Acta Cryst.(2002). E58, o279±o281 DOI: 10.1107/S1600536802002751 K. Rajagopalet al. C5H12NO2+C2Cl3O2ÿ
o279
organic papers
Acta Crystallographica Section E
Structure Reports
Online
ISSN 1600-5368
DL
-Valinium trichloroacetate at 123 K
K. Rajagopal,aR. V.
Krishnakumar,bM. Subha
Nandhini,cA. Mostadd and
S. Natarajanc*
aDepartment of Physics, Saraswathi Narayanan College, Madurai 625 022, India,bDepartment of Physics, Thiagarajar College, Madurai 625 009, India,cDepartment of Physics, Madurai Kamaraj University, Madurai 625 021, India, anddDepartment of Chemistry, University of Oslo, PO Box 1033 Blindern, N-0315 Oslo 3, Norway
Correspondence e-mail: [email protected]
Key indicators Single-crystal X-ray study T= 123 K
Mean(C±C) = 0.002 AÊ Rfactor = 0.033 wRfactor = 0.083
Data-to-parameter ratio = 19.2
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
In the title compound, C5H12NO2+C2Cl3O2ÿ, the valine
molecule is in a cationic state and the trichloroacetic acid is in the anionic state. In the crystal, the intermolecular NÐ H O and OÐH O hydrogen bonds link the molecules to form an in®nite two-dimensional network parallel to (001).
Comment
In our laboratory, we have been elucidating the crystal structures of proton-transfer complexes of the type A.B, whereAis an amino acid andBis a carboxylic acid which is believed to have existed in the pre-biotic earth (Miller & Orgel, 1974; Kvenvoldenet al., 1971). A brief survey of the Cambridge Structural Database (Allen & Kennard, 1993) revealed a scarcity of precise crystallographic data on amino acid±halogenoacetic acid complexes. We report here the crystal structure of a complex ofdl-valine with trichloroacetic acid, namely, dl-valinium trichloroacetate, (I). Systematic X-ray investigations of such compounds are expected to throw light on the importance of halogen±halogen interactions on biomolecular aggregation patterns. The crystal structure of a complex of a dipeptide with trichloroacetic acid, l -phenyl-alanylglycine trichloroacetate has already been reported (Mitra & Subramanian, 1993). The crystal structure of tri-chloroacetic acid remains unknown.
In (I), the valine molecule is in a cationic state with a positively charged amino group and an uncharged carboxylic acid group. The trichloroacetic acid exists in the anionic state with a negatively charged carboxylate group (Fig. 1). The carboxylate group of valine is planar, and the amino N atom deviates from this plane by 0.528 (1) AÊ, leading to the twisting of the CÐN bond out of the plane of the carboxyl group by 21.9 (1). The conformation of the valine molecule,
deter-mined by the internal rotation angles 2 [ÿ22.4 (2)], 11
[ÿ162.9 (1)] and 12 [70.9 (1)], agrees well with the values
observed for the monoclinic form ofdl-valine (Mallikarjunan & Rao, 1969) and for the triclinic form ofdl-valine (Dalhus &
organic papers
o280
K. Rajagopalet al. C5H12NO2+C2Cl3O2ÿ Acta Cryst.(2002). E58, o279±o281GoÈrbitz, 1996). However, in dl-valinium maleate (Alagar et al., 2001), 11 [57.1 (2)] deviates signi®cantly from that
observed in the present study. In the crystal, the valine and the trichloroacetic acid molecules are alternately linked by OÐ H O and NÐH O hydrogen bonds to form in®nite one-dimensional chains along [110]. The inversion-related chains are interlinked by NÐH O hydrogen bonds to form an in®nite two-dimensional network parallel to (001). In this network, the d and l isomers exist as centrosymmetrically hydrogen-bonded dimers (Table 2).
Experimental
Single crystals of (I) were grown from a saturated aqueous solution containing dl-valine and trichloroacetic acid in the stoichiometric ratio 1:1.
Crystal data
C5H12NO2+C2Cl3O2ÿ
Mr= 280.53 Triclinic,P1
a= 7.2380 (14) AÊ
b= 8.4150 (17) AÊ
c= 10.303 (2) AÊ = 106.50 (3) = 97.50 (3) = 95.80 (3) V= 590.2 (2) AÊ3
Z= 2
Dx= 1.578 Mg mÿ3
Dm= 1.60 Mg mÿ3
Dmmeasured by ¯otation in bromoform and xylene MoKradiation Cell parameters from 1024
re¯ections = 2.5±23.0 = 0.77 mmÿ1
T= 123 (2) K Prismatic, colourless 0.500.400.15 mm
Data collection
Bruker SMART CCD diffractometer !scans
Absorption correction: multi-scan (SADABS; Bruker, 1998)
Tmin= 0.68,Tmax= 0.89 7923 measured re¯ections
3537 independent re¯ections 3204 re¯ections withI> 2(I)
Rint= 0.019 max= 30.7
h=ÿ9!10
k=ÿ11!12
l=ÿ14!14
Re®nement
Re®nement onF2
R[F2> 2(F2)] = 0.033
wR(F2) = 0.083
S= 1.04 3537 re¯ections 184 parameters
All H-atom parameters re®ned
w= 1/[2(F
o2) + (0.0346P)2 + 0.3602P]
whereP= (Fo2+ 2Fc2)/3 (/)max< 0.001
max= 0.61 e AÊÿ3
min=ÿ0.59 e AÊÿ3
Table 1
Selected geometric parameters (AÊ,).
Cl1ÐC7 1.7747 (14)
Cl2ÐC7 1.7580 (14)
Cl3ÐC7 1.7749 (17)
O1ÐC1 1.3150 (16)
O2ÐC1 1.2136 (17)
O3ÐC6 1.2538 (15)
O4ÐC6 1.2300 (15)
NÐC2 1.4953 (17)
C1ÐC2 1.5197 (17)
C2ÐC3 1.5320 (19)
C3ÐC5 1.525 (2)
C3ÐC4 1.531 (2)
C6ÐC7 1.5578 (18)
O2ÐC1ÐO1 125.57 (11)
O2ÐC1ÐC2 122.27 (11)
O1ÐC1ÐC2 112.15 (11)
NÐC2ÐC1 107.11 (11)
NÐC2ÐC3 111.25 (10)
C1ÐC2ÐC3 112.46 (10)
C5ÐC3ÐC4 111.94 (15)
C5ÐC3ÐC2 112.10 (11)
C4ÐC3ÐC2 111.28 (13)
O4ÐC6ÐO3 127.11 (12)
O4ÐC6ÐC7 117.64 (11)
O3ÐC6ÐC7 115.22 (11)
C6ÐC7ÐCl2 112.03 (9)
C6ÐC7ÐCl1 111.82 (9)
Cl2ÐC7ÐCl1 108.40 (8)
C6ÐC7ÐCl3 105.78 (9)
Cl2ÐC7ÐCl3 109.62 (8)
Cl1ÐC7ÐCl3 109.13 (8)
Table 2
Hydrogen-bonding geometry (AÊ,).
DÐH A DÐH H A D A DÐH A
O1ÐH10 O3 0.89 (3) 1.72 (3) 2.601 (2) 169 (2) NÐH2N O4i 0.84 (2) 1.93 (2) 2.761 (2) 169.6 (19) NÐH1N O3ii 0.89 (2) 1.94 (2) 2.804 (2) 163.6 (19) NÐH3N O2iii 0.90 (2) 2.00 (2) 2.871 (2) 162.5 (17) Symmetry codes: (i)xÿ1;yÿ1;z; (ii) 1ÿx;1ÿy;2ÿz; (iii)ÿx;1ÿy;2ÿz.
All the H atoms were located from a difference Fourier map and were included in the re®nement with isotropic displacement para-meters. The ranges of CÐH and NÐH bond lengths are 0.96 (3)± 0.98 (2) AÊ and 0.84 (2)±0.90 (2) AÊ, respectively, and the OÐH distance is 0.89 (3) AÊ.
Figure 2
Packing of the molecules of (I), viewed down theaaxis.
Figure 1
Data collection: SMART-NT (Bruker, 1999); cell re®nement:
SMART-NT; data reduction:SAINT-NT(Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to re®ne structure: SHELXL97 (Sheldrick, 1997); molecular graphics:PLATON(Spek, 1999); software used to prepare material for publication:SHELXL97.
KR thanks the UGC for the FIP programme. SN and KR also thank the UGC for the DRS programme and the Bio-informatics Centre, Madurai Kamaraj University, for providing the Cambridge Structural Database (Allen & Kennard, 1993).
References
Alagar, M., Krishnakumar, R. V., Mostad, A. & Natarajan, S. (2001).Acta Cryst.E57, o1102±o1104.
Allen, F. H. & Kennard, O. (1993).Chem. Des. Autom. News.8, 1, 31±37. Bruker. (1998).SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Bruker. (1999).SMART-NTand SAINT-NT. Bruker AXS Inc., Madison,
Wisconsin, USA.
Dalhus, B. & GoÈrbitz, C. H. (1996).Acta Cryst.C52, 1759±1761.
Kvenvolden, K. A., Lawless, J. G. & Ponnamperuma, C. (1971).Proc. Natl Acad. Sci. USA,68, 486±490.
Mallikarjunan, M. & Rao, S. T. (1969).Acta Cryst.B25, 296±303.
Miller, S. L. & Orgel, E. L. (1974).The Origins of Life on The Earth, p. 83. New Jersey: Prentice-Hall.
Mitra, S. N. & Subramanian, E. (1993).Curr. Sci.65, 980±983. Sheldrick, G. M. (1990).Acta Cryst.A46, 467±473.
Sheldrick, G. M. (1997).SHELXL97. University of GoÈttingen, Germany. Spek, A. L. (1999). PLATON for Windows, Utrecht University, The
Netherlands.
supporting information
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Acta Cryst. (2002). E58, o279–o281supporting information
Acta Cryst. (2002). E58, o279–o281 [doi:10.1107/S1600536802002751]
DL
-Valinium trichloroacetate at 123
K
K. Rajagopal, R. V. Krishnakumar, M. Subha Nandhini, A. Mostad and S. Natarajan
S1. Comment
In our laboratory, we have been elucidating the crystal structures of proton-transfer complexes of the type A·B, where A
is a amino acid and B is a carboxylic acid which is believed to have existed in the pre-biotic earth (Miller & Orgel, 1974;
Kvenvolden et al., 1971). A brief survey on the Cambridge structural Database Database (Allen & Kennard, 1993)
revealed scarcity of precise crystallographic data on amino acid–halogeno acetic acid complexes. We report here, the
crystal structure of a complex of DL-valine with trichloroacetic acid, namely, DL-valinium trichloroacetate, (I).
Systematic X-ray investigation, on such compounds are expected to throw light on the importance of halogen–halogen
interactions on biomolecular aggregation patterns. The crystal structure of a complex of a dipeptide with trichloroacetic
acid, L-phenylalanylglycine trichloroaceteate is already reported (Mitra & Subramanian, 1993). The crystal structure of
trichloroacetic acid still remains unknown.
In (I), the valine molecule is in a cationic state with a positively charged amino group and an uncharged carboxylic acid
group. The trichloroacetic acid exists in the anionic state with a negatively charged carboxylate group (Fig. 1). The
carboxylate group of valine is planar and the amino nitrogen deviates from this plane by 0.528 (1) Å leading to the
twisting of the C—N bond out of the plane of the carboxyl group by 21.9 (1)°. The conformation of the valine molecule
determined by the internal rotation angles ψ2 [-22.4 (2)], χ11 [-162.9 (1)] and χ12 [70.9 (1)°] agree well with the values
observed for the monoclinic form of DL-valine (Mallikarjunan & Rao, 1969) and for the triclinic form of DL-valine
(Dalhus & Görbitz, 1996). However, in DL-valinium maleate (Alagar et al., 2001), χ11 [57.1 (2)°] deviates siginificantly
from that observed in the present study. In the crystal, the valine and the trichloroacetic acid molecules are alteratively
linked by O—H···O and N—H···O hydrogen bonds to form infinte one-dimensional chains along [110]. The inversion
related chains are interlinked by N—H···O hydrogen bonds to form infinite two-dimensional network parallel to (001). In
this network, the D and L isomers exist as centrosymmetrically hydrogen-bonded dimers (Table 2).
S2. Experimental
Single crystals of (I) were grown from a saturated aqueous solution containing DL-valine and trichloroacetic acid in
stoichiometric ratio.
S3. Refinement
All the H atoms were located from a difference Fourier map and were included in the refinement with isotropic
displacement parameters. The range of C—H and N—H bond lengths are 0.96 (3)–0.98 (2) Å and 0.84 (2)–0.90 (2) Å,
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[image:5.610.123.482.68.321.2]sup-2
Acta Cryst. (2002). E58, o279–o281Figure 1
The molecular structure of (I) with the atom-numbering scheme and 50% probability displacement ellipsoids.
Figure 2
[image:5.610.124.488.358.670.2]supporting information
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Acta Cryst. (2002). E58, o279–o281DL-valinium trichloroacetate
Crystal data
C5H12NO2+·C2Cl3O2−
Mr = 280.53 Triclinic, P1 Hall symbol: -P 1 a = 7.2380 (14) Å b = 8.4150 (17) Å c = 10.303 (2) Å α = 106.50 (3)° β = 97.50 (3)° γ = 95.80 (3)° V = 590.2 (2) Å3
Z = 2
F(000) = 288 Dx = 1.578 Mg m−3
Dm = 1.60 Mg m−3
Dm measured by floatation in bromoform and xylene
Mo Kα radiation, λ = 0.71073 Å Cell parameters from 1024 reflections θ = 2.5–23.0°
µ = 0.77 mm−1
T = 123 K
Prismatic, colourless 0.50 × 0.40 × 0.15 mm
Data collection
Bruker SMART CCD diffractometer
Radiation source: fine-focus sealed tube Graphite monochromator
Detector resolution: 8 pixels mm-1
ω scans
Absorption correction: empirical (using intensity measurements)
(SADABS; Bruker, 1998)
Tmin = 0.68, Tmax = 0.89 7923 measured reflections 3537 independent reflections 3204 reflections with I > 2σ(I) Rint = 0.019
θmax = 30.7°, θmin = 2.6°
h = −9→10 k = −11→12 l = −14→14
Refinement
Refinement on F2 Least-squares matrix: full R[F2 > 2σ(F2)] = 0.033
wR(F2) = 0.083
S = 1.04 3537 reflections 184 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
All H-atom parameters refined w = 1/[σ2(F
o2) + (0.0346P)2 + 0.3602P] where P = (Fo2 + 2Fc2)/3
(Δ/σ)max < 0.001 Δρmax = 0.61 e Å−3 Δρmin = −0.59 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 (Å2)
x y z Uiso*/Ueq
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Acta Cryst. (2002). E58, o279–o281Cl3 0.47752 (6) 0.72657 (7) 0.59258 (4) 0.05099 (13) O1 0.40290 (13) 0.45980 (12) 0.79978 (11) 0.0270 (2) O2 0.23758 (14) 0.54991 (11) 0.97001 (10) 0.02560 (19) O3 0.65035 (13) 0.72929 (12) 0.89273 (11) 0.0263 (2) O4 0.83858 (13) 0.92835 (12) 0.85109 (12) 0.0294 (2) N 0.03102 (15) 0.24810 (14) 0.91265 (12) 0.0222 (2) C1 0.26405 (16) 0.44550 (15) 0.86814 (13) 0.0207 (2) C2 0.13296 (17) 0.28081 (15) 0.80351 (13) 0.0214 (2) C3 −0.00515 (18) 0.28336 (17) 0.67831 (14) 0.0261 (2) C4 0.0915 (3) 0.2638 (3) 0.55220 (18) 0.0449 (4) C5 −0.1044 (2) 0.4382 (2) 0.70797 (17) 0.0352 (3) C6 0.68459 (17) 0.84578 (14) 0.84195 (13) 0.0202 (2) C7 0.51198 (17) 0.88333 (16) 0.75411 (14) 0.0241 (2) H10 0.475 (4) 0.559 (3) 0.835 (3) 0.056 (7)* H1N 0.116 (3) 0.251 (2) 0.984 (2) 0.035 (5)* H2N −0.033 (3) 0.153 (3) 0.885 (2) 0.032 (5)* H3N −0.042 (3) 0.328 (2) 0.9425 (19) 0.030 (5)* H2 0.206 (3) 0.192 (2) 0.7769 (18) 0.023 (4)* H3 −0.101 (3) 0.181 (2) 0.659 (2) 0.032 (5)* H41 0.182 (4) 0.360 (3) 0.565 (3) 0.057 (7)* H42 −0.002 (4) 0.248 (3) 0.470 (3) 0.067 (8)* H43 0.160 (3) 0.169 (3) 0.535 (2) 0.045 (6)* H51 −0.195 (3) 0.438 (3) 0.631 (2) 0.051 (6)* H52 −0.016 (3) 0.537 (3) 0.724 (2) 0.047 (6)* H53 −0.169 (3) 0.456 (3) 0.788 (2) 0.047 (6)*
Atomic displacement parameters (Å2)
U11 U22 U33 U12 U13 U23
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Acta Cryst. (2002). E58, o279–o281Geometric parameters (Å, º)
Cl1—C7 1.7747 (14) C2—C3 1.5320 (19) Cl2—C7 1.7580 (14) C2—H2 0.957 (18) Cl3—C7 1.7749 (17) C3—C5 1.525 (2) O1—C1 1.3150 (16) C3—C4 1.531 (2) O1—H10 0.89 (3) C3—H3 1.00 (2) O2—C1 1.2136 (17) C4—H41 0.96 (3) O3—C6 1.2538 (15) C4—H42 0.98 (3) O4—C6 1.2300 (15) C4—H43 0.97 (2) N—C2 1.4953 (17) C5—H51 0.96 (2) N—H1N 0.89 (2) C5—H52 0.96 (2) N—H2N 0.84 (2) C5—H53 0.98 (2) N—H3N 0.90 (2) C6—C7 1.5578 (18) C1—C2 1.5197 (17)
C1—O1—H10 111.8 (16) C3—C4—H41 110.6 (15) C2—N—H1N 108.5 (13) C3—C4—H42 110.3 (17) C2—N—H2N 110.6 (14) H41—C4—H42 110 (2) H1N—N—H2N 108.0 (18) C3—C4—H43 112.7 (13) C2—N—H3N 111.8 (12) H41—C4—H43 106 (2) H1N—N—H3N 106.9 (18) H42—C4—H43 107 (2) H2N—N—H3N 110.8 (18) C3—C5—H51 112.5 (14) O2—C1—O1 125.57 (11) C3—C5—H52 110.3 (14) O2—C1—C2 122.27 (11) H51—C5—H52 104.8 (19) O1—C1—C2 112.15 (11) C3—C5—H53 114.8 (13) N—C2—C1 107.11 (11) H51—C5—H53 107.3 (19) N—C2—C3 111.25 (10) H52—C5—H53 106.5 (19) C1—C2—C3 112.46 (10) O4—C6—O3 127.11 (12) N—C2—H2 107.2 (11) O4—C6—C7 117.64 (11) C1—C2—H2 109.2 (11) O3—C6—C7 115.22 (11) C3—C2—H2 109.5 (11) C6—C7—Cl2 112.03 (9) C5—C3—C4 111.94 (15) C6—C7—Cl1 111.82 (9) C5—C3—C2 112.10 (11) Cl2—C7—Cl1 108.40 (8) C4—C3—C2 111.28 (13) C6—C7—Cl3 105.78 (9) C5—C3—H3 108.9 (11) Cl2—C7—Cl3 109.62 (8) C4—C3—H3 107.7 (11) Cl1—C7—Cl3 109.13 (8) C2—C3—H3 104.5 (11)
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Acta Cryst. (2002). E58, o279–o281Hydrogen-bond geometry (Å, º)
D—H···A D—H H···A D···A D—H···A
O1—H10···O3 0.89 (3) 1.72 (3) 2.601 (2) 169 (2) N—H2N···O4i 0.84 (2) 1.93 (2) 2.761 (2) 169.6 (19) N—H1N···O3ii 0.89 (2) 1.94 (2) 2.804 (2) 163.6 (19) N—H3N···O2iii 0.90 (2) 2.00 (2) 2.871 (2) 162.5 (17)