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In the title compound, C3H8NO2+·C2Cl3O2, the β-alanine mol­ecule exists in the cationic form, with a positively charged amino group and an uncharged carboxyl­ic acid group. The tri­chloro­acetic acid mol­ecule exists in the anionic state. The structure is stabilized by a three-dimensional network of O—H...O, N—H...O and N—H...Cl interactions. There are no direct hydrogen-bonded interactions between the tri­chloro­acetate anions. The nature of the interactions between individual mol­ecules is similar to that in DL-valinium tri­chloro­acetate.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803001107/wn6133sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803001107/wn6133Isup2.hkl
Contains datablock I

CCDC reference: 204706

Key indicators

  • Single-crystal X-ray study
  • T = 105 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.045
  • wR factor = 0.104
  • Data-to-parameter ratio = 20.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Amber Alert Alert Level B:
DIFMX_01 Alert B The maximum difference density is > 0.1*ZMAX*1.00 _refine_diff_density_max given = 1.745 Test value = 1.700
Yellow Alert Alert Level C:
DIFMN_02 Alert C The minimum difference density is < -0.1*ZMAX*0.75 _refine_diff_density_min given = -1.394 Test value = -1.275 DIFMN_03 Alert C The minimum difference density is < -0.1*ZMAX*0.75 The relevant atom site should be identified. DIFMX_02 Alert C The minimum difference density is > 0.1*ZMAX*0.75 The relevant atom site should be identified.
0 Alert Level A = Potentially serious problem
1 Alert Level B = Potential problem
3 Alert Level C = Please check

Comment top

Precise X-ray crystallographic investigations on amino acid–carboxylic acid complexes have provided a wealth of information regarding intermolecular interactions and biomolecular aggregation patterns that might well have occurred in prebiotic polymerization (Vijayan, 1988; Prasad & Vijayan, 1993). The crystal structures of β-alanine (Papavinasam et al., 1986), β-alaninium maleate (Rajagopal et al., 2001), bis(β-alanine) hydrogen nitrate (Sridhar et al., 2001), β-alaninium perchlorate (Pandiarajan et al., 2001), β-alaninium oxalate hemihydrate (Krishnakumar et al., 2002), DL-valinium trichloroacetate (Rajagopal et al., 2002) and DL-methioninium trichloroacetate (Rajagopal et al., 2003) have already been reported. A brief survey of the Cambridge Structural Database (Allen, 2002) revealed a scarcity of precise crystallographic data on amino acid–halogenoacetic acid complexes. We report here the crystal structure of a complex of β-alanine with trichloroacetic acid, namely β-alaninium trichloroacetate, (I). β-Alanine (3-aminopropionic acid) is the only naturally occurring β-amino acid and is a component of the naturally occurring peptides carnosine and anserine, and also of pantothenic acid. Trichloroacetic acid is an excellent medicine for people who have dynamic wrinkles.

Fig. 1 shows the molecular structure of (I) with the atom-numbering scheme. The β-alanine molecule in (I) exists in the cationic form, with a positively charged amino group and an uncharged carboxylic acid group. The trichloroacetic acid molecule exists as an anion. The asymmetric unit of (I) consists of one β-alanininium residue and a trichloroacetate anion. The backbone conformation angles ψ1 and ψ2 are 22.3 (3) and −159.62 (1)°, respectively, for the alaninium residue. These are significantly different from the values reported for β-alanine (25.3 and −177.8°), β-alaninium oxalate hemihydrate [8.3 (2) and −173.0 (2)°] and β-alaninium perchlorate [8.0 (4) and −171.5 (3)°], but are in good agreement with the values reported for β-alaninium maleate [24.6 (4) and −155.8 (2)°]. The straight-chain conformation angle χ1 is in the gauche II form [−58.9 (2)°], as was also observed in β-alaninium perchlorate [−65.0 (3)°]. The straight-chain conformation angles for β-alanine, β-alaninium maleate and β-alaninium oxalate hemihydrate are −154.8, −177.4 (2) and 77.0 (2)° respectively, indicating different conformations.

Fig. 2 shows the packing of molecules of (I), viewed down the a axis. In the crystal, the alanine and trichloroacetic acid molecules are alternately linked by O—H···O and N—H···O hydrogen bonds to form infinite one-dimensional chains along [110]. The glide-related chains are interlinked by N—H···O hydrogen bonds to form an infinite two-dimensional network parallel to (001), similar to that in DL-valinium trichloroacetate. The trichloroacetate ions do not have direct hydrogen-bonded interactions among themselves. The β-alaninium ions link trichloroacetate ions through bifurcated N—H···O hydrogen bonds. The O—H···O, N—H···O and N—H···Cl interactions that exist between the trichloroacetate anion and the alaninium residue play an important role in stabilizing the structure. A short contact between Cl1 and Cl2(x − 1/2, −y + 1/2, z − 1/2) of 3.428 (1) Å is also observed in the structure. Strikingly, the title compound, (I), β-alaninium maleate and β-alaninium perchlorate all crystallize in the same space group, but the crystal packings are distinctly different.

Experimental top

Colourless plate-shaped single crystals of (I) were grown from a saturated aqueous solution containing β-alanine and trichloroacetic acid in a 1:1 stoichiometric ratio. The density was determined by the flotation method using a liquid mixture of xylene and bromoform.

Refinement top

All the H atoms were positioned geometrically and were allowed to ride on their respective parent atoms with SHELXL97 (Sheldrick, 1997) defaults for bond lengths and thermal parameters. The residual density peaks in the final difference Fourier map (1.745 and −1.394 e Å−3) indicate ripples around the Cl atoms and have no structural significance.

Computing details top

Data collection: SMART-NT (Bruker, 1999); cell refinement: SMART-NT; data reduction: SAINT-NT (Bruker, 1999); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1999); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing the atom-numbering scheme and 50% probability displacement ellipsoids.
[Figure 2] Fig. 2. Packing of the molecules of (I), viewed down the a axis.
β-alaninium trichloroacetate top
Crystal data top
C3H8NO2+·C2Cl3O2F(000) = 512
Mr = 252.47Dx = 1.702 Mg m3
Dm = 1.69 Mg m3
Dm measured by floatation in a mixture of xylene and bromoform
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 1024 reflections
a = 6.8049 (14) Åθ = 3–28°
b = 21.100 (4) ŵ = 0.91 mm1
c = 6.8968 (14) ÅT = 105 K
β = 95.75 (3)°Plate, colourless
V = 985.3 (3) Å30.4 × 0.3 × 0.3 mm
Z = 4
Data collection top
Bruker SMART
diffractometer
2442 independent reflections
Radiation source: fine-focus sealed tube2350 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.018
Detector resolution: 8 pixels mm-1θmax = 28.3°, θmin = 3.1°
ω scansh = 99
Absorption correction: multi-scan
(SADABS; Bruker, 1998)
k = 2828
Tmin = 0.694, Tmax = 0.761l = 99
12338 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046H-atom parameters constrained
wR(F2) = 0.104 w = 1/[σ2(Fo2) + (0.031P)2 + 2.3578P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
2442 reflectionsΔρmax = 1.75 e Å3
119 parametersΔρmin = 1.39 e Å3
0 restraintsExtinction correction: SHELXL97
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0067 (14)
Crystal data top
C3H8NO2+·C2Cl3O2V = 985.3 (3) Å3
Mr = 252.47Z = 4
Monoclinic, P21/nMo Kα radiation
a = 6.8049 (14) ŵ = 0.91 mm1
b = 21.100 (4) ÅT = 105 K
c = 6.8968 (14) Å0.4 × 0.3 × 0.3 mm
β = 95.75 (3)°
Data collection top
Bruker SMART
diffractometer
2442 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1998)
2350 reflections with I > 2σ(I)
Tmin = 0.694, Tmax = 0.761Rint = 0.018
12338 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0460 restraints
wR(F2) = 0.104H-atom parameters constrained
S = 1.05Δρmax = 1.75 e Å3
2442 reflectionsΔρmin = 1.39 e Å3
119 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
xyzUiso*/Ueq
Cl10.15023 (8)0.16912 (3)0.29334 (9)0.02548 (15)
Cl20.48640 (12)0.19390 (3)0.56369 (12)0.0474 (2)
Cl30.50623 (14)0.21729 (3)0.15200 (16)0.0590 (3)
O10.2626 (2)0.04083 (8)0.6603 (3)0.0228 (3)
H10.30010.00440.64450.034*
O20.0002 (3)0.00889 (8)0.7582 (3)0.0297 (4)
O30.6033 (2)0.07340 (8)0.4162 (2)0.0236 (3)
O40.4179 (2)0.07398 (8)0.1273 (2)0.0218 (3)
N10.3247 (3)0.06472 (9)0.8289 (3)0.0183 (4)
H1A0.41470.06650.91400.027*
H1B0.28290.02500.81970.027*
H1C0.37830.07780.71280.027*
C10.1540 (3)0.10643 (10)0.8966 (3)0.0190 (4)
H1D0.09780.09261.02440.023*
H1E0.20050.14960.90860.023*
C20.0051 (3)0.10514 (10)0.7568 (3)0.0204 (4)
H2A0.04970.12160.63150.024*
H2B0.11210.13300.80610.024*
C30.0876 (3)0.03971 (10)0.7278 (3)0.0180 (4)
C40.4108 (3)0.16624 (10)0.3246 (3)0.0219 (4)
C50.4842 (3)0.09696 (10)0.2860 (3)0.0177 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0223 (3)0.0249 (3)0.0288 (3)0.0054 (2)0.0004 (2)0.0014 (2)
Cl20.0459 (4)0.0352 (4)0.0552 (4)0.0152 (3)0.0237 (3)0.0292 (3)
Cl30.0700 (6)0.0211 (3)0.0958 (7)0.0015 (3)0.0566 (5)0.0146 (4)
O10.0152 (7)0.0206 (7)0.0332 (9)0.0007 (6)0.0059 (6)0.0056 (6)
O20.0298 (9)0.0155 (8)0.0465 (11)0.0005 (6)0.0175 (8)0.0012 (7)
O30.0240 (8)0.0240 (8)0.0229 (8)0.0067 (6)0.0033 (6)0.0041 (6)
O40.0252 (8)0.0204 (7)0.0204 (7)0.0020 (6)0.0060 (6)0.0029 (6)
N10.0156 (8)0.0193 (8)0.0204 (8)0.0018 (6)0.0039 (6)0.0016 (7)
C10.0160 (9)0.0182 (9)0.0224 (10)0.0005 (7)0.0008 (8)0.0039 (8)
C20.0155 (9)0.0153 (9)0.0309 (11)0.0004 (7)0.0054 (8)0.0007 (8)
C30.0156 (9)0.0179 (9)0.0203 (10)0.0009 (7)0.0010 (7)0.0001 (8)
C40.0218 (10)0.0158 (10)0.0285 (11)0.0022 (8)0.0038 (8)0.0026 (8)
C50.0168 (9)0.0151 (9)0.0222 (10)0.0013 (7)0.0076 (7)0.0013 (7)
Geometric parameters (Å, º) top
Cl1—C41.765 (2)N1—H1B0.8900
Cl2—C41.776 (2)N1—H1C0.8900
Cl3—C41.776 (2)C1—C21.521 (3)
O1—C31.321 (3)C1—H1D0.9700
O1—H10.8200C1—H1E0.9700
O2—C31.214 (3)C2—C31.511 (3)
O3—C51.251 (3)C2—H2A0.9700
O4—C51.240 (3)C2—H2B0.9700
N1—C11.494 (3)C4—C51.576 (3)
N1—H1A0.8900
C3—O1—H1109.5C3—C2—H2B108.9
C1—N1—H1A109.5C1—C2—H2B108.9
C1—N1—H1B109.5H2A—C2—H2B107.7
H1A—N1—H1B109.5O2—C3—O1123.4 (2)
C1—N1—H1C109.5O2—C3—C2123.63 (19)
H1A—N1—H1C109.5O1—C3—C2112.95 (18)
H1B—N1—H1C109.5C5—C4—Cl1110.05 (15)
N1—C1—C2111.84 (17)C5—C4—Cl2113.23 (16)
N1—C1—H1D109.2Cl1—C4—Cl2107.24 (13)
C2—C1—H1D109.2C5—C4—Cl3107.79 (15)
N1—C1—H1E109.2Cl1—C4—Cl3109.11 (13)
C2—C1—H1E109.2Cl2—C4—Cl3109.36 (12)
H1D—C1—H1E107.9O4—C5—O3129.1 (2)
C3—C2—C1113.44 (18)O4—C5—C4114.73 (19)
C3—C2—H2A108.9O3—C5—C4116.15 (19)
C1—C2—H2A108.9
N1—C1—C2—C358.9 (2)Cl3—C4—C5—O465.6 (2)
C1—C2—C3—O222.3 (3)Cl1—C4—C5—O3128.13 (18)
C1—C2—C3—O1159.62 (18)Cl2—C4—C5—O38.1 (2)
Cl1—C4—C5—O453.3 (2)Cl3—C4—C5—O3112.97 (19)
Cl2—C4—C5—O4173.27 (16)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O3i0.821.832.649 (2)173
N1—H1A···O4ii0.891.962.840 (2)172
N1—H1B···O20.892.142.785 (3)129
N1—H1B···O4iii0.892.323.016 (2)135
N1—H1C···Cl2iv0.892.783.458 (2)134
N1—H1C···O3iv0.892.042.846 (3)150
Symmetry codes: (i) x+1, y, z+1; (ii) x1, y, z+1; (iii) x, y, z+1; (iv) x1, y, z.

Experimental details

Crystal data
Chemical formulaC3H8NO2+·C2Cl3O2
Mr252.47
Crystal system, space groupMonoclinic, P21/n
Temperature (K)105
a, b, c (Å)6.8049 (14), 21.100 (4), 6.8968 (14)
β (°) 95.75 (3)
V3)985.3 (3)
Z4
Radiation typeMo Kα
µ (mm1)0.91
Crystal size (mm)0.4 × 0.3 × 0.3
Data collection
DiffractometerBruker SMART
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 1998)
Tmin, Tmax0.694, 0.761
No. of measured, independent and
observed [I > 2σ(I)] reflections
12338, 2442, 2350
Rint0.018
(sin θ/λ)max1)0.668
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.104, 1.05
No. of reflections2442
No. of parameters119
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.75, 1.39

Computer programs: SMART-NT (Bruker, 1999), SMART-NT, SAINT-NT (Bruker, 1999), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 1999), SHELXL97.

Selected geometric parameters (Å, º) top
Cl1—C41.765 (2)O2—C31.214 (3)
Cl2—C41.776 (2)O3—C51.251 (3)
Cl3—C41.776 (2)O4—C51.240 (3)
O1—C31.321 (3)
O2—C3—O1123.4 (2)O4—C5—O3129.1 (2)
O2—C3—C2123.63 (19)O4—C5—C4114.73 (19)
O1—C3—C2112.95 (18)O3—C5—C4116.15 (19)
N1—C1—C2—C358.9 (2)C1—C2—C3—O1159.62 (18)
C1—C2—C3—O222.3 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O3i0.821.832.649 (2)173
N1—H1A···O4ii0.891.962.840 (2)172
N1—H1B···O20.892.142.785 (3)129
N1—H1B···O4iii0.892.323.016 (2)135
N1—H1C···Cl2iv0.892.783.458 (2)134
N1—H1C···O3iv0.892.042.846 (3)150
Symmetry codes: (i) x+1, y, z+1; (ii) x1, y, z+1; (iii) x, y, z+1; (iv) x1, y, z.
 

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