organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 12| December 2013| Pages o1829-o1830

Isovaline monohydrate

aDepartment of Chemistry, Howard University, 525 College Street NW, Washington, DC 20059, USA, bDepartment of Chemistry, Catholic University of America, Washington, DC 20064, USA, cNASA Johnson Space Center, Astromaterial and Exploration Science Directorate, Houston, TX 77058, USA, and dSolar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
*Correspondence e-mail: rbutcher99@yahoo.com

(Received 23 October 2013; accepted 20 November 2013; online 27 November 2013)

The title compound, C5H11NO2·H2O, is an isomer of the α-amino acid valine that crystallizes from water in its zwitterion form as a monohydrate. It is not one of the 20 proteinogenic amino acids that are used in living systems and differs from the natural amino acids in that it has no α-H atom. The compound exhibits hydrogen bonding between the water mol­ecule and the carboxyl­ate O atoms and an amine H atom. In addition, there are inter­molecular hydrogen-bonding inter­actions between the carboxyl­ate O atoms and amine H atoms. In the crystal, these extensive N—H⋯O and O—H⋯O hydrogen bonds lead to the formation of a three-dimensional network.

Related literature

The structure of the title compound or its salts have not been reported to the CCDC but there are reports of homoleptic coordination complexes of zinc(II) with isovaline, see: Strasdelt et al. (2001[Strasdelt, H., Busching, I., Behrends, S., Saak, W. & Barklage, W. (2001). Chem. Eur. J. 7, 1133-1137.]). For literature related to eighty amino acids that have been detected in meteorites or comets, see: Glavin & Dworkin (2009[Glavin, D. P. & Dworkin, J. P. (2009). Proc. Natl Acad. Sci. 106, 5487-5492.]); Burton et al. (2012[Burton, A. S., Stern, J. C., Elsila, J. E., Dworkin, J. P. & Glavin, D. P. (2012). Chem. Soc. Rev. 41, 5459-5472.]). For the role that crystallization plays in chiral separation, see: Blackmond & Klussmann (2007[Blackmond, D. G. & Klussmann, M. (2007). Chem. Commun. pp. 3990-3996.]); Blackmond et al. (2008[Blackmond, D., Viedma, C., Ortiz, J., Torres, T. & Izuma, T. (2008). J. Am. Chem. Soc. 130, 15274-15275.]). For the role of the H atom on the α-C atom in enhancing the rate of racemization, see: Yamada et al. (1983[Yamada, S., Hongo, C., Yoshioka, R. & Chibata, I. (1983). J. Org. Chem. 48, 843-846.]). For the mechanism of racemization of amino acids lacking an α-H atom, see: Pizzarello & Groy (2011[Pizzarello, S. & Groy, T. L. (2011). Geochim. Cosmochim. Acta, 75, 645-656.]). For the role that crystallization can play in the enrichment of L-isovaline, see: Glavin & Dworkin (2009[Glavin, D. P. & Dworkin, J. P. (2009). Proc. Natl Acad. Sci. 106, 5487-5492.]); Bada (2009[Bada, J. L. (2009). Proc. Natl Acad. Sci. 106, E85.]); Bonner et al. (1979[Bonner, W. A., Blair, N. E., Lemmon, R. M., Flores, J. J. & Pollock, G. E. (1979). Geochim. Cosmochim. Acta, 43, 1841-1846.]). For normal bond lengths and angles, see: Orpen (1993[Orpen, G. A. (1993). Chem. Soc. Rev. 22, 191-197.]).

[Scheme 1]

Experimental

Crystal data
  • C5H11NO2·H2O

  • Mr = 135.16

  • Orthorhombic, P 21 21 21

  • a = 5.9089 (5) Å

  • b = 10.4444 (10) Å

  • c = 11.9274 (11) Å

  • V = 736.10 (12) Å3

  • Z = 4

  • Cu Kα radiation

  • μ = 0.84 mm−1

  • T = 123 K

  • 0.48 × 0.08 × 0.06 mm

Data collection
  • Agilent Xcalibur (Ruby, Gemini) diffractometer

  • Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012[Agilent (2012). CrysAlis PRO. Agilent Technologies UK Ltd, Yarnton, England.]) Tmin = 0.383, Tmax = 1.000

  • 1662 measured reflections

  • 1204 independent reflections

  • 1072 reflections with I > 2σ(I)

  • Rint = 0.072

Refinement
  • R[F2 > 2σ(F2)] = 0.056

  • wR(F2) = 0.162

  • S = 1.11

  • 1204 reflections

  • 91 parameters

  • 3 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.37 e Å−3

  • Δρmin = −0.27 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1W—H1W1⋯O1i 0.83 (2) 2.05 (2) 2.811 (3) 152 (4)
O1W—H1W2⋯O2ii 0.83 (2) 1.96 (2) 2.787 (3) 171 (5)
N1—H1A⋯O2i 0.91 1.84 2.745 (3) 177
N1—H1C⋯O1W 0.91 2.09 2.792 (4) 133
N1—H1B⋯O1iii 0.91 1.98 2.832 (3) 156
Symmetry codes: (i) x+1, y, z; (ii) [-x+{\script{1\over 2}}, -y+1, z+{\script{1\over 2}}]; (iii) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1].

Data collection: CrysAlis PRO (Agilent, 2012[Agilent (2012). CrysAlis PRO. Agilent Technologies UK Ltd, Yarnton, England.]); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

The alpha amino acids are essential for life as they are the building blocks of all proteins and enzymes. Nature uses almost exclusively the L form of the nineteen naturally occurring chiral amino acids. Glycine is achiral. However, it is known that there are over eighty amino acids that have been detected in meteorites or comets (Glavin & Dworkin 2009; Burton et al., 2012). One of these extraterrestrial non proteinogenic amino acids is isovaline. The majority of these amino acids show little or no enrichment of one enantiomer over the other. An intriguing question is the process that lead to the separation and enrichment of the L enantiomer over the D. There are several possible explanations for this including the role that crystallization plays (Blackmond & Klussmann, 2007). Only two of the twenty amino acids used biologically crystallize in a chiral space group, which allows for spontaneous separation of enantiomers, at the level of the crystal, from a racemic solution (Blackmond et al., 2008). Isovaline, a non proteinogenic amino acid also allows for this separation of enantiomers at the level of the crystal as it crystallizes in the chiral space group, P212121.

Another important aspect in the prebiotic chemistry of the amino acids is the role of racemization. All of the nineteen naturally occurring chiral amino acids have a hydrogen atom on the alpha carbon atom, which enhances the rate of racemization (Yamada et al., 1983). However, little is known about the mechanism of racemization of amino acids lacking an alpha hydrogen atom (Pizzarello & Groy, 2011). The structure of isovaline given here can be used to examine the role that crystallization can play in the enrichment of L isovaline (Glavin & Dworkin 2009; Bada, 2009), and as a starting point in mechanistic studies of racemization mechanisms of isovaline (Bonner et al., 1979).

In the structure of the title compound the amino acid is in the usual zwitterionic form. While the structure of the title compound or its salts have not been reported there are reports of homoleptic coordination complexes of isovaline with zinc(II) (Strasdelt et al. (2001). However, there are several important differences between these structures and the title compound. The metal complexes all crystallized in non-chiral space groups and, of course, when coordinated to a metal, the isovaline will not be in a zwitterionic form but, apart from the COO- group, all the the bond lengths and angles are in the normal range for such compounds (Orpen, 1993). There is extensive N—H···O and O—H···O hydrogen bonding linking the zwitterions into a 3-D array.

Related literature top

The structure of the title compound or its salts have not been reported to the CCDC but there are reports of homoleptic coordination complexes of zinc(II) with isovaline, see: Strasdelt et al. (2001). For literature related to eighty amino acids that have been detected in meteorites or comets, see: Glavin & Dworkin (2009); Burton et al. (2012). For the role that crystallization plays in chiral separation, see: Blackmond & Klussmann (2007); Blackmond et al. (2008). For the role of the H atom on the α-C atom in enhancing the rate of racemization, see: Yamada et al. (1983). For the mechanism of racemization of amino acids lacking an α-H atom, see: Pizzarello & Groy (2011). For the role that crystallization can play in the enrichment of L isovaline, see: Glavin & Dworkin (2009); Bada (2009); Bonner et al. (1979). For normal bond lengths and angles, see: Orpen (1993).

Experimental top

A sample of the title compound was obtained from Acros Organics. Crystals of the title compound were grown from the slow evaporation of a racemic solution of the amino acid in water.

Refinement top

H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with a C—H distances of 0.98 and 0.99 Å and an N—H distance of 0.91 \%A Uiso(H) = 1.2Ueq(C) and 0.96 Å for NH3 [Uiso(H) = 1.5Ueq(C)]. The water H's were refined isotropically with O—H distances constrained to be 0.82 Å and the H—O—H angle close to 104.5°.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Diagram of the title compound showing atom labeling. Atomic displacement parameters are at the 30% probablity level. Hydogen bonds are shown as dashed lines.
[Figure 2] Fig. 2. Packing diagram of the title compound viewed along the a axis showing tthe extensive N—H···O and O—H···O hydrogen bonds as dashed lines.
2-Azaniumyl-2-methylbutanoate monohydrate top
Crystal data top
C5H11NO2·H2OF(000) = 296
Mr = 135.16Dx = 1.220 Mg m3
Orthorhombic, P212121Cu Kα radiation, λ = 1.54184 Å
Hall symbol: P 2ac 2abCell parameters from 679 reflections
a = 5.9089 (5) Åθ = 3.7–75.3°
b = 10.4444 (10) ŵ = 0.84 mm1
c = 11.9274 (11) ÅT = 123 K
V = 736.10 (12) Å3Needle, colorless
Z = 40.48 × 0.08 × 0.06 mm
Data collection top
Agilent Xcalibur (Ruby, Gemini)
diffractometer
1204 independent reflections
Radiation source: Enhance (Cu) X-ray Source1072 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.072
Detector resolution: 10.5081 pixels mm-1θmax = 75.4°, θmin = 5.6°
ω scansh = 74
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2012)
k = 128
Tmin = 0.383, Tmax = 1.000l = 1414
1662 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.056Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.162H atoms treated by a mixture of independent and constrained refinement
S = 1.11 w = 1/[σ2(Fo2) + (0.093P)2 + 0.2964P]
where P = (Fo2 + 2Fc2)/3
1204 reflections(Δ/σ)max < 0.001
91 parametersΔρmax = 0.37 e Å3
3 restraintsΔρmin = 0.27 e Å3
Crystal data top
C5H11NO2·H2OV = 736.10 (12) Å3
Mr = 135.16Z = 4
Orthorhombic, P212121Cu Kα radiation
a = 5.9089 (5) ŵ = 0.84 mm1
b = 10.4444 (10) ÅT = 123 K
c = 11.9274 (11) Å0.48 × 0.08 × 0.06 mm
Data collection top
Agilent Xcalibur (Ruby, Gemini)
diffractometer
1204 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2012)
1072 reflections with I > 2σ(I)
Tmin = 0.383, Tmax = 1.000Rint = 0.072
1662 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0563 restraints
wR(F2) = 0.162H atoms treated by a mixture of independent and constrained refinement
S = 1.11Δρmax = 0.37 e Å3
1204 reflectionsΔρmin = 0.27 e Å3
91 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
O10.0058 (4)0.37096 (19)0.50201 (18)0.0316 (5)
O20.1536 (4)0.4257 (3)0.33811 (19)0.0385 (6)
O1W0.6455 (4)0.4874 (3)0.6172 (2)0.0467 (7)
H1W10.776 (5)0.465 (5)0.601 (3)0.070*
H1W20.661 (8)0.517 (5)0.682 (2)0.070*
N10.4267 (4)0.3850 (2)0.4302 (2)0.0297 (6)
H1A0.56630.39570.39940.045*
H1B0.40740.30140.44930.045*
H1C0.41410.43480.49250.045*
C10.0133 (6)0.4049 (2)0.4006 (3)0.0302 (6)
C20.2504 (5)0.4229 (3)0.3472 (2)0.0294 (6)
C30.2766 (6)0.3382 (3)0.2440 (3)0.0367 (7)
H3A0.25030.24860.26480.055*
H3B0.43010.34740.21390.055*
H3C0.16640.36400.18690.055*
C40.2832 (6)0.5657 (3)0.3178 (3)0.0344 (7)
H4A0.43840.57790.28850.041*
H4B0.17620.58880.25720.041*
C50.2477 (7)0.6556 (3)0.4151 (3)0.0451 (9)
H5A0.25650.74420.38860.068*
H5B0.36500.64080.47160.068*
H5C0.09840.64010.44820.068*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0326 (11)0.0293 (9)0.0329 (10)0.0009 (8)0.0031 (9)0.0061 (9)
O20.0268 (11)0.0510 (13)0.0376 (11)0.0010 (11)0.0007 (9)0.0110 (11)
O1W0.0379 (13)0.0627 (17)0.0396 (13)0.0087 (13)0.0008 (11)0.0148 (12)
N10.0268 (12)0.0270 (11)0.0352 (14)0.0004 (9)0.0016 (11)0.0015 (11)
C10.0324 (15)0.0214 (12)0.0367 (15)0.0017 (11)0.0027 (12)0.0020 (11)
C20.0279 (15)0.0275 (13)0.0328 (14)0.0009 (12)0.0009 (11)0.0051 (13)
C30.0371 (18)0.0392 (16)0.0338 (16)0.0040 (15)0.0005 (13)0.0010 (14)
C40.0320 (15)0.0317 (15)0.0394 (15)0.0038 (13)0.0001 (13)0.0085 (14)
C50.055 (2)0.0260 (14)0.054 (2)0.0030 (14)0.0026 (18)0.0020 (15)
Geometric parameters (Å, º) top
O1—C11.261 (4)C2—C41.545 (4)
O2—C11.255 (4)C3—H3A0.9800
O1W—H1W10.830 (19)C3—H3B0.9800
O1W—H1W20.832 (19)C3—H3C0.9800
N1—C21.490 (4)C4—C51.507 (5)
N1—H1A0.9100C4—H4A0.9900
N1—H1B0.9100C4—H4B0.9900
N1—H1C0.9100C5—H5A0.9800
C1—C21.550 (4)C5—H5B0.9800
C2—C31.524 (4)C5—H5C0.9800
H1W1—O1W—H1W2102 (3)C2—C3—H3B109.5
C2—N1—H1A109.5H3A—C3—H3B109.5
C2—N1—H1B109.5C2—C3—H3C109.5
H1A—N1—H1B109.5H3A—C3—H3C109.5
C2—N1—H1C109.5H3B—C3—H3C109.5
H1A—N1—H1C109.5C5—C4—C2114.2 (3)
H1B—N1—H1C109.5C5—C4—H4A108.7
O2—C1—O1126.2 (3)C2—C4—H4A108.7
O2—C1—C2116.4 (3)C5—C4—H4B108.7
O1—C1—C2117.4 (3)C2—C4—H4B108.7
N1—C2—C3108.1 (3)H4A—C4—H4B107.6
N1—C2—C4108.6 (3)C4—C5—H5A109.5
C3—C2—C4111.3 (3)C4—C5—H5B109.5
N1—C2—C1109.1 (2)H5A—C5—H5B109.5
C3—C2—C1110.7 (3)C4—C5—H5C109.5
C4—C2—C1108.9 (2)H5A—C5—H5C109.5
C2—C3—H3A109.5H5B—C5—H5C109.5
O2—C1—C2—N1175.8 (3)O1—C1—C2—C4114.2 (3)
O1—C1—C2—N14.2 (4)N1—C2—C4—C564.0 (3)
O2—C1—C2—C357.0 (3)C3—C2—C4—C5177.0 (3)
O1—C1—C2—C3123.0 (3)C1—C2—C4—C554.7 (4)
O2—C1—C2—C465.8 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H1W1···O1i0.83 (2)2.05 (2)2.811 (3)152 (4)
O1W—H1W2···O2ii0.83 (2)1.96 (2)2.787 (3)171 (5)
N1—H1A···O2i0.911.842.745 (3)177
N1—H1C···O1W0.912.092.792 (4)133
N1—H1B···O1iii0.911.982.832 (3)156
Symmetry codes: (i) x+1, y, z; (ii) x+1/2, y+1, z+1/2; (iii) x+1/2, y+1/2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H1W1···O1i0.830 (19)2.05 (2)2.811 (3)152 (4)
O1W—H1W2···O2ii0.832 (19)1.962 (19)2.787 (3)171 (5)
N1—H1A···O2i0.911.842.745 (3)177.3
N1—H1C···O1W0.912.092.792 (4)132.6
N1—H1B···O1iii0.911.982.832 (3)155.5
Symmetry codes: (i) x+1, y, z; (ii) x+1/2, y+1, z+1/2; (iii) x+1/2, y+1/2, z+1.
 

Acknowledgements

RJB wishes to acknowledge the NSF–MRI program (grant CHE-0619278) for funds to purchase the diffractometer. GB wishes to acknowledge support of this work from NASA (NNX10AK71A)

References

First citationAgilent (2012). CrysAlis PRO. Agilent Technologies UK Ltd, Yarnton, England.
First citationBada, J. L. (2009). Proc. Natl Acad. Sci. 106, E85.  Web of Science CrossRef PubMed
First citationBlackmond, D. G. & Klussmann, M. (2007). Chem. Commun. pp. 3990–3996.  Web of Science CrossRef
First citationBlackmond, D., Viedma, C., Ortiz, J., Torres, T. & Izuma, T. (2008). J. Am. Chem. Soc. 130, 15274–15275.  Web of Science PubMed
First citationBonner, W. A., Blair, N. E., Lemmon, R. M., Flores, J. J. & Pollock, G. E. (1979). Geochim. Cosmochim. Acta, 43, 1841–1846.  CrossRef CAS Web of Science
First citationBurton, A. S., Stern, J. C., Elsila, J. E., Dworkin, J. P. & Glavin, D. P. (2012). Chem. Soc. Rev. 41, 5459–5472.  Web of Science CrossRef CAS PubMed
First citationGlavin, D. P. & Dworkin, J. P. (2009). Proc. Natl Acad. Sci. 106, 5487–5492.  Web of Science CrossRef PubMed CAS
First citationOrpen, G. A. (1993). Chem. Soc. Rev. 22, 191–197.  CrossRef CAS Web of Science
First citationPizzarello, S. & Groy, T. L. (2011). Geochim. Cosmochim. Acta, 75, 645–656.  Web of Science CSD CrossRef CAS
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationStrasdelt, H., Busching, I., Behrends, S., Saak, W. & Barklage, W. (2001). Chem. Eur. J. 7, 1133–1137.  Web of Science PubMed
First citationYamada, S., Hongo, C., Yoshioka, R. & Chibata, I. (1983). J. Org. Chem. 48, 843–846.  CrossRef CAS Web of Science

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 12| December 2013| Pages o1829-o1830
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds