3-Methyl-2-vinyl­pyridinium phosphate

Abstract

In the title salt, C₈H₁₀N⁺·H₂PO₄ ⁻, the cation is essentially planar (r.m.s. deviation = 0.063 Å). In the crystal, the phosphate anions form inversion R ₂ ²(8) dimers via pairs of O—H⋯O hydrogen bonds. These dimers are further linked by pairs of O—H⋯O hydrogen bonds, also enclosing R ₂ ²(8) loops, forming chains running along [001]. The cations are bonded to the anions via N—H⋯O hydrogen bonds and C—H⋯O contacts.

Related literature  

For the biological activity of 4-amino­pyridine, see: Judge & Bever (2006 ▶); Schwid et al. (1997 ▶); Strupp et al. (2004 ▶). For related structures, see: Anderson et al. (2005 ▶); Fun et al. (2009 ▶); Sabari et al. (2012 ▶).

Experimental  

Crystal data  

• C₈H₁₀N⁺·H₂PO₄ ⁻

• M _r = 217.16

• Monoclinic,

• a = 7.7089 (6) Å

• b = 16.3668 (13) Å

• c = 8.0649 (6) Å

• β = 109.689 (4)°

• V = 958.06 (13) ų

• Z = 4

• Mo Kα radiation

• μ = 0.28 mm⁻¹

• T = 293 K

• 0.30 × 0.30 × 0.20 mm

Data collection  

• Bruker Kappa APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker 2008 ▶) T _min = 0.922, T _max = 0.947

• 8970 measured reflections

• 2362 independent reflections

• 2052 reflections with I > 2σ(I)

• R _int = 0.026

Refinement  

• R[F ² > 2σ(F ²)] = 0.037

• wR(F ²) = 0.114

• S = 1.08

• 2362 reflections

• 136 parameters

• 3 restraints

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.28 e Å⁻³

• Δρ_min = −0.33 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O2	0.86	1.83	2.6558 (18)	160
O3—H3A⋯O1i	0.89 (1)	1.72 (1)	2.5995 (18)	173 (3)
O4—H4A⋯O2ii	0.89 (1)	1.72 (1)	2.6002 (17)	170 (3)
C1—H1A⋯O1iii	0.93	2.48	3.172 (2)	131

Symmetry codes: (i) ; (ii) ; (iii) .

supplementary crystallographic information

Comment

4-Aminopyridine (Fampridine) is used clinically in Lambert-Eaton myastheni syndrome and multiple sclerosis because by blocking potassium channels it prolongs action potentials thereby increasing transmitter release at the neuromuscular junction (Judge & Bever et al., 2006; Schwid et al., 1997; Strupp et al., 2004).

In the title compound (Fig. 1), the bond lengths and angles have normal values. The asymmetric unit is composed of one 3-methyl 2-vinyl pyridinium cation and one phosphate anion. The C1—N1—C5 angle in the pyridinium ring is widened to 123.35 (2) °, compared to 115.25 (13)° in 4-aminopyridine (Anderson et al., 2005), 121.20 (15) in 1-(2-carboxyethyl)-5-ethyl-2-methylpyridinium (Sabari et al., 2012) and 120.7 (2)° in Aminopyridinium (Fun et al., 2009). The 3-methyl 2-vinyl pyridinium ring is essentially planar with the maximum deviation from planarity being 0.008 (2) Å for atom C5. The sum of the bond angles around the N1 atom (359.89°) indicates sp² hybridization.

The phosphate anions form centrosymmetric R₂²(8) dimers via O—H···O hydrogen bonds. These dimers are further linked to chains running along the c axis. The cations are boned to the anions via N—H···O hydrogen bonds and C—H···O contacts.

Experimental

1 g (0.0084 mol) of freshly distilled 3-methyl 2-vinyl pyridine was dissolved in 15 ml of diethyl ether at -10°C under nitrogen atmosphere. To the above solution, 0.5 ml of H₃PO₄ and 10 ml of diethyl ether mixture was added in drops with continuous stirring. The product obtained as a white solid was filtered, washed with diethyl ether and dried under vacuum, the product was recrystallized from methanol. Yield: 100% (1.82 g).

Refinement

All H atoms were found in a difference Fourier map and those bonded to O were refined with a distance restraint of 0.90 (1)Å. The other H atoms were fixed geometrically and allowed to ride on their attached atoms, with C—H ranging from 0.93 to 0.96 Å, and with U_iso = 1.2–1.5U_eq (C,N). The methyl group was allowed to rotate but not to tip.

Figures

Fig. 1.

View of one molecule of the title compound showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level (arbitrary spheres for the H atoms).

Fig. 2.

A view of the crystal packing. Hydrogen bonds are drawn as dashed lines. H atoms not involved in hydrogen bonding have been omitted for clarity.

Crystal data

C8H10N+·H2O4P−	F(000) = 456
Mr = 217.16	Dx = 1.506 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 8834 reflections
a = 7.7089 (6) Å	θ = 2.1–31.2°
b = 16.3668 (13) Å	µ = 0.28 mm−1
c = 8.0649 (6) Å	T = 293 K
β = 109.689 (4)°	Block, colourless
V = 958.06 (13) Å3	0.30 × 0.30 × 0.20 mm
Z = 4

Data collection

Bruker Kappa APEXII CCD diffractometer	2362 independent reflections
Radiation source: fine-focus sealed tube	2052 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
ω and φ scan	θmax = 28.3°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Bruker 2008)	h = −10→10
Tmin = 0.922, Tmax = 0.947	k = −21→17
8970 measured reflections	l = −10→10

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.114	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ2(Fo2) + (0.0631P)2 + 0.2803P] where P = (Fo2 + 2Fc2)/3
2362 reflections	(Δ/σ)max = 0.003
136 parameters	Δρmax = 0.28 e Å−3
3 restraints	Δρmin = −0.33 e Å−3

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
C1	0.5293 (2)	0.35216 (10)	0.9141 (2)	0.0394 (4)
H1A	0.5318	0.4089	0.9225	0.047*
C2	0.6707 (3)	0.30687 (12)	1.0253 (3)	0.0446 (4)
H2	0.7706	0.3322	1.1082	0.054*
C3	0.6608 (2)	0.22259 (11)	1.0112 (3)	0.0420 (4)
H3	0.7546	0.1911	1.0870	0.050*
C4	0.5138 (2)	0.18417 (10)	0.8859 (2)	0.0349 (4)
C5	0.3751 (2)	0.23315 (9)	0.7738 (2)	0.0304 (3)
C6	0.2165 (2)	0.19908 (11)	0.6336 (2)	0.0404 (4)
H6	0.1973	0.1432	0.6382	0.048*
C7	0.1003 (3)	0.23843 (13)	0.5042 (3)	0.0514 (5)
H7A	0.1131	0.2945	0.4934	0.062*
H7B	0.0040	0.2106	0.4221	0.062*
C8	0.5063 (3)	0.09263 (11)	0.8732 (3)	0.0545 (5)
H8A	0.3981	0.0732	0.8944	0.082*
H8B	0.6139	0.0699	0.9594	0.082*
H8C	0.5020	0.0762	0.7576	0.082*
N1	0.38850 (18)	0.31502 (8)	0.79424 (17)	0.0319 (3)
H1	0.3015	0.3448	0.7263	0.038*
O1	0.20750 (17)	0.49478 (7)	0.95492 (15)	0.0374 (3)
O2	0.12761 (18)	0.42554 (7)	0.65535 (15)	0.0414 (3)
O3	−0.11397 (18)	0.44558 (8)	0.78857 (17)	0.0460 (3)
O4	0.0217 (2)	0.56754 (7)	0.68547 (16)	0.0446 (3)
P1	0.06935 (6)	0.48168 (2)	0.77599 (5)	0.03024 (15)
H3A	−0.143 (4)	0.4698 (16)	0.875 (3)	0.082 (9)*
H4A	−0.032 (4)	0.5639 (19)	0.5694 (14)	0.093 (10)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0427 (9)	0.0273 (8)	0.0485 (10)	−0.0054 (6)	0.0156 (8)	−0.0067 (7)
C2	0.0361 (9)	0.0435 (10)	0.0475 (10)	−0.0078 (7)	0.0052 (8)	−0.0079 (8)
C3	0.0358 (9)	0.0410 (10)	0.0443 (10)	0.0033 (7)	0.0070 (8)	0.0046 (8)
C4	0.0373 (8)	0.0276 (8)	0.0396 (9)	0.0001 (6)	0.0127 (7)	0.0030 (6)
C5	0.0335 (8)	0.0259 (7)	0.0333 (8)	−0.0020 (6)	0.0132 (6)	0.0008 (6)
C6	0.0433 (9)	0.0311 (8)	0.0416 (9)	−0.0076 (7)	0.0075 (8)	−0.0013 (7)
C7	0.0503 (11)	0.0437 (10)	0.0529 (11)	0.0008 (8)	0.0077 (9)	−0.0073 (9)
C8	0.0614 (12)	0.0271 (9)	0.0652 (13)	0.0024 (8)	0.0085 (10)	0.0084 (9)
N1	0.0333 (7)	0.0259 (7)	0.0360 (7)	0.0012 (5)	0.0113 (6)	0.0007 (5)
O1	0.0367 (6)	0.0395 (6)	0.0296 (6)	−0.0004 (5)	0.0028 (5)	−0.0013 (5)
O2	0.0573 (8)	0.0318 (6)	0.0308 (6)	0.0166 (5)	0.0092 (5)	0.0004 (5)
O3	0.0444 (7)	0.0518 (8)	0.0377 (7)	−0.0129 (6)	0.0083 (6)	−0.0120 (6)
O4	0.0703 (9)	0.0243 (6)	0.0330 (6)	0.0110 (5)	0.0093 (6)	0.0008 (5)
P1	0.0375 (2)	0.0230 (2)	0.0260 (2)	0.00340 (14)	0.00509 (17)	−0.00119 (14)

Geometric parameters (Å, º)

C1—N1	1.333 (2)	C7—H7A	0.9300
C1—C2	1.372 (3)	C7—H7B	0.9300
C1—H1A	0.9300	C8—H8A	0.9600
C2—C3	1.384 (3)	C8—H8B	0.9600
C2—H2	0.9300	C8—H8C	0.9600
C3—C4	1.389 (2)	N1—H1	0.8600
C3—H3	0.9300	O1—P1	1.4923 (12)
C4—C5	1.397 (2)	O2—P1	1.5122 (12)
C4—C8	1.502 (2)	O3—P1	1.5663 (13)
C5—N1	1.350 (2)	O3—H3A	0.889 (10)
C5—C6	1.467 (2)	O4—P1	1.5691 (12)
C6—C7	1.295 (3)	O4—H4A	0.889 (10)
C6—H6	0.9300
N1—C1—C2	120.08 (16)	C6—C7—H7B	120.0
N1—C1—H1A	120.0	H7A—C7—H7B	120.0
C2—C1—H1A	120.0	C4—C8—H8A	109.5
C1—C2—C3	118.37 (17)	C4—C8—H8B	109.5
C1—C2—H2	120.8	H8A—C8—H8B	109.5
C3—C2—H2	120.8	C4—C8—H8C	109.5
C2—C3—C4	121.31 (17)	H8A—C8—H8C	109.5
C2—C3—H3	119.3	H8B—C8—H8C	109.5
C4—C3—H3	119.3	C1—N1—C5	123.48 (14)
C3—C4—C5	118.04 (15)	C1—N1—H1	118.3
C3—C4—C8	120.31 (16)	C5—N1—H1	118.3
C5—C4—C8	121.65 (16)	P1—O3—H3A	110.5 (19)
N1—C5—C4	118.69 (14)	P1—O4—H4A	113 (2)
N1—C5—C6	118.75 (14)	O1—P1—O2	116.08 (7)
C4—C5—C6	122.55 (15)	O1—P1—O3	110.92 (7)
C7—C6—C5	127.06 (17)	O2—P1—O3	106.41 (8)
C7—C6—H6	116.5	O1—P1—O4	107.46 (7)
C5—C6—H6	116.5	O2—P1—O4	108.58 (7)
C6—C7—H7A	120.0	O3—P1—O4	107.04 (8)
N1—C1—C2—C3	−1.1 (3)	C8—C4—C5—C6	−1.8 (2)
C1—C2—C3—C4	1.1 (3)	N1—C5—C6—C7	13.1 (3)
C2—C3—C4—C5	0.1 (3)	C4—C5—C6—C7	−166.36 (19)
C2—C3—C4—C8	−179.99 (18)	C2—C1—N1—C5	−0.2 (2)
C3—C4—C5—N1	−1.3 (2)	C4—C5—N1—C1	1.3 (2)
C8—C4—C5—N1	178.81 (16)	C6—C5—N1—C1	−178.12 (15)
C3—C4—C5—C6	178.18 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O2	0.86	1.83	2.6558 (18)	160
O3—H3A···O1i	0.89 (1)	1.72 (1)	2.5995 (18)	173 (3)
O4—H4A···O2ii	0.89 (1)	1.72 (1)	2.6002 (17)	170 (3)
C1—H1A···O1iii	0.93	2.48	3.172 (2)	131

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