2-Amino-5-chloro­pyridine–fumaric acid (1/2)

The asymmetric unit of the title compound, C₅H₅ClN₂·0.5C₄H₄O₄, comprises a neutral 2-amino-5-chloro­pyridine mol­ecule and one half of a fumaric acid mol­ecule which lies on an inversion center. The dihedral angle between the pyridine ring and the plane formed by the fumaric acid mol­ecule is 3.22 (8)°. The 2-amino-5-chloro­pyridine mol­ecule is planar, with a maximum deviation of 0.004 (1) Å for the pyridine N atom. In the crystal, the 2-amino-5-chloro­pyridine mol­ecules inter­act with the carboxyl groups of fumaric acid mol­ecules through N—H...O and O—H...N hydrogen bonds, forming centrosymmetric R₂²(8) ring motifs and another N—H...O hydrogen bond links these motifs into a two-dimensional network parallel to (100).

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.042
• wR factor = 0.143
• Data-to-parameter ratio = 25.2

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         27
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          2

Alert level G
PLAT432_ALERT_2_G Short Inter X...Y Contact  C6     ..  C6      ..       3.07 Ang.
PLAT960_ALERT_3_G Number of Intensities with I .LT. - 2*sig(I) ..           2

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   1 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-bond interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). Fumaric acid is among the organic compounds widely found in nature, and is key intermediate in the biosynthesis of organic acids. Fumaric acid is of interest since it is known to form supramolecular assemblies with N–aromatic complexes (Batchelor et al., 2000). In order to study some interesting hydrogen bonding interactions, the synthesis and structure of the title compound, (I), is presented here.

The asymmetric unit of the title compond consists of a 2-amino-5- chloropyridine molecule and a half of the fumaric acid molecule (Fig. 1). The planar fumaric acid molecule is centrosymmetric with the mid-point of the C═C double bond located at an inversion center. The C6–O1 bond distance of 1.2375 (17) Å is much shorter than the C6–O2 bond distance of 13061 (16) Å, suggesting that the carboxyl group is not deprotonated in the crystal structure. The 2-amino- 5-chloropyridine molecule is planar, with a maximum deviation of 0.004 (1) Å for atom N1. The bond lengths (Allen et al., 1987) and angles are normal.

In the crystal packing (Fig. 2), the 2-amino-5-chloropyridine molecules interact with the carboxyl groups (O1 & O2) of fumaric acid molecules through N2—H2A···O1 and O2—H2···N1 hydrogen bonds (Table 1), forming cyclic hydrogen-bonded motifs R₂²(8) (Bernstein et al., 1995) and the N2—H2B···O2 hydrogen bond links these motifs into a two-dimensional network parallel to (100) plane.

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997); Katritzky et al. (1996). For the details of fumaric acid, see: Batchelor et al. (2000). For details of hydrogen bonding, see: Jeffrey & Saenger (1991); Jeffrey (1997); Scheiner (1997). For hydrogen-bond motifs, see: Bernstein et al. (1995). For bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

S2. Experimental

A hot methanol solution (20 ml) of 2-amino-5-chloropyridine (64 mg, Aldrich) and fumaric acid (58 mg, Merck) was mixed and warmed over a a magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound appeared after a few days.

S3. Refinement

All hydrogen atoms were positioned geometrically [C–H = 0.93 Å, N–H = 0.86 Å and O–H = 0.82 Å] and were refined using a riding model, with U_iso(H) = 1.2 U_eq(C, N) or 1.5 U_eq(O).

Computing details

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (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. H atoms not involved in hydrogen bond interactions are omitted for clarity.

2-Amino-5-chloropyridine–(E)-butenedioic acid (1/2)

Crystal data

C5H5ClN2·0.5C4H4O4	F(000) = 384
Mr = 186.60	Dx = 1.597 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3958 reflections
a = 13.678 (4) Å	θ = 3.6–36.5°
b = 5.0586 (15) Å	µ = 0.45 mm^−1
c = 11.531 (3) Å	T = 100 K
β = 103.442 (7)°	Plate, colourless
V = 776.0 (4) Å^3	0.57 × 0.25 × 0.08 mm
Z = 4

Data collection

Bruker APEXII DUO CCD area-detector diffractometer	2771 independent reflections
Radiation source: fine-focus sealed tube	2420 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.036
φ and ω scans	θmax = 32.5°, θmin = 3.6°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −20→16
Tmin = 0.784, Tmax = 0.967	k = −7→7
8439 measured reflections	l = −17→17

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)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.143	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0898P)^2 + 0.4122P] where P = (Fo^2 + 2Fc^2)/3
2771 reflections	(Δ/σ)max = 0.001
110 parameters	Δρmax = 0.70 e Å^−3
0 restraints	Δρmin = −0.59 e Å^−3

Special details

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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
Cl1	0.03621 (3)	−0.27603 (7)	0.40770 (3)	0.01778 (13)
N1	0.25244 (9)	0.1952 (2)	0.34964 (11)	0.0130 (2)
N2	0.34626 (11)	0.2094 (3)	0.20667 (12)	0.0182 (3)
H2A	0.3772	0.3457	0.2420	0.022*
H2B	0.3615	0.1481	0.1436	0.022*
C1	0.17992 (10)	0.0834 (3)	0.39610 (12)	0.0133 (2)
H1A	0.1661	0.1550	0.4648	0.016*
C2	0.12664 (10)	−0.1319 (3)	0.34452 (12)	0.0133 (2)
C3	0.14697 (11)	−0.2407 (3)	0.24014 (13)	0.0149 (3)
H3A	0.1109	−0.3861	0.2037	0.018*
C4	0.22039 (11)	−0.1301 (3)	0.19295 (12)	0.0153 (3)
H4A	0.2349	−0.2000	0.1242	0.018*
C5	0.27436 (10)	0.0926 (3)	0.24997 (12)	0.0133 (2)
O1	0.44882 (8)	0.6317 (2)	0.34908 (10)	0.0177 (2)
O2	0.34481 (8)	0.5851 (2)	0.47334 (9)	0.0143 (2)
H2	0.3331	0.4402	0.4412	0.022*
C6	0.41907 (10)	0.6973 (3)	0.43840 (12)	0.0127 (2)
C7	0.46749 (10)	0.9183 (3)	0.51670 (12)	0.0138 (2)
H7A	0.4520	0.9427	0.5904	0.017*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.01527 (19)	0.01894 (19)	0.0195 (2)	−0.00319 (10)	0.00484 (13)	0.00275 (11)
N1	0.0146 (5)	0.0132 (5)	0.0113 (5)	−0.0018 (4)	0.0033 (4)	−0.0012 (4)
N2	0.0230 (6)	0.0172 (6)	0.0176 (6)	−0.0049 (4)	0.0111 (5)	−0.0033 (4)
C1	0.0145 (6)	0.0146 (5)	0.0112 (5)	−0.0013 (4)	0.0036 (4)	−0.0002 (4)
C2	0.0125 (5)	0.0142 (6)	0.0127 (5)	−0.0013 (4)	0.0021 (4)	0.0015 (4)
C3	0.0157 (6)	0.0144 (5)	0.0133 (6)	−0.0021 (4)	0.0008 (5)	−0.0012 (4)
C4	0.0189 (6)	0.0148 (6)	0.0121 (5)	−0.0006 (4)	0.0035 (4)	−0.0020 (4)
C5	0.0157 (6)	0.0131 (5)	0.0109 (5)	0.0001 (4)	0.0029 (4)	−0.0004 (4)
O1	0.0197 (5)	0.0184 (5)	0.0175 (5)	−0.0051 (4)	0.0089 (4)	−0.0060 (4)
O2	0.0155 (5)	0.0153 (4)	0.0130 (4)	−0.0039 (3)	0.0049 (4)	−0.0023 (3)
C6	0.0120 (5)	0.0124 (5)	0.0133 (6)	−0.0001 (4)	0.0021 (4)	−0.0007 (4)
C7	0.0144 (6)	0.0135 (5)	0.0133 (6)	−0.0011 (4)	0.0030 (4)	−0.0028 (4)

Geometric parameters (Å, º)

Cl1—C2	1.7352 (14)	C3—H3A	0.9300
N1—C1	1.3555 (17)	C4—C5	1.422 (2)
N1—C5	1.3565 (17)	C4—H4A	0.9300
N2—C5	1.3393 (18)	O1—C6	1.2375 (17)
N2—H2A	0.8600	O2—C6	1.3061 (16)
N2—H2B	0.8600	O2—H2	0.8200
C1—C2	1.3675 (19)	C6—C7	1.4920 (19)
C1—H1A	0.9300	C7—C7^i	1.335 (3)
C2—C3	1.409 (2)	C7—H7A	0.9300
C3—C4	1.368 (2)
C1—N1—C5	120.10 (12)	C3—C4—C5	119.37 (13)
C5—N2—H2A	120.0	C3—C4—H4A	120.3
C5—N2—H2B	120.0	C5—C4—H4A	120.3
H2A—N2—H2B	120.0	N2—C5—N1	118.25 (13)
N1—C1—C2	121.69 (12)	N2—C5—C4	121.64 (13)
N1—C1—H1A	119.2	N1—C5—C4	120.10 (12)
C2—C1—H1A	119.2	C6—O2—H2	109.5
C1—C2—C3	119.45 (12)	O1—C6—O2	124.75 (13)
C1—C2—Cl1	120.79 (11)	O1—C6—C7	121.27 (12)
C3—C2—Cl1	119.76 (11)	O2—C6—C7	113.98 (12)
C4—C3—C2	119.29 (13)	C7^i—C7—C6	121.41 (16)
C4—C3—H3A	120.4	C7^i—C7—H7A	119.3
C2—C3—H3A	120.4	C6—C7—H7A	119.3
C5—N1—C1—C2	−0.5 (2)	C1—N1—C5—N2	179.77 (13)
N1—C1—C2—C3	−0.3 (2)	C1—N1—C5—C4	0.9 (2)
N1—C1—C2—Cl1	178.49 (11)	C3—C4—C5—N2	−179.38 (14)
C1—C2—C3—C4	0.6 (2)	C3—C4—C5—N1	−0.5 (2)
Cl1—C2—C3—C4	−178.16 (11)	O1—C6—C7—C7^i	11.5 (3)
C2—C3—C4—C5	−0.2 (2)	O2—C6—C7—C7^i	−168.52 (17)

Symmetry code: (i) −x+1, −y+2, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···N1	0.82	1.82	2.5852 (17)	154
N2—H2A···O1	0.86	2.00	2.856 (2)	171
N2—H2B···O2^ii	0.86	2.26	3.0718 (18)	158

Symmetry code: (ii) x, −y+1/2, z−1/2.