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In the title compound, C8H12N+·C8HN4O2, the anion and cation lie on a crystallographic mirror plane and form planar ribbons via N—H...O [N...O = 2.933 (4) Å, H...O = 2.01 Å and N—H...O = 170°] and N—H...N [N...N = 3.016 (5) Å, H...N = 2.15 Å and N—H...N = 169°] hydrogen bonds. The ribbons are further linked via weak C—H...O and C—H...N hydrogen bonds. In adjacent planes, anions lie opposite cations; π–π interactions (separation a/2 = 3.520 Å) exist between the anions and the cations, and stacks are formed, running along the a axis. The cations are disordered over two interpenetrating sites, with occupancies of 0.833 (5) and 0.167 (5).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103025940/fg1710sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103025940/fg1710Isup2.hkl
Contains datablock I

CCDC reference: 231077

Comment top

We have recently reported the synthesis and structure of the potassium salt of the title anion (Tafeenko et al., 2003). On the basis of the structural data and the calculated charge distribution on the atoms of the anion, the following types of anion–cation interaction can be postulated: (a) "Isotropic" interactions, with each outer hetero-atom of the anion taking part in the formation of a polyhedron enclosing the cation (Li, K, Na and Cs). (b) ππ stacking interactions, involving planar cations (e.g. pyridinium). (c) A transition metal–anion π-system interaction. (e.g. ferrocene). (d) Interaction of the hetero-atoms of the anion and the transition metal to form a coordination compound or chelate complex. An example of type (a) was described by Tafeenko et al. (2003). Interactions of type (b) were expected in the title compound, (I). Interactions of type (c) and (d) are the subject of further investigations.

The synthesis was carried out as shown in the scheme above. The most remarkable features of this reaction are the main roles that are played by the two elementary particles (proton and electron) supplied by the hydrogen iodide. The H atom interacts with the lone pair of the N atom of the N,N-dimethyl-N-phenilamine molecule to form a cation (the lower-right structure in the scheme), whereas the electron induces the rearrangement of the three-membered ring of 2,2,3,3-tetracyanocyclopropanecarboxylic acid to give an anion.

The title compound (Fig. 1) has all atoms of the anion and cation lying in a crystallographic mirror plane, with the exception of the methyl groups of the cation, which are located between planes and have an essential impact on the specific packing geometry. The bond lengths and angles in the anion are similar to those in the corresponding potassium salt (see above). The unique cation is disordered over two interpenetrating sites with occupancies of 0.833 (5) and 0.167 (5) (see Experimental). The methyl groups enlarge the distances (half of the a axis) between the molecular planes and also prevent the formation of a more symmetrical anion–cation stacking. The shortest distance between an anion and a cation that form a stack and lie in adjacent mirror planes is 2.45 Å [H16B···N4(1/2 − x,1 − y+,z − 1/2); Fig. 2a and Table 1; atom H16B belongs to the C16 methyl group]. Although ππ interactions exist between anion and the cation, these interactions might have been stronger if the methyl atoms located between the planes had been absent. The tendency of the anion–cation distances in the stack to decrease is reflected by the atomic displacement tensors of the atoms of the anion. The principal axes of the ellipsoids of these atoms are orthogonal to the mirror plane, but the values for those atoms that are not involved in the ππ interaction are noticeably larger. Another explanation of the enlarged atomic displacement ellipsoids of the anion is steric hindrance of the exocyclic cyano groups (Tafeenko et al., 2003).

In the mirror plane, adjacent anions are linked via N—H···N hydorgen bonds (Table 1 and Fig. 2 b); cations are linked to the resulting anion chain by N—H···O hydrogen bonds. The ribbons so formed extend in the c direction, and adjacent ribbons are linked via weak (Steiner, 1996) C—H···O and C—H···N hydrogen bonds (Fig. 2 b and Table 1).

Experimental top

2,2,3,3-Tetracyanocycloprpanecarboxylic acid was synthesized from α-chloro ketone and TCNE (ethylene-1,1,2,2-tetracarbonitrile). N,N,-dimethyl-N-benzenaminium 3-cyano-4-(dicyanomethylene)-5-oxo-4,5-dihydro-1H-pyrrol-2-olate was obtained by mixing N,N-dimethyl-N-phenilamine and hydrogen iodide and then adding 2,2,3,3-tetracyanocyclopropanecarboxylic acid. The reaction was carried out in aqua-1,4-dioxane (1:1) at room temperature. Yellow crystals were collected from the reaction mixture by filtration and drying.

Refinement top

Four different diffraction experiments were carried out using three different crystals of the title compound, with both room-temperature and 110 K data sets. For full details see the _exptl_special_details section of the archived CIF. All data sets led to the same structure and only the results from the 110 K data set are described here. All H atoms were refined as riding, with N—H distances of 0.88 and 0.93 Å, and C—H distances of 0.95 and 0.98 Å. During the refinement, difference maps showed peaks consistent with the cation atoms N5 and C10–C15 being unequally disordered over two interpenetrating sites. This disorder was allowed for by the use of appropriate SHELXL97 (Sheldrick, 1997) SAME and DFIX restraints. At convergence, the cation disorder was modelled with occupancies of 0.833 (5) and 0.167 (5). The minor-occupancy cation orientation also leads to an N51—H51···N3 hydrogen bond (Table 1). The minor-occupancy methyl C atom (C161) was constrained to have the same coordinates and anisotropic displacement parameters as the major (C16) site.

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT-Plus (Bruker, 1998); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2000) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1]
[Figure 2]
Figure 1. A view of the salt, with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. The cations are disordered over two interpenetrating sites with occupancies of 0.833 (5) and 0.167 (5).

Figure 2a. A view almost normal to the molecular planes, showing how the cations and anions overlap to form ππ stacks along the a axis. Atoms marked with a dollar are at the equivalent position (1/2 − x, 1 − y, z − 1/2).

Figure 2 b. Part of the crystal structure, showing the formation via strong hydrogen bonds (N—H···N and N—H···O) of ribbons of anions and cations along the c axis. The ribbons are connected by weak (C—H···O and C—H···N) hydrogen bonds. Atoms marked with an asterisk (*) or hash (#) are at the equivalent positions (x,y,z − 1) and (x,y + 1,z), respectively.
N,N-dimethylanilinium 3-cyano-4-(dicyanomethylene)-5-oxo-4,5-dihydro-1H-pyrrol-2-olate top
Crystal data top
C8H12N+·C8HN4O2Dx = 1.331 Mg m3
Mr = 307.31Melting point: 221 K
Orthorhombic, Pmn21Mo Kα radiation, λ = 0.71073 Å
a = 7.0399 (7) ÅCell parameters from 925 reflections
b = 12.5636 (12) Åθ = 3–30°
c = 8.6695 (8) ŵ = 0.09 mm1
V = 766.79 (13) Å3T = 110 K
Z = 2Prism, yellow
F(000) = 3200.30 × 0.10 × 0.10 mm
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
936 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.034
Graphite monochromatorθmax = 30.1°, θmin = 1.6°
ϕ and ω scansh = 99
5974 measured reflectionsk = 1617
1283 independent reflectionsl = 1112
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.049Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.112H-atom parameters constrained
S = 1.01 w = 1/[σ2(Fo2) + (0.0684P)2]
where P = (Fo2 + 2Fc2)/3
1282 reflections(Δ/σ)max = 0.001
153 parametersΔρmax = 0.19 e Å3
19 restraintsΔρmin = 0.35 e Å3
Crystal data top
C8H12N+·C8HN4O2V = 766.79 (13) Å3
Mr = 307.31Z = 2
Orthorhombic, Pmn21Mo Kα radiation
a = 7.0399 (7) ŵ = 0.09 mm1
b = 12.5636 (12) ÅT = 110 K
c = 8.6695 (8) Å0.30 × 0.10 × 0.10 mm
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
936 reflections with I > 2σ(I)
5974 measured reflectionsRint = 0.034
1283 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.04919 restraints
wR(F2) = 0.112H-atom parameters constrained
S = 1.01Δρmax = 0.19 e Å3
1282 reflectionsΔρmin = 0.35 e Å3
153 parameters
Special details top

Experimental. Three experiments were carried out at room temperature. (Enraf–Nonius CAD-4 diffractometer, ω – scan, Cu Kα radiation, cell parameters from 25 reflections at 293 (2) K are a=7.0544 (15), b=12.586 (2), c=8.691 (1), space group Pmn21) and one experiment at T = 110 K. Though in principal all four experiments delivered the same structural model, the final model is based on the low temperature data because of the larger amount of reflections with I>2σ(I).

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 (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.50000.11422 (17)0.3697 (3)0.0623 (7)
O20.50000.4752 (2)0.3956 (3)0.0994 (13)
N10.50000.2962 (2)0.3428 (3)0.0617 (8)
H10.50000.29880.24130.074*
N20.50000.3371 (3)1.0000 (4)0.0721 (10)
N30.50000.6137 (3)0.6991 (5)0.1011 (16)
N40.50000.0834 (2)0.7873 (4)0.0569 (7)
C20.50000.2032 (2)0.4266 (4)0.0468 (7)
C30.50000.2325 (2)0.5876 (3)0.0378 (6)
C40.50000.3428 (2)0.5998 (3)0.0410 (7)
C50.50000.3840 (3)0.4354 (4)0.0588 (10)
C60.50000.4110 (2)0.7236 (3)0.0478 (8)
C70.50000.5236 (3)0.7070 (4)0.0664 (11)
C80.50000.3713 (3)0.8772 (4)0.0518 (8)
C90.50000.1527 (2)0.7012 (4)0.0411 (6)
N50.50000.8927 (3)0.4766 (3)0.0413 (8)0.833 (5)
H50.50000.96520.45480.050*0.833 (5)
C100.50000.8365 (3)0.3260 (4)0.0381 (9)0.833 (5)
C110.50000.8970 (3)0.1941 (5)0.0434 (10)0.833 (5)
H110.50000.97250.19980.052*0.833 (5)
C120.50000.8458 (4)0.0520 (5)0.0518 (13)0.833 (5)
H120.50000.88640.04050.062*0.833 (5)
C130.50000.7366 (4)0.0451 (5)0.0538 (14)0.833 (5)
H130.50000.70190.05220.065*0.833 (5)
C140.50000.6769 (4)0.1787 (6)0.0546 (13)0.833 (5)
H140.50000.60140.17300.066*0.833 (5)
C150.50000.7266 (3)0.3204 (5)0.0497 (11)0.833 (5)
H150.50000.68600.41270.060*0.833 (5)
C160.3262 (3)0.8711 (2)0.5681 (3)0.0581 (6)0.83
H16A0.32140.79540.59500.087*0.83
H16B0.21380.88970.50710.087*0.83
H16C0.32840.91380.66260.087*0.83
N510.50000.8200 (17)0.5085 (19)0.053 (3)*0.167 (5)
H510.50000.75300.55400.063*0.167 (5)
C1010.50000.7975 (19)0.339 (2)0.053 (3)*0.167 (5)
C1110.50000.6980 (19)0.282 (3)0.053 (3)*0.167 (5)
H1110.50000.63830.34950.063*0.167 (5)
C1210.50000.684 (2)0.126 (3)0.053 (3)*0.167 (5)
H1210.50000.61420.08450.063*0.167 (5)
C1310.50000.768 (2)0.028 (3)0.053 (3)*0.167 (5)
H1310.50000.75730.08010.063*0.167 (5)
C1410.50000.870 (2)0.088 (3)0.053 (3)*0.167 (5)
H1410.50000.92960.02060.063*0.167 (5)
C1510.50000.884 (2)0.244 (3)0.053 (3)*0.167 (5)
H1510.50000.95390.28580.063*0.167 (5)
C1610.3262 (3)0.8711 (2)0.5681 (3)0.0581 (6)0.17
H16D0.21440.83610.52360.087*0.17
H16E0.32590.94650.53950.087*0.17
H16F0.32260.86450.68070.087*0.17
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.111 (2)0.0367 (12)0.0389 (13)0.0000.0000.0094 (11)
O20.226 (4)0.0340 (14)0.0382 (13)0.0000.0000.0064 (11)
N10.120 (2)0.0401 (16)0.0250 (12)0.0000.0000.0027 (12)
N20.125 (3)0.061 (2)0.0298 (15)0.0000.0000.0013 (15)
N30.213 (5)0.0407 (18)0.050 (2)0.0000.0000.0057 (19)
N40.0887 (19)0.0410 (14)0.0410 (14)0.0000.0000.0074 (13)
C20.076 (2)0.0345 (16)0.0297 (15)0.0000.0000.0029 (12)
C30.0587 (17)0.0295 (15)0.0254 (12)0.0000.0000.0002 (11)
C40.0641 (18)0.0330 (16)0.0261 (13)0.0000.0000.0010 (11)
C50.113 (3)0.0382 (18)0.0250 (13)0.0000.0000.0043 (14)
C60.083 (2)0.0351 (16)0.0253 (14)0.0000.0000.0027 (12)
C70.130 (4)0.0399 (17)0.0295 (16)0.0000.0000.0076 (14)
C80.087 (2)0.0384 (17)0.0299 (15)0.0000.0000.0039 (14)
C90.0594 (17)0.0314 (13)0.0324 (14)0.0000.0000.0020 (12)
N50.0623 (19)0.0310 (18)0.0307 (15)0.0000.0000.0011 (12)
C100.0569 (19)0.032 (2)0.0256 (18)0.0000.0000.0054 (17)
C110.065 (2)0.033 (2)0.032 (2)0.0000.0000.0013 (17)
C120.074 (2)0.052 (4)0.029 (2)0.0000.0000.0001 (19)
C130.080 (3)0.051 (3)0.030 (2)0.0000.0000.011 (2)
C140.083 (3)0.0337 (19)0.047 (3)0.0000.0000.009 (2)
C150.082 (3)0.033 (2)0.034 (2)0.0000.0000.0023 (17)
C160.0669 (13)0.0662 (17)0.0412 (12)0.0016 (11)0.0063 (11)0.0105 (11)
C1610.0669 (13)0.0662 (17)0.0412 (12)0.0016 (11)0.0063 (11)0.0105 (11)
Geometric parameters (Å, º) top
O1—C21.222 (4)C12—H120.9500
O2—C51.197 (4)C13—C141.379 (6)
N1—C51.364 (4)C13—H130.9500
N1—C21.376 (4)C14—C151.378 (6)
N1—H10.8800C14—H140.9500
N2—C81.148 (4)C15—H150.9500
N3—C71.134 (4)C16—H16A0.9800
N4—C91.147 (4)C16—H16B0.9800
C2—C31.444 (4)C16—H16C0.9800
C3—C41.390 (4)N51—C161i1.475 (10)
C3—C91.405 (4)N51—C1011.494 (16)
C4—C61.373 (4)N51—H510.9300
C4—C51.516 (4)C101—C1111.344 (17)
C6—C81.421 (4)C101—C1511.367 (18)
C6—C71.422 (5)C111—C1211.369 (18)
N5—C16i1.484 (3)C111—H1110.9500
N5—C161.484 (3)C121—C1311.35 (2)
N5—C101.485 (4)C121—H1210.9500
N5—H50.9300C131—C1411.376 (19)
C10—C111.373 (5)C131—H1310.9500
C10—C151.381 (6)C141—C1511.364 (19)
C11—C121.389 (6)C141—H1410.9500
C11—H110.9500C151—H1510.9500
C12—C131.374 (8)
C5—N1—C2112.1 (3)C12—C13—C14120.4 (4)
C5—N1—H1124.0C12—C13—H13119.8
C2—N1—H1124.0C14—C13—H13119.8
O1—C2—N1124.3 (3)C15—C14—C13120.1 (4)
O1—C2—C3128.6 (3)C15—C14—H14119.9
N1—C2—C3107.1 (3)C13—C14—H14119.9
C4—C3—C9131.2 (3)C14—C15—C10119.0 (4)
C4—C3—C2109.1 (3)C14—C15—H15120.5
C9—C3—C2119.7 (3)C10—C15—H15120.5
C6—C4—C3132.9 (3)N5—C16—H16A109.5
C6—C4—C5121.5 (3)N5—C16—H16B109.5
C3—C4—C5105.6 (3)H16A—C16—H16B109.5
O2—C5—N1127.2 (3)N5—C16—H16C109.5
O2—C5—C4126.7 (3)H16A—C16—H16C109.5
N1—C5—C4106.2 (3)H16B—C16—H16C109.5
C4—C6—C8120.9 (3)C161i—N51—C101115.2 (8)
C4—C6—C7122.8 (3)C161i—N51—H51104.2
C8—C6—C7116.3 (3)C101—N51—H51104.2
N3—C7—C6177.7 (4)C111—C101—C151121.1 (17)
N2—C8—C6178.5 (4)C111—C101—N51123 (2)
N4—C9—C3176.1 (3)C151—C101—N51116.4 (18)
C16i—N5—C16111.1 (3)C101—C111—C121119 (2)
C16i—N5—C10112.51 (18)C101—C111—H111120.6
C16—N5—C10112.51 (18)C121—C111—H111120.6
C16i—N5—H5106.7C131—C121—C111121 (2)
C16—N5—H5106.7C131—C121—H121119.3
C10—N5—H5106.7C111—C121—H121119.3
C11—C10—C15121.6 (3)C121—C131—C141119 (2)
C11—C10—N5117.9 (3)C121—C131—H131120.3
C15—C10—N5120.5 (4)C141—C131—H131120.3
C10—C11—C12118.8 (4)C151—C141—C131120 (2)
C10—C11—H11120.6C151—C141—H141120.2
C12—C11—H11120.6C131—C141—H141120.2
C13—C12—C11120.1 (4)C141—C151—C101120 (2)
C13—C12—H12120.0C141—C151—H151120.1
C11—C12—H12120.0C101—C151—H151120.1
C16i—N5—C10—C11116.8 (2)C16—N5—C10—C1563.2 (2)
C16—N5—C10—C11116.8 (2)C161i—N51—C101—C111113.5 (12)
C16i—N5—C10—C1563.2 (2)C161i—N51—C101—C15166.5 (12)
Symmetry code: (i) x+1, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···N2ii0.882.153.016 (5)169
N5—H5···O1iii0.932.012.933 (4)170
N51—H51···N30.932.163.07 (2)169
C11—H11···O1iii0.952.313.125 (5)143
C13—H13···N3ii0.952.423.374 (6)180
C14—H14···O20.952.503.156 (6)126
C15—H15···O20.952.653.226 (5)119
C16—H16B···N4iv0.982.453.394 (3)161
Symmetry codes: (ii) x, y, z1; (iii) x, y+1, z; (iv) x+1/2, y+1, z1/2.

Experimental details

Crystal data
Chemical formulaC8H12N+·C8HN4O2
Mr307.31
Crystal system, space groupOrthorhombic, Pmn21
Temperature (K)110
a, b, c (Å)7.0399 (7), 12.5636 (12), 8.6695 (8)
V3)766.79 (13)
Z2
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.30 × 0.10 × 0.10
Data collection
DiffractometerBruker SMART 1000 CCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
5974, 1283, 936
Rint0.034
(sin θ/λ)max1)0.705
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.049, 0.112, 1.01
No. of reflections1282
No. of parameters153
No. of restraints19
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.19, 0.35

Computer programs: SMART (Bruker, 1998), SAINT-Plus (Bruker, 1998), SAINT-Plus, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 2000) and ORTEP-3 (Farrugia, 1997), SHELXL97.

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···N2i0.882.153.016 (5)169
N5—H5···O1ii0.932.012.933 (4)170
N51—H51···N30.932.163.07 (2)169
C11—H11···O1ii0.952.313.125 (5)143
C13—H13···N3i0.952.423.374 (6)180
C14—H14···O20.952.503.156 (6)126
C15—H15···O20.952.653.226 (5)119
C16—H16B···N4iii0.982.453.394 (3)161
Symmetry codes: (i) x, y, z1; (ii) x, y+1, z; (iii) x+1/2, y+1, z1/2.
 

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