DL-Threoninium di­hydrogen phosphate

In the title compound, C₄H₁₀NO₃⁺·H₂PO₄⁻, the threoninium residue forms strong O—H...O hydrogen bonds with the phosphate anion. A gauche I–gauche II conformation with respect to the O^γ and C^γ atoms is observed [the corresponding torsion angles are 59.5 (2) and −64.1 (3)°]. The adjacent threoninium cations, related by an a-glide plane normal to the c axis, are linked via N—H...O hydrogen bond involving ammonium and carboxyl­ic acid groups (DL2 head-to-tail sequence). The structure is stabilized by an extensive network of O—H...O and N—H...O hydrogen bonds, which form a three-dimensional hydrogen-bond system.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.036
• wR factor = 0.091
• Data-to-parameter ratio = 11.6

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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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.

DL-threoninium dihydrogen phosphate

Crystal data

C4H10NO3^+·H2PO4^−	Dx = 1.616 Mg m^−3 Dm = 1.612 Mg m^−3 Dm measured by flotation in a mixture of carbon tetrachloride and xylene
Mr = 217.12	Mo Kα radiation, λ = 0.71069 Å
Orthorhombic, Pbca	Cell parameters from 25 reflections
a = 9.0590 (6) Å	θ = 11.4–14.0°
b = 19.507 (3) Å	µ = 0.32 mm^−1
c = 10.1015 (9) Å	T = 293 K
V = 1785.1 (3) Å^3	Needle, colorless
Z = 8	0.5 × 0.5 × 0.1 mm
F(000) = 912

Data collection

Enraf-Nonius CAD-4 diffractometer	1262 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.016
Graphite monochromator	θmax = 25.0°, θmin = 2.1°
ω–2θ scans	h = −1→10
Absorption correction: ψ scan (North et al., 1968)	k = −23→1
Tmin = 0.889, Tmax = 0.968	l = −1→12
2103 measured reflections	25 standard reflections every 3 reflections
1570 independent reflections	intensity decay: none

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)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.091	w = 1/[σ^2(Fo^2) + (0.0452P)^2 + 0.4021P] where P = (Fo^2 + 2Fc^2)/3
S = 1.23	(Δ/σ)max < 0.001
1570 reflections	Δρmax = 0.31 e Å^−3
135 parameters	Δρmin = −0.24 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: 0.0234 (14)

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
P1	0.58399 (6)	−0.08600 (3)	0.27574 (5)	0.0232 (2)
O1	0.55060 (18)	−0.05023 (8)	0.15034 (15)	0.0320 (4)
O2	0.45308 (17)	−0.11825 (8)	0.34572 (15)	0.0301 (4)
O3	0.6944 (2)	−0.14692 (8)	0.25557 (17)	0.0342 (4)
H3P	0.770 (4)	−0.1346 (18)	0.225 (3)	0.060 (11)*
O4	0.66114 (19)	−0.03383 (8)	0.37212 (16)	0.0332 (4)
H4P	0.651 (4)	−0.0463 (18)	0.457 (3)	0.076 (11)*
O1A	0.37183 (17)	0.07114 (8)	0.37375 (14)	0.0335 (4)
O1B	0.58905 (17)	0.12203 (8)	0.41277 (16)	0.0307 (4)
H1B	0.564 (5)	0.119 (2)	0.511 (5)	0.110 (14)*
O1C	0.3752 (2)	0.21083 (10)	0.1967 (2)	0.0556 (6)
H1C	0.370 (4)	0.2527 (18)	0.204 (3)	0.065 (10)*
C11	0.4849 (2)	0.09915 (11)	0.3369 (2)	0.0246 (5)
C12	0.5166 (2)	0.11161 (10)	0.1910 (2)	0.0241 (5)
H12	0.6134	0.0923	0.1691	0.029*
N11	0.4024 (2)	0.07632 (9)	0.11186 (17)	0.0270 (4)
H11A	0.4196	0.0832	0.0261	0.040*
H11B	0.3139	0.0929	0.1327	0.040*
H11C	0.4049	0.0316	0.1290	0.040*
C13	0.5185 (3)	0.18846 (12)	0.1628 (2)	0.0323 (6)
H13	0.5897	0.2104	0.2223	0.039*
C14	0.5609 (5)	0.20469 (15)	0.0213 (3)	0.0660 (10)
H14A	0.5607	0.2535	0.0085	0.099*
H14B	0.4912	0.1839	−0.0380	0.099*
H14C	0.6578	0.1870	0.0035	0.099*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0253 (3)	0.0247 (3)	0.0195 (3)	−0.0001 (2)	0.0007 (2)	0.0023 (2)
O1	0.0433 (10)	0.0323 (8)	0.0205 (8)	0.0035 (7)	−0.0002 (7)	0.0020 (6)
O2	0.0254 (8)	0.0433 (9)	0.0216 (8)	−0.0064 (7)	−0.0011 (6)	0.0009 (7)
O3	0.0277 (9)	0.0282 (8)	0.0466 (10)	0.0003 (7)	0.0069 (9)	0.0059 (7)
O4	0.0398 (10)	0.0342 (9)	0.0257 (9)	−0.0102 (7)	−0.0009 (8)	0.0010 (7)
O1A	0.0276 (9)	0.0502 (10)	0.0226 (8)	−0.0082 (8)	0.0014 (7)	0.0030 (7)
O1B	0.0287 (9)	0.0413 (9)	0.0222 (8)	−0.0058 (7)	−0.0009 (7)	−0.0018 (7)
O1C	0.0443 (11)	0.0248 (10)	0.0977 (17)	0.0070 (8)	0.0016 (11)	−0.0062 (11)
C11	0.0250 (12)	0.0256 (11)	0.0233 (11)	0.0040 (9)	0.0003 (10)	−0.0011 (9)
C12	0.0232 (11)	0.0274 (11)	0.0217 (11)	0.0012 (9)	0.0002 (9)	−0.0018 (9)
N11	0.0342 (11)	0.0259 (9)	0.0208 (9)	−0.0018 (8)	0.0006 (8)	0.0000 (7)
C13	0.0388 (14)	0.0282 (12)	0.0298 (12)	−0.0055 (10)	−0.0007 (11)	−0.0002 (9)
C14	0.120 (3)	0.0399 (15)	0.0379 (16)	−0.0166 (18)	0.0072 (18)	0.0077 (13)

Geometric parameters (Å, º)

P1—O1	1.4774 (16)	C12—H12	0.980
P1—O2	1.5172 (16)	N11—H11A	0.890
P1—O3	1.5667 (18)	N11—H11B	0.890
P1—O4	1.5722 (16)	N11—H11C	0.890
O3—H3P	0.78 (3)	C13—O1C	1.411 (3)
O4—H4P	0.90 (3)	C13—C14	1.514 (4)
O1A—C11	1.219 (3)	C13—H13	0.980
O1B—C11	1.295 (3)	C14—H14A	0.960
O1B—H1B	1.02 (5)	C14—H14B	0.960
C11—C12	1.521 (3)	C14—H14C	0.960
C12—N11	1.477 (3)	O1C—H1C	0.82 (4)
C12—C13	1.526 (3)
O1—P1—O2	115.80 (9)	C12—N11—H11B	109.5
O1—P1—O3	112.18 (9)	H11A—N11—H11B	109.5
O2—P1—O3	104.19 (9)	C12—N11—H11C	109.5
O1—P1—O4	108.44 (9)	H11A—N11—H11C	109.5
O2—P1—O4	109.10 (9)	H11B—N11—H11C	109.5
O3—P1—O4	106.72 (10)	O1C—C13—C14	113.5 (2)
P1—O3—H3P	112 (2)	O1C—C13—C12	104.35 (19)
P1—O4—H4P	112 (2)	C14—C13—C12	112.6 (2)
C11—O1B—H1B	113 (2)	O1C—C13—H13	108.7
O1A—C11—O1B	125.9 (2)	C14—C13—H13	108.7
O1A—C11—C12	121.75 (19)	C12—C13—H13	108.7
O1B—C11—C12	112.39 (19)	C13—C14—H14A	109.5
N11—C12—C11	108.52 (17)	C13—C14—H14B	109.5
N11—C12—C13	111.38 (18)	H14A—C14—H14B	109.5
C11—C12—C13	109.88 (17)	C13—C14—H14C	109.5
N11—C12—H12	109.0	H14A—C14—H14C	109.5
C11—C12—H12	109.0	H14B—C14—H14C	109.5
C13—C12—H12	109.0	C13—O1C—H1C	112 (2)
C12—N11—H11A	109.5
O1A—C11—C12—N11	−7.8 (3)	N11—C12—C13—O1C	59.5 (2)
O1B—C11—C12—N11	172.87 (17)	C11—C12—C13—O1C	−60.8 (2)
O1A—C11—C12—C13	114.2 (2)	N11—C12—C13—C14	−64.1 (3)
O1B—C11—C12—C13	−65.1 (2)	C11—C12—C13—C14	175.7 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3P···O2^i	0.78 (3)	1.84 (3)	2.617 (2)	172 (4)
O4—H4P···O1A^ii	0.90 (3)	1.79 (4)	2.685 (2)	179 (3)
O1B—H1B···O2^ii	1.02 (5)	1.45 (5)	2.470 (2)	173 (4)
O1C—H1C···O3^iii	0.82 (4)	2.08 (4)	2.886 (3)	165 (3)
N11—H11A···O1^iv	0.89	1.91	2.730 (2)	152
N11—H11B···O1B^v	0.89	2.16	2.986 (3)	153
N11—H11C···O1	0.89	2.08	2.837 (2)	142

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