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Acta Cryst. (2009). E65, m521    [ doi:10.1107/S1600536809013270 ]

Bis(4-aminopyridinium) tetrachloridocobaltate(II)

S. R. Jebas, A. Sinthiya, B. Ravindran Durai Nayagam, D. Schollmeyer and S. A. C. Raj

Abstract top

In the title compound, (C5H7N2)2[CoCl4], the cobalt(II) ion is coordinated by four chloride ions in a slightly distorted tetrahedral geometry. The crystal packing is stabilized by intermolecular N-H...Cl hydrogen bonding, forming a three-dimensional network. The crystal was a non-merohedral twin emulating tetragonal symmetry, but being in fact orthorhombic.

Comment top

4-aminopyridine (Fampridine) is used clinically in Lambert-Eaton myasthenic syndrome and multiple sclerosis because by blocking potassium channels it prolongs action potentials thereby increasing transmitter release at the neuromuscular junction (Judge & Bever, 2006; Schwid et al., 1997; Strupp et al., 2004). The structure of 4-aminopyridine has been reported (Chao & Schempp, 1977). Redetermination of the structure of 4-aminopyridine has been reported (Anderson et al., 2005). As a part of our investigation of the reactions of the 4-aminopyridine with metals, we report here the crystal structure of the title compound (I).

The asymmetric unit of (I), consists of two molecules of 4-aminopyridinium cation and a [CoCl4]2- anion. The bond lengths and bond angles of the 4-aminopyridinium are comparable with the values reported earlier for the 4-aminopyridine in the its uncomplexed form (Anderson et al., 2005; Chao & Schempp, 1977). Protonation of the atoms N4 and N11 of the 4-aminopyridine leads to the widening of C3–N4–C5 and C10–N11–C12 angles in the pyridine ring to 121.3 (7)° and 120.4 (7)°, compared to 115.25 (13)° in 4-aminopyridine (Anderson et al., 2005). The 4-aminopyridine ring is essentially planar with the maximum deviation from planarity of 0.014 (3) Å for the atoms C8 and N11 respectively.

The anion exhibits distorted tetraedral geometry, with the CoII ion is surrounded by four Cl atoms, with Cl—Co—Cl angles ranging from 106.19 (11)–115.63 (8) Å. The mean Co—Cl bond length, 2.2707 (2) Å, is close to those observed in similar complex (Jebas et al., 2006; Zhang et al., 2005).

The crystal packing (Fig. 2) is consolidated by intermolecular N—H···Cl hydrogen bonding to form a three dimensional network.

Related literature top

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); Chao & Schempp (1977); Jebas et al. (2006); Zhang et al. (2005). For bond-length data, see: Anderson et al. (2005).

Experimental top

4-aminopyridine (0.094 g, 1 mmol) and and CoCl2 (0.169 g, 1 mmol) in ethanol (10 ml each) and the solution was stirred well for 3 h. Blue crystals of (I) were obtained by slow evaporation of the solution over a period of one month.

Refinement top

The crystals of (I) crystallized with nearly tetragonal lattice parameters. It was was not possible to solve and refine the structure in any tetragonal space group but it could be easily solved and refined in orthorhombic space group P212121. PLATON and the intensity statistic indicate twinning. Applying the twin instruction TWIN 0 1 0 1 0 0 0 0 -1 with a BASF of 0.340 (1) the R1 value drops to 0.021 (0.095 without TWIN instruction). The nonstandard setting for the orthorhombic cell was kept to simplify the twin matrix.

All the hydrogen atoms were fixed on the calculated positions and allowed to ride on their parent atoms with the C—H = 0.95 Å (aromatic); N—H = 0.84–0.89 Å with Uiso(C) in the range of 1.2Ueq(C)-1.5Ueq(N).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); 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 top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme. Intramolecular hydrogen bondings are shown as dashed lines.
[Figure 2] Fig. 2. The crystal packing of the title compound, viewed down the a axis, showing the three dimensional network.
Bis(4-aminopyridinium) tetrachloridocobalt(II) top
Crystal data top
(C5H7N2)2[CoCl4]F(000) = 788
Mr = 390.98Dx = 1.611 Mg m−3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 9192 reflections
a = 15.0051 (12) Åθ = 2.7–27.8°
b = 14.9751 (12) ŵ = 1.72 mm−1
c = 7.1723 (6) ÅT = 173 K
V = 1611.6 (2) Å3Block, blue
Z = 40.25 × 0.22 × 0.17 mm
Data collection top
Bruker APEXII SMART CCD
diffractometer		3884 independent reflections
Radiation source: sealed Tube3802 reflections with I > 2σ(I)
graphiteRint = 0.035
CCD scanθmax = 28.0°, θmin = 1.4°
Absorption correction: multi-scan
(SADABS; Bruker, 2008)		h = −19→19
Tmin = 0.650, Tmax = 0.746k = −19→19
45299 measured reflectionsl = −9→9
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.021H-atom parameters constrained
wR(F2) = 0.052 w = 1/[σ2(Fo2) + (0.0281P)2 + 0.361P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
3884 reflectionsΔρmax = 0.25 e Å−3
173 parametersΔρmin = −0.12 e Å−3
0 restraintsAbsolute structure: Flack (1983), 1654 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: −0.12 (2)
Crystal data top
(C5H7N2)2[CoCl4]V = 1611.6 (2) Å3
Mr = 390.98Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 15.0051 (12) ŵ = 1.72 mm−1
b = 14.9751 (12) ÅT = 173 K
c = 7.1723 (6) Å0.25 × 0.22 × 0.17 mm
Data collection top
Bruker APEXII SMART CCD
diffractometer		3884 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2008)		3802 reflections with I > 2σ(I)
Tmin = 0.650, Tmax = 0.746Rint = 0.035
45299 measured reflectionsθmax = 28.0°
Refinement top
R[F2 > 2σ(F2)] = 0.021H-atom parameters constrained
wR(F2) = 0.052Δρmax = 0.25 e Å−3
S = 1.02Δρmin = −0.12 e Å−3
3884 reflectionsAbsolute structure: Flack (1983), 1654 Friedel pairs
173 parametersFlack parameter: −0.12 (2)
0 restraints
Special details top

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. Structure was refined as tetragonal twin with basf=0.34063

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Co10.49922 (2)0.24481 (2)0.37955 (6)0.02580 (7)
Cl10.45208 (4)0.12712 (5)0.20160 (11)0.03485 (16)
Cl20.59477 (5)0.18722 (5)0.59594 (11)0.03872 (17)
Cl30.38406 (6)0.30281 (5)0.54058 (11)0.04194 (19)
Cl40.56931 (5)0.33990 (5)0.18373 (14)0.04232 (17)
C10.19394 (17)0.06484 (18)0.2826 (4)0.0289 (5)
C20.2459 (2)−0.0132 (2)0.2552 (4)0.0337 (6)
H20.3091−0.00950.25400.040*
C30.2050 (2)−0.0935 (2)0.2307 (4)0.0379 (7)
H30.2400−0.14550.21160.045*
N40.11624 (18)−0.10010 (17)0.2331 (3)0.0413 (6)
H40.0873−0.15080.22480.050*
C50.0644 (2)−0.0280 (2)0.2604 (4)0.0403 (7)
H50.0015−0.03480.26310.048*
C60.10048 (18)0.0545 (2)0.2843 (4)0.0342 (6)
H60.06300.10490.30210.041*
N70.23233 (15)0.14446 (15)0.3030 (4)0.0382 (5)
H7A0.20020.18830.33300.057*
H7B0.29090.15530.28950.057*
C80.32310 (18)0.44022 (18)0.0283 (4)0.0289 (5)
C90.3084 (2)0.34727 (18)0.0205 (4)0.0326 (6)
H90.35620.30660.03890.039*
C100.2245 (2)0.3171 (2)−0.0139 (4)0.0398 (7)
H100.21420.2546−0.02040.048*
N110.15584 (17)0.37337 (19)−0.0389 (3)0.0418 (6)
H110.10000.3568−0.03770.050*
C120.1679 (2)0.4632 (2)−0.0254 (4)0.0382 (7)
H120.11830.5021−0.03850.046*
C130.24960 (17)0.4974 (3)0.0064 (4)0.0331 (6)
H130.25750.56020.01400.040*
N140.40431 (15)0.47315 (16)0.0593 (3)0.0375 (5)
H14A0.45220.43830.07670.056*
H14B0.41300.52880.06560.056*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Co10.02267 (19)0.0223 (2)0.03247 (13)0.00081 (16)−0.00149 (13)−0.00034 (12)
Cl10.0261 (3)0.0370 (4)0.0415 (4)−0.0058 (2)0.0005 (3)−0.0129 (3)
Cl20.0389 (4)0.0279 (3)0.0493 (4)0.0002 (2)−0.0190 (3)0.0004 (3)
Cl30.0407 (4)0.0315 (4)0.0536 (4)0.0119 (3)0.0134 (3)0.0012 (3)
Cl40.0296 (3)0.0346 (4)0.0628 (4)−0.0003 (3)0.0073 (3)0.0151 (3)
C10.0278 (13)0.0327 (14)0.0263 (13)0.0030 (10)−0.0015 (11)0.0023 (11)
C20.0296 (15)0.0333 (15)0.0383 (15)0.0032 (11)0.0010 (11)0.0018 (13)
C30.0486 (17)0.0302 (14)0.0349 (15)0.0031 (12)−0.0027 (13)−0.0019 (11)
N40.0536 (15)0.0364 (13)0.0338 (12)−0.0155 (11)−0.0055 (11)0.0029 (10)
C50.0334 (16)0.0515 (17)0.0359 (15)−0.0080 (13)−0.0017 (12)0.0069 (12)
C60.0289 (14)0.0408 (16)0.0329 (14)0.0033 (11)−0.0021 (12)0.0026 (12)
N70.0303 (11)0.0273 (12)0.0570 (15)0.0018 (8)0.0002 (11)0.0017 (11)
C80.0279 (13)0.0328 (13)0.0261 (12)0.0014 (10)0.0004 (11)0.0015 (11)
C90.0403 (15)0.0260 (13)0.0317 (13)0.0018 (11)0.0001 (12)0.0001 (11)
C100.0500 (17)0.0372 (17)0.0321 (14)−0.0146 (14)0.0024 (13)−0.0031 (12)
N110.0305 (12)0.0627 (17)0.0322 (11)−0.0136 (12)−0.0010 (10)−0.0001 (12)
C120.0342 (15)0.0499 (18)0.0304 (14)0.0011 (12)0.0018 (12)0.0038 (13)
C130.0307 (14)0.0327 (16)0.0357 (14)0.0041 (10)0.0040 (13)0.0027 (11)
N140.0279 (11)0.0295 (11)0.0550 (15)−0.0007 (8)−0.0018 (11)−0.0008 (10)
Geometric parameters (Å, °) top
Co1—Cl32.2527 (8)N7—H7A0.8422
Co1—Cl42.2597 (8)N7—H7B0.8984
Co1—Cl22.2822 (8)C8—N141.333 (3)
Co1—Cl12.2880 (8)C8—C131.405 (4)
C1—N71.332 (3)C8—C91.410 (4)
C1—C61.411 (4)C9—C101.360 (4)
C1—C21.419 (4)C9—H90.9500
C2—C31.361 (4)C10—N111.344 (4)
C2—H20.9500C10—H100.9500
C3—N41.335 (4)N11—C121.360 (4)
C3—H30.9500N11—H110.8737
N4—C51.345 (4)C12—C131.348 (4)
N4—H40.8772C12—H120.9500
C5—C61.359 (4)C13—H130.9500
C5—H50.9500N14—H14A0.8967
C6—H60.9500N14—H14B0.8440
Cl3—Co1—Cl4115.64 (3)C1—N7—H7A118.5
Cl3—Co1—Cl2106.20 (4)C1—N7—H7B124.9
Cl4—Co1—Cl2111.62 (3)H7A—N7—H7B116.6
Cl3—Co1—Cl1110.24 (3)N14—C8—C13120.7 (3)
Cl4—Co1—Cl1106.41 (4)N14—C8—C9121.0 (2)
Cl2—Co1—Cl1106.41 (3)C13—C8—C9118.3 (3)
N7—C1—C6121.8 (2)C10—C9—C8118.7 (3)
N7—C1—C2121.0 (3)C10—C9—H9120.7
C6—C1—C2117.2 (3)C8—C9—H9120.7
C3—C2—C1119.8 (3)N11—C10—C9121.7 (3)
C3—C2—H2120.1N11—C10—H10119.1
C1—C2—H2120.1C9—C10—H10119.1
N4—C3—C2121.0 (3)C10—N11—C12120.6 (3)
N4—C3—H3119.5C10—N11—H11123.8
C2—C3—H3119.5C12—N11—H11114.0
C3—N4—C5121.2 (3)C13—C12—N11120.6 (3)
C3—N4—H4123.8C13—C12—H12119.7
C5—N4—H4114.8N11—C12—H12119.7
N4—C5—C6121.2 (3)C12—C13—C8120.1 (3)
N4—C5—H5119.4C12—C13—H13120.0
C6—C5—H5119.4C8—C13—H13120.0
C5—C6—C1119.6 (3)C8—N14—H14A122.7
C5—C6—H6120.2C8—N14—H14B121.0
C1—C6—H6120.2H14A—N14—H14B116.3
N7—C1—C2—C3−178.6 (3)N14—C8—C9—C10−179.2 (3)
C6—C1—C2—C30.5 (4)C13—C8—C9—C102.2 (4)
C1—C2—C3—N4−0.4 (4)C8—C9—C10—N11−0.5 (4)
C2—C3—N4—C5−0.2 (5)C9—C10—N11—C12−1.8 (4)
C3—N4—C5—C60.8 (4)C10—N11—C12—C132.5 (5)
N4—C5—C6—C1−0.7 (4)N11—C12—C13—C8−0.8 (4)
N7—C1—C6—C5179.1 (3)N14—C8—C13—C12179.8 (3)
C2—C1—C6—C50.0 (4)C9—C8—C13—C12−1.5 (4)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N4—H4···Cl2i0.882.943.563 (3)130
N4—H4···Cl3i0.882.673.335 (3)134
N7—H7A···Cl2ii0.842.503.338 (2)175
N7—H7B···Cl10.902.533.387 (2)158
N11—H11···Cl1iii0.872.523.272 (3)144
N14—H14B···Cl2iv0.842.643.394 (3)149
N14—H14A···Cl40.902.423.303 (2)169
Symmetry codes: (i) −x+1/2, −y, z−1/2; (ii) x−1/2, −y+1/2, −z+1; (iii) x−1/2, −y+1/2, −z; (iv) −x+1, y+1/2, −z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N4—H4···Cl2i0.882.943.563 (3)130
N4—H4···Cl3i0.882.673.335 (3)134
N7—H7A···Cl2ii0.842.503.338 (2)175
N7—H7B···Cl10.902.533.387 (2)158
N11—H11···Cl1iii0.872.523.272 (3)144
N14—H14B···Cl2iv0.842.643.394 (3)149
N14—H14A···Cl40.902.423.303 (2)169
Symmetry codes: (i) −x+1/2, −y, z−1/2; (ii) x−1/2, −y+1/2, −z+1; (iii) x−1/2, −y+1/2, −z; (iv) −x+1, y+1/2, −z+1/2.
references
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