Buy article online - an online subscription or single-article purchase is required to access this article.
X-ray diffraction data up to d = 0.50 Å resolution have been collected at 100 K for a DL-alanyl-methionine single crystal using a CCD area detector. Multipolar crystallographic refinement was carried out and the electron density of the molecule has been analyzed. The deformation electron density around the S atom reveals two lone pairs with an sp3 hybridization and agrees with the results of density functional theory calculations. The topological properties of the covalent bonds and of the hydrogen bonds have been investigated. Two weak polar intramolecular interactions of the type C5 (pentagonal cyclic structure) have unfavorable geometrical parameters for hydrogen bonds and are devoid of critical points. The two electron lone pairs of the carbonyl oxygen appear asymmetric in the experimental deformation density. This could be attributed to the different strength of the hydrogen bond and intramolecular polar interaction involving the carbonyl oxygen. In the ab-initio-derived deformation maps, the asymmetry of the electron doublets is reproduced only very partially.
Supporting information
CCDC reference: 170353
Data collection: COLLECT software (Nonius ,1998); cell refinement: DENZO, SCALEPACK Otwinowski & Minor,(1997); data reduction: SORTAV Blessing; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
Δ,
L-Alanyl-
L,
D-methionine
top
Crystal data top
C8H16N2O3S | F(000) = 472 |
Mr = 220.29 | Dx = 1.390 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71070 Å |
a = 13.089 (2) Å | Cell parameters from 159 reflections |
b = 5.329 (1) Å | θ = 3.0–19.0° |
c = 15.921 (6) Å | µ = 0.29 mm−1 |
β = 108.57 (2)° | T = 100 K |
V = 1052.7 (3) Å3 | Irregular, colourless |
Z = 4 | 0.52 × 0.49 × 0.29 mm |
Data collection top
Nonius Kappa-CCD diffractometer | 8736 independent reflections |
Radiation source: fine-focus sealed tube | 6979 reflections with > σ(I) |
Graphite monochromator | Rint = 0.049 |
oscillation scans | θmax = 45.2°, θmin = 3.6° |
Absorption correction: empirical (using intensity measurements) SORTAV Blessing (1997) | h = −26→26 |
Tmin = 0.854, Tmax = 0.871 | k = −10→10 |
100180 measured reflections | l = −31→31 |
Refinement top
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)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.025 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.52 | w = 1/[σ2(Fo2) + (0.0605P)2] where P = (Fo2 + 2Fc2)/3 |
7619 reflections | (Δ/σ)max = 0.001 |
191 parameters | Δρmax = 0.63 e Å−3 |
0 restraints | Δρmin = −0.49 e Å−3 |
Crystal data top
C8H16N2O3S | V = 1052.7 (3) Å3 |
Mr = 220.29 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 13.089 (2) Å | µ = 0.29 mm−1 |
b = 5.329 (1) Å | T = 100 K |
c = 15.921 (6) Å | 0.52 × 0.49 × 0.29 mm |
β = 108.57 (2)° | |
Data collection top
Nonius Kappa-CCD diffractometer | 8736 independent reflections |
Absorption correction: empirical (using intensity measurements) SORTAV Blessing (1997) | 6979 reflections with > σ(I) |
Tmin = 0.854, Tmax = 0.871 | Rint = 0.049 |
100180 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.025 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.52 | Δρmax = 0.63 e Å−3 |
7619 reflections | Δρmin = −0.49 e Å−3 |
191 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.427362 (10) | 0.05001 (2) | 0.613740 (8) | 0.01083 (8) | |
H11 | 0.4128 | 0.2361 | 0.5964 | 0.016* | |
H12 | 0.4160 | −0.0487 | 0.5557 | 0.016* | |
H13 | 0.5065 | 0.0237 | 0.6526 | 0.016* | |
C1A | 0.354002 (10) | −0.04696 (2) | 0.660310 (8) | 0.01073 (9) | |
H1A | 0.3749 | −0.2444 | 0.6765 | 0.050* | |
C1B | 0.237652 (10) | −0.02747 (2) | 0.599510 (8) | 0.01692 (11) | |
H1B1 | 0.2262 | −0.1457 | 0.5439 | 0.050* | |
H1B2 | 0.2215 | 0.1611 | 0.5789 | 0.050* | |
H1B3 | 0.1840 | −0.0848 | 0.6334 | 0.050* | |
C1 | 0.367822 (10) | 0.10629 (2) | 0.744040 (8) | 0.01047 (9) | |
O1 | 0.390342 (10) | 0.33249 (2) | 0.747420 (8) | 0.01411 (8) | |
N2 | 0.347542 (10) | −0.02002 (2) | 0.809530 (8) | 0.01167 (8) | |
H2 | 0.3353 | −0.1781 | 0.8030 | 0.014* | |
C2A | 0.345292 (10) | 0.09803 (2) | 0.891330 (8) | 0.01044 (9) | |
H2A | 0.4068 | 0.2459 | 0.9098 | 0.050* | |
C2B | 0.235272 (10) | 0.21813 (2) | 0.880880 (8) | 0.01286 (9) | |
H2B1 | 0.2143 | 0.3435 | 0.8238 | 0.050* | |
H2B2 | 0.2424 | 0.3335 | 0.9391 | 0.050* | |
C2G | 0.145782 (10) | 0.02659 (2) | 0.869940 (8) | 0.01637 (11) | |
H2G1 | 0.1338 | −0.0901 | 0.8113 | 0.050* | |
H2G2 | 0.1672 | −0.0979 | 0.9273 | 0.050* | |
S2D | 0.020882 (10) | 0.18454 (2) | 0.861990 (8) | 0.02164 (5) | |
C2E | −0.059588 (10) | −0.08541 (2) | 0.866730 (8) | 0.02542 (15) | |
H2E1 | −0.1421 | −0.0242 | 0.8565 | 0.050* | |
H2E2 | −0.0302 | −0.1713 | 0.9322 | 0.050* | |
H2E3 | −0.0558 | −0.2170 | 0.8155 | 0.050* | |
C2 | 0.375272 (10) | −0.09560 (2) | 0.966500 (8) | 0.01006 (8) | |
O2 | 0.382592 (10) | −0.01904 (2) | 1.042860 (8) | 0.01454 (9) | |
O22 | 0.388922 (10) | −0.31918 (2) | 0.947440 (8) | 0.01328 (8) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.01297 (18) | 0.01095 (18) | 0.01017 (17) | −0.00029 (14) | 0.00594 (14) | −0.00051 (13) |
C1A | 0.0135 (2) | 0.0111 (2) | 0.00888 (18) | −0.00085 (16) | 0.00538 (16) | −0.00062 (14) |
C1B | 0.0130 (2) | 0.0251 (3) | 0.0128 (2) | −0.0022 (2) | 0.00434 (18) | −0.0040 (2) |
C1 | 0.0130 (2) | 0.01081 (19) | 0.00827 (18) | −0.00053 (16) | 0.00431 (15) | −0.00006 (14) |
O1 | 0.0213 (2) | 0.01106 (17) | 0.01112 (16) | −0.00305 (15) | 0.00673 (15) | −0.00079 (12) |
N2 | 0.0174 (2) | 0.01053 (18) | 0.00872 (16) | −0.00101 (15) | 0.00649 (15) | −0.00028 (13) |
C2A | 0.0134 (2) | 0.01043 (19) | 0.00846 (18) | −0.00061 (16) | 0.00490 (15) | −0.00019 (14) |
C2B | 0.0144 (2) | 0.0123 (2) | 0.0126 (2) | 0.00086 (17) | 0.00529 (17) | 0.00029 (16) |
C2G | 0.0135 (2) | 0.0150 (2) | 0.0207 (3) | 0.00043 (18) | 0.0055 (2) | 0.00102 (19) |
S2D | 0.01546 (8) | 0.01934 (9) | 0.03244 (11) | 0.00232 (5) | 0.01090 (7) | 0.00346 (6) |
C2E | 0.0180 (3) | 0.0268 (4) | 0.0327 (4) | −0.0038 (3) | 0.0099 (3) | 0.0023 (3) |
C2 | 0.0121 (2) | 0.00999 (19) | 0.00883 (17) | −0.00114 (15) | 0.00429 (15) | 0.00003 (14) |
O2 | 0.0235 (2) | 0.01206 (17) | 0.00885 (16) | −0.00114 (15) | 0.00631 (15) | −0.00081 (12) |
O22 | 0.0195 (2) | 0.00950 (16) | 0.01211 (17) | 0.00044 (14) | 0.00678 (15) | −0.00015 (12) |
Geometric parameters (Å, º) top
N1—C1A | 1.4807 (5) | C2A—C2B | 1.5363 (5) |
C1A—C1 | 1.5260 (5) | C2B—C2G | 1.5211 (5) |
C1A—C1B | 1.5260 (5) | C2G—S2D | 1.8086 (6) |
C1—O1 | 1.2402 (5) | S2D—C2E | 1.8017 (6) |
C1—N2 | 1.3381 (5) | C2—O2 | 1.2567 (5) |
N2—C2A | 1.4556 (5) | C2—O22 | 1.2580 (5) |
C2A—C2 | 1.5348 (5) | | |
| | | |
N1—C1A—C1 | 109.57 (4) | N2—C2A—C2B | 111.7 (4) |
N1—C1A—C1B | 109.53 (4) | C2—C2A—C2B | 111.35 (4) |
C1—C1A—C1B | 109.54 (4) | C2G—C2B—C2A | 113.11 (4) |
O1—C1—N2 | 124.12 (4) | C2B—C2G—S2D | 109.93 (4) |
O1—C1—C1A | 121.37 (4) | C2E—S2D—C2G | 98.75 (4) |
N2—C1—C1A | 114.39 (4) | O2—C2—O22 | 124.63 (4) |
C1—N2—C2A | 123.02 (4) | O2—C2—C2A | 117.16 (4) |
N2—C2A—C2 | 109.39 (4) | O22—C2—C2A | 118.20 (4) |
Experimental details
Crystal data |
Chemical formula | C8H16N2O3S |
Mr | 220.29 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 100 |
a, b, c (Å) | 13.089 (2), 5.329 (1), 15.921 (6) |
β (°) | 108.57 (2) |
V (Å3) | 1052.7 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.29 |
Crystal size (mm) | 0.52 × 0.49 × 0.29 |
|
Data collection |
Diffractometer | Nonius Kappa-CCD diffractometer |
Absorption correction | Empirical (using intensity measurements) SORTAV Blessing (1997) |
Tmin, Tmax | 0.854, 0.871 |
No. of measured, independent and observed [ > σ(I)] reflections | 100180, 8736, 6979 |
Rint | 0.049 |
(sin θ/λ)max (Å−1) | 0.999 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.025, 1.52 |
No. of reflections | 7619 |
No. of parameters | 191 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.63, −0.49 |
Selected bond lengths (Å) topN1—C1A | 1.4807 (5) | C2A—C2B | 1.5363 (5) |
C1A—C1 | 1.5260 (5) | C2B—C2G | 1.5211 (5) |
C1A—C1B | 1.5260 (5) | C2G—S2D | 1.8086 (6) |
C1—O1 | 1.2402 (5) | S2D—C2E | 1.8017 (6) |
C1—N2 | 1.3381 (5) | C2—O2 | 1.2567 (5) |
N2—C2A | 1.4556 (5) | C2—O22 | 1.2580 (5) |
C2A—C2 | 1.5348 (5) | | |
Subscribe to Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
The full text of this article is available to subscribers to the journal.
If you have already registered and are using a computer listed in your registration details, please email
support@iucr.org for assistance.