0319 (6) | |
N3' | 0.2825 (3) | 0.9345 (2) | 0.1097 (2) | 0.0530 (8) | |
H3N' | 0.231 (3) | 0.954 (2) | 0.135 (2) | 0.064* | |
H4N' | 0.331 (3) | 0.956 (2) | 0.079 (2) | 0.064* | |
C1' | 0.1777 (3) | 0.51443 (19) | −0.0382 (2) | 0.0316 (7) | |
C2' | 0.2809 (3) | 0.5284 (2) | −0.0707 (2) | 0.0396 (8) | |
H2' | 0.3693 | 0.5280 | −0.0298 | 0.048* | |
C3' | 0.2526 (3) | 0.5427 (2) | −0.1626 (2) | 0.0435 (9) | |
H3' | 0.3217 | 0.5534 | −0.1860 | 0.052* | |
C4' | 0.1232 (3) | 0.5415 (2) | −0.2218 (2) | 0.0399 (8) | |
H4' | 0.1014 | 0.5532 | −0.2856 | 0.048* | |
C5' | 0.0284 (3) | 0.52294 (19) | −0.1848 (2) | 0.0383 (8) | |
H5' | −0.0600 | 0.5187 | −0.2254 | 0.046* | |
C6' | 0.3086 (3) | 0.6566 (2) | 0.1335 (2) | 0.0322 (7) | |
C7' | 0.3853 (3) | 0.7034 (2) | 0.0929 (2) | 0.0387 (8) | |
H7' | 0.4440 | 0.6716 | 0.0703 | 0.046* | |
C8' | 0.3772 (3) | 0.7951 (2) | 0.0850 (2) | 0.0445 (9) | |
H8' | 0.4303 | 0.8262 | 0.0572 | 0.053* | |
C9' | 0.2918 (3) | 0.8427 (2) | 0.1175 (2) | 0.0379 (8) | |
C10' | 0.2156 (3) | 0.7958 (2) | 0.1587 (2) | 0.0456 (9) | |
H10' | 0.1580 | 0.8276 | 0.1821 | 0.055* | |
C11' | 0.2228 (3) | 0.7045 (2) | 0.1659 (2) | 0.0430 (8) | |
H11' | 0.1689 | 0.6735 | 0.1931 | 0.052* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0332 (5) | 0.0302 (5) | 0.0424 (5) | 0.0037 (3) | 0.0200 (4) | 0.0063 (4) |
O1 | 0.0304 (13) | 0.0564 (16) | 0.0480 (16) | 0.0020 (10) | 0.0098 (12) | 0.0152 (11) |
O2 | 0.0635 (16) | 0.0267 (13) | 0.0639 (17) | 0.0087 (10) | 0.0446 (14) | 0.0030 (11) |
N1 | 0.0356 (15) | 0.0228 (14) | 0.0308 (15) | −0.0014 (10) | 0.0174 (12) | 0.0015 (10) |
N2 | 0.0365 (16) | 0.0204 (16) | 0.0369 (16) | −0.0026 (11) | 0.0167 (13) | −0.0012 (11) |
N3 | 0.0455 (19) | 0.045 (2) | 0.0377 (18) | −0.0066 (14) | 0.0117 (14) | 0.0091 (15) |
C1 | 0.0259 (16) | 0.0278 (18) | 0.0268 (18) | 0.0033 (12) | 0.0063 (14) | 0.0045 (13) |
C2 | 0.041 (2) | 0.033 (2) | 0.043 (2) | −0.0041 (14) | 0.0200 (17) | −0.0029 (15) |
C3 | 0.050 (2) | 0.031 (2) | 0.055 (2) | −0.0087 (15) | 0.022 (2) | −0.0094 (16) |
C4 | 0.065 (3) | 0.036 (2) | 0.057 (2) | −0.0062 (17) | 0.033 (2) | −0.0190 (17) |
C5 | 0.049 (2) | 0.041 (2) | 0.045 (2) | −0.0038 (15) | 0.0277 (18) | −0.0131 (16) |
C6 | 0.0257 (17) | 0.0259 (17) | 0.0338 (19) | −0.0016 (12) | 0.0153 (15) | −0.0031 (13) |
C7 | 0.0277 (17) | 0.0263 (18) | 0.041 (2) | −0.0067 (12) | 0.0156 (16) | −0.0047 (14) |
C8 | 0.0276 (17) | 0.036 (2) | 0.035 (2) | −0.0029 (13) | 0.0059 (15) | −0.0034 (14) |
C9 | 0.0335 (19) | 0.0307 (19) | 0.034 (2) | −0.0012 (13) | 0.0146 (16) | −0.0001 (14) |
C10 | 0.0366 (19) | 0.035 (2) | 0.038 (2) | −0.0111 (13) | 0.0155 (17) | 0.0014 (15) |
C11 | 0.0269 (17) | 0.035 (2) | 0.0362 (19) | −0.0079 (13) | 0.0078 (15) | −0.0027 (14) |
S1' | 0.0285 (5) | 0.0435 (6) | 0.0418 (5) | 0.0018 (3) | 0.0111 (4) | 0.0119 (4) |
O1' | 0.0300 (13) | 0.0497 (15) | 0.0592 (16) | 0.0073 (10) | 0.0158 (12) | 0.0126 (11) |
O2' | 0.0408 (14) | 0.0559 (16) | 0.0377 (14) | −0.0063 (10) | 0.0108 (11) | 0.0173 (11) |
N1' | 0.0285 (16) | 0.0426 (18) | 0.0410 (18) | −0.0064 (12) | 0.0159 (14) | 0.0062 (12) |
N2' | 0.0303 (16) | 0.0323 (16) | 0.0355 (17) | 0.0021 (10) | 0.0145 (13) | 0.0037 (11) |
N3' | 0.063 (2) | 0.050 (2) | 0.044 (2) | 0.0037 (16) | 0.0161 (17) | 0.0014 (15) |
C1' | 0.035 (2) | 0.0231 (18) | 0.042 (2) | 0.0010 (12) | 0.0205 (17) | 0.0045 (13) |
C2' | 0.0345 (19) | 0.041 (2) | 0.047 (2) | −0.0065 (14) | 0.0194 (17) | −0.0030 (16) |
C3' | 0.047 (2) | 0.043 (2) | 0.053 (2) | −0.0060 (16) | 0.034 (2) | −0.0016 (17) |
C4' | 0.047 (2) | 0.041 (2) | 0.040 (2) | 0.0008 (15) | 0.0269 (19) | −0.0018 (15) |
C5' | 0.038 (2) | 0.036 (2) | 0.040 (2) | 0.0008 (14) | 0.0128 (17) | −0.0002 (15) |
C6' | 0.0257 (17) | 0.040 (2) | 0.0292 (19) | −0.0028 (13) | 0.0076 (14) | 0.0047 (14) |
C7' | 0.040 (2) | 0.040 (2) | 0.042 (2) | −0.0048 (15) | 0.0208 (17) | −0.0037 (15) |
C8' | 0.049 (2) | 0.044 (2) | 0.046 (2) | −0.0077 (16) | 0.0223 (19) | 0.0029 (16) |
C9' | 0.040 (2) | 0.036 (2) | 0.0295 (19) | 0.0028 (14) | 0.0014 (16) | 0.0027 (15) |
C10' | 0.040 (2) | 0.050 (2) | 0.049 (2) | 0.0083 (16) | 0.0189 (18) | 0.0018 (18) |
C11' | 0.036 (2) | 0.054 (2) | 0.044 (2) | 0.0010 (16) | 0.0211 (17) | 0.0066 (17) |
S1—O1 | 1.448 (2) | S1'—O1' | 1.433 (2) |
S1—O2 | 1.452 (2) | S1'—O2' | 1.437 (2) |
S1—N1 | 1.598 (2) | S1'—N1' | 1.643 (3) |
S1—C6 | 1.746 (3) | S1'—C6' | 1.739 (3) |
N1—C1 | 1.361 (3) | N1'—C1' | 1.409 (4) |
N2—C1 | 1.352 (4) | N1'—H1N' | 0.87 (4) |
N2—C5 | 1.356 (4) | N2'—C5' | 1.338 (4) |
N2—H2N | 0.84 (3) | N2'—C1' | 1.343 (4) |
N3—C9 | 1.359 (4) | N3'—C9' | 1.376 (4) |
N3—H3N | 0.85 (2) | N3'—H3N' | 0.84 (2) |
N3—H4N | 0.89 (2) | N3'—H4N' | 0.88 (2) |
C1—C2 | 1.403 (4) | C1'—C2' | 1.389 (4) |
C2—C3 | 1.368 (4) | C2'—C3' | 1.366 (4) |
C2—H2 | 0.9500 | C2'—H2' | 0.9500 |
C3—C4 | 1.385 (4) | C3'—C4' | 1.386 (4) |
C3—H3 | 0.9500 | C3'—H3' | 0.9500 |
C4—C5 | 1.349 (4) | C4'—C5' | 1.364 (4) |
C4—H4 | 0.9500 | C4'—H4' | 0.9500 |
C5—H5 | 0.9500 | C5'—H5' | 0.9500 |
C6—C7 | 1.390 (4) | C6'—C7' | 1.389 (4) |
C6—C11 | 1.401 (4) | C6'—C11' | 1.395 (4) |
C7—C8 | 1.377 (4) | C7'—C8' | 1.375 (4) |
C7—H7 | 0.9500 | C7'—H7' | 0.9500 |
C8—C9 | 1.398 (4) | C8'—C9' | 1.390 (4) |
C8—H8 | 0.9500 | C8'—H8' | 0.9500 |
C9—C10 | 1.395 (4) | C9'—C10' | 1.392 (4) |
C10—C11 | 1.385 (4) | C10'—C11' | 1.368 (4) |
C10—H10 | 0.9500 | C10'—H10' | 0.9500 |
C11—H11 | 0.9500 | C11'—H11' | 0.9500 |
O1—S1—O2 | 115.78 (14) | O1'—S1'—O2' | 119.17 (14) |
O1—S1—N1 | 112.15 (13) | O1'—S1'—N1' | 108.04 (15) |
O2—S1—N1 | 104.22 (12) | O2'—S1'—N1' | 104.16 (13) |
O1—S1—C6 | 107.05 (13) | O1'—S1'—C6' | 108.26 (13) |
O2—S1—C6 | 107.39 (14) | O2'—S1'—C6' | 109.11 (14) |
N1—S1—C6 | 110.13 (12) | N1'—S1'—C6' | 107.52 (14) |
C1—N1—S1 | 121.1 (2) | C1'—N1'—S1' | 123.9 (2) |
C1—N2—C5 | 123.7 (3) | C1'—N1'—H1N' | 112 (2) |
C1—N2—H2N | 116.7 (19) | S1'—N1'—H1N' | 116 (2) |
C5—N2—H2N | 119.5 (19) | C5'—N2'—C1' | 117.7 (3) |
C9—N3—H3N | 121 (2) | C9'—N3'—H3N' | 110 (3) |
C9—N3—H4N | 118 (2) | C9'—N3'—H4N' | 111 (2) |
H3N—N3—H4N | 119 (3) | H3N'—N3'—H4N' | 138 (4) |
N2—C1—N1 | 113.9 (2) | N2'—C1'—C2' | 121.9 (3) |
N2—C1—C2 | 116.7 (3) | N2'—C1'—N1' | 113.6 (2) |
N1—C1—C2 | 129.3 (3) | C2'—C1'—N1' | 124.5 (3) |
C3—C2—C1 | 119.8 (3) | C3'—C2'—C1' | 118.7 (3) |
C3—C2—H2 | 120.1 | C3'—C2'—H2' | 120.6 |
C1—C2—H2 | 120.1 | C1'—C2'—H2' | 120.6 |
C2—C3—C4 | 121.1 (3) | C2'—C3'—C4' | 120.0 (3) |
C2—C3—H3 | 119.4 | C2'—C3'—H3' | 120.0 |
C4—C3—H3 | 119.4 | C4'—C3'—H3' | 120.0 |
C5—C4—C3 | 118.7 (3) | C5'—C4'—C3' | 117.4 (3) |
C5—C4—H4 | 120.7 | C5'—C4'—H4' | 121.3 |
C3—C4—H4 | 120.7 | C3'—C4'—H4' | 121.3 |
C4—C5—N2 | 120.0 (3) | N2'—C5'—C4' | 124.1 (3) |
C4—C5—H5 | 120.0 | N2'—C5'—H5' | 118.0 |
N2—C5—H5 | 120.0 | C4'—C5'—H5' | 118.0 |
C7—C6—C11 | 119.1 (3) | C7'—C6'—C11' | 118.7 (3) |
C7—C6—S1 | 120.1 (2) | C7'—C6'—S1' | 120.8 (2) |
C11—C6—S1 | 120.6 (2) | C11'—C6'—S1' | 120.5 (2) |
C8—C7—C6 | 120.6 (3) | C8'—C7'—C6' | 120.7 (3) |
C8—C7—H7 | 119.7 | C8'—C7'—H7' | 119.7 |
C6—C7—H7 | 119.7 | C6'—C7'—H7' | 119.7 |
C7—C8—C9 | 121.1 (3) | C7'—C8'—C9' | 120.5 (3) |
C7—C8—H8 | 119.4 | C7'—C8'—H8' | 119.7 |
C9—C8—H8 | 119.4 | C9'—C8'—H8' | 119.7 |
N3—C9—C10 | 121.0 (3) | N3'—C9'—C8' | 121.0 (3) |
N3—C9—C8 | 120.9 (3) | N3'—C9'—C10' | 120.3 (3) |
C10—C9—C8 | 118.0 (3) | C8'—C9'—C10' | 118.7 (3) |
C11—C10—C9 | 121.4 (3) | C11'—C10'—C9' | 120.9 (3) |
C11—C10—H10 | 119.3 | C11'—C10'—H10' | 119.6 |
C9—C10—H10 | 119.3 | C9'—C10'—H10' | 119.6 |
C10—C11—C6 | 119.8 (3) | C10'—C11'—C6' | 120.5 (3) |
C10—C11—H11 | 120.1 | C10'—C11'—H11' | 119.7 |
C6—C11—H11 | 120.1 | C6'—C11'—H11' | 119.7 |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2N···N1i | 0.84 (3) | 2.09 (3) | 2.929 (4) | 178 (3) |
N3—H3N···O2ii | 0.85 (2) | 2.17 (2) | 3.013 (3) | 171 (3) |
N3—H4N···O1iii | 0.89 (2) | 2.04 (2) | 2.927 (4) | 173 (3) |
N1′—H1N′···N2′iv | 0.87 (4) | 2.06 (4) | 2.932 (4) | 175 (3) |
N3′—H3N′···O2′v | 0.84 (2) | 2.46 (3) | 3.186 (4) | 145 (3) |
Symmetry codes: (i) −x+2, −y+2, −z; (ii) −x+3/2, y−1/2, −z+1/2; (iii) x+1/2, −y+3/2, z+1/2; (iv) −x, −y+1, −z; (v) −x+1/2, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C11H11N3O2S |
Mr | 249.29 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 120 |
a, b, c (Å) | 10.827 (2), 14.932 (3), 15.486 (3) |
β (°) | 110.07 (3) |
V (Å3) | 2351.6 (9) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.27 |
Crystal size (mm) | 0.25 × 0.20 × 0.15 |
Data collection | |
Diffractometer | Bruker–Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.903, 0.956 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 23782, 4717, 2572 |
Rint | 0.140 |
(sin θ/λ)max (Å−1) | 0.627 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.130, 0.90 |
No. of reflections | 4717 |
No. of parameters | 327 |
No. of restraints | 4 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.26, −0.35 |
Computer programs: COLLECT (Hooft, 1998), DENZO (Otwinowski & Minor, 1997) and COLLECT, DENZO and COLLECT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), XP (Bruker, 1998) and Mercury (Bruno et al., 2002), SHELXL97.
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2N···N1i | 0.84 (3) | 2.09 (3) | 2.929 (4) | 178 (3) |
N3—H3N···O2ii | 0.85 (2) | 2.17 (2) | 3.013 (3) | 171 (3) |
N3—H4N···O1iii | 0.89 (2) | 2.04 (2) | 2.927 (4) | 173 (3) |
N1'—H1N'···N2'iv | 0.87 (4) | 2.06 (4) | 2.932 (4) | 175 (3) |
N3'—H3N'···O2'v | 0.84 (2) | 2.46 (3) | 3.186 (4) | 145 (3) |
Symmetry codes: (i) −x+2, −y+2, −z; (ii) −x+3/2, y−1/2, −z+1/2; (iii) x+1/2, −y+3/2, z+1/2; (iv) −x, −y+1, −z; (v) −x+1/2, y+1/2, −z+1/2. |
Sulfapyridine, (4-amino-N-(2-pyridyl)benzenesulfonamide)sulfonamide, was the first synthetic antibacterial agent effective against pneumonia. Its success marked the rise of the modern pharmaceutical industry. The versatile polymorphic behaviour of sulfapyridine has been studied extensively. Reimers (1941) determined the melting points of four forms. Castle & Witt (1946) identified five forms by melting point and optical characteristics. Burger et al. (1980) studied the thermodynamic relationships between five forms. Yang & Guillory (1972) reported the existence of six forms. Kuhnert-Brandstätter & Bachleitner-Hoffmann (1971) identified seven forms by hot-stage microscopy. It is easy to observe a multiplicity of forms, particularly by differential scanning calorimetry or by hot stage microscopy. It is difficult to reconcile the forms identified in the literature, because of the different techniques used and the absence of spectral reference data. However, comparison of the data suggests that nine forms may have been identified, which is also the number of forms noted in our own work. It is also difficult to obtain samples of sufficient purity and crystal size to obtain crystal structures. The CSD (Cambridge Structural Database; Allen, 2002) contains structures of four modifications, II–V, determined by Basak et al. (1984), Bar & Bernstein (1985) and Bernstein (1988). Colourless crystals of form VI of sulfapyridine were obtained by pouring molten sulfapyridine into boiling toluene, as detailed below.
Sulfapyridine can adopt two tautomeric forms (see scheme). The previously reported polymorphs II–V all contain exclusively the imide–pyridinium form. The NH2 and NH groups provide three possible hydrogen-bond donor sites for hydrogen bonds. There are four potential acceptor sites per molecule, provided by the SO2 and the NH2 groups and the N atoms of either the imide (imide form) or the pyridyl ring (amide form) group. Different combinations of these donor and acceptor functions are employed in polymorphs II—V, so that different hydrogen-bonded nets are observed in these structures. However, all these modifications except polymorph III contain a (pyridine)N—H···N(imide) bonded dimer. It can adopt a centrosymmetric configuration (forms II and IV) or pseudo-twofold symmetry (form V).
The structure determination of form VI revealed the presence of two independent molecules (Fig. 1), one adopting the imide and the other the amide form. Their main conformational difference is a rotation of the pyridyl ring about the C—N bond, so that the corresponding S—N—C—N torsion angle is 167.6 (2)° for the imide and -153.7 (2)° for the amide form. The two independent molecules are involved in two distinct patterns of classical hydrogen bonding (see Table 1 for parameters). Both patterns are based on the N—H···N-bonded centrosymmetric dimer with a central R22(8) ring (Bernstein et al., 1995), which was also present in forms II and IV. The geometry of the two independent dimers is similar, but the H atom bonded to N is of course in a different position in the two tautomers. Each dimeric unit contains an additional pair of intermolecular C—H···O contacts [imide dimer: C···O = 3.091 (4) Å, C—H···O = 128°; amide dimer: C···O = 3.314 (4) Å, C—H···O = 140°].
Furthermore, the imide molecule forms hydrogen bonds to four imide neighbours. These N—H···O interactions involve both aniline H atoms and both sulfonyl O atoms as acceptors. They connect four dimeric units to give a centrosymmetric R44(12) ring, as shown in Fig. 2(a). The ring is itself just a fragment of a three-dimensional hydrogen-bonded network of imide molecules (Fig. 3). By contrast, molecules adopting the amide form are linked into a two-dimensional net. Each amide molecule forms just one pair of N—H···O contacts in addition to its dimeric bonds. Fig. 2(b) shows how four dimeric units are connected in a centrosymmetric R66(42) ring. This two-dimensional net has a simple (4,4) topology (Wells, 1977) if each dimeric unit is regarded is a single node and the four N—H···O interactions that connect to four neighbouring dimers are regarded as vertices. The two-dimensional hydorgen-bonded amide nets lie parallel to the (101) plane and interpenetrate the three-dimensional imide net (Fig. 3).
Sulfathiazole is another sulfa drug whose polymorphism has been studied extensively (Apperley et al., 1999). The arrangement of hydrogen-bond donor and acceptor functions in the molecule of sulfathiazole is very similar to that found in sulfapyridine. The amide/imide N—H···N-bonded dimer that dominates the known sulfapyridine structures is observed in only one of the five structurally characterized polymorphs of sulfathiazole. A comparison between this form I of sulfathiazole (P21/c, Z = 8, a = 10.554 Å, b= 13.220 Å, c = 17.050 Å, β = 108.1°; Kruger & Gafner, 1972; P21/c, Z = 8, a = 10.554 Å, b = 13.220 Å, c = 17.050 Å, β = 108.1°) and the new polymorph VI of sulfapyridine reveals a very close relationship. In fact they are structural analogues. The main features discussed above for the sulfapyridine VI structure – the combination of hydrogen-bond donor and acceptor functions employed, the way in which the three- and two-dimensional networks are generated, and how they interpenetrate – are also present in sulfathiazole I (see also Blagden et al., 1998). There is an important difference, though, since the sulfathiazole polymorph contains just one tautomeric form of the molecule, the imide. A comparison using the program XPac (Gelbrich & Hursthouse, 2005; Gelbrich, 2006) confirms that the resulting packing arrangements of molecules are also very similar. This is illustrated in Fig. 4. The molecules in these two structures pack in a similar fashion along the respective [100] (10.83 and 10.55 Å) and [010] (14.93 and 13.22 Å) directions. Their packing parallel to the c axis in sulfapyridine VI is the same as that along the diagonal of the ac plane in sulfathiazole I (15.49 and 17.04 Å). Note that the corresponding P21/c to P21/n transformation of the original cell of sulfathiazole I with T = (100 010 101) leaves the length of the c axis and the β angle almost unchanged (dimensions of the transformed P21/n cell: a = 10.554 Å, b = 13.220 Å, c = 17.045 Å, β = 108.0°). The fact that sulfathiazole I is the stable polymorph between 389 K and the melting point at 475 K, whilst the isostructural sulfapyridine VI has no range of stability and is converted into the stable form within a few days storage, shows how sensitive stability is to small structural changes. Grzesiak et al. (2003) noted that the CSD contains six different structures of ROY {5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile; see also Shuang Chen et al., 2005} and five of sulfathiazole. Sulfapyridine now joins sulfathiazole as an example of a compound with five known structures.
The hydrogen-bond donor function associated with the aniline atom H4N' of the amide molecule is not used in any of the interactions discussed above for sulfapyridine VI. The closest intermolecular contact of H4N' exists to the O1(1 - x, 2 - y, -z) atom of an imide molecule [N···O = 3.384 (4) Å, H···O = 2.72 (3) Å and N—H···O = 134.3 (s.u.?)°]. The shortest intermolecular contacts of atom O1', which is not engaged in classical hydrogen bonding, are C3'—H3'···O1'(-x + 1, -y + 1, -z) and C7—H7···O1'(-x + 3/2, y + 1/2, -z + 1/2) [C···O = 3.333 (4) and 3.386 (4) Å, and C—H···O = 129 and 127°].