A 1:1 cocrystal of 2,7-di­cyano-9-di­cyano­methyl­ene-4,5-di­nitro­fluorene and benzo­nitrile

The title complex contains infinite stacks of alternating C₁₈H₄N₆O₄ and C₇H₅N mol­ecules; the former is warped to a much larger extent than in its charge-transfer complex with tetra­thia­fulvalene.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.047
• wR factor = 0.105
• Data-to-parameter ratio = 13.0

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT029_ALERT_3_B _diffrn_measured_fraction_theta_full Low .......       0.99

Alert level C
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C2     -   C17      =       1.45 Ang.
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C7     -   C18      =       1.45 Ang.
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C14    -   C15      =       1.44 Ang.
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C14    -   C16      =       1.44 Ang.
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C19    -   C20      =       1.45 Ang.

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   5 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

During our studies of charge-transfer complexes (CTC), we have observed an interesting case of donor-induced cocrystallization (Batsanov et al., 2001). Normally, 2,4,5,7-tetranitro-9-fluorenone (TeNF) and 2,4,5,7-tetranitro-9-dicyanomethylenefluorene (DTeNF) crystallize from chlorobenzene as solvent-free species. However, when tetrathiafulvalene (TTF) was added to the solutions (in an unsuccessful attempt to prepare CTC), both acceptors crystallized from it as solvates, viz. TeNF·2PhCl and DTeNF·PhCl.

Herein we report another example of this effect. While attempting to crystallize, from a benzonitrile solution, a CTC of the acceptor 2,7-dicyano-4,5-dinitro-9-dicyanomethylenefluorene, (I), and the donor 2,6-dibutoxy-9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene, (II), we obtained instead cocrystals of (I) with the solvent in a 1:1 ratio, i.e. (I)·PhCN. A CTC of (I) with TTF, (I)·TTF·PhCl, or (III), has been characterized previously by X-ray crystallography (Perepichka et al., 1998; Kuz'mina et al., 2002), but the crystal structure of pure (I) or of any molecular complex thereof without charge transfer, has not been reported thus far.

The crystal structure of (I)·PhCN comprises infinite mixed stacks, parallel to the x axis, of alternating molecules of (I) and benzonitrile (Fig. 1 and Table 1). The fluorene moiety of (I) is warped, as in other fluorene derivatives with nitro substituents in positions 4 and 5 (Silverman et al., 1974; Batsanov et al., 2001). The twist is obviously caused by steric repulsion between these two nitro groups. However, it is noteworthy that the distortion is much stronger in (I)·PhCl than in (III). Thus, the deviation of the 13 fluorene C atoms from their mean plane averages 0.11 Å in (I)·PhCl versus 0.06 Å in (III). In (I)·PhCN, both six-membered rings of the fluorene moiety adopt envelope conformations: the C1–C4/C10 and C5–C8/C13 moieties are planar, with atoms C11 or C12 tilted out of their planes. A similar conformation was observed in (III). However, the dihedral angle between the C1–C4/C10 and C5–C8/C13 moieties in (I)·PhCN equals 15.8 (1)°, against 7.9° in (III). The twist around the C9═C14 bond, i.e. the dihedral angle between the C9/C10/C13/C14 and C9/C14–C16/N15/N16 planes, is small in both structures, 4.0 (1)° in (I)·PhCN against 3.7° in (III). The C9═C14 bond itself is marginally longer in (III) than in (I)·PhCN, viz. 1.379 (6) and 1.362 (3) Å, respectively, while the adjacent C9—C10 and C9—C13 bonds of the five-membered ring average 1.463 (6) Å in (III) versus 1.476 (3) Å in (I)·PhCN. All these differences can be expalined by the acceptor molecule (I) in (III) aquiring an overall negative charge, which enhances its aromaticity, while no appreciable charge transfer takes place in (I)·PhCN.

S2. Experimental

Acceptor (I) was prepared as described by Perepichka et al. (1998), donor (II) as described by Bryce et al. (2000). 5.5 mg (0.015 mmol) of (I) was dissolved in freshly distilled benzonitrile (0.5 ml) in a small (2 ml volume) vial, on heating at 343 K for 10–15 min. 7.8 mg (0.015 mol) of (II) was dissolved in benzonitrile (0.5 ml) at 333 K and the solution was added to that of (I). The brown–green solution was permitted to cool to room temperature and left overnight, whereupon small orange crystals of X-ray quality were formed.

S3. Refinement

Amino H atoms were refined in isotropic approximation, then constrained with the same bond direction but idealized N—H bond lengths (0.89 Å). Other H atoms were treated as riding in idealized positions, with C—H bond lengths of 0.95 Å.

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SMART; data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. The molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level.

2,7-dicyano-9-dicyanomethylene-4,5-dinitrofluorene–benzonitrile (1/1)

Crystal data

C18H4N6O4·C7H5N	Z = 2
Mr = 471.39	F(000) = 480
Triclinic, P1	Dx = 1.501 Mg m^−3
a = 7.211 (1) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.480 (2) Å	Cell parameters from 465 reflections
c = 16.451 (3) Å	θ = 10.4–24.7°
α = 96.16 (1)°	µ = 0.11 mm^−1
β = 102.41 (1)°	T = 120 K
γ = 105.30 (1)°	Plate, orange
V = 1043.2 (3) Å^3	0.25 × 0.15 × 0.05 mm

Data collection

Bruker SMART 1K CCD area-detector diffractometer	2544 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.047
Graphite monochromator	θmax = 26.4°, θmin = 2.3°
Detector resolution: 8 pixels mm^-1	h = −8→9
ω scans	k = −11→9
6896 measured reflections	l = −20→20
4232 independent reflections

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.106	H-atom parameters constrained
S = 0.95	w = 1/[σ^2(Fo^2) + (0.045P)^2] where P = (Fo^2 + 2Fc^2)/3
4232 reflections	(Δ/σ)max = 0.001
325 parameters	Δρmax = 0.21 e Å^−3
0 restraints	Δρmin = −0.22 e Å^−3

Special details

Experimental. 4 sets of ω scans (each scan 0.3° in ω, exposure time 30 s) with different ϕ and 2θ angles, nominally covered over a hemisphere of reciprocal space. Crystal to detector distance 4.54 cm. The absence of crystal decay was monitored by repeating the first 36 frames at the end of data collection and comparing duplicate reflections.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O41	0.1731 (2)	−0.09162 (17)	−0.02009 (10)	0.0305 (4)
O42	0.4425 (2)	−0.07027 (16)	0.07705 (10)	0.0255 (4)
O51	0.1296 (2)	−0.10331 (16)	0.15695 (10)	0.0239 (4)
O52	0.2792 (2)	−0.25105 (17)	0.21642 (11)	0.0339 (4)
N4	0.3089 (3)	−0.0226 (2)	0.04124 (11)	0.0213 (4)
N5	0.2677 (3)	−0.1273 (2)	0.20614 (12)	0.0220 (4)
N15	0.7261 (3)	0.7694 (2)	0.22365 (14)	0.0357 (6)
N16	0.9302 (3)	0.6144 (2)	0.45112 (13)	0.0321 (5)
N17	0.1533 (3)	0.5074 (2)	−0.07597 (14)	0.0403 (6)
N18	0.7960 (3)	0.0597 (2)	0.54665 (14)	0.0364 (6)
C1	0.3972 (3)	0.4362 (2)	0.11717 (14)	0.0208 (5)
H1	0.4260	0.5405	0.1319	0.025*
C2	0.2882 (3)	0.3628 (2)	0.03608 (14)	0.0218 (5)
C3	0.2573 (3)	0.2117 (2)	0.01248 (14)	0.0218 (5)
H3	0.1930	0.1640	−0.0441	0.026*
C4	0.3212 (3)	0.1319 (2)	0.07223 (14)	0.0189 (5)
C5	0.4252 (3)	0.0026 (2)	0.25974 (14)	0.0175 (5)
C6	0.5119 (3)	−0.0175 (2)	0.33912 (14)	0.0213 (5)
H6	0.4862	−0.1139	0.3533	0.026*
C7	0.6377 (3)	0.1049 (2)	0.39839 (14)	0.0203 (5)
C8	0.6714 (3)	0.2478 (2)	0.37938 (14)	0.0189 (5)
H8	0.7515	0.3314	0.4208	0.023*
C9	0.5895 (3)	0.4019 (2)	0.26282 (13)	0.0181 (5)
C10	0.4625 (3)	0.3544 (2)	0.17583 (13)	0.0171 (5)
C11	0.4095 (3)	0.1977 (2)	0.15654 (13)	0.0171 (5)
C12	0.4677 (3)	0.1415 (2)	0.23564 (13)	0.0161 (5)
C13	0.5856 (3)	0.2653 (2)	0.29891 (13)	0.0168 (5)
C14	0.7010 (3)	0.5431 (2)	0.29986 (14)	0.0198 (5)
C15	0.7108 (3)	0.6680 (3)	0.25660 (15)	0.0242 (5)
C16	0.8276 (3)	0.5801 (2)	0.38425 (15)	0.0227 (5)
C17	0.2122 (3)	0.4442 (3)	−0.02604 (16)	0.0265 (6)
C18	0.7266 (3)	0.0810 (2)	0.48134 (16)	0.0254 (6)
N19	0.4294 (3)	0.6420 (2)	0.43518 (14)	0.0343 (5)
C19	0.3208 (3)	0.5331 (3)	0.39504 (15)	0.0260 (6)
C20	0.1874 (3)	0.3977 (2)	0.34088 (14)	0.0208 (5)
C21	0.0849 (3)	0.4054 (2)	0.26009 (14)	0.0212 (5)
H21	0.0983	0.4983	0.2419	0.025*
C22	−0.0367 (3)	0.2757 (2)	0.20669 (14)	0.0211 (5)
H22	−0.1068	0.2797	0.1516	0.025*
C23	−0.0559 (3)	0.1408 (2)	0.23345 (14)	0.0216 (5)
H23	−0.1392	0.0524	0.1966	0.026*
C24	0.0460 (3)	0.1334 (2)	0.31411 (14)	0.0235 (5)
H24	0.0312	0.0402	0.3321	0.028*
C25	0.1693 (3)	0.2619 (2)	0.36840 (15)	0.0235 (5)
H25	0.2399	0.2573	0.4233	0.028*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O41	0.0310 (10)	0.0289 (9)	0.0215 (9)	0.0023 (8)	−0.0013 (8)	−0.0053 (7)
O42	0.0280 (9)	0.0263 (9)	0.0243 (9)	0.0117 (7)	0.0068 (7)	0.0040 (7)
O51	0.0188 (8)	0.0249 (9)	0.0239 (9)	0.0034 (7)	0.0018 (7)	0.0022 (7)
O52	0.0405 (11)	0.0139 (9)	0.0400 (11)	0.0023 (8)	0.0011 (9)	0.0061 (7)
N4	0.0231 (11)	0.0226 (11)	0.0165 (10)	0.0043 (9)	0.0057 (9)	0.0011 (8)
N5	0.0228 (11)	0.0184 (11)	0.0218 (11)	0.0015 (8)	0.0053 (9)	0.0030 (8)
N15	0.0379 (13)	0.0222 (12)	0.0420 (14)	0.0036 (10)	0.0051 (11)	0.0074 (10)
N16	0.0334 (12)	0.0254 (12)	0.0301 (13)	0.0042 (10)	0.0019 (11)	−0.0032 (9)
N17	0.0446 (14)	0.0412 (14)	0.0341 (14)	0.0132 (11)	0.0026 (11)	0.0158 (11)
N18	0.0362 (13)	0.0386 (13)	0.0304 (13)	0.0081 (10)	0.0003 (11)	0.0131 (10)
C1	0.0207 (12)	0.0170 (12)	0.0245 (13)	0.0048 (10)	0.0057 (10)	0.0044 (10)
C2	0.0184 (12)	0.0254 (13)	0.0223 (13)	0.0059 (10)	0.0051 (10)	0.0087 (10)
C3	0.0175 (12)	0.0241 (13)	0.0196 (12)	0.0024 (10)	0.0019 (10)	0.0015 (10)
C4	0.0172 (11)	0.0179 (12)	0.0187 (12)	0.0023 (9)	0.0037 (10)	0.0001 (9)
C5	0.0165 (12)	0.0154 (11)	0.0178 (12)	0.0027 (9)	0.0030 (9)	−0.0013 (9)
C6	0.0229 (12)	0.0174 (12)	0.0244 (13)	0.0060 (10)	0.0071 (10)	0.0057 (9)
C7	0.0193 (12)	0.0246 (13)	0.0171 (12)	0.0065 (10)	0.0043 (10)	0.0052 (10)
C8	0.0193 (12)	0.0181 (12)	0.0164 (12)	0.0030 (9)	0.0036 (10)	−0.0001 (9)
C9	0.0143 (11)	0.0206 (12)	0.0191 (12)	0.0041 (9)	0.0049 (10)	0.0032 (9)
C10	0.0144 (11)	0.0175 (12)	0.0185 (12)	0.0033 (9)	0.0042 (9)	0.0030 (9)
C11	0.0129 (11)	0.0207 (12)	0.0182 (12)	0.0051 (9)	0.0042 (9)	0.0049 (9)
C12	0.0136 (11)	0.0180 (12)	0.0160 (12)	0.0041 (9)	0.0040 (9)	0.0000 (9)
C13	0.0144 (11)	0.0184 (12)	0.0176 (12)	0.0045 (9)	0.0048 (9)	0.0023 (9)
C14	0.0176 (12)	0.0187 (12)	0.0222 (13)	0.0043 (9)	0.0050 (10)	0.0019 (9)
C15	0.0219 (13)	0.0174 (13)	0.0274 (14)	0.0020 (10)	0.0022 (11)	−0.0036 (10)
C16	0.0222 (13)	0.0151 (12)	0.0277 (14)	0.0024 (10)	0.0061 (11)	−0.0012 (10)
C17	0.0251 (13)	0.0260 (14)	0.0253 (14)	0.0054 (11)	0.0027 (11)	0.0043 (11)
C18	0.0250 (13)	0.0221 (13)	0.0264 (14)	0.0032 (10)	0.0045 (11)	0.0060 (10)
N19	0.0291 (12)	0.0328 (13)	0.0351 (13)	0.0056 (10)	0.0050 (10)	−0.0038 (10)
C19	0.0223 (13)	0.0292 (14)	0.0264 (14)	0.0086 (11)	0.0070 (11)	0.0006 (11)
C20	0.0184 (12)	0.0216 (13)	0.0208 (13)	0.0036 (10)	0.0062 (10)	0.0002 (9)
C21	0.0232 (12)	0.0191 (12)	0.0234 (13)	0.0062 (10)	0.0098 (11)	0.0044 (10)
C22	0.0234 (12)	0.0237 (13)	0.0177 (12)	0.0096 (10)	0.0055 (10)	0.0033 (10)
C23	0.0204 (12)	0.0183 (12)	0.0256 (14)	0.0047 (10)	0.0069 (10)	0.0025 (10)
C24	0.0262 (13)	0.0227 (13)	0.0270 (14)	0.0126 (11)	0.0099 (11)	0.0082 (10)
C25	0.0207 (12)	0.0292 (14)	0.0210 (13)	0.0092 (11)	0.0041 (10)	0.0040 (10)

Geometric parameters (Å, º)

O41—N4	1.225 (2)	C8—C13	1.383 (3)
O42—N4	1.234 (2)	C8—H8	0.9481
O51—N5	1.229 (2)	C9—C14	1.362 (3)
O52—N5	1.225 (2)	C9—C10	1.473 (3)
N4—C4	1.471 (3)	C9—C13	1.478 (3)
N5—C5	1.477 (3)	C10—C11	1.414 (3)
N15—C15	1.145 (3)	C11—C12	1.478 (3)
N16—C16	1.145 (3)	C12—C13	1.419 (3)
N17—C17	1.142 (3)	C14—C16	1.437 (3)
N18—C18	1.147 (3)	C14—C15	1.439 (3)
C1—C10	1.383 (3)	N19—C19	1.149 (3)
C1—C2	1.394 (3)	C19—C20	1.450 (3)
C1—H1	0.9481	C20—C25	1.394 (3)
C2—C3	1.388 (3)	C20—C21	1.395 (3)
C2—C17	1.446 (3)	C21—C22	1.386 (3)
C3—C4	1.379 (3)	C21—H21	0.9481
C3—H3	0.9481	C22—C23	1.379 (3)
C4—C11	1.394 (3)	C22—H22	0.9481
C5—C6	1.378 (3)	C23—C24	1.391 (3)
C5—C12	1.392 (3)	C23—H23	0.9481
C6—C7	1.394 (3)	C24—C25	1.387 (3)
C6—H6	0.9481	C24—H24	0.9481
C7—C8	1.394 (3)	C25—H25	0.9481
C7—C18	1.446 (3)
O41—N4—O42	125.01 (18)	C4—C11—C10	117.12 (19)
O41—N4—C4	117.96 (18)	C4—C11—C12	134.7 (2)
O42—N4—C4	116.94 (17)	C10—C11—C12	108.20 (17)
O52—N5—O51	124.57 (18)	C5—C12—C13	117.42 (19)
O52—N5—C5	117.86 (18)	C5—C12—C11	134.72 (18)
O51—N5—C5	117.48 (18)	C13—C12—C11	107.77 (18)
C10—C1—C2	118.9 (2)	C8—C13—C12	121.6 (2)
C10—C1—H1	120.5	C8—C13—C9	130.11 (19)
C2—C1—H1	120.5	C12—C13—C9	108.31 (18)
C3—C2—C1	120.7 (2)	C9—C14—C16	123.1 (2)
C3—C2—C17	118.8 (2)	C9—C14—C15	123.1 (2)
C1—C2—C17	120.4 (2)	C16—C14—C15	113.71 (18)
C4—C3—C2	119.2 (2)	N15—C15—C14	177.5 (3)
C4—C3—H3	120.4	N16—C16—C14	177.7 (2)
C2—C3—H3	120.4	N17—C17—C2	179.0 (3)
C3—C4—C11	121.7 (2)	N18—C18—C7	179.0 (2)
C3—C4—N4	116.63 (19)	N19—C19—C20	177.2 (3)
C11—C4—N4	121.41 (19)	C25—C20—C21	121.0 (2)
C6—C5—C12	121.58 (18)	C25—C20—C19	120.1 (2)
C6—C5—N5	115.92 (19)	C21—C20—C19	118.9 (2)
C12—C5—N5	122.10 (19)	C22—C21—C20	119.2 (2)
C5—C6—C7	119.5 (2)	C22—C21—H21	120.4
C5—C6—H6	120.3	C20—C21—H21	120.4
C7—C6—H6	120.3	C23—C22—C21	120.2 (2)
C6—C7—C8	120.9 (2)	C23—C22—H22	119.9
C6—C7—C18	118.4 (2)	C21—C22—H22	119.9
C8—C7—C18	120.65 (19)	C22—C23—C24	120.5 (2)
C13—C8—C7	118.65 (19)	C22—C23—H23	119.8
C13—C8—H8	120.7	C24—C23—H23	119.8
C7—C8—H8	120.7	C25—C24—C23	120.3 (2)
C14—C9—C10	126.4 (2)	C25—C24—H24	119.9
C14—C9—C13	126.9 (2)	C23—C24—H24	119.9
C10—C9—C13	106.48 (17)	C24—C25—C20	118.9 (2)
C1—C10—C11	121.12 (19)	C24—C25—H25	120.6
C1—C10—C9	130.80 (19)	C20—C25—H25	120.6
C11—C10—C9	108.07 (18)