N-Methyl-DL-aspartic acid mono­hydrate

The title compound, C₅H₉NO₄·H₂O, has been synthesized and crystallized. It crystallizes in Cc with one mol­ecule in the asymmetric unit. The compound is found in its zwitterionic form. D and L forms of the compound are linked in the crystal via O—H...O and N—H...O hydrogen bonds, both directly between the aspartic acid-derivative entities and to the crystal water mol­ecule. A weak intramolecular N—H...O interaction is found. The carbon skeleton is slightly twisted with C—C—C—C = 166.83 (11)°. A comparison with other derivatives of aspartic acid shows only two rotamers – one with a near planar carbon skeleton and one with a significantly twisted carbon skeleton.

Computing details

Data collection: MAR; cell refinement: DENZO (Otwinoski & Minor, 1993); data reduction: DENZO (Otwinoski & Minor, 1993) and CCP4 (Evans, 1994)); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976).

N-Methyl-DL-Aspartic Acid

Crystal data

C5H9NO4·H2O	F(000) = 352
Mr = 165.15	Dx = 1.490 Mg m^−3
Monoclinic, Cc	Synchrotron radiation, λ = 0.70000 Å
a = 9.282 Å	Cell parameters from 6678 reflections
b = 10.803 Å	θ = 3.0–28.0°
c = 7.887 Å	µ = 0.13 mm^−1
β = 111.45°	T = 122 K
V = 736.1 Å^3	Multi-faceted, colourless
Z = 4	0.2 × 0.15 × 0.15 mm

Data collection

MAR Image Plate diffractometer	891 reflections with I > 2σ(I)
Radiation source: European Synchrotron Radiation Facility	Rint = 0.029
Si(111) monochromator	θmax = 28.0°, θmin = 3.0°
Detector resolution: 6.66 pixels mm^-1	h = −12→11
φ scans	k = −14→14
6678 measured reflections	l = −9→9
893 independent reflections

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.030	w = 1/[σ^2(Fo^2) + (0.048P)^2 + 0.1021P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.074	(Δ/σ)max = 0.042
S = 1.31	Δρmax = 0.39 e Å^−3
893 reflections	Δρmin = −0.22 e Å^−3
145 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
2 restraints	Extinction coefficient: 0.048 (9)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983)
Secondary atom site location: difference Fourier map	Absolute structure parameter: −0.2 (9)

Special details

Experimental. Two data sets were collected. One low resolution data set to up to 0.9 Å and one medium resolution from 1.7 Å to 0.7 Å. Scan range 5°.

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.38612 (13)	0.09177 (10)	−0.08917 (15)	0.0135 (3)
O2	0.20517 (14)	0.23216 (11)	−0.23859 (16)	0.0145 (3)
C1	0.29997 (16)	0.18271 (14)	−0.09703 (18)	0.0088 (3)
C2	0.30871 (15)	0.23675 (12)	0.0865 (2)	0.0078 (3)
H1	0.412 (3)	0.2411 (19)	0.166 (4)	0.005 (4)*
N1	0.24935 (15)	0.36751 (11)	0.05886 (18)	0.0092 (3)
H2	0.189 (3)	0.379 (2)	−0.058 (5)	0.018 (6)*
H3	0.195 (3)	0.383 (2)	0.121 (3)	0.004 (4)*
C5	0.37574 (19)	0.46106 (14)	0.0977 (2)	0.0172 (3)
H4	0.330 (3)	0.542 (3)	0.079 (4)	0.028 (8)*
H5	0.437 (3)	0.443 (3)	0.026 (4)	0.025 (7)*
H6	0.446 (3)	0.450 (3)	0.223 (4)	0.020 (6)*
C3	0.21565 (16)	0.15826 (13)	0.1710 (2)	0.0087 (3)
H7	0.104 (3)	0.169 (3)	0.109 (4)	0.015 (5)*
H8	0.245 (3)	0.069 (3)	0.165 (5)	0.020 (6)*
C4	0.25388 (16)	0.19328 (12)	0.36860 (19)	0.0093 (3)
O3	0.36350 (17)	0.25899 (13)	0.4512 (2)	0.0220 (3)
O4	0.15812 (13)	0.14691 (11)	0.44050 (16)	0.0152 (3)
H9	0.183 (4)	0.176 (3)	0.543 (5)	0.022 (6)*
OW	0.57309 (13)	0.01479 (11)	0.73230 (17)	0.0125 (3)
H1W	0.509 (4)	0.046 (4)	0.778 (6)	0.040 (8)*
H2W	0.515 (3)	−0.021 (3)	0.639 (5)	0.023 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0193 (5)	0.0131 (5)	0.0113 (6)	0.0039 (4)	0.0094 (4)	−0.0004 (4)
O2	0.0175 (5)	0.0200 (5)	0.0061 (6)	0.0051 (4)	0.0044 (4)	−0.0003 (4)
C1	0.0111 (5)	0.0116 (6)	0.0056 (6)	−0.0008 (4)	0.0054 (5)	−0.0009 (4)
C2	0.0097 (6)	0.0081 (6)	0.0060 (6)	0.0012 (4)	0.0035 (5)	−0.0003 (4)
N1	0.0134 (5)	0.0090 (5)	0.0070 (6)	0.0019 (4)	0.0058 (4)	0.0002 (4)
C5	0.0198 (7)	0.0108 (7)	0.0226 (9)	−0.0031 (5)	0.0098 (6)	0.0003 (5)
C3	0.0104 (6)	0.0110 (6)	0.0059 (6)	−0.0008 (4)	0.0044 (5)	−0.0012 (4)
C4	0.0132 (6)	0.0091 (6)	0.0066 (6)	0.0010 (5)	0.0048 (5)	0.0001 (5)
O3	0.0242 (6)	0.0319 (7)	0.0104 (6)	−0.0158 (5)	0.0071 (5)	−0.0081 (5)
O4	0.0182 (5)	0.0223 (6)	0.0087 (6)	−0.0055 (4)	0.0091 (4)	−0.0039 (4)
OW	0.0138 (4)	0.0151 (5)	0.0111 (6)	−0.0006 (4)	0.0074 (4)	−0.0020 (4)

Geometric parameters (Å, º)

O1—C1	1.2539 (19)	C5—H5	0.96 (3)
O2—C1	1.2600 (18)	C5—H6	0.97 (3)
C1—C2	1.535 (2)	C3—C4	1.5145 (14)
C2—N1	1.5029 (17)	C3—H7	0.98 (3)
C2—C3	1.5268 (19)	C3—H8	1.00 (3)
C2—H1	0.93 (2)	C4—O3	1.2161 (19)
N1—C5	1.4927 (19)	C4—O4	1.3157 (18)
N1—H2	0.89 (3)	O4—H9	0.82 (4)
N1—H3	0.84 (3)	OW—H1W	0.87 (4)
C5—H4	0.96 (3)	OW—H2W	0.83 (3)
O1—C1—O2	127.02 (14)	N1—C5—H5	109.5 (17)
O1—C1—C2	116.01 (12)	H4—C5—H5	115 (2)
O2—C1—C2	116.95 (13)	N1—C5—H6	108.4 (16)
N1—C2—C3	110.45 (11)	H4—C5—H6	111 (3)
N1—C2—C1	109.32 (12)	H5—C5—H6	105 (2)
C3—C2—C1	110.93 (11)	C4—C3—C2	110.71 (11)
N1—C2—H1	106.3 (13)	C4—C3—H7	106.9 (16)
C3—C2—H1	110.0 (16)	C2—C3—H7	112.7 (16)
C1—C2—H1	109.7 (16)	C4—C3—H8	108.9 (19)
C5—N1—C2	112.81 (11)	C2—C3—H8	107.8 (17)
C5—N1—H2	105.1 (16)	H7—C3—H8	110 (2)
C2—N1—H2	110.0 (16)	O3—C4—O4	123.78 (14)
C5—N1—H3	109.8 (15)	O3—C4—C3	122.17 (14)
C2—N1—H3	112.0 (15)	O4—C4—C3	114.05 (12)
H2—N1—H3	107 (2)	C4—O4—H9	107 (2)
N1—C5—H4	108.5 (17)	H1W—OW—H2W	103 (3)
O1—C1—C2—N1	159.02 (12)	C1—C2—N1—C5	−95.90 (14)
O2—C1—C2—N1	−22.54 (17)	N1—C2—C3—C4	−71.80 (14)
O1—C1—C2—C3	−78.94 (15)	C1—C2—C3—C4	166.83 (11)
O2—C1—C2—C3	99.49 (15)	C2—C3—C4—O3	−11.94 (19)
C3—C2—N1—C5	141.77 (13)	C2—C3—C4—O4	167.77 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
OW—H1W···O1^i	0.87 (4)	1.87 (5)	2.7337 (15)	169 (4)
OW—H2W···O1^ii	0.83 (3)	1.92 (3)	2.7472 (17)	175 (3)
O4—H9···O2^i	0.82 (4)	1.77 (4)	2.5761 (18)	171 (3)
N1—H2···O2	0.89 (3)	2.18 (3)	2.6658 (18)	114 (2)
N1—H2···OW^iii	0.89 (3)	2.18 (3)	2.9596 (18)	146 (2)
N1—H3···OW^iv	0.84 (3)	2.00 (2)	2.7931 (17)	158 (2)

Symmetry codes: (i) x, y, z+1; (ii) x, −y, z+1/2; (iii) x−1/2, y+1/2, z−1; (iv) x−1/2, −y+1/2, z−1/2.