Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103019280/fg1702sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103019280/fg1702MAsup2.hkl |
CCDC reference: 224669
The title compound was obtained from Bachem and used as received. Crystals of MA were grown by slow diffusion of acteonitrile into an aqueous solution of the peptide.
Due to the low parameter-to-reflection ratio, only fully ordered S and O atoms, and the terminal C atoms of the L-Met side chains, were refined anisotropically. A full anisotropic refinement (908 parameters) was found to give only a very moderate decrease in the R value (to 0.0556) and a small increase in the s.u.s of the geometric parameters. Refinement of the complex disorder for the L-Met side chain of peptide molecule A was handled by mild SHELXTL SAME 0.02 0.03 constraints (Sheldrick, 1997) for six different orientations. H atoms were placed geometrically and refined with constraints. Free rotation of amino and methyl groups (without disorder) was permitted. Uiso(H) values were 1.2Ueq of the carrier atom, or 1.5Ueq for methyl and amino groups. Friedel pairs were merged in the final refinements.
Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
C8H16N2O3S | Dx = 1.295 Mg m−3 |
Mr = 220.29 | Mo Kα radiation, λ = 0.71073 Å |
Hexagonal, P61 | Cell parameters from 14292 reflections |
a = 37.6488 (15) Å | θ = 1.1–25.1° |
c = 9.6613 (8) Å | µ = 0.27 mm−1 |
V = 11859.6 (12) Å3 | T = 105 K |
Z = 42 | Needle, colourless |
F(000) = 4956 | 0.80 × 0.18 × 0.15 mm |
Siemens SMART CCD area-detector diffractometer | 7460 independent reflections |
Radiation source: fine-focus sealed tube | 4308 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.195 |
Detector resolution: 8.3 pixels mm-1 | θmax = 25.1°, θmin = 1.1° |
Sets of exposures each taken over 0.3° ω rotation scans | h = −44→44 |
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | k = −40→44 |
Tmin = 0.789, Tmax = 0.960 | l = −11→8 |
79465 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)] = 0.058 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.145 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0446P)2 + 18.1456P] where P = (Fo2 + 2Fc2)/3 |
7460 reflections | (Δ/σ)max = 0.001 |
633 parameters | Δρmax = 0.48 e Å−3 |
93 restraints | Δρmin = −0.35 e Å−3 |
C8H16N2O3S | Z = 42 |
Mr = 220.29 | Mo Kα radiation |
Hexagonal, P61 | µ = 0.27 mm−1 |
a = 37.6488 (15) Å | T = 105 K |
c = 9.6613 (8) Å | 0.80 × 0.18 × 0.15 mm |
V = 11859.6 (12) Å3 |
Siemens SMART CCD area-detector diffractometer | 7460 independent reflections |
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | 4308 reflections with I > 2σ(I) |
Tmin = 0.789, Tmax = 0.960 | Rint = 0.195 |
79465 measured reflections |
R[F2 > 2σ(F2)] = 0.058 | 93 restraints |
wR(F2) = 0.145 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0446P)2 + 18.1456P] where P = (Fo2 + 2Fc2)/3 |
7460 reflections | Δρmax = 0.48 e Å−3 |
633 parameters | Δρmin = −0.35 e Å−3 |
Geometry. All H atoms are in theoretical positions, X—H bonds and X—Y—H bond angles have only been listed for molecule C (first molecule without any kind of disorder) |
Refinement. Data were collected by measuring three sets of exposures with the detector set at 2θ = 26°, crystal-to-detector distance 4.98 cm. Refinement of F2 against ALL reflections. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
O1A | 0.18323 (15) | 0.22244 (17) | 0.7450 (6) | 0.0369 (15) | |
O2A | 0.06150 (16) | 0.2261 (2) | 0.8514 (6) | 0.0516 (19) | |
O3A | 0.10056 (14) | 0.26074 (15) | 1.0316 (6) | 0.0271 (13) | |
N1A | 0.17569 (17) | 0.18119 (18) | 0.5228 (7) | 0.0267 (16)* | |
H1A | 0.1698 | 0.1621 | 0.4556 | 0.040* | |
H2A | 0.1885 | 0.1765 | 0.5944 | 0.040* | |
H3A | 0.1924 | 0.2067 | 0.4876 | 0.040* | |
N2A | 0.12328 (14) | 0.22243 (13) | 0.7239 (5) | 0.0261 (15)* | |
H4A | 0.1000 | 0.2135 | 0.6789 | 0.031* | |
C11A | 0.13697 (14) | 0.17837 (13) | 0.5730 (5) | 0.025 (2)* | 0.285 (9) |
H11A | 0.1238 | 0.1853 | 0.4959 | 0.030* | 0.285 (9) |
C21A | 0.10979 (14) | 0.13439 (13) | 0.6146 (5) | 0.052 (4)* | 0.285 (9) |
H211 | 0.1067 | 0.1165 | 0.5352 | 0.062* | 0.285 (9) |
H212 | 0.0822 | 0.1299 | 0.6380 | 0.062* | 0.285 (9) |
C31A | 0.1268 (7) | 0.1221 (5) | 0.740 (3) | 0.056 (9)* | 0.285 (9) |
H311 | 0.1280 | 0.1390 | 0.8200 | 0.068* | 0.285 (9) |
H312 | 0.1553 | 0.1291 | 0.7182 | 0.068* | 0.285 (9) |
S11A | 0.0983 (4) | 0.0686 (3) | 0.7905 (12) | 0.066 (3)* | 0.285 (9) |
C41A | 0.1398 (8) | 0.0654 (9) | 0.872 (4) | 0.077 (11)* | 0.285 (9) |
H411 | 0.1298 | 0.0373 | 0.9038 | 0.116* | 0.285 (9) |
H412 | 0.1501 | 0.0843 | 0.9504 | 0.116* | 0.285 (9) |
H413 | 0.1619 | 0.0730 | 0.8044 | 0.116* | 0.285 (9) |
C12A | 0.13697 (14) | 0.17837 (13) | 0.5730 (5) | 0.025 (2)* | 0.190 (8) |
H12A | 0.1261 | 0.1878 | 0.4953 | 0.030* | 0.190 (8) |
C22A | 0.1024 (6) | 0.1373 (10) | 0.619 (6) | 0.052 (4)* | 0.190 (8) |
H221 | 0.0857 | 0.1221 | 0.5376 | 0.062* | 0.190 (8) |
H222 | 0.0845 | 0.1415 | 0.6839 | 0.062* | 0.190 (8) |
C32A | 0.1189 (10) | 0.1118 (9) | 0.691 (5) | 0.056 (9)* | 0.190 (8) |
H321 | 0.1423 | 0.1302 | 0.7503 | 0.068* | 0.190 (8) |
H322 | 0.1295 | 0.1008 | 0.6186 | 0.068* | 0.190 (8) |
S12A | 0.0819 (6) | 0.0696 (4) | 0.7947 (17) | 0.066 (3)* | 0.190 (8) |
C42A | 0.0836 (16) | 0.0282 (9) | 0.708 (5) | 0.077 (11)* | 0.190 (8) |
H421 | 0.1109 | 0.0383 | 0.6680 | 0.116* | 0.190 (8) |
H422 | 0.0630 | 0.0175 | 0.6341 | 0.116* | 0.190 (8) |
H423 | 0.0778 | 0.0063 | 0.7745 | 0.116* | 0.190 (8) |
C13A | 0.13697 (14) | 0.17837 (13) | 0.5730 (5) | 0.025 (2)* | 0.229 (7) |
H13A | 0.1252 | 0.1869 | 0.4954 | 0.030* | 0.229 (7) |
C23A | 0.1060 (12) | 0.1339 (7) | 0.609 (4) | 0.052 (4)* | 0.229 (7) |
H231 | 0.0858 | 0.1331 | 0.6766 | 0.062* | 0.229 (7) |
H232 | 0.1204 | 0.1207 | 0.6527 | 0.062* | 0.229 (7) |
C33A | 0.0834 (7) | 0.1099 (7) | 0.476 (3) | 0.032 (8)* | 0.229 (7) |
H331 | 0.0993 | 0.0979 | 0.4354 | 0.038* | 0.229 (7) |
H332 | 0.0841 | 0.1299 | 0.4076 | 0.038* | 0.229 (7) |
S13A | 0.0317 (3) | 0.0700 (4) | 0.4937 (13) | 0.054 (3)* | 0.229 (7) |
C43A | 0.0234 (13) | 0.0414 (12) | 0.338 (4) | 0.087 (16)* | 0.229 (7) |
H431 | −0.0056 | 0.0201 | 0.3321 | 0.130* | 0.229 (7) |
H432 | 0.0404 | 0.0285 | 0.3392 | 0.130* | 0.229 (7) |
H433 | 0.0307 | 0.0598 | 0.2586 | 0.130* | 0.229 (7) |
C14A | 0.13697 (14) | 0.17837 (13) | 0.5730 (5) | 0.025 (2)* | 0.142 (6) |
H14A | 0.1208 | 0.1820 | 0.4977 | 0.030* | 0.142 (6) |
C24A | 0.1124 (18) | 0.1377 (8) | 0.652 (3) | 0.052 (4)* | 0.142 (6) |
H241 | 0.0925 | 0.1399 | 0.7132 | 0.062* | 0.142 (6) |
H242 | 0.1316 | 0.1340 | 0.7126 | 0.062* | 0.142 (6) |
C34A | 0.0888 (13) | 0.0989 (7) | 0.561 (5) | 0.032 (8)* | 0.142 (6) |
H341 | 0.0717 | 0.0757 | 0.6238 | 0.038* | 0.142 (6) |
H342 | 0.1093 | 0.0931 | 0.5189 | 0.038* | 0.142 (6) |
S14A | 0.0563 (7) | 0.0988 (6) | 0.425 (2) | 0.054 (3)* | 0.142 (6) |
C44A | 0.048 (3) | 0.0548 (19) | 0.328 (7) | 0.087 (16)* | 0.142 (6) |
H441 | 0.0267 | 0.0489 | 0.2566 | 0.130* | 0.142 (6) |
H442 | 0.0379 | 0.0311 | 0.3894 | 0.130* | 0.142 (6) |
H443 | 0.0732 | 0.0602 | 0.2830 | 0.130* | 0.142 (6) |
C15A | 0.13697 (14) | 0.17837 (13) | 0.5730 (5) | 0.025 (2)* | 0.101 (5) |
H15A | 0.1228 | 0.1843 | 0.4964 | 0.030* | 0.101 (5) |
C25A | 0.109 (3) | 0.1356 (7) | 0.634 (4) | 0.052 (4)* | 0.101 (5) |
H251 | 0.0818 | 0.1328 | 0.6527 | 0.062* | 0.101 (5) |
H252 | 0.1206 | 0.1337 | 0.7236 | 0.062* | 0.101 (5) |
C35A | 0.103 (2) | 0.0992 (9) | 0.543 (5) | 0.032 (8)* | 0.101 (5) |
H351 | 0.0854 | 0.0737 | 0.5956 | 0.038* | 0.101 (5) |
H352 | 0.1297 | 0.1014 | 0.5301 | 0.038* | 0.101 (5) |
S15A | 0.0800 (8) | 0.0926 (8) | 0.375 (3) | 0.054 (3)* | 0.101 (5) |
C45A | 0.081 (6) | 0.049 (4) | 0.310 (10) | 0.087 (16)* | 0.101 (5) |
H451 | 0.0679 | 0.0413 | 0.2190 | 0.130* | 0.101 (5) |
H452 | 0.0660 | 0.0256 | 0.3742 | 0.130* | 0.101 (5) |
H453 | 0.1095 | 0.0548 | 0.3026 | 0.130* | 0.101 (5) |
C16A | 0.13697 (14) | 0.17837 (13) | 0.5730 (5) | 0.025 (2)* | 0.051 (5) |
H16A | 0.1220 | 0.1834 | 0.4968 | 0.030* | 0.051 (5) |
C26A | 0.109 (5) | 0.1387 (17) | 0.652 (7) | 0.052 (4)* | 0.051 (5) |
H261 | 0.0822 | 0.1375 | 0.6692 | 0.062* | 0.051 (5) |
H262 | 0.1213 | 0.1398 | 0.7432 | 0.062* | 0.051 (5) |
C36A | 0.100 (2) | 0.0990 (8) | 0.58 (2) | 0.032 (8)* | 0.051 (5) |
H361 | 0.1178 | 0.0894 | 0.6210 | 0.038* | 0.051 (5) |
H362 | 0.1099 | 0.1064 | 0.4804 | 0.038* | 0.051 (5) |
S16A | 0.0490 (15) | 0.0564 (14) | 0.572 (6) | 0.054 (3)* | 0.051 (5) |
C5A | 0.1498 (2) | 0.2104 (2) | 0.6874 (9) | 0.0259 (19)* | |
C6A | 0.1336 (2) | 0.2509 (2) | 0.8409 (8) | 0.0259 (19)* | |
H61A | 0.1496 | 0.2447 | 0.9094 | 0.031* | |
C7A | 0.1607 (2) | 0.2958 (2) | 0.7940 (9) | 0.034 (2)* | |
H71A | 0.1851 | 0.2988 | 0.7466 | 0.051* | |
H72A | 0.1692 | 0.3139 | 0.8751 | 0.051* | |
H73A | 0.1452 | 0.3032 | 0.7306 | 0.051* | |
C8A | 0.0947 (2) | 0.2451 (2) | 0.9135 (9) | 0.0265 (19)* | |
O1B | 0.20914 (19) | 0.2428 (2) | 1.0720 (7) | 0.0514 (18) | |
O2B | 0.2107 (2) | 0.11874 (19) | 1.1726 (7) | 0.062 (2) | |
O3B | 0.18084 (17) | 0.12809 (16) | 1.3539 (6) | 0.0349 (14) | |
N1B | 0.25303 (18) | 0.28194 (18) | 0.8571 (7) | 0.0280 (16)* | |
H1B | 0.2730 | 0.2973 | 0.7947 | 0.042* | |
H2B | 0.2539 | 0.2982 | 0.9283 | 0.042* | |
H3B | 0.2281 | 0.2706 | 0.8152 | 0.042* | |
C1B | 0.25972 (18) | 0.2490 (2) | 0.9113 (8) | 0.0221 (18)* | |
H11B | 0.2581 | 0.2306 | 0.8340 | 0.027* | |
C2B | 0.3007 (2) | 0.2661 (2) | 0.9851 (8) | 0.035 (2)* | |
H21B | 0.3052 | 0.2431 | 1.0097 | 0.042* | |
H22B | 0.2995 | 0.2793 | 1.0723 | 0.042* | |
C3B | 0.3373 (2) | 0.2975 (2) | 0.8990 (9) | 0.043 (2)* | |
H31B | 0.3626 | 0.3056 | 0.9524 | 0.051* | |
H32B | 0.3347 | 0.3223 | 0.8882 | 0.051* | |
S1B | 0.34361 (7) | 0.28148 (8) | 0.7287 (3) | 0.0584 (8) | |
C4B | 0.3612 (3) | 0.2467 (3) | 0.7781 (14) | 0.087 (4) | |
H41B | 0.3657 | 0.2346 | 0.6949 | 0.130* | |
H42B | 0.3405 | 0.2249 | 0.8366 | 0.130* | |
H43B | 0.3870 | 0.2617 | 0.8296 | 0.130* | |
C5B | 0.2256 (2) | 0.2252 (2) | 1.0137 (9) | 0.032 (2)* | 0.609 (18) |
N2B | 0.21559 (18) | 0.18678 (18) | 1.0442 (7) | 0.0292 (16)* | 0.609 (18) |
H4B | 0.2250 | 0.1732 | 0.9970 | 0.035* | 0.609 (18) |
C6B | 0.1871 (4) | 0.1685 (4) | 1.1650 (14) | 0.025 (4)* | 0.609 (18) |
H61B | 0.1921 | 0.1900 | 1.2351 | 0.030* | 0.609 (18) |
C7B | 0.1423 (4) | 0.1484 (4) | 1.1077 (16) | 0.046 (5)* | 0.609 (18) |
H71B | 0.1376 | 0.1696 | 1.0679 | 0.069* | 0.609 (18) |
H72B | 0.1228 | 0.1345 | 1.1833 | 0.069* | 0.609 (18) |
H73B | 0.1384 | 0.1283 | 1.0361 | 0.069* | 0.609 (18) |
C8B | 0.1928 (2) | 0.1343 (2) | 1.2299 (9) | 0.031 (2)* | 0.609 (18) |
C52B | 0.2256 (2) | 0.2252 (2) | 1.0137 (9) | 0.032 (2)* | 0.391 (18) |
N22B | 0.21559 (18) | 0.18678 (18) | 1.0442 (7) | 0.0292 (16)* | 0.391 (18) |
H44B | 0.2330 | 0.1792 | 1.0155 | 0.035* | 0.391 (18) |
C62B | 0.1795 (4) | 0.1553 (5) | 1.119 (2) | 0.039 (7)* | 0.391 (18) |
H62B | 0.1640 | 0.1675 | 1.1628 | 0.047* | 0.391 (18) |
C72B | 0.1513 (7) | 0.1200 (6) | 1.016 (2) | 0.093 (13)* | 0.391 (18) |
H74B | 0.1419 | 0.1312 | 0.9421 | 0.139* | 0.391 (18) |
H75B | 0.1275 | 0.0987 | 1.0660 | 0.139* | 0.391 (18) |
H76B | 0.1669 | 0.1081 | 0.9753 | 0.139* | 0.391 (18) |
C82B | 0.1928 (2) | 0.1343 (2) | 1.2299 (9) | 0.031 (2)* | 0.391 (18) |
S1C | 0.11237 (7) | 0.33742 (7) | 0.4718 (3) | 0.0447 (7) | |
O1C | 0.20555 (16) | 0.25792 (15) | 0.4151 (6) | 0.0371 (15) | |
O2C | 0.31654 (18) | 0.39087 (16) | 0.5201 (6) | 0.0431 (16) | |
O3C | 0.30297 (16) | 0.34630 (15) | 0.6904 (6) | 0.0318 (14) | |
N1C | 0.15996 (17) | 0.26467 (17) | 0.2057 (6) | 0.0232 (15)* | |
H1C | 0.1453 | 0.2715 | 0.1473 | 0.035* | |
H2C | 0.1426 | 0.2451 | 0.2660 | 0.035* | |
H3C | 0.1737 | 0.2548 | 0.1558 | 0.035* | |
N2C | 0.25790 (17) | 0.32187 (18) | 0.3684 (7) | 0.0245 (16)* | |
H4C | 0.2655 | 0.3439 | 0.3176 | 0.029* | |
C1C | 0.1901 (2) | 0.3019 (2) | 0.2845 (8) | 0.0264 (19)* | |
H11C | 0.2057 | 0.3254 | 0.2198 | 0.032* | |
C2C | 0.1681 (2) | 0.3134 (2) | 0.3947 (9) | 0.031 (2)* | |
H21C | 0.1530 | 0.2898 | 0.4577 | 0.037* | |
H22C | 0.1890 | 0.3365 | 0.4504 | 0.037* | |
C3C | 0.1382 (2) | 0.3256 (3) | 0.3373 (9) | 0.037 (2)* | |
H31C | 0.1175 | 0.3030 | 0.2798 | 0.044* | |
H32C | 0.1533 | 0.3499 | 0.2769 | 0.044* | |
C4C | 0.0750 (3) | 0.2869 (3) | 0.5347 (10) | 0.048 (3) | |
H41C | 0.0591 | 0.2896 | 0.6100 | 0.072* | |
H42C | 0.0892 | 0.2728 | 0.5689 | 0.072* | |
H43C | 0.0565 | 0.2709 | 0.4590 | 0.072* | |
C5C | 0.2192 (2) | 0.2916 (2) | 0.3601 (8) | 0.0236 (19)* | |
C6C | 0.2888 (2) | 0.3204 (2) | 0.4581 (8) | 0.0240 (18)* | |
H61C | 0.2759 | 0.2934 | 0.5071 | 0.029* | |
C7C | 0.3241 (2) | 0.3246 (2) | 0.3712 (9) | 0.036 (2)* | |
H71C | 0.3139 | 0.3020 | 0.3046 | 0.053* | |
H72C | 0.3446 | 0.3238 | 0.4314 | 0.053* | |
H73C | 0.3366 | 0.3507 | 0.3213 | 0.053* | |
C8C | 0.3032 (2) | 0.3548 (2) | 0.5656 (10) | 0.0273 (19)* | |
S1D | 0.55988 (7) | 0.65229 (7) | −0.0389 (3) | 0.0414 (6) | |
O1D | 0.39930 (14) | 0.51352 (14) | 0.2271 (5) | 0.0233 (12) | |
O2D | 0.51081 (15) | 0.49066 (16) | 0.3427 (6) | 0.0301 (14) | |
O3D | 0.47308 (14) | 0.47098 (15) | 0.5357 (5) | 0.0251 (13) | |
N1D | 0.41305 (16) | 0.55734 (17) | 0.0054 (6) | 0.0194 (14)* | |
H1D | 0.4211 | 0.5752 | −0.0669 | 0.029* | |
H2D | 0.4061 | 0.5679 | 0.0784 | 0.029* | |
H3D | 0.3910 | 0.5330 | −0.0202 | 0.029* | |
N2D | 0.45478 (17) | 0.50522 (16) | 0.2125 (6) | 0.0198 (14)* | |
H4D | 0.4776 | 0.5113 | 0.1682 | 0.024* | |
C1D | 0.4474 (2) | 0.5506 (2) | 0.0464 (8) | 0.0173 (17)* | |
H11D | 0.4520 | 0.5359 | −0.0313 | 0.021* | |
C2D | 0.4879 (2) | 0.5908 (2) | 0.0717 (8) | 0.0244 (19)* | |
H21D | 0.4825 | 0.6098 | 0.1262 | 0.029* | |
H22D | 0.5067 | 0.5849 | 0.1260 | 0.029* | |
C3D | 0.5085 (2) | 0.6112 (2) | −0.0659 (8) | 0.0265 (19)* | |
H31D | 0.4923 | 0.6220 | −0.1117 | 0.032* | |
H32D | 0.5090 | 0.5905 | −0.1278 | 0.032* | |
C4D | 0.5736 (3) | 0.6661 (3) | −0.2178 (10) | 0.046 (3) | |
H41D | 0.6019 | 0.6890 | −0.2233 | 0.069* | |
H42D | 0.5550 | 0.6742 | −0.2591 | 0.069* | |
H43D | 0.5714 | 0.6424 | −0.2682 | 0.069* | |
C5D | 0.4322 (2) | 0.5217 (2) | 0.1710 (8) | 0.0164 (17)* | |
C6D | 0.4420 (2) | 0.4773 (2) | 0.3301 (8) | 0.0212 (18)* | |
H61D | 0.4263 | 0.4851 | 0.3949 | 0.025* | |
C7D | 0.4138 (2) | 0.4328 (2) | 0.2851 (9) | 0.029 (2)* | |
H71D | 0.3902 | 0.4307 | 0.2346 | 0.043* | |
H72D | 0.4041 | 0.4151 | 0.3670 | 0.043* | |
H73D | 0.4289 | 0.4241 | 0.2248 | 0.043* | |
C8D | 0.4791 (2) | 0.4807 (2) | 0.4093 (9) | 0.0239 (19)* | |
S1E | 0.44667 (7) | 0.37542 (7) | −0.0899 (3) | 0.0418 (6) | |
O1E | 0.37015 (15) | 0.47775 (15) | −0.0811 (6) | 0.0305 (14) | |
O2E | 0.25479 (19) | 0.34443 (16) | 0.0128 (6) | 0.0489 (17) | |
O3E | 0.27593 (15) | 0.38887 (15) | 0.1882 (6) | 0.0285 (13) | |
N1E | 0.41613 (17) | 0.47283 (17) | −0.2927 (7) | 0.0233 (15)* | |
H1E | 0.4301 | 0.4668 | −0.3565 | 0.035* | |
H2E | 0.4338 | 0.4894 | −0.2264 | 0.035* | |
H3E | 0.4042 | 0.4859 | −0.3349 | 0.035* | |
N2E | 0.31676 (17) | 0.41394 (17) | −0.1332 (7) | 0.0215 (15)* | |
H4E | 0.3088 | 0.3921 | −0.1856 | 0.026* | |
C1E | 0.3838 (2) | 0.4342 (2) | −0.2276 (8) | 0.0228 (18)* | |
H11E | 0.3674 | 0.4138 | −0.3009 | 0.027* | |
C2E | 0.4024 (2) | 0.4161 (2) | −0.1295 (8) | 0.0275 (19)* | |
H21E | 0.4203 | 0.4374 | −0.0621 | 0.033* | |
H22E | 0.3800 | 0.3934 | −0.0770 | 0.033* | |
C3E | 0.4274 (2) | 0.4001 (2) | −0.2015 (9) | 0.031 (2)* | |
H31E | 0.4509 | 0.4234 | −0.2485 | 0.037* | |
H32E | 0.4101 | 0.3804 | −0.2738 | 0.037* | |
C4E | 0.4879 (2) | 0.4189 (2) | −0.0025 (11) | 0.045 (3) | |
H41E | 0.5010 | 0.4093 | 0.0636 | 0.068* | |
H42E | 0.4769 | 0.4340 | 0.0471 | 0.068* | |
H43E | 0.5082 | 0.4370 | −0.0707 | 0.068* | |
C5E | 0.3560 (2) | 0.4443 (2) | −0.1410 (8) | 0.0215 (18)* | |
C6E | 0.2870 (2) | 0.4155 (2) | −0.0431 (8) | 0.0232 (18)* | |
H61E | 0.3005 | 0.4420 | 0.0088 | 0.028* | |
C7E | 0.2512 (2) | 0.4126 (2) | −0.1276 (9) | 0.037 (2)* | |
H71E | 0.2615 | 0.4359 | −0.1915 | 0.056* | |
H72E | 0.2311 | 0.4132 | −0.0649 | 0.056* | |
H73E | 0.2382 | 0.3870 | −0.1803 | 0.056* | |
C8E | 0.2716 (2) | 0.3797 (2) | 0.0612 (9) | 0.0259 (19)* | |
S1F | 0.22974 (6) | 0.44203 (7) | 0.2393 (3) | 0.0391 (6) | |
O1F | 0.36847 (15) | 0.49991 (15) | 0.5758 (6) | 0.0285 (13) | |
O2F | 0.36876 (15) | 0.59318 (15) | 0.6888 (5) | 0.0263 (13) | |
O3F | 0.42758 (15) | 0.60012 (15) | 0.7674 (5) | 0.0296 (14) | |
N1F | 0.32798 (17) | 0.45291 (17) | 0.3430 (6) | 0.0214 (15)* | |
H1F | 0.3085 | 0.4374 | 0.2793 | 0.032* | |
H2F | 0.3266 | 0.4369 | 0.4156 | 0.032* | |
H3F | 0.3533 | 0.4642 | 0.3034 | 0.032* | |
N2F | 0.37579 (16) | 0.55468 (16) | 0.4544 (6) | 0.0181 (14)* | |
H4F | 0.3659 | 0.5639 | 0.3901 | 0.022* | |
C1F | 0.3206 (2) | 0.4865 (2) | 0.3935 (8) | 0.0185 (17)* | |
H11F | 0.3188 | 0.5020 | 0.3124 | 0.022* | |
C2F | 0.2815 (2) | 0.4692 (2) | 0.4766 (8) | 0.028 (2)* | |
H21F | 0.2755 | 0.4916 | 0.4939 | 0.034* | |
H22F | 0.2865 | 0.4603 | 0.5676 | 0.034* | |
C3F | 0.2435 (2) | 0.4331 (2) | 0.4124 (9) | 0.029 (2)* | |
H31F | 0.2199 | 0.4256 | 0.4748 | 0.034* | |
H32F | 0.2479 | 0.4093 | 0.4078 | 0.034* | |
C4F | 0.2128 (3) | 0.4784 (3) | 0.2804 (12) | 0.056 (3) | |
H41F | 0.2046 | 0.4865 | 0.1952 | 0.084* | |
H42F | 0.2353 | 0.5027 | 0.3246 | 0.084* | |
H43F | 0.1893 | 0.4655 | 0.3437 | 0.084* | |
C5F | 0.3575 (2) | 0.5149 (2) | 0.4810 (8) | 0.0238 (19)* | |
C6F | 0.4126 (2) | 0.5834 (2) | 0.5327 (8) | 0.0233 (18)* | |
H61F | 0.4302 | 0.5707 | 0.5455 | 0.028* | |
C7F | 0.4369 (2) | 0.6232 (2) | 0.4517 (9) | 0.034 (2)* | |
H71F | 0.4444 | 0.6173 | 0.3610 | 0.051* | |
H72F | 0.4618 | 0.6419 | 0.5030 | 0.051* | |
H73F | 0.4200 | 0.6361 | 0.4390 | 0.051* | |
C8F | 0.4016 (2) | 0.5927 (2) | 0.6747 (8) | 0.0215 (18)* | |
S1G | 0.48922 (7) | 0.69230 (6) | 1.1627 (3) | 0.0366 (6) | |
O1G | 0.34698 (14) | 0.65748 (15) | 1.0745 (6) | 0.0250 (12) | |
O2G | 0.36663 (15) | 0.58233 (15) | 1.1957 (5) | 0.0272 (13) | |
O3G | 0.30482 (16) | 0.56694 (15) | 1.2755 (5) | 0.0303 (14) | |
N1G | 0.38671 (17) | 0.70903 (17) | 0.8385 (7) | 0.0225 (15)* | |
H1G | 0.4042 | 0.7231 | 0.7680 | 0.034* | |
H2G | 0.3899 | 0.7267 | 0.9078 | 0.034* | |
H3G | 0.3604 | 0.6966 | 0.8070 | 0.034* | |
N2G | 0.34686 (16) | 0.60675 (16) | 0.9478 (6) | 0.0172 (14)* | |
H4G | 0.3573 | 0.6006 | 0.8763 | 0.021* | |
C1G | 0.3961 (2) | 0.6773 (2) | 0.8922 (8) | 0.0190 (17)* | |
H11G | 0.4012 | 0.6634 | 0.8131 | 0.023* | |
C2G | 0.4341 (2) | 0.6986 (2) | 0.9830 (8) | 0.0258 (19)* | |
H21G | 0.4284 | 0.7120 | 1.0614 | 0.031* | |
H22G | 0.4568 | 0.7204 | 0.9283 | 0.031* | |
C3G | 0.4478 (2) | 0.6695 (2) | 1.0402 (9) | 0.032 (2)* | |
H31G | 0.4564 | 0.6586 | 0.9618 | 0.038* | |
H32G | 0.4240 | 0.6461 | 1.0852 | 0.038* | |
C4G | 0.5302 (3) | 0.7288 (3) | 1.0552 (13) | 0.059 (3) | |
H41G | 0.5552 | 0.7437 | 1.1107 | 0.089* | |
H42G | 0.5227 | 0.7483 | 1.0168 | 0.089* | |
H43G | 0.5350 | 0.7144 | 0.9795 | 0.089* | |
C5G | 0.3600 (2) | 0.6458 (2) | 0.9777 (8) | 0.0194 (17)* | |
C6G | 0.3152 (2) | 0.5736 (2) | 1.0320 (7) | 0.0185 (17)* | |
H61G | 0.2902 | 0.5764 | 1.0341 | 0.022* | |
C7G | 0.3041 (2) | 0.5319 (2) | 0.9698 (8) | 0.0269 (19)* | |
H71G | 0.2945 | 0.5303 | 0.8746 | 0.040* | |
H72G | 0.2824 | 0.5100 | 1.0252 | 0.040* | |
H73G | 0.3284 | 0.5287 | 0.9699 | 0.040* | |
C8G | 0.3302 (2) | 0.5750 (2) | 1.1805 (8) | 0.0208 (18)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1A | 0.030 (3) | 0.053 (4) | 0.036 (4) | 0.027 (3) | −0.013 (3) | −0.018 (3) |
O2A | 0.020 (3) | 0.091 (5) | 0.039 (4) | 0.024 (3) | −0.010 (3) | −0.027 (4) |
O3A | 0.024 (3) | 0.037 (3) | 0.025 (3) | 0.019 (3) | −0.003 (3) | −0.007 (3) |
O1B | 0.071 (5) | 0.081 (5) | 0.037 (4) | 0.063 (4) | 0.008 (4) | −0.008 (4) |
O2B | 0.081 (5) | 0.050 (4) | 0.072 (5) | 0.044 (4) | 0.043 (4) | 0.016 (4) |
O3B | 0.054 (4) | 0.033 (3) | 0.025 (3) | 0.028 (3) | 0.006 (3) | 0.005 (3) |
S1B | 0.0396 (14) | 0.0586 (17) | 0.070 (2) | 0.0191 (13) | 0.0136 (15) | 0.0148 (16) |
C4B | 0.066 (8) | 0.078 (8) | 0.125 (12) | 0.042 (7) | 0.026 (8) | 0.006 (9) |
S1C | 0.0449 (14) | 0.0439 (14) | 0.0554 (17) | 0.0298 (12) | 0.0001 (13) | −0.0101 (13) |
O1C | 0.029 (3) | 0.028 (3) | 0.046 (4) | 0.008 (3) | −0.010 (3) | 0.006 (3) |
O2C | 0.064 (4) | 0.029 (3) | 0.031 (4) | 0.019 (3) | −0.023 (3) | −0.009 (3) |
O3C | 0.045 (3) | 0.026 (3) | 0.023 (3) | 0.016 (3) | −0.002 (3) | 0.002 (3) |
C4C | 0.034 (5) | 0.068 (7) | 0.044 (6) | 0.027 (5) | 0.004 (5) | −0.004 (6) |
S1D | 0.0281 (12) | 0.0357 (13) | 0.0466 (15) | 0.0057 (11) | 0.0023 (12) | −0.0006 (12) |
O1D | 0.019 (3) | 0.028 (3) | 0.024 (3) | 0.013 (2) | 0.007 (3) | 0.003 (3) |
O2D | 0.022 (3) | 0.049 (4) | 0.028 (3) | 0.024 (3) | 0.006 (3) | 0.014 (3) |
O3D | 0.025 (3) | 0.033 (3) | 0.022 (3) | 0.018 (3) | 0.000 (3) | 0.005 (3) |
C4D | 0.036 (5) | 0.040 (5) | 0.056 (7) | 0.014 (4) | 0.013 (5) | 0.013 (5) |
S1E | 0.0378 (13) | 0.0390 (13) | 0.0541 (16) | 0.0233 (11) | 0.0053 (13) | 0.0156 (13) |
O1E | 0.028 (3) | 0.028 (3) | 0.033 (3) | 0.012 (3) | 0.005 (3) | −0.009 (3) |
O2E | 0.073 (4) | 0.022 (3) | 0.037 (4) | 0.013 (3) | 0.012 (4) | −0.003 (3) |
O3E | 0.033 (3) | 0.022 (3) | 0.026 (3) | 0.010 (3) | −0.005 (3) | −0.003 (3) |
C4E | 0.029 (5) | 0.042 (5) | 0.064 (7) | 0.017 (4) | 0.013 (5) | 0.024 (5) |
S1F | 0.0295 (12) | 0.0375 (13) | 0.0462 (16) | 0.0138 (10) | −0.0087 (12) | −0.0020 (12) |
O1F | 0.032 (3) | 0.029 (3) | 0.026 (3) | 0.016 (3) | −0.009 (3) | 0.002 (3) |
O2F | 0.029 (3) | 0.039 (3) | 0.020 (3) | 0.023 (3) | 0.000 (3) | −0.002 (3) |
O3F | 0.031 (3) | 0.029 (3) | 0.021 (3) | 0.009 (3) | −0.012 (3) | −0.002 (3) |
C4F | 0.038 (5) | 0.054 (6) | 0.081 (9) | 0.027 (5) | −0.009 (6) | 0.000 (6) |
S1G | 0.0356 (13) | 0.0321 (12) | 0.0436 (15) | 0.0181 (11) | −0.0097 (12) | −0.0013 (11) |
O1G | 0.025 (3) | 0.031 (3) | 0.022 (3) | 0.016 (2) | −0.002 (3) | −0.008 (3) |
O2G | 0.029 (3) | 0.028 (3) | 0.028 (3) | 0.016 (3) | −0.005 (3) | 0.000 (3) |
O3G | 0.033 (3) | 0.032 (3) | 0.022 (3) | 0.014 (3) | 0.004 (3) | −0.003 (3) |
C4G | 0.033 (5) | 0.035 (5) | 0.099 (9) | 0.008 (4) | −0.002 (6) | 0.022 (6) |
O1A—C5A | 1.237 (9) | C4C—H41C | 0.9800 |
O2A—C8A | 1.242 (9) | C4C—H42C | 0.9800 |
O3A—C8A | 1.252 (9) | C4C—H43C | 0.9800 |
N1A—C11A | 1.489 (7) | C6C—C7C | 1.511 (10) |
N2A—C5A | 1.333 (8) | C6C—C8C | 1.531 (11) |
N2A—C6A | 1.471 (9) | C6C—H61C | 1.0000 |
C11A—C21A | 1.5019 | C7C—H71C | 0.9800 |
C11A—C5A | 1.525 (9) | C7C—H72C | 0.9800 |
C21A—C31A | 1.544 (13) | C7C—H73C | 0.9800 |
C31A—S11A | 1.815 (12) | S1D—C3D | 1.790 (7) |
S11A—C41A | 1.803 (13) | S1D—C4D | 1.804 (10) |
C22A—C32A | 1.547 (14) | O1D—C5D | 1.240 (8) |
C32A—S12A | 1.806 (12) | O2D—C8D | 1.239 (8) |
S12A—C42A | 1.796 (14) | O3D—C8D | 1.262 (9) |
C23A—C33A | 1.56 (2) | N1D—C1D | 1.488 (8) |
C33A—S13A | 1.777 (18) | N2D—C5D | 1.342 (9) |
S13A—C43A | 1.78 (2) | N2D—C6D | 1.455 (9) |
C24A—C34A | 1.55 (2) | C1D—C5D | 1.529 (10) |
C34A—S14A | 1.796 (19) | C1D—C2D | 1.539 (9) |
S14A—C44A | 1.79 (2) | C2D—C3D | 1.537 (11) |
C25A—C35A | 1.54 (2) | C6D—C7D | 1.533 (10) |
C35A—S15A | 1.79 (2) | C6D—C8D | 1.540 (10) |
S15A—C45A | 1.78 (2) | S1E—C3E | 1.798 (8) |
C26A—C36A | 1.54 (2) | S1E—C4E | 1.806 (9) |
C36A—S16A | 1.79 (2) | O1E—C5E | 1.239 (8) |
C6A—C8A | 1.537 (11) | O2E—C8E | 1.243 (9) |
C6A—C7A | 1.541 (10) | O3E—C8E | 1.263 (9) |
O1B—C5B | 1.244 (9) | N1E—C1E | 1.489 (9) |
O2B—C8B | 1.221 (9) | N2E—C5E | 1.344 (9) |
O3B—C8B | 1.261 (10) | N2E—C6E | 1.442 (9) |
N1B—C1B | 1.480 (9) | C1E—C2E | 1.528 (10) |
C1B—C5B | 1.510 (10) | C1E—C5E | 1.529 (10) |
C1B—C2B | 1.519 (7) | C2E—C3E | 1.514 (10) |
C2B—C3B | 1.536 (10) | C6E—C7E | 1.533 (10) |
C3B—S1B | 1.808 (8) | C6E—C8E | 1.543 (10) |
S1B—C4B | 1.803 (10) | S1F—C4F | 1.820 (9) |
C5B—N2B | 1.334 (9) | S1F—C3F | 1.830 (8) |
N2B—C6B | 1.500 (11) | O1F—C5F | 1.249 (9) |
C6B—C8B | 1.542 (12) | O2F—C8F | 1.254 (8) |
C6B—C7B | 1.563 (18) | O3F—C8F | 1.250 (8) |
C62B—C72B | 1.57 (2) | N1F—C1F | 1.505 (8) |
S1C—C3C | 1.807 (9) | N2F—C5F | 1.324 (9) |
S1C—C4C | 1.815 (9) | N2F—C6F | 1.471 (9) |
O1C—C5C | 1.226 (8) | C1F—C2F | 1.508 (10) |
O2C—C8C | 1.269 (9) | C1F—C5F | 1.517 (10) |
O3C—C8C | 1.246 (10) | C2F—C3F | 1.529 (10) |
N1C—C1C | 1.497 (9) | C6F—C8F | 1.523 (11) |
N1C—H1C | 0.9100 | C6F—C7F | 1.525 (10) |
N1C—H2C | 0.9100 | S1G—C3G | 1.797 (8) |
N1C—H3C | 0.9100 | S1G—C4G | 1.797 (10) |
N2C—C5C | 1.330 (9) | O1G—C5G | 1.235 (8) |
N2C—C6C | 1.474 (9) | O2G—C8G | 1.266 (8) |
N2C—H4C | 0.8800 | O3G—C8G | 1.248 (9) |
C1C—C5C | 1.519 (10) | N1G—C1G | 1.497 (8) |
C1C—C2C | 1.538 (10) | N2G—C5G | 1.329 (8) |
C1C—H11C | 1.0000 | N2G—C6G | 1.467 (9) |
C2C—C3C | 1.517 (10) | C1G—C2G | 1.522 (10) |
C2C—H21C | 0.9900 | C1G—C5G | 1.522 (10) |
C2C—H22C | 0.9900 | C2G—C3G | 1.529 (10) |
C3C—H31C | 0.9900 | C6G—C8G | 1.532 (11) |
C3C—H32C | 0.9900 | C6G—C7G | 1.532 (9) |
C5A—N2A—C6A | 118.8 (6) | N2C—C6C—C8C | 108.6 (6) |
N1A—C11A—C21A | 105.6 (3) | C7C—C6C—C8C | 111.6 (6) |
N1A—C11A—C5A | 105.6 (5) | N2C—C6C—H61C | 108.9 |
C21A—C11A—C5A | 116.7 (3) | C7C—C6C—H61C | 108.9 |
C11A—C21A—C31A | 112.5 (6) | C8C—C6C—H61C | 108.9 |
C21A—C31A—S11A | 116.1 (10) | C6C—C7C—H71C | 109.5 |
C41A—S11A—C31A | 98.0 (9) | C6C—C7C—H72C | 109.5 |
C22A—C32A—S12A | 115.1 (12) | H71C—C7C—H72C | 109.5 |
C42A—S12A—C32A | 99.0 (10) | C6C—C7C—H73C | 109.5 |
C23A—C33A—S13A | 117.2 (17) | H71C—C7C—H73C | 109.5 |
C33A—S13A—C43A | 102.4 (15) | H72C—C7C—H73C | 109.5 |
C24A—C34A—S14A | 119 (2) | O3C—C8C—O2C | 123.9 (8) |
C44A—S14A—C34A | 101.4 (17) | O3C—C8C—C6C | 119.1 (7) |
C25A—C35A—S15A | 120 (2) | O2C—C8C—C6C | 116.9 (8) |
C45A—S15A—C35A | 102.5 (18) | C3D—S1D—C4D | 98.0 (4) |
C26A—C36A—S16A | 119 (2) | C5D—N2D—C6D | 120.7 (6) |
O1A—C5A—N2A | 123.6 (7) | N1D—C1D—C5D | 106.4 (5) |
O1A—C5A—C11A | 118.5 (6) | N1D—C1D—C2D | 113.3 (6) |
N2A—C5A—C11A | 117.8 (6) | C5D—C1D—C2D | 114.1 (6) |
N2A—C6A—C8A | 111.2 (6) | C3D—C2D—C1D | 111.0 (6) |
N2A—C6A—C7A | 111.3 (6) | C2D—C3D—S1D | 111.3 (5) |
C8A—C6A—C7A | 110.7 (6) | O1D—C5D—N2D | 122.6 (7) |
O2A—C8A—O3A | 126.9 (8) | O1D—C5D—C1D | 119.5 (6) |
O2A—C8A—C6A | 118.3 (8) | N2D—C5D—C1D | 117.8 (6) |
O3A—C8A—C6A | 114.7 (7) | N2D—C6D—C7D | 111.5 (6) |
N1B—C1B—C5B | 106.1 (6) | N2D—C6D—C8D | 111.7 (6) |
N1B—C1B—C2B | 111.9 (6) | C7D—C6D—C8D | 109.5 (6) |
C5B—C1B—C2B | 109.1 (6) | O2D—C8D—O3D | 126.5 (7) |
C1B—C2B—C3B | 113.7 (6) | O2D—C8D—C6D | 117.6 (7) |
C2B—C3B—S1B | 117.0 (5) | O3D—C8D—C6D | 115.7 (7) |
C4B—S1B—C3B | 99.2 (5) | C3E—S1E—C4E | 101.4 (4) |
O1B—C5B—N2B | 122.1 (8) | C5E—N2E—C6E | 123.0 (6) |
O1B—C5B—C1B | 119.0 (7) | N1E—C1E—C2E | 111.4 (6) |
N2B—C5B—C1B | 118.8 (7) | N1E—C1E—C5E | 108.4 (6) |
C5B—N2B—C6B | 114.8 (7) | C2E—C1E—C5E | 107.2 (6) |
N2B—C6B—C8B | 109.4 (7) | C3E—C2E—C1E | 114.0 (7) |
N2B—C6B—C7B | 107.3 (11) | C2E—C3E—S1E | 114.9 (6) |
C8B—C6B—C7B | 107.9 (10) | O1E—C5E—N2E | 124.7 (7) |
O2B—C8B—O3B | 125.1 (8) | O1E—C5E—C1E | 120.5 (6) |
O2B—C8B—C6B | 123.8 (9) | N2E—C5E—C1E | 114.7 (6) |
O3B—C8B—C6B | 110.7 (8) | N2E—C6E—C7E | 110.4 (6) |
C3C—S1C—C4C | 102.3 (4) | N2E—C6E—C8E | 108.7 (6) |
C1C—N1C—H1C | 109.5 | C7E—C6E—C8E | 110.6 (6) |
C1C—N1C—H2C | 109.5 | O2E—C8E—O3E | 125.8 (8) |
H1C—N1C—H2C | 109.5 | O2E—C8E—C6E | 117.0 (8) |
C1C—N1C—H3C | 109.5 | O3E—C8E—C6E | 117.1 (7) |
H1C—N1C—H3C | 109.5 | C4F—S1F—C3F | 100.1 (4) |
H2C—N1C—H3C | 109.5 | C5F—N2F—C6F | 119.8 (6) |
C5C—N2C—C6C | 123.4 (6) | N1F—C1F—C2F | 111.1 (6) |
C5C—N2C—H4C | 118.3 | N1F—C1F—C5F | 106.5 (5) |
C6C—N2C—H4C | 118.3 | C2F—C1F—C5F | 111.1 (6) |
N1C—C1C—C5C | 108.1 (6) | C1F—C2F—C3F | 116.5 (7) |
N1C—C1C—C2C | 110.7 (6) | C2F—C3F—S1F | 115.7 (5) |
C5C—C1C—C2C | 107.4 (6) | O1F—C5F—N2F | 123.4 (7) |
N1C—C1C—H11C | 110.2 | O1F—C5F—C1F | 118.9 (6) |
C5C—C1C—H11C | 110.2 | N2F—C5F—C1F | 117.6 (7) |
C2C—C1C—H11C | 110.2 | N2F—C6F—C8F | 111.6 (6) |
C3C—C2C—C1C | 114.7 (7) | N2F—C6F—C7F | 109.9 (6) |
C3C—C2C—H21C | 108.6 | C8F—C6F—C7F | 109.5 (6) |
C1C—C2C—H21C | 108.6 | O3F—C8F—O2F | 125.9 (7) |
C3C—C2C—H22C | 108.6 | O3F—C8F—C6F | 115.2 (6) |
C1C—C2C—H22C | 108.6 | O2F—C8F—C6F | 118.9 (7) |
H21C—C2C—H22C | 107.6 | C3G—S1G—C4G | 101.1 (5) |
C2C—C3C—S1C | 112.6 (6) | C5G—N2G—C6G | 121.1 (6) |
C2C—C3C—H31C | 109.1 | N1G—C1G—C2G | 108.3 (5) |
S1C—C3C—H31C | 109.1 | N1G—C1G—C5G | 109.6 (5) |
C2C—C3C—H32C | 109.1 | C2G—C1G—C5G | 109.6 (6) |
S1C—C3C—H32C | 109.1 | C1G—C2G—C3G | 113.4 (6) |
H31C—C3C—H32C | 107.8 | C2G—C3G—S1G | 114.8 (5) |
S1C—C4C—H41C | 109.5 | O1G—C5G—N2G | 124.3 (7) |
S1C—C4C—H42C | 109.5 | O1G—C5G—C1G | 119.5 (6) |
H41C—C4C—H42C | 109.5 | N2G—C5G—C1G | 116.0 (6) |
S1C—C4C—H43C | 109.5 | N2G—C6G—C8G | 111.2 (6) |
H41C—C4C—H43C | 109.5 | N2G—C6G—C7G | 110.1 (6) |
H42C—C4C—H43C | 109.5 | C8G—C6G—C7G | 108.0 (6) |
O1C—C5C—N2C | 124.9 (7) | O3G—C8G—O2G | 125.6 (7) |
O1C—C5C—C1C | 119.4 (7) | O3G—C8G—C6G | 117.2 (6) |
N2C—C5C—C1C | 115.6 (7) | O2G—C8G—C6G | 117.2 (7) |
N2C—C6C—C7C | 109.8 (6) | ||
N1A—C11A—C21A—C31A | 65.8 (16) | N1D—C1D—C5D—O1D | −9.4 (8) |
C5A—C11A—C21A—C31A | −51.2 (16) | C2D—C1D—C5D—O1D | 116.2 (7) |
C11A—C21A—C31A—S11A | −175.6 (16) | N1D—C1D—C5D—N2D | 168.5 (6) |
C21A—C31A—S11A—C41A | 154 (2) | C2D—C1D—C5D—N2D | −65.8 (8) |
C22A—C32A—S12A—C42A | 121 (5) | C5D—N2D—C6D—C7D | 88.7 (8) |
C23A—C33A—S13A—C43A | −162 (3) | C5D—N2D—C6D—C8D | −148.4 (6) |
C24A—C34A—S14A—C44A | 166 (4) | N2D—C6D—C8D—O2D | −29.5 (9) |
C25A—C35A—S15A—C45A | 178 (8) | C7D—C6D—C8D—O2D | 94.5 (8) |
C6A—N2A—C5A—O1A | −1.3 (10) | N2D—C6D—C8D—O3D | 153.6 (6) |
C6A—N2A—C5A—C11A | 175.5 (5) | C7D—C6D—C8D—O3D | −82.4 (8) |
N1A—C11A—C5A—O1A | −21.3 (8) | N1E—C1E—C2E—C3E | −67.8 (8) |
C21A—C11A—C5A—O1A | 95.6 (7) | C5E—C1E—C2E—C3E | 173.7 (6) |
N1A—C11A—C5A—N2A | 161.7 (5) | C1E—C2E—C3E—S1E | −175.9 (5) |
C21A—C11A—C5A—N2A | −81.3 (7) | C4E—S1E—C3E—C2E | −74.7 (7) |
C5A—N2A—C6A—C8A | −151.7 (6) | C6E—N2E—C5E—O1E | −5.8 (12) |
C5A—N2A—C6A—C7A | 84.4 (8) | C6E—N2E—C5E—C1E | 172.0 (6) |
N2A—C6A—C8A—O2A | −16.8 (10) | N1E—C1E—C5E—O1E | −33.5 (10) |
C7A—C6A—C8A—O2A | 107.4 (8) | C2E—C1E—C5E—O1E | 86.8 (8) |
N2A—C6A—C8A—O3A | 163.6 (6) | N1E—C1E—C5E—N2E | 148.5 (6) |
C7A—C6A—C8A—O3A | −72.2 (9) | C2E—C1E—C5E—N2E | −91.1 (8) |
N1B—C1B—C2B—C3B | −52.0 (9) | C5E—N2E—C6E—C7E | 120.1 (7) |
C5B—C1B—C2B—C3B | −169.0 (6) | C5E—N2E—C6E—C8E | −118.4 (7) |
C1B—C2B—C3B—S1B | −54.3 (9) | N2E—C6E—C8E—O2E | −59.7 (9) |
C2B—C3B—S1B—C4B | −72.8 (7) | C7E—C6E—C8E—O2E | 61.7 (9) |
N1B—C1B—C5B—O1B | −25.6 (9) | N2E—C6E—C8E—O3E | 122.7 (7) |
C2B—C1B—C5B—O1B | 95.1 (9) | C7E—C6E—C8E—O3E | −115.9 (8) |
N1B—C1B—C5B—N2B | 158.0 (7) | N1F—C1F—C2F—C3F | −48.5 (9) |
C2B—C1B—C5B—N2B | −81.4 (9) | C5F—C1F—C2F—C3F | −166.8 (6) |
O1B—C5B—N2B—C6B | −7.1 (13) | C1F—C2F—C3F—S1F | −55.6 (8) |
C1B—C5B—N2B—C6B | 169.2 (8) | C4F—S1F—C3F—C2F | −69.8 (6) |
C5B—N2B—C6B—C8B | −154.9 (9) | C6F—N2F—C5F—O1F | 4.2 (11) |
C5B—N2B—C6B—C7B | 88.2 (11) | C6F—N2F—C5F—C1F | −177.8 (6) |
N2B—C6B—C8B—O2B | −15.3 (16) | N1F—C1F—C5F—O1F | −51.8 (9) |
C7B—C6B—C8B—O2B | 101.3 (11) | C2F—C1F—C5F—O1F | 69.3 (8) |
N2B—C6B—C8B—O3B | 157.5 (9) | N1F—C1F—C5F—N2F | 130.1 (7) |
C7B—C6B—C8B—O3B | −86.0 (12) | C2F—C1F—C5F—N2F | −108.9 (8) |
N1C—C1C—C2C—C3C | −63.5 (9) | C5F—N2F—C6F—C8F | −79.7 (8) |
C5C—C1C—C2C—C3C | 178.7 (6) | C5F—N2F—C6F—C7F | 158.6 (7) |
C1C—C2C—C3C—S1C | 178.4 (5) | N2F—C6F—C8F—O3F | 148.8 (6) |
C4C—S1C—C3C—C2C | −76.0 (7) | C7F—C6F—C8F—O3F | −89.3 (8) |
C6C—N2C—C5C—O1C | −6.9 (12) | N2F—C6F—C8F—O2F | −32.5 (9) |
C6C—N2C—C5C—C1C | 168.5 (6) | C7F—C6F—C8F—O2F | 89.4 (8) |
N1C—C1C—C5C—O1C | −40.6 (10) | N1G—C1G—C2G—C3G | −177.8 (6) |
C2C—C1C—C5C—O1C | 78.9 (9) | C5G—C1G—C2G—C3G | 62.7 (8) |
N1C—C1C—C5C—N2C | 143.7 (7) | C1G—C2G—C3G—S1G | −173.6 (6) |
C2C—C1C—C5C—N2C | −96.8 (8) | C4G—S1G—C3G—C2G | −65.5 (7) |
C5C—N2C—C6C—C7C | 120.5 (8) | C6G—N2G—C5G—O1G | −0.9 (11) |
C5C—N2C—C6C—C8C | −117.2 (8) | C6G—N2G—C5G—C1G | 173.7 (6) |
N2C—C6C—C8C—O3C | 128.9 (7) | N1G—C1G—C5G—O1G | −54.2 (9) |
C7C—C6C—C8C—O3C | −110.0 (8) | C2G—C1G—C5G—O1G | 64.5 (8) |
N2C—C6C—C8C—O2C | −54.5 (9) | N1G—C1G—C5G—N2G | 131.0 (7) |
C7C—C6C—C8C—O2C | 66.7 (9) | C2G—C1G—C5G—N2G | −110.3 (7) |
N1D—C1D—C2D—C3D | −77.0 (8) | C5G—N2G—C6G—C8G | −63.6 (8) |
C5D—C1D—C2D—C3D | 161.1 (6) | C5G—N2G—C6G—C7G | 176.7 (6) |
C1D—C2D—C3D—S1D | −169.0 (5) | N2G—C6G—C8G—O3G | 141.2 (6) |
C4D—S1D—C3D—C2D | 177.5 (6) | C7G—C6G—C8G—O3G | −97.9 (7) |
C6D—N2D—C5D—O1D | −1.9 (10) | N2G—C6G—C8G—O2G | −41.9 (8) |
C6D—N2D—C5D—C1D | −179.8 (6) | C7G—C6G—C8G—O2G | 79.1 (8) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1A···O3Bi | 0.91 | 1.82 | 2.661 (8) | 153 |
N1A—H2A···O2Aii | 0.91 | 1.90 | 2.761 (8) | 158 |
N1A—H3A···O1C | 0.91 | 1.87 | 2.728 (8) | 156 |
N2A—H4A···O3Biii | 0.88 | 2.20 | 3.034 (7) | 159 |
N1B—H1B···O3C | 0.91 | 1.90 | 2.729 (8) | 150 |
N1B—H2B···O2Eiv | 0.91 | 1.91 | 2.765 (8) | 156 |
N1B—H3B···O1A | 0.91 | 1.88 | 2.685 (8) | 146 |
N2B—H4B···O3Aii | 0.88 | 2.08 | 2.932 (8) | 162 |
N1C—H1C···O3Ai | 0.91 | 1.89 | 2.742 (8) | 155 |
N1C—H2C···O2Biii | 0.91 | 1.83 | 2.675 (8) | 153 |
N1C—H3C···O1Bi | 0.91 | 1.80 | 2.702 (8) | 169 |
N2C—H4C···O3E | 0.88 | 1.98 | 2.853 (8) | 172 |
N1D—H1D···O3Fi | 0.91 | 1.81 | 2.702 (8) | 166 |
N1D—H2D···O2Gi | 0.91 | 2.14 | 2.994 (8) | 155 |
N1D—H3D···O1E | 0.91 | 1.91 | 2.729 (7) | 148 |
N2D—H4D···O3Dv | 0.88 | 2.07 | 2.943 (8) | 170 |
N1E—H1E···O3Di | 0.91 | 1.86 | 2.739 (8) | 161 |
N1E—H2E···O2Dv | 0.91 | 1.95 | 2.718 (8) | 141 |
N1E—H3E···O1Fi | 0.91 | 1.88 | 2.775 (8) | 166 |
N2E—H4E···O3Ci | 0.88 | 2.02 | 2.887 (8) | 168 |
N1F—H1F···O3E | 0.91 | 1.84 | 2.676 (8) | 152 |
N1F—H2F···O2C | 0.91 | 1.87 | 2.750 (8) | 161 |
N1F—H3F···O1D | 0.91 | 1.94 | 2.747 (7) | 146 |
N2F—H4F···O2Gi | 0.88 | 2.00 | 2.794 (8) | 150 |
N1G—H1G···O3Gvi | 0.91 | 1.80 | 2.693 (8) | 165 |
N1G—H2G···O2Fvii | 0.91 | 1.96 | 2.846 (8) | 165 |
N1G—H3G···O1Gviii | 0.91 | 1.88 | 2.741 (7) | 156 |
N2G—H4G···O2F | 0.88 | 1.92 | 2.761 (8) | 161 |
Symmetry codes: (i) x, y, z−1; (ii) y, −x+y, z−1/6; (iii) x−y, x, z−5/6; (iv) x, y, z+1; (v) −x+1, −y+1, z−1/2; (vi) −y+1, x−y+1, z−2/3; (vii) −y+1, x−y+1, z+1/3; (viii) −x+y, −x+1, z−1/3. |
Experimental details
Crystal data | |
Chemical formula | C8H16N2O3S |
Mr | 220.29 |
Crystal system, space group | Hexagonal, P61 |
Temperature (K) | 105 |
a, c (Å) | 37.6488 (15), 9.6613 (8) |
V (Å3) | 11859.6 (12) |
Z | 42 |
Radiation type | Mo Kα |
µ (mm−1) | 0.27 |
Crystal size (mm) | 0.80 × 0.18 × 0.15 |
Data collection | |
Diffractometer | Siemens SMART CCD area-detector diffractometer |
Absorption correction | Empirical (using intensity measurements) (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.789, 0.960 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 79465, 7460, 4308 |
Rint | 0.195 |
(sin θ/λ)max (Å−1) | 0.596 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.058, 0.145, 1.03 |
No. of reflections | 7460 |
No. of parameters | 633 |
No. of restraints | 93 |
H-atom treatment | H-atom parameters constrained |
w = 1/[σ2(Fo2) + (0.0446P)2 + 18.1456P] where P = (Fo2 + 2Fc2)/3 | |
Δρmax, Δρmin (e Å−3) | 0.48, −0.35 |
Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1998), SAINT, SHELXTL (Bruker, 2000), SHELXTL.
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1A···O3Bi | 0.91 | 1.82 | 2.661 (8) | 153 |
N1A—H2A···O2Aii | 0.91 | 1.90 | 2.761 (8) | 158 |
N1A—H3A···O1C | 0.91 | 1.87 | 2.728 (8) | 156 |
N2A—H4A···O3Biii | 0.88 | 2.20 | 3.034 (7) | 159 |
N1B—H1B···O3C | 0.91 | 1.90 | 2.729 (8) | 150 |
N1B—H2B···O2Eiv | 0.91 | 1.91 | 2.765 (8) | 156 |
N1B—H3B···O1A | 0.91 | 1.88 | 2.685 (8) | 146 |
N2B—H4B···O3Aii | 0.88 | 2.08 | 2.932 (8) | 162 |
N1C—H1C···O3Ai | 0.91 | 1.89 | 2.742 (8) | 155 |
N1C—H2C···O2Biii | 0.91 | 1.83 | 2.675 (8) | 153 |
N1C—H3C···O1Bi | 0.91 | 1.80 | 2.702 (8) | 169 |
N2C—H4C···O3E | 0.88 | 1.98 | 2.853 (8) | 172 |
N1D—H1D···O3Fi | 0.91 | 1.81 | 2.702 (8) | 166 |
N1D—H2D···O2Gi | 0.91 | 2.14 | 2.994 (8) | 155 |
N1D—H3D···O1E | 0.91 | 1.91 | 2.729 (7) | 148 |
N2D—H4D···O3Dv | 0.88 | 2.07 | 2.943 (8) | 170 |
N1E—H1E···O3Di | 0.91 | 1.86 | 2.739 (8) | 161 |
N1E—H2E···O2Dv | 0.91 | 1.95 | 2.718 (8) | 141 |
N1E—H3E···O1Fi | 0.91 | 1.88 | 2.775 (8) | 166 |
N2E—H4E···O3Ci | 0.88 | 2.02 | 2.887 (8) | 168 |
N1F—H1F···O3E | 0.91 | 1.84 | 2.676 (8) | 152 |
N1F—H2F···O2C | 0.91 | 1.87 | 2.750 (8) | 161 |
N1F—H3F···O1D | 0.91 | 1.94 | 2.747 (7) | 146 |
N2F—H4F···O2Gi | 0.88 | 2.00 | 2.794 (8) | 150 |
N1G—H1G···O3Gvi | 0.91 | 1.80 | 2.693 (8) | 165 |
N1G—H2G···O2Fvii | 0.91 | 1.96 | 2.846 (8) | 165 |
N1G—H3G···O1Gviii | 0.91 | 1.88 | 2.741 (7) | 156 |
N2G—H4G···O2F | 0.88 | 1.92 | 2.761 (8) | 161 |
Symmetry codes: (i) x, y, z−1; (ii) y, −x+y, z−1/6; (iii) x−y, x, z−5/6; (iv) x, y, z+1; (v) −x+1, −y+1, z−1/2; (vi) −y+1, x−y+1, z−2/3; (vii) −y+1, x−y+1, z+1/3; (viii) −x+y, −x+1, z−1/3. |
Molecule | N1-C1-C5-N2 | C1-C5-N2-C6 | C5-N2-C6-C8 | N2-C6-C8-O2 | N1-C1-C2-C3 | C1-C2-C3-S1 | C2-C3-S1-C4 | Occupancy |
(ψ1) | (ω1) | (ϕ2) | (ψT)(a) | (χ11) | (χ12) | (χ13) | ||
A1 | 161.7 (5) | 175.5 (5) | -151.7 (6) | -16.8 (10) | 65.8 (16) | -175.6 (16) | 154 (2) | 0.285 (9) |
A2 | 161.7 (5) | 175.5 (5) | -151.7 (6) | -16.8 (10) | 35 (6) | 162 (3) | 121 (5) | 0.190 (8) |
A3 | 161.7 (5) | 175.5 (5) | -151.7 (6) | -16.8 (10) | -83 (3) | -147 (3) | -162 (4) | 0.229 (7) |
A4 | 161.7 (5) | 175.5 (5) | -151.7 (6) | -16.8 (10) | -78 (4) | -50 (6) | 165 (4) | 0.142 (6) |
A5 | 161.7 (5) | 175.5 (5) | -151.7 (6) | -16.8 (10) | -49 (5) | -60 (6) | 154 (2) | 0.101 (5) |
A6 | 161.7 (5) | 175.5 (5) | -151.7 (6) | -16.8 (10) | -50 (14) | -135 (8) | (b) | 0.051 (5) |
B (major) | 158.0 (7) | 169.2 (8) | -154.9 (9) | -15.3 (16) | -52.0 (9) | -54.3 (9) | -72.8 (7) | 0.609 (18) |
B (minor) | 158.0 (7) | -167.8 (11) | -133.1 (11) | -59.0 (17) | -52.0 (9) | -54.3 (9) | -72.8 (7) | 0.391 (18) |
C | 143.7 (7) | 168.5 (6) | -117.2 (8) | -54.5 (9) | -63.5 (9) | 178.4 (5) | -76.0 (7) | 1.0 |
D | 168.5 (6) | -179.8 (6) | -148.4 (6) | -29.5 (9) | -77.0 (8) | -169.0 (5) | 177.5 (6) | 1.0 |
E | 148.5 (6) | 172.0 (6) | -118.4 (4) | -59.7 (9) | -67.8 (8) | -175.9 (5) | -74.7 (7) | 1.0 |
F | 130.1 (7) | -177.8 (6) | -79.7 (8) | -32.5 (9) | -48.5 (9) | -55.6 (8) | -69.8 (6) | 1.0 |
G | 131.0 (7) | 173.7 (6) | -63.6 (8) | -41.9 (8) | -177.8 (6) | -173.6 (6) | -65.5 (7) | 1.0 |
(a) Measured to the O atom giving the smallest positive or negative value. (b) C atom not located. |
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The crystal structure of L-Val-L-Ala (VA; Görbitz & Gundersen, 1996) comprised the first example of nanotube formation by such a small molecule. Subsequently, the retroanalogue L-Ala-L-Val (Görbitz, 2002a), as well as a series of other dipeptides with L-Ala, L-Val and L-Ile residues (Görbitz, 2003), have been found to form structures very similar to VA, differing only in the way the side chains partly fill the channels along the hexagonal axes, which translates directly to pore size.
To investigate whether crystallization in the VA class is compatible with dipeptides incorporating unbranched side chains (apart from the methyl group of L-Ala), crystallization and structure determination have been carried out for the title compound, L-Met-L-Ala, hereinafter MA. \sch
Compound MA was crystallized for the first time in our laboratory in 1996 using 2-propanol as the precipitating agent. High initial solute concentrations led to the formation of ultrathin plates that were, after several attempts, found to be the 1:2 2-propanol solvate (Görbitz, 2000), while bundles of very thin needles appeared when low concentrations were used (0.16–0.32 mg of peptide in 30 µl of water). At the time, we had a traditional diffractometer with a scintillation counter that was able to detect only a few hundred reflections for one of these crystals. It was not possible to solve the structure from this experimental material, but the apparent cell dimensions [P61, a = 14.261 (7) and c = 9.715 (5) Å] indicated that the MA structure was very similar to that of VA [a = 14.424 (4) and c = 9.996 (6) Å; Görbitz & Gundersen, 1996]. Later, it was found that larger needles could be grown with acetonitrile rather than 2-propanol as the precipitating agent, and when data were collected using a CCD detector it immediately became evident that the MA unit cell was in fact much larger, with Z' = 7, and that the first data collection had provided a sub-cell of the true crystal lattice.
Structures with Z'= 7 are extremely uncommon; the C-terminal dipeptide fragment (Boc-L-Phe-L-Leu-OBzl) of enkephalin, in space group P21 (Antolić et al., 1999), is the only example in the Cambridge Structural Database [CSD, Version 5.24; Allen, 2002]. There is also just a single observation of Z = 42 (acoradiene in space group R3, Z' = 2.33; Chen & Lin, 1993), while about 25 organic molecules, all achiral, have Z > 42 (Z' 0.5–16). Statistical data for Z' values have been provided by Kumar et al. (2000).
The seven independent peptide molecules in the crystal structure of MA are shown in Fig. 1. Bond lengths and angles are normal. Torsion angles are listed in Table 1. The peptide main chain is observed in three different conformations: extended (molecules A, B and D), semi-extended (molecules C and E) and S-shaped (molecules F and G). Structures in the VA class all have extended conformations, with ψ1 in the range 151–171° and ϕ2 in the range −129 – −154° (Görbitz, 2003).
An understanding of the side-chain conformations in MA can be gained by considering the crystal-packing arrangement shown in Fig. 2. Compared with the VA class, the lengths of the a and b axes are more than doubled [from approximately 14.2 to 37.6488 (15) Å], which makes room for the increase from Z' = 1 to Z' = 7. In the process, two different types of hydrophobic columns are created.
Column 1 and its surroundings on the hexagonal axis closely mimic the structures of the VA class. The side chains in these structures are unable to fill the central cavity, leaving a conspicuous empty (or solvent-filled) channel or nanotube of varying diameter (Görbitz & Gundersen, 1996; Görbitz, 2002a, 2003). The long L-Met side chains of molecule A, however, can fill these channels more or less completely, but not in a very straightforward manner, since selection of any one L-Met conformation leads to serious intermolecular steric conflict between adjacent molecules related by the 61 screw axis. Accordingly, the side chain is heavily disordered. The refinement of the structure applied six different orientations, A1—A6 (Table 1), which can conveniently be divided into two groups, namely A1 and A2 with χ11 = gauche+, and A3—A6 with χ11 = gauche-.
The rare gauche+/trans/trans A1 conformation, observed only once before in peptides (for D,L-Ala-L,D-Met; Guillot et al., 2001), is exceptional, in that it does not create side-chain-side-chain conflict when introduced in adjacent molecule-A positions. Instead, atom C41A comes close to the C7B methyl group of one (but not both) of the two neighbouring B molecules. This forces a disorder for molecule B, with two alternative L-Ala methyl positions (Fig. 1). Each molecule A in conformation A1 must be flanked by one B molecule in the major orientation and one in the minor orientation. It follows that adjacent A1 conformations are prohibited.
Conformation A2 is essentially the same as A1, but the torsion angles are shifted to more awkward values (Table 1), which serves to eliminate the conflict with atom C7B, at the expense of reintroducing side-chain conflict with neighbouring molecules in conformations A1 and A2. The result of this analysis is that two neighbouring A molecules must always have side-chain orientations from different groups [(A1, A2) or (A3—A6)] in order to avoid steric conflict. The sum of the occupancies for A1 and A2 should thus ideally be 1/2, the same as for A3—A6. This is in close agreement with the refinement results (Table 1; sum of all occupancies constrained to 1.00).
Column 2 has no crystallographic symmetry, but the peptide backbones are related by pseudo-sixfold screw symmetry. The column is generated from an intricate close-packing of L-Met side chains from molecules B, C, D, E, F and G, together with minor contributions from the L-Ala side chains of molecules A, C, D, E, F and G (the L-Ala side chain of molecule B is part of column 1).
It is noteworthy that, in three previous structures of peptides with N-terminal L-Met residues [L-Met-L-Met (Stenkamp & Jensen, 1975), L-Met-L-Glu-L-His-L-Phe hydrate (Admiraal & Vos, 1983) and L-Met-L-Ala 2-propanol solvate (Z' = 2; Görbitz, 2000)], both χ11 and χ12 torsion angles were trans. The MA conformations represent a clear departure from this pattern. Overall, molecules C and E are very similar, while the other molecules differ in either their side-chain or their main-chain conformations.
The hydrogen-bond geometry for MA is listed in Table 2. The hydrogen bonding in the MA crystal structure closely follows the pattern of the VA class, including the left-handed dipeptide double helix described previously (Görbitz & Gundersen, 1996; Görbitz, 2002b, 2003). In the VA class, this motif involves molecules related by threefold screw symmetry, as seen for G molecules in the MA structure (G, G* and G# in Fig. 2). Pseudo-threefold screw symmetry, which is very accurate if the side chains are disregarded, relates molecules A + B + C and D + E + F in exactly the same manner.