Redetermination of α-ammonio-α-methyl­propionoate

The redetermined structure of the title compound, C₄H₉NO₂, comprises a simple amino acid derivative arranged in an extensive hydrogen-bonded network, with the three hydrogen-bond donor elements (N—H) associating with the two hydrogen-bond acceptor elements (carboxyl­ate O atoms). The addition of one C—H...O close contact results in both carboxyl­ate O atoms being involved in three-centre hydrogen-bonding associations.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.045
• wR factor = 0.130
• Data-to-parameter ratio = 15.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_353  Alert C Long  N-H Bond (0.87A)     N(1)   -   H(1)   =       1.04 Ang.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

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Computing details

Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); cell refinement: DENZO and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON97 (Spek, 1997); software used to prepare material for publication: SHELXL97.

α-Ammonium-α-methylpropionoate

Crystal data

NH4^+·C4H5O2^−	F(000) = 448
Mr = 103.12	Dx = 1.265 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.6273 (8) Å	Cell parameters from 2205 reflections
b = 9.0102 (8) Å	θ = 2.9–27.5°
c = 11.3370 (7) Å	µ = 0.10 mm^−1
β = 93.749 (6)°	T = 150 K
V = 1083.2 (1) Å^3	Block, colourless
Z = 8	0.30 × 0.10 × 0.08 mm

Data collection

Bruker-Nonius KappaCCD area-detector diffractometer	1208 independent reflections
Radiation source: Bruker-Nonius FR591 rotating anode	755 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.070
Detector resolution: 9.091 pixels mm^-1	θmax = 27.4°, θmin = 3.0°
φ and ω scans	h = −13→11
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	k = −10→11
Tmin = 0.970, Tmax = 0.992	l = −14→13
3853 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.045	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.130	w = 1/[σ^2(Fo^2) + (0.0628P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max < 0.001
1208 reflections	Δρmax = 0.17 e Å^−3
79 parameters	Δρmin = −0.19 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.013 (3)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.6110 (1)	0.0816 (1)	0.16015 (9)	0.0349 (4)
O2	0.7255 (1)	−0.1208 (2)	0.13672 (9)	0.0450 (5)
N1	0.6528 (1)	0.1015 (2)	0.3894 (1)	0.0295 (4)
H1	0.674 (2)	0.092 (2)	0.480 (2)	0.059 (6)*
H2	0.564 (2)	0.103 (2)	0.366 (2)	0.046 (6)*
H3	0.691 (2)	0.193 (3)	0.364 (2)	0.059 (7)*
C1	0.6794 (2)	−0.0217 (2)	0.1983 (1)	0.0283 (5)
C2	0.7096 (2)	−0.0321 (2)	0.3335 (1)	0.0281 (5)
C3	0.6450 (2)	−0.1696 (2)	0.3791 (1)	0.0350 (5)
H31	0.6549	−0.1716	0.4657	0.044*
H32	0.6834	−0.2587	0.3473	0.044*
H33	0.5551	−0.1670	0.3538	0.044*
C4	0.8514 (2)	−0.0314 (2)	0.3654 (2)	0.0418 (6)
H41	0.8887	0.0585	0.3338	0.052*
H42	0.8898	−0.1191	0.3313	0.052*
H43	0.8668	−0.0332	0.4516	0.052*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0400 (8)	0.0380 (8)	0.0264 (7)	0.0044 (6)	−0.0004 (5)	0.0065 (5)
O2	0.0717 (11)	0.0413 (9)	0.0219 (7)	0.0169 (7)	0.0017 (6)	−0.0034 (6)
N1	0.0389 (11)	0.0276 (10)	0.0216 (8)	−0.0011 (7)	−0.0007 (6)	−0.0021 (6)
C1	0.0357 (10)	0.0298 (11)	0.0194 (9)	−0.0041 (8)	0.0009 (7)	0.0005 (7)
C2	0.0367 (11)	0.0271 (10)	0.0200 (8)	0.0029 (8)	−0.0009 (7)	−0.0025 (7)
C3	0.0506 (13)	0.0290 (11)	0.0252 (9)	0.0047 (9)	0.0015 (8)	0.0035 (7)
C4	0.0395 (12)	0.0497 (14)	0.0351 (10)	0.0040 (10)	−0.0041 (8)	−0.0003 (9)

Geometric parameters (Å, º)

O1—C1	1.241 (2)	C2—C4	1.527 (2)
O2—C1	1.252 (2)	C3—H31	0.98
N1—C2	1.505 (2)	C3—H32	0.98
N1—H1	1.04 (2)	C3—H33	0.98
N1—H2	0.96 (2)	C4—H41	0.98
N1—H3	0.97 (3)	C4—H42	0.98
C1—C2	1.549 (2)	C4—H43	0.98
C2—C3	1.523 (3)
C2—N1—H1	106 (1)	C4—C2—C1	111.8 (1)
C2—N1—H2	108 (1)	C2—C3—H31	109.5
H1—N1—H2	115 (2)	C2—C3—H32	109.5
C2—N1—H3	111 (1)	H31—C3—H32	109.5
H1—N1—H3	107 (2)	C2—C3—H33	109.5
H2—N1—H3	109 (2)	H31—C3—H33	109.5
O1—C1—O2	125.6 (1)	H32—C3—H33	109.5
O1—C1—C2	117.9 (1)	C2—C4—H41	109.5
O2—C1—C2	116.5 (2)	C2—C4—H42	109.5
N1—C2—C3	107.8 (1)	H41—C4—H42	109.5
N1—C2—C4	108.3 (1)	C2—C4—H43	109.5
C3—C2—C4	112.5 (2)	H41—C4—H43	109.5
N1—C2—C1	107.8 (1)	H42—C4—H43	109.5
C3—C2—C1	108.5 (1)
O1—C1—C2—N1	−4.5 (2)	O2—C1—C2—C3	−67.1 (2)
O2—C1—C2—N1	176.4 (2)	O1—C1—C2—C4	−123.5 (2)
O1—C1—C2—C3	111.9 (2)	O2—C1—C2—C4	57.5 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O2^i	1.04 (2)	1.84 (2)	2.8645 (18)	167 (2)
N1—H2···O1^ii	0.96 (2)	1.88 (2)	2.828 (2)	170 (2)
N1—H3···O2^iii	0.97 (3)	1.90 (3)	2.841 (2)	163 (2)
C3—H31···O1^i	0.98	2.42	3.326 (2)	153

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