β-Alaninium perchlorate

In the title compound, C₃H₈NO₂⁺·ClO₄⁻, a normal O—H...O hydrogen bond is observed which forms a dimer between the carboxyl­ic acid groups of two β-alaninium residues related by an inversion center. An intramolecular hydrogen bond is observed between the amino-N and carboxyl-O atoms. The amino-N atom is also involved in a three-centered hydrogen bond with O atoms of the perchlorate anion across the center of inversion, forming infinite chains.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• Disorder in solvent or counterion
• R factor = 0.062
• wR factor = 0.216
• Data-to-parameter ratio = 9.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_302  Alert C Anion/Solvent Disorder .......................      27.00 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

Alanine is the second simplest amino acid, but the most common in proteins. β-Alanine is the only naturally occurring β-amino acid. The crystal structure of L-alanine (Lehmann et al., 1972), L-alanine hydrochloride (Di Blasio et al., 1977), β-alanine (Papavinasam et al., 1986), bis(DL-alanine) phosphate (Averbuch-Pouchot et al., 1988), DL-alanine nitrate (Asath Bahadur & Rajaram, 1995) and bis (β-alanine) hydrogen nitrate (Sridhar et al., 2001) have been reported. In the present investigation, β-alanine was reacted with perchloric acid to produe the title compound (I) which was investigated to study the conformation and hydrogen bonds in the presence of an inorganic acid.

The asymmetric unit of (I) consists of one β-alaninium residue and a perchlorate anion. The backbone conformation angles ψ¹ and ψ² are 8.0 (4) and -171.5 (3)°, respectively, for the alaninium residue. The straight-chain conformation angle χ¹ is in the gauche II form [-65.0 (3)°].

In the perchlorate anion, all the O atoms are found to have orientational disorder. This leads to considerable variations in the Cl—O bond distances and the tetrahedral symmetry of the anion.

In biological molecules, such as amino acids, hydrogen bonds play an important role. In the present structure, a normal O—H···O hydrogen bond (2.726 Å) is observed which forms a dimer between the carboxylic acid groups of two β-alaninium residues related by an inversion center. The hydrogen bonds that exist between the perchlorate anion and the alaninium residue play an important role in stabilizing the structure. The amino N atom is also involved in a chelated three-centered hydrogen bond with acceptor O atoms (O2 and O3) of the perchlorate anion. The amino N atom is also found to be engaged in a three-centered hydrogen bond, with (i) the carboxyl atom O1A (intramolecular hydrogen bond) and atom O4 of the perchlorate anion and (ii) two O atoms of the perchlorate anions across a center of inversion, forming infinite chains. The presence of the three-centered hydrogen bond is due to an excess of acceptors over donors or proton deficiency (Jeffrey & Saenger, 1991).

S2. Experimental

The title compound was crystallized from an aqueous solution of β-alanine and perchloric acid in a 1:1 stoichiometric ratio by slow evaporation.

S3. Refinement

The perchlorate anion exhibits orientational disorder. The site-occupation factors for O1/O2/O3/O4 and O1'/O2'/O3'/O4' are 0.57 and 0.43, respectively. These O atoms were refined anisotropically with fixed site-occupation factors. All H atoms were fixed by geometric constraints using HFIX and allowed to ride on the attached atom.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1999); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The molecular structures of the cation and anion of (I), showing the atomic numbering scheme and 50% probability displacement ellipsoids (Johnson, 1976). The minor-site disordered O atoms have been omitted.
	Fig. 2. Packing diagram of the structure viewed down the b axis. The minor-site disordered O atoms have been omitted.

β-alaninium perchlorate

Crystal data

C3H8NO2^+·ClO4^−	F(000) = 392
Mr = 189.55	Dx = 1.697 Mg m^−3 Dm = 1.690 Mg m^−3 Dm measured by flotation using a mixture of carbon tetrachloride and xylene
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 7.024 (3) Å	Cell parameters from 25 reflections
b = 7.556 (4) Å	θ = 6.4–13.6°
c = 14.102 (4) Å	µ = 0.50 mm^−1
β = 97.52 (4)°	T = 293 K
V = 742.0 (5) Å^3	Needle, colorless
Z = 4	0.3 × 0.2 × 0.1 mm

Data collection

Enraf-Nonis CAD-4 diffractometer	1049 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.029
Graphite monochromator	θmax = 24.8°, θmin = 2.9°
ω–2θ scans	h = −8→8
Absorption correction: ψ scan (North et al., 1968)	k = 0→8
Tmin = 0.886, Tmax = 0.951	l = 0→16
1521 measured reflections	3 standard reflections every 60 min
1297 independent reflections	intensity decay: none

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)] = 0.062	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.216	H-atom parameters constrained
S = 1.12	w = 1/[σ^2(Fo^2) + (0.1724P)^2] where P = (Fo^2 + 2Fc^2)/3
1297 reflections	(Δ/σ)max = 0.001
136 parameters	Δρmax = 0.48 e Å^−3
0 restraints	Δρmin = −0.39 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)
Cl1	0.13952 (11)	0.24718 (8)	0.63655 (6)	0.0451 (5)
O1	0.066 (4)	0.366 (2)	0.5722 (12)	0.205 (12)	0.57
O2	0.0861 (17)	0.2379 (18)	0.7242 (9)	0.142 (5)	0.57
O3	0.3261 (15)	0.273 (2)	0.6322 (7)	0.178 (7)	0.57
O4	0.1127 (18)	0.0873 (11)	0.5831 (7)	0.122 (3)	0.57
O1'	0.117 (3)	0.380 (2)	0.5706 (14)	0.113 (6)	0.43
O2'	0.1444 (14)	0.3251 (11)	0.7333 (8)	0.074 (3)	0.43
O3'	0.316 (3)	0.157 (3)	0.6435 (11)	0.197 (13)	0.43
O4'	−0.016 (3)	0.153 (4)	0.6366 (11)	0.236 (11)	0.43
O1A	0.6625 (3)	0.9350 (3)	0.58291 (18)	0.0535 (7)
O1B	0.4108 (4)	0.7704 (3)	0.5274 (2)	0.0569 (8)
H12	0.3714	0.8640	0.5028	0.085*
C11	0.5775 (4)	0.7949 (4)	0.5755 (2)	0.0401 (7)
C12	0.6627 (4)	0.6308 (5)	0.6248 (2)	0.0509 (8)
H12A	0.5684	0.5772	0.6603	0.061*
H12B	0.6914	0.5465	0.5768	0.061*
C13	0.8431 (5)	0.6667 (4)	0.6921 (2)	0.0512 (9)
H13A	0.8164	0.7550	0.7386	0.061*
H13B	0.8829	0.5591	0.7266	0.061*
N11	1.0036 (4)	0.7311 (3)	0.6404 (2)	0.0487 (8)
H11A	1.1073	0.7512	0.6824	0.073*
H11B	0.9682	0.8308	0.6094	0.073*
H11C	1.0304	0.6493	0.5987	0.073*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0484 (7)	0.0417 (7)	0.0469 (7)	0.0035 (3)	0.0124 (4)	0.0032 (2)
O1	0.40 (3)	0.139 (13)	0.076 (8)	0.160 (16)	0.024 (11)	−0.001 (8)
O2	0.108 (7)	0.243 (16)	0.072 (5)	−0.013 (7)	0.003 (4)	0.003 (8)
O3	0.096 (6)	0.33 (2)	0.092 (6)	−0.062 (8)	−0.049 (5)	0.056 (8)
O4	0.178 (9)	0.084 (4)	0.109 (6)	−0.025 (5)	0.039 (7)	0.003 (4)
O1'	0.184 (12)	0.087 (10)	0.072 (9)	−0.032 (9)	0.031 (8)	0.014 (7)
O2'	0.076 (6)	0.081 (6)	0.062 (4)	0.017 (4)	−0.004 (4)	−0.015 (4)
O3'	0.195 (17)	0.32 (3)	0.090 (9)	0.166 (19)	0.081 (11)	0.059 (13)
O4'	0.197 (16)	0.37 (3)	0.113 (11)	−0.163 (18)	−0.102 (12)	0.075 (15)
O1A	0.0478 (14)	0.0367 (12)	0.0738 (16)	0.0015 (9)	−0.0004 (11)	0.0018 (10)
O1B	0.0460 (15)	0.0408 (13)	0.0805 (19)	−0.0022 (8)	−0.0042 (13)	0.0109 (9)
C11	0.0378 (15)	0.0401 (14)	0.0439 (16)	0.0016 (13)	0.0106 (12)	−0.0043 (13)
C12	0.0535 (18)	0.0421 (18)	0.062 (2)	0.0031 (14)	0.0263 (14)	0.0043 (13)
C13	0.0537 (18)	0.049 (2)	0.0516 (18)	0.0076 (14)	0.0096 (14)	0.0068 (12)
N11	0.0452 (16)	0.0476 (16)	0.0522 (17)	0.0052 (10)	0.0026 (12)	0.0012 (10)

Geometric parameters (Å, º)

Cl1—O4'	1.305 (14)	C11—C12	1.506 (4)
Cl1—O1	1.333 (15)	C12—C13	1.505 (5)
Cl1—O3	1.334 (11)	C12—H12A	0.9700
Cl1—O2	1.339 (13)	C12—H12B	0.9700
Cl1—O1'	1.365 (17)	C13—N11	1.502 (4)
Cl1—O3'	1.410 (14)	C13—H13A	0.9700
Cl1—O4	1.424 (9)	C13—H13B	0.9700
Cl1—O2'	1.483 (10)	N11—H11A	0.8900
O1A—C11	1.213 (4)	N11—H11B	0.8900
O1B—C11	1.287 (4)	N11—H11C	0.8900
O1B—H12	0.8200
O4'—Cl1—O1	96.7 (15)	O1'—Cl1—O2'	108.7 (9)
O4'—Cl1—O3	155.2 (17)	O3'—Cl1—O2'	102.4 (9)
O1—Cl1—O3	99.6 (12)	O4—Cl1—O2'	144.1 (6)
O4'—Cl1—O2	68.6 (11)	C11—O1B—H12	109.5
O1—Cl1—O2	122.1 (10)	O1A—C11—O1B	125.0 (3)
O3—Cl1—O2	116.4 (6)	O1A—C11—C12	121.2 (3)
O4'—Cl1—O1'	112.4 (12)	O1B—C11—C12	113.8 (3)
O1—Cl1—O1'	16.2 (17)	C13—C12—C11	113.2 (3)
O3—Cl1—O1'	83.5 (11)	C13—C12—H12A	108.9
O2—Cl1—O1'	130.2 (11)	C11—C12—H12A	108.9
O4'—Cl1—O3'	117.7 (18)	C13—C12—H12B	108.9
O1—Cl1—O3'	129.5 (12)	C11—C12—H12B	108.9
O3—Cl1—O3'	38.1 (12)	H12A—C12—H12B	107.8
O2—Cl1—O3'	105.1 (8)	N11—C13—C12	112.0 (3)
O1'—Cl1—O3'	115.3 (12)	N11—C13—H13A	109.2
O4'—Cl1—O4	58.9 (14)	C12—C13—H13A	109.2
O1—Cl1—O4	101.5 (9)	N11—C13—H13B	109.2
O3—Cl1—O4	99.4 (8)	C12—C13—H13B	109.2
O2—Cl1—O4	114.2 (7)	H13A—C13—H13B	107.9
O1'—Cl1—O4	105.6 (10)	C13—N11—H11A	109.5
O3'—Cl1—O4	71.3 (11)	C13—N11—H11B	109.5
O4'—Cl1—O2'	97.7 (12)	H11A—N11—H11B	109.5
O1—Cl1—O2'	108.6 (7)	C13—N11—H11C	109.5
O3—Cl1—O2'	94.6 (7)	H11A—N11—H11C	109.5
O2—Cl1—O2'	31.5 (6)	H11B—N11—H11C	109.5
O1A—C11—C12—C13	8.0 (4)	C11—C12—C13—N11	−65.0 (3)
O1B—C11—C12—C13	−171.5 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1B—H12···O1A^i	0.82	1.94	2.726 (3)	161
N11—H11A···O2^ii	0.89	2.37	3.243 (12)	165
N11—H11A···O2′^ii	0.89	2.06	2.939 (10)	172
N11—H11A···O3^ii	0.89	2.60	3.288 (9)	135
N11—H11A···O3′^ii	0.89	2.55	3.19 (2)	130
N11—H11B···O4^iii	0.89	2.24	2.941 (9)	135
N11—H11B···O4′^iii	0.89	2.46	3.19 (3)	139
N11—H11B···O1A	0.89	2.27	2.875 (3)	125
N11—H11C···O1^iv	0.89	2.19	2.971 (15)	146
N11—H11C···O1′^iv	0.89	2.17	2.97 (2)	149
N11—H11C···O1^v	0.89	2.42	3.064 (17)	129
N11—H11C···O1′^v	0.89	2.49	3.10 (2)	127

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