N-Di­chloro­acetyl-DL-valine–water (1/0.41)

In the title compound, C₇H₁₁Cl₂NO₃·0.41H₂O, the D and L forms are linked by N—H...O and C—H...O hydrogen bonds to form centrosymmetric dimers. These hydrogen bonds form rings of graph-set motif R₂²(14), R₂²(10) and R₂¹(6). The dimers are linked together by O—H...O hydrogen bonds to form two-dimensional molecular networks.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• Disorder in solvent or counterion
• R factor = 0.040
• wR factor = 0.095
• Data-to-parameter ratio = 17.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_302  Alert C Anion/Solvent Disorder .........................      41.00 Perc.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

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S1. Comment

Valine is an important amino acid and the structures of L-valine (Torii & Iitaka, 1970), DL-Valine (Mallikarjunan & Rao, 1969) L-valine hydrochloride (Ando et al., 1967), DL-valine hydrochloride (Blasio et al., 1977) and L-valine L-valinium perchlorate monohydrate (Pandiarajan et al., 2001) have been reported. The structures of the model peptides N-acetyl-D,L-valine (Carroll et al., 1990) and N-carboxy-L-valine anhydride (Kanazawa et al., 1984) have also been reported. We report here the structure of the title compound, (I), a valine derivative.

The C1—C2—N1—C3 torsion angle, which describes the planarity of the peptide unit, is 176.95 (17)°. The torsion angle ϕ₁ (C4—C3—N1—C2) is −128.83 (19)°. The torsion angles around the C3—C4 and C3—C5 bonds (Fig.1 and Table 1) are comparable to those observed for DL-valine hydrochloride (Blasio et al., 1977). In the crystal structure, the enantiomers are linked by centrosymmetric N1—H1A···O3ⁱ and C1—H1···O3ⁱ hydrogen bonds to form dimers. In a dimer, the N—H···O and C—H···O hydrogen bonds form rings of graph-set motif (Etter, 1990) R₂²(10) and R₂²(14), respectively. In addition, the N—H···O and C—H···O hydrogen bonds together form a ring of graph-set motif R₂¹(6) (Fig. 2). The dimers are linked together by O2—H2···O1ⁱⁱ hydrogen bonds to form two-dimensional molecular networks parallel to the bc plane. [Symmetry codes are given in Table 2.]

S2. Experimental

L-valine and dichloroacetic acid in equal molar ratio were mixed together, and kept at 443 K for 5 h. The resulting solution was kept at room temperature overnight to obtain the title compound. Single crystals suitable for an X-ray diffraction study were obtained by recrystallizing the title compound from 70% aqueous ethanol.

S3. Refinement

A solvent water O atom with partial occupancy was found in the crystal. The occupancy of this atom was initially refined and later fixed at 0.41(su?). This atom lies at a distance of 2.239 (5) Å from O2(1 − x, y − 1/2, 1/2 − z). The positional and isotropic displacement parameters of solvent water H atoms were refined [O—H = 0.84 (5) or 0.93 Å and U_iso(H) = 0.08 (2) or 0.034 (14) Ų]. All other H atoms were fixed geometrically and allowed to ride on their parent atoms, with SHELXTL (Bruker, 2000) defaults for the bond distances and isotropic displacement parameters.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); 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.

Figures

	Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. A view of the hydrogen-bonded network parallel to the bc plane. Solvent water molecules with partial occupancy have been omitted.

2-(2,2-dichloroacetylamino)-3-methyl butyric acid hydrate (1/0.41)

Crystal data

C7H11Cl2NO3·0.41H2O	F(000) = 488.4
Mr = 235.45	Dx = 1.403 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 785 reflections
a = 9.298 (2) Å	θ = 2.6–19.5°
b = 9.011 (1) Å	µ = 0.57 mm^−1
c = 13.990 (2) Å	T = 293 K
β = 108.07 (1)°	Prism, colorless
V = 1114.3 (3) Å^3	0.28 × 0.15 × 0.15 mm
Z = 4

Data collection

Bruker Smart Apex CCD area-detector diffactometer diffractometer	2417 independent reflections
Radiation source: sealed tube	1788 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.016
ϕ and ω scans	θmax = 27.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −11→11
Tmin = 0.90, Tmax = 0.91	k = −11→11
6265 measured reflections	l = −17→17

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.095	H atoms treated by a mixture of independent and constrained refinement
S = 1.14	w = 1/[σ^2(Fo^2) + (0.0388P)^2 + 0.1217P] where P = (Fo^2 + 2Fc^2)/3
2417 reflections	(Δ/σ)max < 0.001
135 parameters	Δρmax = 0.30 e Å^−3
0 restraints	Δρmin = −0.16 e Å^−3

Special details

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	Occ. (<1)
C1	1.0096 (3)	0.4937 (2)	0.23560 (15)	0.0468 (5)
H1	1.0378	0.4104	0.2827	0.056*
C2	0.8755 (2)	0.5754 (2)	0.25229 (14)	0.0371 (4)
C3	0.7364 (2)	0.6161 (2)	0.37047 (15)	0.0418 (5)
H3	0.6974	0.6997	0.3250	0.050*
C4	0.8014 (2)	0.6775 (2)	0.47481 (14)	0.0382 (4)
C5	0.6029 (3)	0.5107 (3)	0.36352 (18)	0.0574 (6)
H5	0.5276	0.5670	0.3844	0.069*
C6	0.5291 (3)	0.4636 (3)	0.25586 (18)	0.0610 (7)
H6A	0.4460	0.3983	0.2523	0.091*
H6B	0.6018	0.4130	0.2317	0.091*
H6C	0.4926	0.5497	0.2151	0.091*
C7	0.6482 (3)	0.3819 (3)	0.43219 (19)	0.0630 (7)
H7A	0.5618	0.3195	0.4254	0.094*
H7B	0.6869	0.4164	0.5003	0.094*
H7C	0.7251	0.3263	0.4154	0.094*
Cl1	0.96075 (7)	0.42561 (7)	0.11181 (4)	0.0600 (2)
Cl2	1.16245 (7)	0.61549 (7)	0.25804 (5)	0.0675 (2)
N1	0.85305 (17)	0.54462 (17)	0.33871 (11)	0.0348 (4)
H1A	0.9099	0.4796	0.3776	0.042*
O1	0.80101 (17)	0.66421 (17)	0.19258 (11)	0.0532 (4)
O2	0.70716 (17)	0.76853 (17)	0.49730 (11)	0.0552 (4)
H2	0.7381	0.7880	0.5575	0.083*
O3	0.92209 (17)	0.64560 (16)	0.53092 (10)	0.0496 (4)
O4	0.3307 (5)	0.5128 (5)	0.0274 (3)	0.0485 (9)	0.41
H4A	0.237 (8)	0.485 (7)	0.032 (5)	0.08 (2)*	0.41
H4B	0.313 (5)	0.586 (6)	−0.012 (4)	0.034 (14)*	0.41

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0625 (14)	0.0456 (12)	0.0385 (12)	0.0084 (10)	0.0246 (11)	0.0012 (9)
C2	0.0382 (11)	0.0431 (11)	0.0286 (10)	−0.0016 (9)	0.0083 (9)	0.0065 (9)
C3	0.0398 (12)	0.0434 (11)	0.0438 (12)	0.0045 (9)	0.0154 (10)	−0.0023 (9)
C4	0.0441 (12)	0.0408 (11)	0.0351 (11)	0.0033 (9)	0.0200 (10)	0.0002 (9)
C5	0.0562 (15)	0.0645 (15)	0.0647 (16)	−0.0009 (12)	0.0382 (13)	−0.0153 (13)
C6	0.0550 (15)	0.0699 (16)	0.0694 (17)	−0.0018 (12)	0.0358 (13)	−0.0185 (13)
C7	0.0644 (17)	0.0661 (16)	0.0744 (17)	−0.0038 (12)	0.0447 (14)	−0.0146 (13)
Cl1	0.0652 (4)	0.0667 (4)	0.0613 (4)	0.0042 (3)	0.0387 (3)	−0.0131 (3)
Cl2	0.0562 (4)	0.0684 (4)	0.0874 (5)	0.0003 (3)	0.0362 (4)	−0.0003 (3)
N1	0.0380 (9)	0.0420 (9)	0.0275 (8)	0.0100 (7)	0.0145 (7)	0.0049 (6)
O1	0.0620 (10)	0.0590 (9)	0.0444 (9)	0.0095 (8)	0.0248 (8)	0.0104 (7)
O2	0.0558 (9)	0.0698 (10)	0.0402 (9)	0.0054 (8)	0.0152 (7)	−0.0146 (7)
O3	0.0515 (10)	0.0519 (9)	0.0402 (8)	0.0091 (7)	0.0067 (7)	−0.0078 (7)
O4	0.051 (3)	0.054 (2)	0.036 (2)	0.0013 (19)	0.0064 (18)	0.0068 (18)

Geometric parameters (Å, º)

C1—C2	1.527 (3)	C5—C6	1.509 (3)
C1—Cl2	1.745 (2)	C5—H5	0.98
C1—Cl1	1.759 (2)	C6—H6A	0.96
C1—H1	0.98	C6—H6B	0.96
C2—O1	1.208 (2)	C6—H6C	0.96
C2—N1	1.319 (2)	C7—H7A	0.96
C3—N1	1.445 (2)	C7—H7B	0.96
C3—C4	1.502 (3)	C7—H7C	0.96
C3—C5	1.542 (3)	N1—H1A	0.86
C3—H3	0.98	O2—H2	0.82
C4—O3	1.188 (2)	O4—H4A	0.93 (7)
C4—O2	1.308 (2)	O4—H4B	0.84 (5)
C5—C7	1.482 (3)
C2—C1—Cl2	109.11 (14)	C7—C5—H5	107.3
C2—C1—Cl1	110.19 (15)	C6—C5—H5	107.3
Cl2—C1—Cl1	110.11 (11)	C3—C5—H5	107.3
C2—C1—H1	109.1	C5—C6—H6A	109.5
Cl2—C1—H1	109.1	C5—C6—H6B	109.5
Cl1—C1—H1	109.1	H6A—C6—H6B	109.5
O1—C2—N1	123.61 (18)	C5—C6—H6C	109.5
O1—C2—C1	122.27 (17)	H6A—C6—H6C	109.5
N1—C2—C1	114.06 (17)	H6B—C6—H6C	109.5
N1—C3—C4	110.41 (16)	C5—C7—H7A	109.5
N1—C3—C5	111.88 (16)	C5—C7—H7B	109.5
C4—C3—C5	111.21 (17)	H7A—C7—H7B	109.5
N1—C3—H3	107.7	C5—C7—H7C	109.5
C4—C3—H3	107.7	H7A—C7—H7C	109.5
C5—C3—H3	107.7	H7B—C7—H7C	109.5
O3—C4—O2	123.97 (18)	C2—N1—C3	122.38 (16)
O3—C4—C3	124.48 (18)	C2—N1—H1A	118.8
O2—C4—C3	111.54 (17)	C3—N1—H1A	118.8
C7—C5—C6	112.1 (2)	C4—O2—H2	109.5
C7—C5—C3	112.3 (2)	H4A—O4—H4B	105 (5)
C6—C5—C3	110.10 (18)
Cl2—C1—C2—O1	75.0 (2)	N1—C3—C5—C7	63.7 (2)
Cl1—C1—C2—O1	−46.0 (2)	C4—C3—C5—C7	−60.3 (2)
Cl2—C1—C2—N1	−102.43 (17)	N1—C3—C5—C6	−62.1 (2)
Cl1—C1—C2—N1	136.57 (16)	C4—C3—C5—C6	173.93 (18)
N1—C3—C4—O3	−14.7 (3)	O1—C2—N1—C3	−0.5 (3)
C5—C3—C4—O3	110.1 (2)	C1—C2—N1—C3	176.95 (17)
N1—C3—C4—O2	166.68 (16)	C4—C3—N1—C2	−128.83 (19)
C5—C3—C4—O2	−68.5 (2)	C5—C3—N1—C2	106.7 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O3^i	0.86	2.03	2.876 (2)	169
O2—H2···O1^ii	0.82	1.85	2.667 (2)	178
C1—H1···O3^i	0.98	2.57	3.371 (3)	139
C3—H3···O1	0.98	2.36	2.769 (3)	104

Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) x, −y+3/2, z+1/2.