2-Amino-5-chloro­pyridinium (Z)-3-carb­oxy­prop-2-enoate 0.25-hydrate

In the title hydrated salt, C₅H₆ClN₂⁺·C₄H₃O₄⁻·0.25H₂O, the water O atom lies on a twofold axis with 0.25 occupancy. The 2-amino-5-chloro­pyridinium cation is almost planar, with a maximum deviation of 0.015 (3) Å. In the hydrogen malate anion, an intra­molecular O—H...O hydrogen bond generates an S(7) ring and results in a folded conformation. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl­ate O atoms of the anion via a pair of N—H...O hydrogen bonds, forming an R₂²(8) ring motif. The ion pairs are further connected via O—H...O, N—H...O and C—H...O hydrogen bonds, forming layers parallel to the ab plane which stack down the c axis.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.003 Å
• Disorder in main residue
• R factor = 0.048
• wR factor = 0.109
• Data-to-parameter ratio = 23.1

checkCIF/PLATON results

No syntax errors found



Alert level C
SHFSU01_ALERT_2_C  Test not performed. _refine_ls_shift/su_max and
            _refine_ls_shift/esd_max not present.
            Absolute value of the parameter shift to su ratio given   0.001
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.49
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          3
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         10
PLAT915_ALERT_3_C Low Friedel Pair Coverage ......................      82.51 Perc.
PLAT041_ALERT_1_C Calc. and Reported SumFormula    Strings  Differ          ?
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.25 Ratio
PLAT076_ALERT_1_C Occupancy       0.50 less than 1.0 for Sp.pos  .        O1W
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          5

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           32.11
           From the CIF: _reflns_number_total               3485
           Count of symmetry unique reflns         2147
           Completeness (_total/calc)            162.32%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured      1338
           Fraction of Friedel pairs measured     0.623
           Are heavy atom types Z>Si present        yes
PLAT083_ALERT_2_G SHELXL Second Parameter in WGHT Unusually Large.       6.99
PLAT301_ALERT_3_G Note: Main Residue  Disorder ...................       3.00 Perc.
PLAT063_ALERT_4_G Crystal Size Likely too Large for Beam Size ....       0.90 mm
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          5

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

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 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

There is growing interest in the construction of supramolecular assemblies with hydrogen bonds as the building blocks (Aakeröy & Seddon, 1993; Fredericks & Hamilton, 1996). The maleic acid anion can exist in the fully deprotonated form or as hydrogen maleate, with one of the carboxylic acid groups protonated. The crystal structures of glycinium maleate (Rajagopal et al., 2001a), β-alaninium maleate (Rajagopal et al., 2001b), sarcosinium maleate (Rajagopal et al., 2002) and L-alaninium maleate (Alagar et al., 2001) have been reported in the literature. The present study reports the crystal structure of 2-amino-5-chloropyridinium hydrogen maleate 0.25-hydrate, (I), a complex of 2-amino-5-chloropyridinium with maleic acid.

The asymmetric unit (Fig. 1), contains a 2-amino-5-chloropyridinium cation, a hydrogen malate anion and a water molecule with occupany 0.25 (the O atom of the water molecule lies on a twofold axis). The 2-amino-5-chloropyridinium cation is essentially planar, with a maximum deviation of 0.015 (3) Å for atom C1. In the 2-amino-5-chloropyridinium cation, a wide angle [C1—N1—C5 = 123.39 (18)°] is subtended at the protonated N1 atom. The dihedral angle between the pyridine ring and the mean plane formed by the hydrogen maleate anion is 22.39 (10)°.

In the crystal packing, the protonated N1 atom and the 2-amino group (N2) are hydrogen-bonded to the carboxylate oxygen atoms (O1 and O2) via a pair of intermolecular N1—H1N1···O1 and N2—H1N2···O2 hydrogen bonds, forming a ring motif R₂²(8) (Bernstein et al., 1995). The ion pairs are further connected via N2—H2N2···O4, O1W—H1W1···O1, C3—H3A···O4 and C4—H4A···O3 (Table 1) hydrogen bonds, forming two-dimensional networks parallel to the ab plane (Fig. 2) which stacked down the c-axis. In the hydrogen malate anion, an intramolecular O3—H1O3···O2 hydrogen bond generates an S(7) ring and results in a folded conformation.

Related literature

For hydrogen bonds in supramolecular assemblies, see: Aakeröy & Seddon (1993); Fredericks & Hamilton (1996). For related structures of maleate salts, see: Rajagopal et al. (2001a,b, 2002); Alagar et al. (2001). For hydrogen-bond motifs, see: Bernstein et al. (1995). 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 maleic acid (58 mg, Merck) were mixed and warmed over a heating magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and colourless needles of (I) appeared after a few days.

S3. Refinement

All hydrogen atoms were positioned geometrically [C—H = 0.93 Å, N—H = 0.8196–0.86 Å and O—H = 0.8190–0.9462 Å] and were refined using a riding model, with U_iso(H) = 1.2 U_eq(C, N) or 1.5 U_eq(O). 1354 Friedel pairs were used to determine the absolute structure.

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. Dashed lines indicate hydrogen bonds.
	Fig. 2. The crystal packing of (I), showing hydrogen-bonded (dashed lines) 2D networks parallel to to the ab-plane. H atoms not involved in the intermolecular interactions have been omitted for clarity.

2-Amino-5-chloropyridinium (Z)-3-carboxyprop-2-enoate 0.25-hydrate

Crystal data

C5H6ClN2^+·C4H3O4^−·0.25H2O	F(000) = 2056
Mr = 249.14	Dx = 1.537 Mg m^−3
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: F 2 -2d	Cell parameters from 2106 reflections
a = 23.899 (4) Å	θ = 3.1–30.2°
b = 48.298 (8) Å	µ = 0.36 mm^−1
c = 3.7314 (7) Å	T = 100 K
V = 4307.1 (13) Å^3	Needle, colourless
Z = 16	0.90 × 0.09 × 0.07 mm

Data collection

Bruker APEXII DUO CCD diffractometer	3485 independent reflections
Radiation source: fine-focus sealed tube	2896 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
φ and ω scans	θmax = 32.1°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −35→19
Tmin = 0.739, Tmax = 0.976	k = −72→72
8113 measured reflections	l = −5→5

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)] = 0.048	H-atom parameters constrained
wR(F^2) = 0.109	w = 1/[σ^2(Fo^2) + (0.0339P)^2 + 6.9914P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
3485 reflections	Δρmax = 0.28 e Å^−3
151 parameters	Δρmin = −0.28 e Å^−3
1 restraint	Absolute structure: Flack (1983), 1354 Fridel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.03 (8)

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	Occ. (<1)
Cl1	0.69696 (2)	0.016473 (11)	0.8123 (2)	0.03527 (16)
N1	0.55035 (7)	0.05354 (4)	0.7539 (6)	0.0249 (4)
H1N1	0.5183	0.0512	0.6816	0.030*
N2	0.51706 (8)	0.09744 (4)	0.8771 (6)	0.0314 (5)
H1N2	0.4843	0.0922	0.8093	0.038*
H2N2	0.5223	0.1141	0.9500	0.038*
C1	0.59109 (8)	0.03419 (4)	0.7366 (7)	0.0247 (4)
H1A	0.5830	0.0164	0.6549	0.030*
C2	0.64399 (8)	0.04084 (4)	0.8395 (7)	0.0238 (4)
C3	0.65571 (9)	0.06771 (4)	0.9713 (6)	0.0252 (4)
H3A	0.6917	0.0723	1.0464	0.030*
C4	0.61411 (9)	0.08674 (4)	0.9871 (6)	0.0251 (4)
H4A	0.6215	0.1044	1.0751	0.030*
C5	0.55917 (8)	0.07983 (4)	0.8695 (6)	0.0243 (4)
O1	0.44806 (7)	0.03654 (4)	0.5270 (6)	0.0387 (4)
O2	0.41927 (7)	0.08014 (4)	0.4907 (5)	0.0368 (4)
O3	0.34524 (7)	0.10600 (3)	0.1851 (5)	0.0331 (4)
H1O3	0.3779	0.0991	0.2975	0.050*
O4	0.26906 (7)	0.09571 (3)	−0.1213 (6)	0.0354 (4)
C6	0.41315 (9)	0.05435 (5)	0.4340 (7)	0.0314 (5)
C7	0.36132 (9)	0.04403 (5)	0.2533 (7)	0.0309 (5)
H7A	0.3578	0.0249	0.2461	0.037*
C8	0.31932 (9)	0.05795 (5)	0.1004 (7)	0.0289 (5)
H8A	0.2910	0.0468	0.0086	0.035*
C9	0.30996 (9)	0.08816 (5)	0.0515 (7)	0.0280 (5)
O1W	0.5000	0.0000	0.0840 (17)	0.0348 (11)	0.50
H1W1	0.4736	0.0067	0.1941	0.052*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0224 (2)	0.0272 (2)	0.0563 (4)	0.00083 (19)	0.0022 (3)	0.0053 (3)
N1	0.0196 (7)	0.0327 (8)	0.0223 (10)	−0.0017 (6)	−0.0009 (8)	0.0005 (7)
N2	0.0242 (8)	0.0334 (9)	0.0365 (13)	0.0029 (7)	−0.0077 (9)	−0.0069 (9)
C1	0.0244 (9)	0.0272 (9)	0.0225 (11)	−0.0014 (7)	0.0012 (9)	0.0035 (8)
C2	0.0208 (8)	0.0274 (8)	0.0232 (11)	0.0006 (7)	0.0015 (9)	0.0062 (9)
C3	0.0212 (9)	0.0319 (10)	0.0224 (11)	−0.0026 (7)	−0.0018 (8)	0.0038 (9)
C4	0.0253 (9)	0.0296 (9)	0.0206 (11)	−0.0029 (7)	−0.0013 (8)	0.0007 (9)
C5	0.0232 (9)	0.0323 (9)	0.0175 (11)	−0.0003 (7)	−0.0022 (9)	0.0014 (9)
O1	0.0255 (7)	0.0530 (9)	0.0376 (11)	−0.0024 (7)	−0.0090 (8)	0.0088 (10)
O2	0.0282 (8)	0.0445 (9)	0.0377 (11)	−0.0109 (7)	−0.0125 (8)	0.0055 (8)
O3	0.0286 (8)	0.0378 (8)	0.0329 (10)	−0.0097 (6)	−0.0083 (7)	0.0059 (7)
O4	0.0291 (8)	0.0396 (8)	0.0376 (11)	−0.0043 (7)	−0.0123 (8)	0.0101 (8)
C6	0.0231 (10)	0.0481 (13)	0.0231 (12)	−0.0091 (9)	−0.0039 (9)	0.0069 (10)
C7	0.0266 (10)	0.0370 (11)	0.0293 (13)	−0.0111 (8)	−0.0072 (10)	0.0117 (10)
C8	0.0238 (9)	0.0372 (10)	0.0256 (12)	−0.0113 (8)	−0.0061 (9)	0.0117 (10)
C9	0.0238 (9)	0.0360 (10)	0.0241 (12)	−0.0067 (8)	−0.0006 (9)	0.0062 (10)
O1W	0.033 (2)	0.0282 (19)	0.043 (3)	0.0037 (17)	0.000	0.000

Geometric parameters (Å, º)

Cl1—C2	1.731 (2)	C4—H4A	0.9300
N1—C1	1.351 (3)	O1—C6	1.248 (3)
N1—C5	1.357 (3)	O2—C6	1.272 (3)
N1—H1N1	0.8196	O3—C9	1.304 (3)
N2—C5	1.318 (3)	O3—H1O3	0.9462
N2—H1N2	0.8600	O4—C9	1.226 (3)
N2—H2N2	0.8600	C6—C7	1.496 (3)
C1—C2	1.360 (3)	C7—C8	1.336 (3)
C1—H1A	0.9300	C7—H7A	0.9300
C2—C3	1.416 (3)	C8—C9	1.488 (3)
C3—C4	1.355 (3)	C8—H8A	0.9300
C3—H3A	0.9300	O1W—H1W1	0.8190
C4—C5	1.424 (3)
C1—N1—C5	123.39 (18)	C5—C4—H4A	119.9
C1—N1—H1N1	124.1	N2—C5—N1	119.47 (19)
C5—N1—H1N1	112.3	N2—C5—C4	123.1 (2)
C5—N2—H1N2	120.0	N1—C5—C4	117.41 (18)
C5—N2—H2N2	120.0	C9—O3—H1O3	117.9
H1N2—N2—H2N2	120.0	O1—C6—O2	123.5 (2)
N1—C1—C2	119.54 (19)	O1—C6—C7	116.7 (2)
N1—C1—H1A	120.2	O2—C6—C7	119.8 (2)
C2—C1—H1A	120.2	C8—C7—C6	130.3 (2)
C1—C2—C3	119.90 (19)	C8—C7—H7A	114.8
C1—C2—Cl1	120.18 (17)	C6—C7—H7A	114.8
C3—C2—Cl1	119.92 (15)	C7—C8—C9	131.2 (2)
C4—C3—C2	119.45 (19)	C7—C8—H8A	114.4
C4—C3—H3A	120.3	C9—C8—H8A	114.4
C2—C3—H3A	120.3	O4—C9—O3	121.3 (2)
C3—C4—C5	120.3 (2)	O4—C9—C8	118.4 (2)
C3—C4—H4A	119.9	O3—C9—C8	120.2 (2)
C5—N1—C1—C2	0.2 (3)	C3—C4—C5—N2	−179.8 (2)
N1—C1—C2—C3	1.4 (3)	C3—C4—C5—N1	2.0 (3)
N1—C1—C2—Cl1	−178.96 (18)	O1—C6—C7—C8	−174.0 (3)
C1—C2—C3—C4	−1.2 (4)	O2—C6—C7—C8	7.2 (4)
Cl1—C2—C3—C4	179.14 (19)	C6—C7—C8—C9	1.2 (5)
C2—C3—C4—C5	−0.5 (4)	C7—C8—C9—O4	175.2 (3)
C1—N1—C5—N2	179.8 (2)	C7—C8—C9—O3	−3.6 (4)
C1—N1—C5—C4	−1.9 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N1···O1	0.82	1.91	2.714 (3)	166
N2—H1N2···O2	0.86	2.04	2.870 (3)	161
N2—H2N2···O4	0.86	2.05	2.902 (3)	169
O3—H1O3···O2	0.95	1.53	2.447 (2)	162
O1W—H1W1···O1	0.82	2.00	2.718 (4)	146
C3—H3A···O4^i	0.93	2.50	3.388 (3)	160
C4—H4A···O3	0.93	2.42	3.263 (3)	151

Symmetry code: (i) x+1/2, y, z+3/2.