Acta Cryst.(2002). E58, o469±o470 DOI: 10.1107/S1600536802004117 Jana MaderovaÂet al. C6H9NO6
o469
organic papers
Acta Crystallographica Section E Structure Reports Online
ISSN 1600-5368
N-(Carboxymethyl)aspartic acid
Jana MaderovaÂ,a* FrantisÏek
PavelcÏõÂkaand JaromõÂir Marekb
aDepartment of Inorganic Chemistry, Faculty
of Natural Sciences, Comenius University, Mlynska dolina CH-2, SK-842 15 Bratislava, Slovak Republic, andbLaboratory of Biomolecular Structure and Dynamics, and Department of Inorganic Chemistry, Faculty of Science, Masaryk University, KotlaÂrÏska 2, CZ-611 37 Brno, Czech Republic
Correspondence e-mail: [email protected]
Key indicators
Single-crystal X-ray study T= 120 K
Mean(C±C) = 0.002 AÊ Rfactor = 0.033 wRfactor = 0.082
Data-to-parameter ratio = 10.0
For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.
#2002 International Union of Crystallography Printed in Great Britain ± all rights reserved
The title molecule, C6H9NO6, exists in a zwitterionic form. The
transfer of the H atom to the N atom involves two carboxyl groups and, as a result, their H atoms are disordered. The crystal structure is stabilized by OÐH O, NÐH O and CÐH O hydrogen bonds.
Comment
The structure of the title compound, (I), has been analysed as part of a general study of the chemistry of aspartic acid derivatives as potential ligands in coordination compounds (PavelcÏõÂk & Majer, 1978). The title compound is a potential tetradentate chelating agent that is isomeric with and chemi-cally quite similar to NTA (nitrilotriacetic acid), but the compound is chiral as in EDDS (N,N -ethylenediamin-disuccinic acid) (Scarbrough & Voet, 1976).
The molecular structure and atom-numbering scheme are shown in Fig. 1. In the crystal, the title molecule exists in a zwitterionic form with a carboxyl H atom transferred to the N atom. In 50% of the population, the H atom is transfered from O2, whereas in the remaining population, it is transfered from O4. This is evident from the CÐO and C O bond distances observed for the carboxyl groups (Table 1). In the solid state, intermolecular OÐH O, NÐH O and CÐH O hydrogen bonds link the molecules to form a three-dimen-sional network (Table 2).
Experimental
The title compound was prepared by dissolving maleic anhydride and glycine in an aqueous solution of NaOH. The solution was re¯uxed for 48 h. The pH was adjusted to 7 with HCl. The resulting solution was ®ltered off and the pH was adjusted with HCl to 2. After several days, colourless crystals were obtained.
Crystal data
C6H9NO6
Mr= 191.14
Monoclinic, P21=n
a= 5.3430 (5) AÊ
b= 16.033 (2) AÊ
c= 9.0895 (12) AÊ
= 95.384 (12)
V= 775.2 (2) AÊ3
Z= 4
Dx= 1.638 Mg mÿ3
MoKradiation Cell parameters from 36
re¯ections
= 16.9±25.0
= 0.15 mmÿ1
T= 120 (2) K Prism, colourless 0.600.400.30 mm
Data collection
Kuma KM-4 four-circle-axis diffractometer with Oxford Cryosystems Cryostream cooler (Cosier & Glazer, 1986)
!scans
Absorption correction: none 2969 measured re¯ections 1368 independent re¯ections 1179 re¯ections withI> 2(I)
Rint= 0.036 max= 25.1
h=ÿ6!0
k=ÿ19!19
l=ÿ10!10 3 standard re¯ections
every 200 re¯ections intensity decay: <2%
Re®nement
Re®nement onF2
R[F2> 2(F2)] = 0.033
wR(F2) = 0.082
S= 1.09 1368 re¯ections 137 parameters
H atoms treated by a mixture of independent and constrained re®nement
w= 1/[2(F
o2) + (0.04P)2
+ 0.2243P]
whereP= (Fo2+ 2Fc2)/3
(/)max< 0.001
max= 0.29 e AÊÿ3
min=ÿ0.24 e AÊÿ3
Table 1
Selected interatomic distances (AÊ).
O1ÐC2 1.2268 (18) O2ÐC2 1.2750 (18) O3ÐC4 1.2387 (18) O4ÐC4 1.2813 (18)
O5ÐC7 1.2097 (18) O6ÐC7 1.3115 (19) N5ÐC6 1.4797 (19) N5ÐC1 1.5055 (18)
Table 2
Hydrogen-bonding geometry (AÊ,).
DÐH A DÐH H A D A DÐH A
O2ÐH2 O2i 0.91 (5) 1.52 (6) 2.429 (2) 174 (6)
O4ÐH4 O4ii 0.83 (4) 1.60 (4) 2.433 (2) 177 (4)
O6ÐH6 O3iii 0.94 (3) 1.58 (2) 2.517 (2) 170 (2)
N5ÐH5A O4 0.91 2.09 2.751 (2) 128 N5ÐH5A O5iv 0.91 2.32 3.040 (2) 136
N5ÐH5B O6v 0.91 2.47 3.302 (2) 152
C3ÐH3B O2vi 0.95 2.43 3.249 (2) 144
C6ÐH6A O1vii 0.95 2.31 3.227 (2) 162 Symmetry codes: (i) 1ÿx;1ÿy;1ÿz; (ii) 1ÿx;1ÿy;2ÿz; (iii)ÿ1
2ÿx;12y;32ÿz;
(iv)1
2x;32ÿy;12z; (v) 1x;y;z; (vi)ÿx;1ÿy;1ÿz; (vii)xÿ21;32ÿy;12z.
Initially, all the H atoms were located from a difference Fourier map and the NH group was found to be protonated. The CÐO and C O distances in the carboxyl groups showed that the H atom might be transfered from two carboxyl groups (C2/O1/O2/H2 and C4/O3/ O4/H4), indicating disorder of H2 and H4. In the difference map, H2 and H4 were found to lie on centres of inversion such that two inversion related molecules share H2 and H4. However, re®nement using this model resulted in a very long OÐH distance of 1.21 AÊ. The Uisovalues of both H2 and H4 were found to be relatively high at
0.07 AÊ2. Hence, H2 and H4 were placed at calculated positions and
their occupancies were initially re®ned and ®nally ®xed at 0.5. At this stage, no peaks were observed at the centres of inversion. Even if the positional constraints were released, the H2 and H4 positions did not move to the inversion centres. Now the Uisovalues of H2 and H4
showed values comparable to other H atoms. Another re®nement model with three atoms (N5, O2 and O4) sharing four H atoms (H2, H4, H5Aand H5B) was investigated. The re®nement using this model resulted in nearly full occupancies for H5A and H5B and partial occupancies for H2 and H4, as in the previous model. Hence the earlier model was retained. During the ®nal stages of the re®nement, the H atoms attached to C and N atoms were ®xed geometrically and allowed to ride on the parent atoms.
Data collection: KM-4 CCD System Software(Kuma, 1998); cell re®nement:KM-4CCD System Software; data reduction:KM-4CCD System Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to re®ne structure:SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Johnson & Burnett, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
This work was supported by the VEGA (grant No. 1/7264/ 20) of the Ministry of Education of the Slovak Republic.
References
Cosier, J. & Glazer, A. M. (1986).J. Appl. Cryst.19, 105±107.
Johnson, C. K. & Burnett, M. N. (1996).ORTEPIII. Oak Ridge National Laboratory, Tennessee, USA.
Kuma (1998).KM-4CCD System Software. Version 1.149. Kuma Diffraction Instruments, Wrocøaw, Poland, and Universite de Lausanne, Switzerland. PavelcÏõÂk, F. & Majer, J. (1978).Acta Cryst.B34, 3582±3585.
Scarbrough, F. E. & Voet, D. (1976).Acta Cryst.B32, 2715±2717. Sheldrick, G. M. (1990).Acta Cryst.A46, 467±473.
Sheldrick, G. M. (1997).SHELXL97. University of GoÈttingen, Germany.
Figure 1
supporting information
sup-1
Acta Cryst. (2002). E58, o469–o470
supporting information
Acta Cryst. (2002). E58, o469–o470 [https://doi.org/10.1107/S1600536802004117]
N
-(Carboxymethyl)aspartic acid
Jana Maderov
á
, Franti
š
ek Pavel
čí
k and Jarom
í
ir Marek
N-carboxymethylaspartic acid
Crystal data
C6H9NO6
Mr = 191.14
Monoclinic, P21/n Hall symbol: -p 2yn
a = 5.3430 (5) Å
b = 16.033 (2) Å
c = 9.0895 (12) Å
β = 95.384 (12)°
V = 775.2 (2) Å3
Z = 4
F(000) = 400
Dx = 1.638 Mg m−3 Melting point: 470 K
Mo Kα radiation, λ = 0.71073 Å Cell parameters from 36 reflections
θ = 16.9–25.0°
µ = 0.15 mm−1
T = 120 K Prism, colourless 0.60 × 0.40 × 0.30 mm
Data collection
Kuma KM-4 four-circle κ-axis
diffractometer with Oxford Cryosystems Cryostream cooler (Cosier & Glazer, 1986) Radiation source: fine-focus sealed tube Graphite monochromator
ω scans
2969 measured reflections 1368 independent reflections
1179 reflections with I > 2σ(I)
Rint = 0.036
θmax = 25.1°, θmin = 4.0°
h = −6→0
k = −19→19
l = −10→10
3 standard reflections every 200 reflections intensity decay: <2%
Refinement
Refinement on F2 Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.033
wR(F2) = 0.082
S = 1.09 1368 reflections 137 parameters 0 restraints
Primary atom site location: structure-invariant direct methods
Secondary atom site location: difference Fourier map
Hydrogen site location: inferred from neighbouring sites
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ2(F
o2) + (0.04P)2 + 0.2243P] where P = (Fo2 + 2Fc2)/3
(Δ/σ)max < 0.001 Δρmax = 0.29 e Å−3 Δρmin = −0.24 e Å−3
Special details
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)
x y z Uiso*/Ueq Occ. (<1)
O1 0.4767 (2) 0.64415 (6) 0.61666 (11) 0.0170 (3) O2 0.3125 (2) 0.51825 (7) 0.55872 (11) 0.0166 (3) O3 0.1324 (2) 0.41892 (6) 0.90873 (10) 0.0163 (3) O4 0.3500 (2) 0.53653 (6) 0.91396 (11) 0.0149 (3) O5 −0.1229 (2) 0.79036 (6) 0.60638 (11) 0.0181 (3) O6 −0.4103 (2) 0.81542 (7) 0.76614 (12) 0.0198 (3) N5 0.1317 (2) 0.67990 (8) 0.79540 (13) 0.0139 (3)
H5A 0.2223 0.6587 0.8766 0.022 (5)*
H5B 0.2319 0.7171 0.7531 0.028 (5)*
C1 0.0714 (3) 0.60976 (9) 0.68777 (14) 0.0128 (3)
H1 −0.0521 0.6287 0.6133 0.010 (4)*
C2 0.3118 (3) 0.59085 (9) 0.61593 (14) 0.0128 (3) C3 −0.0301 (3) 0.53366 (9) 0.76034 (15) 0.0131 (3)
H3A −0.1696 0.5497 0.8114 0.021 (4)*
H3B −0.0886 0.4949 0.6858 0.009 (4)*
C4 0.1610 (3) 0.49154 (9) 0.86692 (14) 0.0120 (3) C6 −0.0857 (3) 0.72573 (9) 0.84479 (15) 0.0162 (3)
H6A −0.0312 0.7593 0.9277 0.014 (4)*
H6B −0.2055 0.6870 0.8747 0.020 (4)*
C7 −0.2076 (3) 0.78008 (9) 0.72387 (15) 0.0147 (3)
H2 0.459 (10) 0.505 (4) 0.520 (6) 0.032 (13)* 0.50
H4 0.452 (7) 0.513 (2) 0.975 (4) 0.018 (11)* 0.50
H6 −0.476 (4) 0.8558 (15) 0.698 (3) 0.049 (6)*
Atomic displacement parameters (Å2)
U11 U22 U33 U12 U13 U23
supporting information
sup-3
Acta Cryst. (2002). E58, o469–o470 Geometric parameters (Å, º)
O1—C2 1.2268 (18) N5—H5A 0.91
O2—C2 1.2750 (18) N5—H5B 0.91
O2—H2 0.91 (5) C1—C3 1.512 (2)
O3—C4 1.2387 (18) C1—C2 1.525 (2)
O4—C4 1.2813 (18) C1—H1 0.95
O4—H4 0.83 (4) C3—C4 1.501 (2)
O5—C7 1.2097 (18) C3—H3A 0.95
O6—C7 1.3115 (19) C3—H3B 0.95
O6—H6 0.94 (3) C6—C7 1.502 (2)
N5—C6 1.4797 (19) C6—H6A 0.95
N5—C1 1.5055 (18) C6—H6B 0.95
C2—O2—H2 113 (4) C4—C3—C1 113.24 (12)
C4—O4—H4 114 (3) C4—C3—H3A 108.9
C7—O6—H6 111.7 (14) C1—C3—H3A 108.9
C6—N5—C1 116.23 (12) C4—C3—H3B 108.9
C6—N5—H5A 108.2 C1—C3—H3B 108.9
C1—N5—H5A 108.2 H3A—C3—H3B 107.7
C6—N5—H5B 108.2 O3—C4—O4 122.88 (14)
C1—N5—H5B 108.2 O3—C4—C3 121.66 (13)
H5A—N5—H5B 107.4 O4—C4—C3 115.43 (13)
N5—C1—C3 112.52 (11) N5—C6—C7 111.40 (12)
N5—C1—C2 106.82 (11) N5—C6—H6A 109.3
C3—C1—C2 112.18 (12) C7—C6—H6A 109.3
N5—C1—H1 108.4 N5—C6—H6B 109.3
C3—C1—H1 108.4 C7—C6—H6B 109.3
C2—C1—H1 108.4 H6A—C6—H6B 108.0
O1—C2—O2 127.48 (14) O5—C7—O6 125.98 (14)
O1—C2—C1 119.49 (13) O5—C7—C6 123.55 (14)
O2—C2—C1 113.02 (13) O6—C7—C6 110.45 (12)
C6—N5—C1—C3 −74.25 (15) C2—C1—C3—C4 53.05 (15)
C6—N5—C1—C2 162.23 (11) C1—C3—C4—O3 −162.31 (13)
N5—C1—C2—O1 −21.35 (16) C1—C3—C4—O4 19.55 (17)
C3—C1—C2—O1 −145.08 (13) C1—N5—C6—C7 −72.22 (16)
N5—C1—C2—O2 159.50 (11) N5—C6—C7—O5 −6.3 (2)
C3—C1—C2—O2 35.77 (16) N5—C6—C7—O6 175.42 (12)
N5—C1—C3—C4 −67.44 (15)
Hydrogen-bond geometry (Å, º)
D—H···A D—H H···A D···A D—H···A
O2—H2···O2i 0.91 (5) 1.52 (6) 2.429 (2) 174 (6)
O4—H4···O4ii 0.83 (4) 1.60 (4) 2.433 (2) 177 (4)
O6—H6···O3iii 0.94 (3) 1.58 (2) 2.517 (2) 170 (2)
N5—H5A···O5iv 0.91 2.32 3.040 (2) 136
N5—H5B···O6v 0.91 2.47 3.302 (2) 152
C3—H3B···O2vi 0.95 2.43 3.249 (2) 144
C6—H6A···O1vii 0.95 2.31 3.227 (2) 162
