Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106022827/dn3018sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270106022827/dn3018Isup2.hkl |
CCDC reference: 618629
The title compound was synthesized by dropwise addition of a diethyl ether solution of cloroacetyl chloride (0.11 mol in 23 ml) and aqueous 1 M sodium hydroxide (0.1 mol) over a water solution of 6-aminohexanoic acid (0.1 mol in 25 ml) and NaOH (0.1 mol). The reaction mixture was maintained at a temperature of 273 K for 2 h. The pH was kept close to 11–12 by gradual addition of aqueous 1 M sodium hydroxide to neutralize the hydrochloric acid produced during the condensation. After 16 h of stirring at room temperature, the solution was acidified with 1 M HCl to pH 1.5. A white solid was filtered off and recrystallized from water to give colourless prismatic crystals (yield 85%, m.p. 359 K). 1H NMR (TFA/CDCl3, TMS, internal reference): δ 8.40 (b, 1H, COOH), 6.66 (b, 1H, NH), 4.06 (s, 2H, ClCH2CO), 3.32 (q, 2H, NHCH2), 2.36 (t, 2H, CH2COOH), 1.65 (m, 4H, NHCH2CH2 + CH2CH2COOH), 1.41 (m, 2H, NHCH2CH2CH2) p.p.m. IR (KBr): 3331 (amide A), 2946 and 2864 (CH2), 1697 (C═O), 1647 (amide I), 1543 (amide II), 1262 (C—O) cm−1.
All H atoms were placed in calculated positions. H atoms bonded to C atoms and amide H atoms were treated as riding, with C—H distances of 0.97 Å, H—N distances of 0.86 Å and Uiso(H) = 1.2Ueq(C,N). Acid H atoms were refined as rotating atoms with H—O distances of 0.82 Å and Uiso(H) = 1.5Ueq(O).
Data collection: CAD-4 Software (Kiers, 1994); cell refinement: CAD-4 Software (Kiers, 1994); data reduction: WinGX-PC (Version 1.64.05; Farrugia, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and WinGX-PC.
C8H14ClNO3 | F(000) = 880 |
Mr = 207.65 | Dx = 1.360 Mg m−3 |
Monoclinic, Cc | Melting point: 359 K |
Hall symbol: C -2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 29.149 (4) Å | Cell parameters from 25 reflections |
b = 5.139 (4) Å | θ = 12–21° |
c = 14.498 (4) Å | µ = 0.35 mm−1 |
β = 110.90 (2)° | T = 293 K |
V = 2028.9 (17) Å3 | Prism, colourless |
Z = 8 | 0.42 × 0.18 × 0.10 mm |
Enraf–Nonius CAD-4 diffractometer | Rint = 0.000 |
Radiation source: fine-focus sealed tube | θmax = 30.0°, θmin = 2.8° |
Graphite monochromator | h = −40→38 |
ω/2θ scans | k = 0→7 |
3057 measured reflections | l = 0→20 |
3057 independent reflections | 1 standard reflections every 120 min |
2118 reflections with I > 2σ(I) | intensity decay: 1% |
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)] = 0.048 | H-atom parameters constrained |
wR(F2) = 0.132 | w = 1/[σ2(Fo2) + (0.072P)2 + 0.2711P] where P = (Fo2 + 2Fc2)/3 |
S = 1.06 | (Δ/σ)max < 0.001 |
3057 reflections | Δρmax = 0.36 e Å−3 |
237 parameters | Δρmin = −0.25 e Å−3 |
2 restraints | Absolute structure: Flack (1983), 97 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.05 (9) |
C8H14ClNO3 | V = 2028.9 (17) Å3 |
Mr = 207.65 | Z = 8 |
Monoclinic, Cc | Mo Kα radiation |
a = 29.149 (4) Å | µ = 0.35 mm−1 |
b = 5.139 (4) Å | T = 293 K |
c = 14.498 (4) Å | 0.42 × 0.18 × 0.10 mm |
β = 110.90 (2)° |
Enraf–Nonius CAD-4 diffractometer | Rint = 0.000 |
3057 measured reflections | 1 standard reflections every 120 min |
3057 independent reflections | intensity decay: 1% |
2118 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.048 | H-atom parameters constrained |
wR(F2) = 0.132 | Δρmax = 0.36 e Å−3 |
S = 1.06 | Δρmin = −0.25 e Å−3 |
3057 reflections | Absolute structure: Flack (1983), 97 Friedel pairs |
237 parameters | Absolute structure parameter: 0.05 (9) |
2 restraints |
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. Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) 24.7343 (0.0491) x − 2.6500 (0.0134) y − 5.9942 (0.0370) z = 7.8970 (0.0372) * 0.0011 (0.0015) O2B * −0.0030 (0.0041) C8B * 0.0010 (0.0014) O3B * 0.0009 (0.0012) C7B Rms deviation of fitted atoms = 0.0017 − 3.6578 (0.0485) x + 0.3762 (0.0117) y + 14.0494 (0.0130) z = 1.3198 (0.0257) Angle to previous plane (with approximate e.s.d.) = 74.84 (1/5) * 0.0036 (0.0029) N1B * 0.0078 (0.0033) C2B * −0.0013 (0.0011) O1B * −0.0055 (0.0022) C1B * −0.0046 (0.0024) C3B Rms deviation of fitted atoms = 0.0051 25.1878 (0.0478) x − 2.5272 (0.0135) y − 5.9209 (0.0381) z = 2.7493 (0.0111) Angle to previous plane (with approximate e.s.d.) = 75.49 (1/5) * 0.0003 (0.0016) O2A * −0.0008 (0.0041) C8A * 0.0003 (0.0014) O3A * 0.0002 (0.0012) C7A Rms deviation of fitted atoms = 0.0005 − 3.2890 (0.0545) x − 0.5862 (0.0111) y + 13.9522 (0.0139) z = 4.4854 (0.0125) Angle to previous plane (with approximate e.s.d.) = 81.54 (1/5) * −0.0119 (0.0029) N1A * −0.0009 (0.0031) C2A * −0.0024 (0.0012) O1A * 0.0063 (0.0019) C1A * 0.0089 (0.0022) C3A Rms deviation of fitted atoms = 0.0073 25.1837 (0.0288) x − 2.5528 (0.0071) y − 5.5853 (0.0134) z = 8.4557 (0.0143) Angle to previous plane (with approximate e.s.d.) = 82.98 (0.13) * 0.0549 (0.0037) O2B * 0.0119 (0.0041) C8B * 0.0268 (0.0037) O3B * −0.0468 (0.0036) C7B * −0.0136 (0.0038) O2A_$1 * −0.0138 (0.0041) C8A_$1 * −0.0392 (0.0039) O3A_$1 * 0.0198 (0.0038) C7A_$1 Rms deviation of fitted atoms = 0.0323 |
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 | ||
Cl1A | 0.38325 (4) | 0.1348 (2) | 0.41502 (7) | 0.0604 (3) | |
C1A | 0.35546 (15) | 0.4359 (7) | 0.4240 (3) | 0.0525 (9) | |
H11A | 0.3733 | 0.5100 | 0.4884 | 0.063* | |
H12A | 0.3595 | 0.5532 | 0.3750 | 0.063* | |
C2A | 0.30173 (13) | 0.4286 (6) | 0.4106 (3) | 0.0423 (8) | |
O1A | 0.28301 (13) | 0.6419 (5) | 0.4150 (3) | 0.0626 (9) | |
N1A | 0.27822 (11) | 0.2029 (5) | 0.3947 (2) | 0.0410 (7) | |
H1A | 0.2942 | 0.0649 | 0.3912 | 0.049* | |
C3A | 0.22708 (16) | 0.1768 (7) | 0.3831 (3) | 0.0481 (9) | |
H31A | 0.2152 | 0.3424 | 0.3978 | 0.058* | |
H32A | 0.2242 | 0.0502 | 0.4303 | 0.058* | |
C4A | 0.19499 (14) | 0.0921 (7) | 0.2796 (3) | 0.0500 (9) | |
H41A | 0.2082 | −0.0678 | 0.2636 | 0.060* | |
H42A | 0.1623 | 0.0546 | 0.2791 | 0.060* | |
C5A | 0.19105 (15) | 0.2908 (7) | 0.2004 (3) | 0.0452 (9) | |
H51A | 0.2237 | 0.3273 | 0.2002 | 0.054* | |
H52A | 0.1780 | 0.4513 | 0.2163 | 0.054* | |
C6A | 0.15869 (17) | 0.2033 (8) | 0.0984 (3) | 0.0555 (11) | |
H61A | 0.1720 | 0.0442 | 0.0821 | 0.067* | |
H62A | 0.1262 | 0.1646 | 0.0988 | 0.067* | |
C7A | 0.15433 (18) | 0.4030 (8) | 0.0202 (3) | 0.0595 (11) | |
H71A | 0.1870 | 0.4413 | 0.0206 | 0.071* | |
H72A | 0.1414 | 0.5620 | 0.0375 | 0.071* | |
C8A | 0.12245 (16) | 0.3273 (8) | −0.0830 (4) | 0.0500 (10) | |
O2A | 0.09809 (15) | 0.1270 (7) | −0.1013 (3) | 0.0731 (11) | |
O3A | 0.12320 (14) | 0.4899 (7) | −0.1494 (2) | 0.0769 (10) | |
H3A | 0.1034 | 0.4445 | −0.2031 | 0.115* | |
Cl1B | 0.28875 (4) | 0.7901 (2) | 0.15777 (9) | 0.0652 (3) | |
C1B | 0.31372 (14) | 1.0982 (7) | 0.1458 (3) | 0.0507 (9) | |
H11B | 0.2955 | 1.1653 | 0.0804 | 0.061* | |
H12B | 0.3082 | 1.2161 | 0.1931 | 0.061* | |
C2B | 0.36732 (14) | 1.1046 (7) | 0.1606 (3) | 0.0424 (8) | |
O1B | 0.38567 (12) | 1.3202 (5) | 0.1589 (3) | 0.0619 (9) | |
N1B | 0.39234 (11) | 0.8842 (5) | 0.1727 (2) | 0.0406 (7) | |
H1B | 0.3776 | 0.7395 | 0.1728 | 0.049* | |
C3B | 0.44432 (16) | 0.8806 (8) | 0.1857 (3) | 0.0465 (9) | |
H31B | 0.4503 | 1.0088 | 0.1422 | 0.056* | |
H32B | 0.4526 | 0.7110 | 0.1667 | 0.056* | |
C4B | 0.47728 (14) | 0.9372 (7) | 0.2903 (3) | 0.0470 (8) | |
H41B | 0.4670 | 1.1002 | 0.3106 | 0.056* | |
H42B | 0.5105 | 0.9605 | 0.2916 | 0.056* | |
C5B | 0.47777 (14) | 0.7277 (7) | 0.3653 (3) | 0.0448 (9) | |
H51B | 0.4448 | 0.7061 | 0.3658 | 0.054* | |
H52B | 0.4878 | 0.5635 | 0.3453 | 0.054* | |
C6B | 0.51220 (17) | 0.7940 (8) | 0.4687 (3) | 0.0521 (10) | |
H61B | 0.5450 | 0.8198 | 0.4675 | 0.062* | |
H62B | 0.5018 | 0.9570 | 0.4887 | 0.062* | |
C7B | 0.51440 (17) | 0.5903 (8) | 0.5441 (3) | 0.0567 (10) | |
H71B | 0.4813 | 0.5588 | 0.5427 | 0.068* | |
H72B | 0.5262 | 0.4296 | 0.5253 | 0.068* | |
C8B | 0.54611 (16) | 0.6554 (8) | 0.6468 (3) | 0.0489 (10) | |
O2B | 0.57205 (15) | 0.8504 (7) | 0.6669 (3) | 0.0740 (11) | |
O3B | 0.54496 (14) | 0.4923 (7) | 0.7135 (2) | 0.0768 (10) | |
H3B | 0.5652 | 0.5348 | 0.7670 | 0.115* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl1A | 0.0557 (6) | 0.0517 (5) | 0.0721 (7) | 0.0087 (4) | 0.0209 (5) | −0.0085 (5) |
C1A | 0.057 (2) | 0.0366 (17) | 0.059 (2) | −0.0003 (16) | 0.0155 (18) | −0.0044 (16) |
C2A | 0.058 (2) | 0.0247 (15) | 0.0404 (17) | 0.0045 (13) | 0.0132 (16) | 0.0002 (13) |
O1A | 0.073 (2) | 0.0292 (12) | 0.082 (2) | 0.0124 (12) | 0.0232 (19) | −0.0024 (13) |
N1A | 0.0461 (17) | 0.0263 (12) | 0.0484 (18) | 0.0054 (10) | 0.0141 (14) | −0.0018 (11) |
C3A | 0.048 (2) | 0.044 (2) | 0.052 (2) | 0.0039 (15) | 0.0168 (19) | 0.0012 (16) |
C4A | 0.048 (2) | 0.0408 (19) | 0.058 (2) | −0.0037 (14) | 0.0147 (18) | 0.0027 (16) |
C5A | 0.049 (2) | 0.0371 (18) | 0.049 (2) | −0.0021 (15) | 0.0160 (17) | −0.0039 (15) |
C6A | 0.059 (3) | 0.048 (2) | 0.052 (3) | −0.0101 (17) | 0.011 (2) | −0.0044 (18) |
C7A | 0.066 (3) | 0.053 (2) | 0.052 (2) | −0.0127 (19) | 0.013 (2) | −0.0034 (19) |
C8A | 0.043 (2) | 0.055 (2) | 0.051 (3) | −0.0053 (16) | 0.015 (2) | 0.0012 (17) |
O2A | 0.085 (2) | 0.0651 (19) | 0.057 (2) | −0.0328 (17) | 0.0106 (18) | −0.0031 (16) |
O3A | 0.086 (2) | 0.080 (2) | 0.0505 (19) | −0.0343 (18) | 0.0080 (17) | 0.0040 (17) |
Cl1B | 0.0575 (6) | 0.0453 (5) | 0.0936 (9) | −0.0028 (5) | 0.0279 (6) | 0.0090 (6) |
C1B | 0.054 (2) | 0.0345 (18) | 0.061 (2) | 0.0068 (15) | 0.0173 (18) | 0.0037 (16) |
C2B | 0.054 (2) | 0.0290 (17) | 0.0395 (18) | −0.0009 (14) | 0.0103 (16) | 0.0001 (13) |
O1B | 0.0631 (19) | 0.0272 (12) | 0.089 (3) | −0.0032 (11) | 0.0198 (18) | 0.0064 (13) |
N1B | 0.0455 (18) | 0.0269 (13) | 0.0482 (19) | −0.0014 (12) | 0.0151 (15) | −0.0009 (12) |
C3B | 0.050 (2) | 0.0434 (19) | 0.050 (2) | 0.0008 (15) | 0.0229 (19) | 0.0005 (16) |
C4B | 0.0476 (19) | 0.0373 (16) | 0.054 (2) | −0.0049 (14) | 0.0156 (16) | −0.0008 (16) |
C5B | 0.0462 (19) | 0.0356 (17) | 0.049 (2) | −0.0031 (15) | 0.0130 (17) | −0.0049 (16) |
C6B | 0.059 (2) | 0.0423 (19) | 0.050 (3) | −0.0098 (16) | 0.014 (2) | −0.0024 (17) |
C7B | 0.062 (2) | 0.050 (2) | 0.050 (2) | −0.0122 (18) | 0.011 (2) | −0.0031 (18) |
C8B | 0.051 (2) | 0.047 (2) | 0.047 (2) | −0.0063 (16) | 0.015 (2) | −0.0023 (16) |
O2B | 0.091 (3) | 0.067 (2) | 0.053 (2) | −0.0340 (18) | 0.0115 (19) | −0.0013 (15) |
O3B | 0.093 (2) | 0.071 (2) | 0.0539 (19) | −0.0322 (18) | 0.0109 (17) | 0.0042 (16) |
Cl1A—C1A | 1.773 (4) | Cl1B—C1B | 1.777 (4) |
C1A—C2A | 1.508 (6) | C1B—C2B | 1.500 (6) |
C1A—H11A | 0.9700 | C1B—H11B | 0.9700 |
C1A—H12A | 0.9700 | C1B—H12B | 0.9700 |
C2A—O1A | 1.236 (4) | C2B—O1B | 1.234 (4) |
C2A—N1A | 1.325 (4) | C2B—N1B | 1.324 (4) |
N1A—C3A | 1.445 (5) | N1B—C3B | 1.459 (5) |
N1A—H1A | 0.8600 | N1B—H1B | 0.8600 |
C3A—C4A | 1.521 (6) | C3B—C4B | 1.506 (6) |
C3A—H31A | 0.9700 | C3B—H31B | 0.9700 |
C3A—H32A | 0.9700 | C3B—H32B | 0.9700 |
C4A—C5A | 1.510 (6) | C4B—C5B | 1.527 (5) |
C4A—H41A | 0.9700 | C4B—H41B | 0.9700 |
C4A—H42A | 0.9700 | C4B—H42B | 0.9700 |
C5A—C6A | 1.511 (6) | C5B—C6B | 1.515 (6) |
C5A—H51A | 0.9700 | C5B—H51B | 0.9700 |
C5A—H52A | 0.9700 | C5B—H52B | 0.9700 |
C6A—C7A | 1.501 (6) | C6B—C7B | 1.498 (6) |
C6A—H61A | 0.9700 | C6B—H61B | 0.9700 |
C6A—H62A | 0.9700 | C6B—H62B | 0.9700 |
C7A—C8A | 1.503 (6) | C7B—C8B | 1.484 (6) |
C7A—H71A | 0.9700 | C7B—H71B | 0.9700 |
C7A—H72A | 0.9700 | C7B—H72B | 0.9700 |
C8A—O2A | 1.224 (5) | C8B—O2B | 1.226 (5) |
C8A—O3A | 1.281 (6) | C8B—O3B | 1.289 (5) |
O3A—H3A | 0.8200 | O3B—H3B | 0.8200 |
C2A—C1A—Cl1A | 116.7 (3) | C2B—C1B—Cl1B | 116.6 (3) |
C2A—C1A—H11A | 108.1 | C2B—C1B—H11B | 108.1 |
Cl1A—C1A—H11A | 108.1 | Cl1B—C1B—H11B | 108.1 |
C2A—C1A—H12A | 108.1 | C2B—C1B—H12B | 108.1 |
Cl1A—C1A—H12A | 108.1 | Cl1B—C1B—H12B | 108.1 |
H11A—C1A—H12A | 107.3 | H11B—C1B—H12B | 107.3 |
O1A—C2A—N1A | 125.1 (4) | O1B—C2B—N1B | 123.3 (3) |
O1A—C2A—C1A | 115.4 (3) | O1B—C2B—C1B | 117.0 (4) |
N1A—C2A—C1A | 119.6 (3) | N1B—C2B—C1B | 119.8 (3) |
C2A—N1A—C3A | 123.4 (3) | C2B—N1B—C3B | 121.7 (3) |
C2A—N1A—H1A | 118.3 | C2B—N1B—H1B | 119.2 |
C3A—N1A—H1A | 118.3 | C3B—N1B—H1B | 119.2 |
N1A—C3A—C4A | 112.8 (4) | N1B—C3B—C4B | 112.8 (4) |
N1A—C3A—H31A | 109.0 | N1B—C3B—H31B | 109.0 |
C4A—C3A—H31A | 109.0 | C4B—C3B—H31B | 109.0 |
N1A—C3A—H32A | 109.0 | N1B—C3B—H32B | 109.0 |
C4A—C3A—H32A | 109.0 | C4B—C3B—H32B | 109.0 |
H31A—C3A—H32A | 107.8 | H31B—C3B—H32B | 107.8 |
C5A—C4A—C3A | 114.2 (3) | C3B—C4B—C5B | 114.9 (3) |
C5A—C4A—H41A | 108.7 | C3B—C4B—H41B | 108.5 |
C3A—C4A—H41A | 108.7 | C5B—C4B—H41B | 108.5 |
C5A—C4A—H42A | 108.7 | C3B—C4B—H42B | 108.5 |
C3A—C4A—H42A | 108.7 | C5B—C4B—H42B | 108.5 |
H41A—C4A—H42A | 107.6 | H41B—C4B—H42B | 107.5 |
C4A—C5A—C6A | 113.2 (3) | C6B—C5B—C4B | 112.4 (3) |
C4A—C5A—H51A | 108.9 | C6B—C5B—H51B | 109.1 |
C6A—C5A—H51A | 108.9 | C4B—C5B—H51B | 109.1 |
C4A—C5A—H52A | 108.9 | C6B—C5B—H52B | 109.1 |
C6A—C5A—H52A | 108.9 | C4B—C5B—H52B | 109.1 |
H51A—C5A—H52A | 107.7 | H51B—C5B—H52B | 107.9 |
C7A—C6A—C5A | 113.0 (3) | C7B—C6B—C5B | 113.9 (3) |
C7A—C6A—H61A | 109.0 | C7B—C6B—H61B | 108.8 |
C5A—C6A—H61A | 109.0 | C5B—C6B—H61B | 108.8 |
C7A—C6A—H62A | 109.0 | C7B—C6B—H62B | 108.8 |
C5A—C6A—H62A | 109.0 | C5B—C6B—H62B | 108.8 |
H61A—C6A—H62A | 107.8 | H61B—C6B—H62B | 107.7 |
C6A—C7A—C8A | 115.5 (3) | C8B—C7B—C6B | 115.1 (3) |
C6A—C7A—H71A | 108.4 | C8B—C7B—H71B | 108.5 |
C8A—C7A—H71A | 108.4 | C6B—C7B—H71B | 108.5 |
C6A—C7A—H72A | 108.4 | C8B—C7B—H72B | 108.5 |
C8A—C7A—H72A | 108.4 | C6B—C7B—H72B | 108.5 |
H71A—C7A—H72A | 107.5 | H71B—C7B—H72B | 107.5 |
O2A—C8A—O3A | 123.3 (4) | O2B—C8B—O3B | 122.2 (4) |
O2A—C8A—C7A | 122.6 (4) | O2B—C8B—C7B | 122.2 (4) |
O3A—C8A—C7A | 114.1 (4) | O3B—C8B—C7B | 115.6 (4) |
C8A—O3A—H3A | 109.5 | C8B—O3B—H3B | 109.5 |
Cl1A—C1A—C2A—O1A | −178.4 (3) | Cl1B—C1B—C2B—O1B | −175.3 (3) |
Cl1A—C1A—C2A—N1A | 1.2 (5) | Cl1B—C1B—C2B—N1B | 5.9 (5) |
O1A—C2A—N1A—C3A | −1.7 (6) | O1B—C2B—N1B—C3B | 0.4 (5) |
C1A—C2A—N1A—C3A | 178.7 (4) | C1B—C2B—N1B—C3B | 179.0 (4) |
C2A—N1A—C3A—C4A | 113.4 (4) | C2B—N1B—C3B—C4B | 81.8 (4) |
N1A—C3A—C4A—C5A | −66.4 (4) | N1B—C3B—C4B—C5B | 67.7 (4) |
C3A—C4A—C5A—C6A | −179.6 (4) | C3B—C4B—C5B—C6B | 179.1 (4) |
C4A—C5A—C6A—C7A | 179.2 (4) | C4B—C5B—C6B—C7B | −178.9 (4) |
C5A—C6A—C7A—C8A | −179.8 (4) | C5B—C6B—C7B—C8B | −177.4 (4) |
C6A—C7A—C8A—O2A | 6.3 (7) | C6B—C7B—C8B—O2B | −6.4 (7) |
C6A—C7A—C8A—O3A | −173.6 (4) | C6B—C7B—C8B—O3B | 174.2 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1A···O1Ai | 0.86 | 2.24 | 2.897 (5) | 133 |
N1A—H1A···Cl1A | 0.86 | 2.52 | 2.990 (3) | 115 |
N1B—H1B···O1Bi | 0.86 | 2.19 | 2.907 (4) | 141 |
N1B—H1B···Cl1B | 0.86 | 2.53 | 2.989 (4) | 114 |
O3A—H3A···O2Bii | 0.82 | 1.84 | 2.646 (5) | 166 |
O3B—H3B···O2Aiii | 0.82 | 1.87 | 2.669 (5) | 166 |
C1A—H11A···O1Biv | 0.97 | 2.52 | 3.435 (6) | 157 |
C1B—H11B···O1Av | 0.97 | 2.50 | 3.413 (6) | 157 |
C3A—H31A···O1A | 0.97 | 2.45 | 2.836 (5) | 104 |
Symmetry codes: (i) x, y−1, z; (ii) x−1/2, y−1/2, z−1; (iii) x+1/2, y+1/2, z+1; (iv) x, −y+2, z+1/2; (v) x, −y+2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C8H14ClNO3 |
Mr | 207.65 |
Crystal system, space group | Monoclinic, Cc |
Temperature (K) | 293 |
a, b, c (Å) | 29.149 (4), 5.139 (4), 14.498 (4) |
β (°) | 110.90 (2) |
V (Å3) | 2028.9 (17) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.35 |
Crystal size (mm) | 0.42 × 0.18 × 0.10 |
Data collection | |
Diffractometer | Enraf–Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3057, 3057, 2118 |
Rint | 0.000 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.048, 0.132, 1.06 |
No. of reflections | 3057 |
No. of parameters | 237 |
No. of restraints | 2 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.36, −0.25 |
Absolute structure | Flack (1983), 97 Friedel pairs |
Absolute structure parameter | 0.05 (9) |
Computer programs: CAD-4 Software (Kiers, 1994), WinGX-PC (Version 1.64.05; Farrugia, 1999), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976) and PLATON (Spek, 2003), SHELXL97 and WinGX-PC.
Cl1A—C1A—C2A—N1A | 1.2 (5) | Cl1B—C1B—C2B—N1B | 5.9 (5) |
C1A—C2A—N1A—C3A | 178.7 (4) | C1B—C2B—N1B—C3B | 179.0 (4) |
C2A—N1A—C3A—C4A | 113.4 (4) | C2B—N1B—C3B—C4B | 81.8 (4) |
N1A—C3A—C4A—C5A | −66.4 (4) | N1B—C3B—C4B—C5B | 67.7 (4) |
C3A—C4A—C5A—C6A | −179.6 (4) | C3B—C4B—C5B—C6B | 179.1 (4) |
C4A—C5A—C6A—C7A | 179.2 (4) | C4B—C5B—C6B—C7B | −178.9 (4) |
C5A—C6A—C7A—C8A | −179.8 (4) | C5B—C6B—C7B—C8B | −177.4 (4) |
C6A—C7A—C8A—O3A | −173.6 (4) | C6B—C7B—C8B—O3B | 174.2 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1A···O1Ai | 0.86 | 2.243 | 2.897 (5) | 132.74 |
N1A—H1A···Cl1A | 0.86 | 2.519 | 2.990 (3) | 115.33 |
N1B—H1B···O1Bi | 0.86 | 2.185 | 2.907 (4) | 141.41 |
N1B—H1B···Cl1B | 0.86 | 2.532 | 2.989 (4) | 114.13 |
O3A—H3A···O2Bii | 0.82 | 1.843 | 2.646 (5) | 165.96 |
O3B—H3B···O2Aiii | 0.82 | 1.866 | 2.669 (5) | 165.84 |
C1A—H11A···O1Biv | 0.97 | 2.523 | 3.435 (6) | 156.71 |
C1B—H11B···O1Av | 0.97 | 2.499 | 3.413 (6) | 156.99 |
C3A—H31A···O1A | 0.97 | 2.446 | 2.836 (5) | 103.68 |
Symmetry codes: (i) x, y−1, z; (ii) x−1/2, y−1/2, z−1; (iii) x+1/2, y+1/2, z+1; (iv) x, −y+2, z+1/2; (v) x, −y+2, z−1/2. |
The development of materials for biomedical applications, such as orthopedic devices, scaffolds for tissue engineering, bioabsorbable surgical sutures and drug delivery systems, is nowadays a subject of considerable interest. Polyesters constitute the main family of biodegradable polymers that has until now been commercialized for the indicated uses (Huang, 1985). Natural hydroxy acid derivatives, such as the polymers constituted by glycolic acid units, are the most widely applied since these materials may be safe for in vivo use.
Efforts are also focused on providing new materials that can cover a wider range of properties. Poly(ester amide)s can be mentioned as a promising family because of the occurrence of strong intermolecular interactions between amide groups and the presence of degradable ester groups (Montané et al., 2002). Recently, we have found that alternating poly(ester amide)s constituted by glycolic acid and ω-amino acid units can be prepared easily by a solid- or a melt-state thermal polycondensation that involves a metal salt of the appropriate chlorinated derivative [ClCH2CONH(CH2)n-1COO− M+] (Vera, Rodríguez-Galán & Puiggalí, 2004; Vera, Franco & Puiggalí, 2004). The high yield and molecular weight that can be attained by this method have aroused interest in these polymers. Solid-state polycondensation of halogenated carboxylates had previously been assayed to obtain polyglycolide (Herzberg & Epple, 2001) and other polyesters (Epple & Kirschnick, 1997). Unfortunately, the occurrence of secondary reactions limited the molecular weight of the polymer and the applicability of the method.
A molecular solid-state reaction relies on a suitable arrangement of the reactants in the crystal, and consequently structural studies become interesting. The title compound has been chosen for being the precursor of metal salts that can be polymerized to obtain the alternating poly(ester amide) constituted by glycolic acid and 6-aminohexanoic residues. Structural data of related compounds are only available for N-chloroacetyl-β-alanine (Urpí et al., 2003). In this case, the polymerization of the corresponding salt led to a low molecular weight sample since a stable seven-membered cyclic compound was favored (Rodríguez-Galán et al., 2003).
The asymmetric unit of (I), with two crystallographically independent molecules, A and B, is shown in Fig. 1, whereas selected torsion angles and hydrogen bond geometry are reported in Tables 1 and 2. Both molecules show a twisted conformation caused by the deviation of the CONH—CH2CH2 and NHCH2—CH2CH2 torsion angles of the 6-aminohexanoic residue from 180°. This twisting constitutes the main crystallographic difference between the two molecules [torsion angle values of 113.4 (4) and −66.4 (4)° for molecule A, and 81.8 (4) and 67.7 (4)° for molecule B] and demonstrates the absence of an additional symmetry element. The experimental values found for the CONH—CH2CH2 torsion angle agree with that determined by quantum mechanical calculations of small molecules. A stabilization near 90° was found and was attributed to the overlap between the nitrogen lone pair and the CH2—CH2 bond (Dasgupta et al., 1996). The value of 113.4° found in molecule A for the CONH—CH2CH2 torsion angle also allows a weak intramolecular hydrogen bond to be established between atom H31A of a methylene group and atom O1A of the amide group (Table 2 and Fig. 1). This hydrogen bond is of S(5) type according to the graph-set theory (Etter, 1990). Note that this interaction cannot be found in molecule B.
Inspection of the Cambridge Structural Database (CSD, Version 5.27 of January 2006; CONQUEST Version 1.8; Allen, 2002; Bruno et al., 2002) shows that only three compounds with ε-aminohexanoic units have been solved. The conjugate of indole-3-acetic acid with this ω-amino acid has a similar conformation to molecule B, with values of 99.8 and 54.4° for the two indicated torsion angles, which cause a folding of the aliphatic side chain over the indole ring (Nigović et al., 1992). However, it should be pointed out that an all trans conformation was found for the ε-aminohexanoic units in the other two studied derivatives [6,6'-ureylenedihexanoic acid and 6,6'-(oxalyldiimino)dihexanoic acid (Coe et al., 1997)], and also that this zigzag conformation is usually postulated for aliphatic polyamides derived from ω-amino acids (Kohan, 1995).
The ClCH2—CONH torsion angle has a cis conformation, which is in agreement with the results obtained with other related structures such as chloroacetylglycylglycine (Rao & Mallikarjunan, 1973), 2-chloroacetamide (Kalyanaraman et al., 1978) and N-chloroacetyl-β-alanine (Urpí et al., 2003). This conformation appears stabilized by the Cl···HN intramolecular electrostatic interaction (Table 2), which is of S(5) type (Etter, 1990).
The molecular conformation is finally characterized by the planarity within experimental accuracy of both the amide and the carboxylic acid groups. The r.m.s. deviations are 0.0073 Å for atoms C1A, C2A, O1A, N1A and C3A, 0.0051 Å for atoms C1B, C2B, O1B, N1B and C3B, 0.0005 Å for atoms C7A, C8A, O2A and O3A, and 0.0017 Å for atoms C7B, C8B, O2B and O3B, from the mean planes passing through these atoms.
The packing is characterized by the establishment of a network of intermolecular hydrogen bonds that involve amide–amide and acid–acid interactions. Hydrogen bonds between amide groups [C(4) type; Etter, 1990] are established between equivalent molecules along a direction parallel to the crystallographic b axis (Fig. 2). Note that the hydrogen-bonding geometry is slightly different for molecules A and B (Table 2) owing to their distinct molecular conformation. The carboxylic amide groups of the two molecules of the asymmetric unit appear shifted along the a axis and point towards approximately the same sense. However, the crystal structure becomes non-polar owing to the c-glide plane symmetry. These carboxylic acid groups are also involved in weak intermolecular hydrogen bonds with the C1 methylene groups. This interaction is established between inequivalent molecules (Table 2 and Fig. 2) and gives rise to a ring of the R22(8) type (Etter, 1990).
Hydrogen bonding of carboxylic acid groups is of the cyclic dimer type R22(8) (Etter, 1990). It involves two crystallographically inequivalent molecules and does not occur about a center of inversion. There are, therefore, two inequivalent hydrogen bonds involving atoms O2A and O2B as acceptors and atoms O3A and O3B as donors. Note, however, that a pseudo-center of symmetry exists at the 'mid-point' of the cyclic dimer portion since the torsion angles of the -(CH2)4COOH groups are very close to 180° for both molecules of the asymmetric unit. The disubstituted eight-membered ring is almost planar, with an r.m.s. deviation of 0.0323 Å for atoms C7A, C8A, O2A, O3A, C7B, C8B, O2B and O3B from the mean plane passing through them, as expected from the interaction of the hydrogen-bonding protons and the lone pairs of the carbonyl O atoms that have sp2-hybridization (Robertson, 1964). The observed hydrogen-bond geometry (Table 2) is fully consistent with the average geometry deduced from the data corresponding to 2228 fragments deposited in the Cambridge Structural Database; O—O distance and OHO angle of 2.647 Å and 170.45°, respectively. Furthermore, the experimental C═O—H angles (119.77 and 118.80°) are also close to the mean value of 122.01°. A stacking of cyclic dimers where carboxyl groups are offset along their shorter C═O bonds is observed, as commonly found in the packing of carboxylic acids (Leiserowitz, 1976).
There are great differences between the packing of the title compound and the related N-chloroacetyl-β-alanine (Urpí et al., 2003), where a ribbon structure was generated owing to the establishment of a network of hydrogen bonds between amide and acid groups. This feature suggests that the length of the amino acid unit has a strong influence on the packing preferences.