2-Amino-5-bromo­pyridinium hydrogen succinate

In the title compound, C₅H₆BrN₂⁺·C₄H₅O₄⁻, the pyridine N atom of the 2-amino-5-bromo­pyridine mol­ecule is protonated. The protonated N atom and the amino group are linked via N—H...O hydrogen bonds to the carboxyl­ate O atoms of the singly deprotonated succinate anion. The hydrogen succinate anions are linked via O—H...O hydrogen bonds. A weak inter­molecular C—H...O hydrogen bond is also observed.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.025
• wR factor = 0.057
• Data-to-parameter ratio = 16.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C9
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  Br1     ..       3.58 Ang.
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  Br1     ..       3.58 Ang.
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          6

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.49
           From the CIF: _reflns_number_total               2472
           Count of symmetry unique reflns         1482
           Completeness (_total/calc)            166.80%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       990
           Fraction of Friedel pairs measured     0.668
           Are heavy atom types Z>Si present        yes
PLAT917_ALERT_2_G The FCF is likely NOT based on a BASF/TWIN Flack          !
PLAT960_ALERT_3_G Number of Intensities with I .LT. - 2*sig(I) ..           1
PLAT063_ALERT_4_G Crystal Size Likely too Large for Beam Size ....       0.80 mm
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          1

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   5 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   4 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Pyridine and its derivatives play an important role in heterocyclic chemistry (Pozharski et al., 1997; Katritzky et al., 1996). They are often involved in hydrogen-bonding interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). Succinic acid derivatives are mostly used in chemicals, food and pharmaceuticals (Sauer et al., 2008). The crystal structures of 2-amino-5-bromopyridine (Goubitz et al., 2001) and 2-amino-5-bromopyridinium propynoate (Vaday & Foxman, 1999) have been reported. In this paper, we present the X-ray single-crystal structure of 2-amino-5-bromopyridinium hydrogen succinate (I).

The asymmetric unit of (I) (Fig. 1) contains a 2-amino-5-bromopyridinium cation and a hydrogen succinate anion, indicating that proton transfer has occurred during the co-crystallization experiment. In the 2-amino-5-bromopyridinium cation, a wider than normal angle [122.9 (2)°] is subtended at the protonated N1 atom. The bond lengths (Allen et al., 1987) and angles are normal.

In the crystal packing (Fig. 2), the protonated N1 atom and the 2-amino group (N2) is hydrogen-bonded to the carboxylate oxygen atoms (O1 and O2) via a pair of N—H···O hydrogen bonds, forming a R₂²(8) ring motif (Bernstein et al., 1995). The hydrogen succinate anions self-assemble via O4—H4···O2 (Table 1) hydrogen bonds. Furthermore, the crystal structure is stabilized by weak C—H···O hydrogen bonds, forming a 3D-network.

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997); Katritzky et al. (1996). For related structures, see: Goubitz et al. (2001); Vaday & Foxman (1999). For applications of succinic acid, see: Sauer et al. (2008). For bond-length data, see: Allen et al. (1987). For details of hydrogen bonding, see: Jeffrey & Saenger (1991); Jeffrey (1997); Scheiner (1997). For hydrogen-bond motifs, see: Bernstein et al. (1995).

S2. Experimental

A hot methanol solution (10 ml) of 2-amino-5-bromopyridine (87 mg, Aldrich) and a hot aqueous solution (10 ml) of succinic acid (59 mg, Merck) were mixed and warmed over a water bath for 10 minutes. The resulting solution was allowed to cool slowly at room temperature. Single crystals of the title compound appeared from the mother liquor after a few days.

S3. Refinement

Atom H1N1 was located in a difference Fourier map and refined freely. The remaining H atoms were positioned geometrically [C–H = 0.93 or 0.97 Å, O—H = 0.82 Å and N—H = 0.86 Å] and were refined using a riding model, with U_iso(H) = 1.2 or 1.5U_eq(C). 995 Friedel pairs were used to determine the absolute configuration.

Computing details

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); 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) and PLATON (Spek, 2009).

Figures

	Fig. 1. The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The crystal packing of the title compound, showing hydrogen-bonded (dashed lines) networks.

2-Amino-5-bromopyridinium hydrogen succinate

Crystal data

C5H6N2Br^+·C4H5O4^−	F(000) = 584
Mr = 291.11	Dx = 1.756 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 4688 reflections
a = 5.3275 (2) Å	θ = 3.0–26.7°
b = 13.6226 (5) Å	µ = 3.74 mm^−1
c = 15.1687 (5) Å	T = 296 K
V = 1100.86 (7) Å^3	Needle, yellow
Z = 4	0.80 × 0.15 × 0.13 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	2472 independent reflections
Radiation source: fine-focus sealed tube	2138 reflections with I > 2s(I)
Graphite monochromator	Rint = 0.029
ϕ and ω scans	θmax = 27.5°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −6→6
Tmin = 0.155, Tmax = 0.650	k = −17→16
10042 measured reflections	l = −19→18

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)] = 0.025	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.057	w = 1/[σ^2(Fo^2) + (0.0248P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.99	(Δ/σ)max = 0.002
2472 reflections	Δρmax = 0.21 e Å^−3
150 parameters	Δρmin = −0.31 e Å^−3
0 restraints	Absolute structure: Flack (1983), 995 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.013 (8)

Special details

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
O1	0.0791 (3)	0.66915 (12)	0.38303 (10)	0.0490 (4)
O2	0.2588 (3)	0.53970 (10)	0.32236 (11)	0.0441 (4)
O3	0.0528 (4)	0.80559 (14)	0.20813 (14)	0.0633 (6)
O4	−0.3210 (4)	0.86482 (12)	0.24424 (12)	0.0561 (5)
H4	−0.2572	0.9169	0.2290	0.084*
C6	0.0954 (4)	0.60694 (15)	0.32351 (14)	0.0341 (5)
C7	−0.0907 (5)	0.61018 (17)	0.24855 (15)	0.0450 (6)
H7A	−0.1850	0.5493	0.2485	0.054*
H7B	0.0017	0.6134	0.1935	0.054*
C8	−0.2747 (5)	0.69486 (17)	0.25115 (16)	0.0437 (6)
H8A	−0.4068	0.6826	0.2085	0.052*
H8B	−0.3515	0.6971	0.3091	0.052*
C9	−0.1593 (5)	0.79274 (16)	0.23193 (13)	0.0377 (5)
Br1	1.17196 (5)	0.336238 (18)	0.513704 (18)	0.05230 (10)
N1	0.6002 (4)	0.52635 (13)	0.45518 (13)	0.0345 (4)
N2	0.4388 (4)	0.66737 (14)	0.51595 (13)	0.0459 (5)
H2A	0.3300	0.6690	0.4741	0.055*
H2B	0.4388	0.7123	0.5558	0.055*
C1	0.7639 (4)	0.45042 (15)	0.45213 (15)	0.0377 (5)
H1	0.7547	0.4047	0.4067	0.045*
C2	0.9404 (4)	0.44144 (16)	0.51537 (15)	0.0380 (5)
C3	0.9540 (5)	0.51139 (18)	0.58345 (16)	0.0414 (6)
H3	1.0756	0.5056	0.6271	0.050*
C4	0.7899 (5)	0.58693 (16)	0.58521 (14)	0.0405 (5)
H4A	0.7984	0.6332	0.6302	0.049*
C5	0.6060 (4)	0.59588 (15)	0.51909 (14)	0.0343 (5)
H1N1	0.482 (5)	0.5320 (17)	0.4180 (16)	0.047 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0616 (11)	0.0425 (9)	0.0428 (8)	0.0111 (9)	−0.0104 (8)	−0.0157 (8)
O2	0.0495 (10)	0.0309 (8)	0.0520 (9)	0.0067 (7)	−0.0090 (8)	−0.0090 (7)
O3	0.0470 (12)	0.0576 (12)	0.0852 (14)	−0.0024 (9)	0.0118 (11)	0.0229 (10)
O4	0.0603 (11)	0.0347 (9)	0.0733 (12)	0.0024 (10)	0.0199 (11)	0.0111 (8)
C6	0.0412 (13)	0.0265 (10)	0.0347 (11)	−0.0057 (9)	0.0013 (9)	−0.0001 (9)
C7	0.0572 (17)	0.0345 (12)	0.0432 (13)	−0.0017 (11)	−0.0075 (12)	−0.0049 (10)
C8	0.0426 (15)	0.0392 (12)	0.0493 (13)	−0.0033 (10)	−0.0088 (11)	0.0050 (10)
C9	0.0418 (13)	0.0385 (12)	0.0330 (10)	−0.0026 (12)	−0.0029 (12)	0.0039 (9)
Br1	0.04413 (14)	0.04024 (13)	0.07255 (17)	0.00556 (11)	−0.00191 (13)	0.00411 (12)
N1	0.0360 (11)	0.0308 (10)	0.0367 (10)	−0.0035 (8)	−0.0032 (9)	−0.0029 (8)
N2	0.0480 (11)	0.0377 (10)	0.0520 (10)	0.0049 (9)	−0.0099 (10)	−0.0151 (10)
C1	0.0415 (13)	0.0291 (11)	0.0426 (11)	−0.0051 (10)	0.0030 (10)	−0.0034 (9)
C2	0.0364 (12)	0.0334 (11)	0.0442 (11)	−0.0016 (9)	0.0024 (11)	0.0036 (10)
C3	0.0397 (13)	0.0436 (13)	0.0410 (12)	−0.0064 (12)	−0.0046 (11)	0.0035 (11)
C4	0.0443 (14)	0.0411 (12)	0.0362 (11)	−0.0048 (12)	−0.0015 (11)	−0.0057 (10)
C5	0.0355 (11)	0.0303 (10)	0.0370 (10)	−0.0069 (9)	0.0046 (10)	−0.0002 (9)

Geometric parameters (Å, º)

O1—C6	1.241 (2)	N1—C1	1.354 (3)
O2—C6	1.264 (3)	N1—C5	1.356 (3)
O3—C9	1.199 (3)	N1—H1N1	0.85 (3)
O4—C9	1.319 (3)	N2—C5	1.321 (3)
O4—H4	0.8200	N2—H2A	0.8600
C6—C7	1.509 (3)	N2—H2B	0.8600
C7—C8	1.514 (3)	C1—C2	1.349 (3)
C7—H7A	0.9700	C1—H1	0.9300
C7—H7B	0.9700	C2—C3	1.407 (3)
C8—C9	1.497 (3)	C3—C4	1.351 (3)
C8—H8A	0.9700	C3—H3	0.9300
C8—H8B	0.9700	C4—C5	1.407 (3)
Br1—C2	1.891 (2)	C4—H4A	0.9300
C9—O4—H4	109.5	C1—N1—H1N1	121.6 (17)
O1—C6—O2	123.6 (2)	C5—N1—H1N1	115.4 (17)
O1—C6—C7	118.8 (2)	C5—N2—H2A	120.0
O2—C6—C7	117.60 (18)	C5—N2—H2B	120.0
C6—C7—C8	115.32 (18)	H2A—N2—H2B	120.0
C6—C7—H7A	108.4	C2—C1—N1	119.6 (2)
C8—C7—H7A	108.4	C2—C1—H1	120.2
C6—C7—H7B	108.4	N1—C1—H1	120.2
C8—C7—H7B	108.4	C1—C2—C3	119.8 (2)
H7A—C7—H7B	107.5	C1—C2—Br1	120.93 (17)
C9—C8—C7	114.1 (2)	C3—C2—Br1	119.31 (18)
C9—C8—H8A	108.7	C4—C3—C2	119.8 (2)
C7—C8—H8A	108.7	C4—C3—H3	120.1
C9—C8—H8B	108.7	C2—C3—H3	120.1
C7—C8—H8B	108.7	C3—C4—C5	120.2 (2)
H8A—C8—H8B	107.6	C3—C4—H4A	119.9
O3—C9—O4	123.3 (2)	C5—C4—H4A	119.9
O3—C9—C8	125.1 (2)	N2—C5—N1	118.3 (2)
O4—C9—C8	111.5 (2)	N2—C5—C4	123.99 (19)
C1—N1—C5	122.9 (2)	N1—C5—C4	117.7 (2)
O1—C6—C7—C8	3.3 (3)	C1—C2—C3—C4	0.2 (3)
O2—C6—C7—C8	−177.4 (2)	Br1—C2—C3—C4	179.88 (18)
C6—C7—C8—C9	70.8 (3)	C2—C3—C4—C5	−0.1 (3)
C7—C8—C9—O3	6.8 (3)	C1—N1—C5—N2	179.6 (2)
C7—C8—C9—O4	−173.26 (18)	C1—N1—C5—C4	−0.7 (3)
C5—N1—C1—C2	0.8 (3)	C3—C4—C5—N2	−180.0 (2)
N1—C1—C2—C3	−0.5 (3)	C3—C4—C5—N1	0.4 (3)
N1—C1—C2—Br1	179.82 (16)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N1···O2	0.85 (3)	1.88 (3)	2.720 (3)	171 (3)
N2—H2A···O1	0.86	1.92	2.782 (3)	178
N2—H2B···O1^i	0.86	2.01	2.805 (3)	154
O4—H4···O2^ii	0.82	1.85	2.609 (2)	154
C1—H1···O3^iii	0.93	2.43	3.280 (3)	152

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