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The crystal structure of the title potassium salt, K+·C8HN4O2-, of the organic anion 3-cyano-4-(dicyanomethylene)-5-oxo-4,5-dihydro-1H-pyrrol-2-olate shows that the dicyanomethylene moiety is able to accept an electron in the same way as does tetracyanoethylene, to yield the novel product. The organic anion is nearly planar, with deviations caused by steric crowding among the exocyclic cyano groups. The K+ cations lie within tricapped trigonal prisms that stack to form channels. The three-dimensional structure is completed by the formation of hydrogen-bonded chains by the anions.
Supporting information
CCDC reference: 224502
The starting compound was synthesized from α-chloro ketone and tetracyanoethylene. Potassium 3-cyano-4-(dicyanomethylene)-5-oxo-4,5-dihydro-1H-pyrrol-2-olate, (I), was obtained by mixing 4,13-dioxo-5,12-dioxadispiro[2.2.5.2]tridecane-1,1,2,2-tetracarbonitrile with potassium iodide in water-1,4-dioxane (Ratio?), followed by refluxing of the resulting solution for 1 h. Yellow crystals of (I) were collected from the reaction mixture by filtration and drying.
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo, 1995); 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.
Potassium 3-cyano-4-(dicyanomethylene)-5-oxo-4,5-dihydro-1
H-pyrrol-2-olate
top
Crystal data top
[K(C8HN4O2)] | Dx = 1.773 Mg m−3 |
Mr = 224.23 | Melting point: 618 K |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 4.1614 (10) Å | Cell parameters from 23 reflections |
b = 9.391 (2) Å | θ = 14–24° |
c = 21.571 (3) Å | µ = 0.61 mm−1 |
β = 95.02 (1)° | T = 293 K |
V = 839.7 (3) Å3 | Prism, yellow |
Z = 4 | 0.20 × 0.15 × 0.10 mm |
F(000) = 448 | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0.000 |
Radiation source: fine-focus sealed tube | θmax = 30.0°, θmin = 1.9° |
Graphite monochromator | h = −5→5 |
non–profiled ω scan | k = 0→13 |
2434 measured reflections | l = 0→30 |
2434 independent reflections | 2 standard reflections every 60 min |
1935 reflections with I > 2σ(I) | intensity decay: none |
Refinement top
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) = 0.095 | All H-atom parameters refined |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0469P)2 + 0.203P] where P = (Fo2 + 2Fc2)/3 |
2434 reflections | (Δ/σ)max = 0.001 |
141 parameters | Δρmax = 0.29 e Å−3 |
0 restraints | Δρmin = −0.33 e Å−3 |
Crystal data top
[K(C8HN4O2)] | V = 839.7 (3) Å3 |
Mr = 224.23 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 4.1614 (10) Å | µ = 0.61 mm−1 |
b = 9.391 (2) Å | T = 293 K |
c = 21.571 (3) Å | 0.20 × 0.15 × 0.10 mm |
β = 95.02 (1)° | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0.000 |
2434 measured reflections | 2 standard reflections every 60 min |
2434 independent reflections | intensity decay: none |
1935 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.095 | All H-atom parameters refined |
S = 1.04 | Δρmax = 0.29 e Å−3 |
2434 reflections | Δρmin = −0.33 e Å−3 |
141 parameters | |
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
K | 0.14533 (9) | 0.88691 (4) | 0.400597 (18) | 0.03293 (12) | |
O1 | 0.6384 (3) | 1.08161 (12) | 0.36809 (6) | 0.0359 (3) | |
O2 | 0.9404 (4) | 1.42910 (15) | 0.23638 (6) | 0.0425 (3) | |
N | 0.8321 (4) | 1.22833 (16) | 0.29427 (7) | 0.0323 (3) | |
N1 | 0.6057 (4) | 1.71163 (17) | 0.33655 (8) | 0.0431 (4) | |
N2 | 0.1762 (4) | 1.59565 (16) | 0.44838 (7) | 0.0380 (4) | |
N3 | 0.2725 (4) | 1.14414 (17) | 0.49494 (8) | 0.0432 (4) | |
C2 | 0.8220 (4) | 1.37460 (18) | 0.28018 (8) | 0.0297 (3) | |
C3 | 0.6544 (4) | 1.44146 (17) | 0.32824 (7) | 0.0261 (3) | |
C4 | 0.5583 (4) | 1.33835 (16) | 0.36916 (7) | 0.0235 (3) | |
C5 | 0.6759 (4) | 1.19805 (16) | 0.34570 (7) | 0.0257 (3) | |
C6 | 0.6248 (4) | 1.59091 (17) | 0.33237 (8) | 0.0291 (3) | |
C7 | 0.3885 (4) | 1.34901 (16) | 0.42127 (7) | 0.0247 (3) | |
C8 | 0.2696 (4) | 1.48459 (17) | 0.43802 (7) | 0.0265 (3) | |
C9 | 0.3285 (4) | 1.23226 (17) | 0.46078 (8) | 0.0288 (3) | |
H | 0.905 (6) | 1.164 (3) | 0.2740 (10) | 0.049 (7)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
K | 0.0342 (2) | 0.02549 (18) | 0.0402 (2) | 0.00231 (14) | 0.00941 (15) | 0.00279 (14) |
O1 | 0.0461 (8) | 0.0220 (6) | 0.0410 (7) | 0.0046 (5) | 0.0113 (6) | 0.0014 (5) |
O2 | 0.0519 (8) | 0.0429 (8) | 0.0354 (7) | −0.0045 (6) | 0.0189 (6) | 0.0029 (6) |
N | 0.0414 (8) | 0.0278 (7) | 0.0291 (7) | 0.0042 (6) | 0.0112 (6) | −0.0048 (6) |
N1 | 0.0509 (10) | 0.0290 (8) | 0.0501 (10) | 0.0024 (7) | 0.0085 (8) | 0.0077 (7) |
N2 | 0.0478 (9) | 0.0294 (7) | 0.0376 (8) | 0.0071 (7) | 0.0090 (7) | −0.0012 (6) |
N3 | 0.0557 (11) | 0.0306 (8) | 0.0461 (9) | 0.0021 (7) | 0.0208 (8) | 0.0052 (7) |
C2 | 0.0310 (8) | 0.0321 (8) | 0.0262 (8) | −0.0018 (7) | 0.0031 (6) | 0.0002 (6) |
C3 | 0.0314 (8) | 0.0230 (7) | 0.0240 (7) | 0.0004 (6) | 0.0028 (6) | 0.0017 (6) |
C4 | 0.0248 (7) | 0.0211 (7) | 0.0241 (7) | 0.0015 (5) | −0.0008 (6) | −0.0006 (6) |
C5 | 0.0277 (7) | 0.0238 (7) | 0.0252 (7) | 0.0016 (6) | 0.0012 (6) | −0.0029 (6) |
C6 | 0.0312 (8) | 0.0278 (8) | 0.0287 (8) | 0.0002 (6) | 0.0049 (6) | 0.0056 (6) |
C7 | 0.0291 (8) | 0.0207 (6) | 0.0244 (7) | 0.0020 (6) | 0.0034 (6) | 0.0000 (6) |
C8 | 0.0305 (8) | 0.0258 (7) | 0.0236 (7) | 0.0016 (6) | 0.0047 (6) | 0.0008 (6) |
C9 | 0.0331 (8) | 0.0246 (7) | 0.0298 (8) | 0.0022 (6) | 0.0085 (6) | −0.0018 (6) |
Geometric parameters (Å, º) top
K—O1i | 2.8329 (14) | N—C2 | 1.407 (2) |
K—O1 | 2.8805 (14) | N—H | 0.82 (2) |
K—N2ii | 2.9218 (16) | N1—C6 | 1.141 (2) |
K—N1ii | 2.9584 (18) | N2—C8 | 1.142 (2) |
K—O2iii | 2.9716 (14) | N3—C9 | 1.145 (2) |
K—N3iv | 2.9787 (17) | C4—C5 | 1.508 (2) |
K—N1v | 3.0195 (19) | C4—C7 | 1.383 (2) |
K—N3 | 3.1730 (19) | C3—C4 | 1.392 (2) |
K—N3vi | 3.174 (2) | C3—C6 | 1.412 (2) |
K—Ki | 4.1614 (10) | C2—C3 | 1.443 (2) |
O1—C5 | 1.2109 (19) | C7—C8 | 1.424 (2) |
O2—C2 | 1.216 (2) | C7—C9 | 1.424 (2) |
N—C5 | 1.364 (2) | | |
| | | |
O1i—K—O1 | 93.49 (4) | O1—K—N3vi | 73.47 (4) |
O1i—K—N2ii | 134.45 (5) | N2ii—K—N3vi | 69.90 (5) |
O1—K—N2ii | 132.05 (5) | N1ii—K—N3vi | 78.18 (5) |
O1i—K—N1ii | 137.91 (5) | O2iii—K—N3vi | 137.38 (4) |
O1—K—N1ii | 74.65 (4) | N3iv—K—N3vi | 85.05 (5) |
N2ii—K—N1ii | 68.50 (4) | N1v—K—N3vi | 139.95 (4) |
O1i—K—O2iii | 69.26 (4) | N3—K—N3vi | 62.65 (5) |
O1—K—O2iii | 72.51 (4) | Ki—K—Kvii | 180.0 |
N2ii—K—O2iii | 118.25 (4) | C2—N—C5 | 111.84 (14) |
N1ii—K—O2iii | 68.66 (4) | C5—N—H | 120.3 (16) |
O1i—K—N3iv | 77.24 (4) | C2—N—H | 127.7 (16) |
O1—K—N3iv | 136.20 (5) | O1—C5—N | 126.86 (15) |
N2ii—K—N3iv | 69.64 (4) | O1—C5—C4 | 126.74 (14) |
N1ii—K—N3iv | 138.04 (5) | N—C5—C4 | 106.41 (13) |
O2iii—K—N3iv | 137.57 (5) | C7—C4—C3 | 131.35 (15) |
O1i—K—N1v | 74.38 (5) | C7—C4—C5 | 122.67 (14) |
O1—K—N1v | 138.74 (4) | C3—C4—C5 | 105.97 (13) |
N2ii—K—N1v | 70.06 (5) | C4—C3—C6 | 128.29 (15) |
N1ii—K—N1v | 88.23 (5) | C4—C3—C2 | 109.67 (14) |
O2iii—K—N1v | 66.30 (4) | C6—C3—C2 | 121.87 (15) |
N3iv—K—N1v | 80.38 (5) | O2—C2—N | 124.92 (16) |
O1i—K—N3 | 75.30 (4) | O2—C2—C3 | 128.99 (17) |
O1—K—N3 | 65.82 (4) | N—C2—C3 | 106.07 (14) |
N2ii—K—N3 | 119.13 (5) | N1—C6—C3 | 178.7 (2) |
N1ii—K—N3 | 130.13 (5) | C4—C7—C8 | 118.99 (14) |
O2iii—K—N3 | 122.34 (4) | C4—C7—C9 | 124.03 (14) |
N3iv—K—N3 | 70.43 (5) | C8—C7—C9 | 116.97 (14) |
N1v—K—N3 | 141.64 (5) | N2—C8—C7 | 176.43 (17) |
O1i—K—N3vi | 137.77 (4) | N3—C9—C7 | 175.85 (18) |
| | | |
C2—N—C5—O1 | 178.22 (17) | C5—N—C2—O2 | −179.29 (17) |
C2—N—C5—C4 | −1.70 (19) | C5—N—C2—C3 | 2.1 (2) |
O1—C5—C4—C7 | 0.2 (3) | C4—C3—C2—O2 | 179.84 (18) |
N—C5—C4—C7 | −179.83 (15) | C6—C3—C2—O2 | −4.5 (3) |
O1—C5—C4—C3 | −179.27 (17) | C4—C3—C2—N | −1.59 (19) |
N—C5—C4—C3 | 0.65 (17) | C6—C3—C2—N | 174.06 (16) |
C7—C4—C3—C6 | 5.8 (3) | C3—C4—C7—C8 | 3.2 (3) |
C5—C4—C3—C6 | −174.70 (17) | C5—C4—C7—C8 | −176.23 (14) |
C7—C4—C3—C2 | −178.86 (16) | C3—C4—C7—C9 | −175.56 (17) |
C5—C4—C3—C2 | 0.59 (17) | C5—C4—C7—C9 | 5.1 (2) |
Symmetry codes: (i) x−1, y, z; (ii) x, y−1, z; (iii) −x+1, y−1/2, −z+1/2; (iv) −x, −y+2, −z+1; (v) x−1, y−1, z; (vi) −x+1, −y+2, −z+1; (vii) x+1, y, z. |
Experimental details
Crystal data |
Chemical formula | [K(C8HN4O2)] |
Mr | 224.23 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 4.1614 (10), 9.391 (2), 21.571 (3) |
β (°) | 95.02 (1) |
V (Å3) | 839.7 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.61 |
Crystal size (mm) | 0.20 × 0.15 × 0.10 |
|
Data collection |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2434, 2434, 1935 |
Rint | 0.000 |
(sin θ/λ)max (Å−1) | 0.703 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.095, 1.04 |
No. of reflections | 2434 |
No. of parameters | 141 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.29, −0.33 |
Selected geometric parameters (Å, º) topK—O1i | 2.8329 (14) | N—C2 | 1.407 (2) |
K—O1 | 2.8805 (14) | N—H | 0.82 (2) |
K—N2ii | 2.9218 (16) | N1—C6 | 1.141 (2) |
K—N1ii | 2.9584 (18) | N2—C8 | 1.142 (2) |
K—O2iii | 2.9716 (14) | N3—C9 | 1.145 (2) |
K—N3iv | 2.9787 (17) | C4—C5 | 1.508 (2) |
K—N1v | 3.0195 (19) | C4—C7 | 1.383 (2) |
K—N3 | 3.1730 (19) | C3—C4 | 1.392 (2) |
K—N3vi | 3.174 (2) | C3—C6 | 1.412 (2) |
O1—C5 | 1.2109 (19) | C2—C3 | 1.443 (2) |
O2—C2 | 1.216 (2) | C7—C8 | 1.424 (2) |
N—C5 | 1.364 (2) | C7—C9 | 1.424 (2) |
| | | |
C2—N—C5 | 111.84 (14) | O2—C2—N | 124.92 (16) |
O1—C5—N | 126.86 (15) | O2—C2—C3 | 128.99 (17) |
O1—C5—C4 | 126.74 (14) | N—C2—C3 | 106.07 (14) |
N—C5—C4 | 106.41 (13) | N1—C6—C3 | 178.7 (2) |
C7—C4—C3 | 131.35 (15) | C4—C7—C8 | 118.99 (14) |
C7—C4—C5 | 122.67 (14) | C4—C7—C9 | 124.03 (14) |
C3—C4—C5 | 105.97 (13) | C8—C7—C9 | 116.97 (14) |
C4—C3—C6 | 128.29 (15) | N2—C8—C7 | 176.43 (17) |
C4—C3—C2 | 109.67 (14) | N3—C9—C7 | 175.85 (18) |
C6—C3—C2 | 121.87 (15) | | |
Symmetry codes: (i) x−1, y, z; (ii) x, y−1, z; (iii) −x+1, y−1/2, −z+1/2; (iv) −x, −y+2, −z+1; (v) x−1, y−1, z; (vi) −x+1, −y+2, −z+1. |
Charge distribution on the atoms of the anion and neutral radical topAtom | Radical | Anion |
O1 | -0.257 | -0.333 |
O2 | -0.251 | -0.374 |
N1 | 0.057 | -0.142 |
N2 | 0.057 | -0.114 |
N3 | 0.063 | -0.112 |
N | -0.390 | -0.420 |
C2 | 0.344 | 0.389 |
C3 | -0.003 | -0.340 |
C4 | -0.055 | 0.122 |
C5 | 0.345 | 0.330 |
C6 | -0.107 | -0.011 |
C7 | 0.176 | -0.145 |
C8 | -0.133 | -0.042 |
C9 | -0.124 | -0.039 |
H | 0.278 | 0.237 |
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Tetracyanoethylene (TCNE) is widely used for preparing photochromic materials (Huffman et al., 1967), anticancerous (Nasakin et al., 2000) and biologically active compounds (Abdel-Rahman, 1989; Tacconi et al., 1976) and is the basic reagent for the synthesis of new hetero- and carbocyclic compounds with specific physical and chemical properties (Nasakin et al., 1992, 1994, 1997; Sheverdov et al., 2001). One of the most remarkable features of TCNE is its ability to accept an electron easily, to be transformed into an anion or radical anion (Lemenovskiy et al., 1981; Zheludev et al., 1994). Hence, we hypothesize that the same ability could be an intrinsic property of substances or intermediates that contain a fragment of TCNE, specifically dicyanomethylene. This article reports on the positive realisation of this idea. We suppose that hetero- and carbocyclic compounds containing two, three or four cyano groups are promising starting reagents for transformations to anions or radical anions. An iodide anion was used as the reducing agent in the reaction with 4,13-dioxo-5,12-dioxadispiro[2.2.5.2]-tridecane-1,1,2,2-tetra-carbonitrile (see Scheme). \sch
The X-ray analysis of the product isolated from a water-dioxane solution showed that a salt with a new organic anion, potassium 3-cyano-4-(dicyanomethylene)-5-oxo-4,5-dihydro-1H-pyrrol-2-olate, (I), had been synthesized. Although the mechanism of this reaction needs further clarification, we can formulate two aspects of the reaction on the basis of the resulting molecular structure: a) electron transport from the iodide anion into the organic moiety and b) recyclization as a consequence of (NC)2C—C(CN)2 C—C bond breaking. Note that the negative charge on one C atom (see Scheme) only partly reflects the real charge distribution. The charges on the atoms of the anion and on the corresponding radical were calculated by quantum-chemical methods using the semi-empirical AM1 Hamiltonian (Dewar et al., 1985). The results of the calculation are represented in Table 2 (see also Fig. 1), which shows the charge distribution in the anion and the difference in charge distribution between anion and radical. Going from the radical to the anion noticeably increases the negative charge on the external heteroatoms and atoms C3 and C7.
All external heteroatoms of (I) are involved in the formation of a practically ideal tricapped trigonal prism that encloses a cation (Figs. 2 and 3). There is good indirect evidence that all external heteroatoms bear negative charge. The K···A distances (where A is O or N) range from 2.833 (1) for K···O1i to 3.174 (2) Å for K···N3vi [Table 1; symmetry codes: (i) x − 1, y, z; (vi) 1 − x, 2 − y, 1 − z]. Each prism is joined to two neighbouring prisms through a common base, and in this way a channel along the a axis is formed, in which the K+ cations are located (Figs. 2 and 3). The shortest K···K distance is 4.161 (1) Å.
The anions in (I) are connected by an N—H···O2vii interaction to form extended chains which run along the b axis, with N—H 0.82 (2), H···O2vii 2.31 (2) and N···O2vii 3.056 (2) Å, and N—H···O2vii 151 (2)° [symmetry code: (vii) 2 − x, y − 1/2, 1/2 − z].
The five-membered ring of (I) is planar, with a maximum deviation (for N) of 0.011 (1) Å. Atoms O1 [deviation 0.025 (1) Å] and O2 [deviation 0.015 (1) Å] lie in this plane. While atom C7 [deviation 0.0095 (16) Å] also lies nearly exactly in the plane, atoms C6 [deviation −0.116 (2) Å] and N1 [deviation −0.230 (2) Å] are displaced from this plane, as a result of steric hindrance and repulsion by the neighbouring cyano groups (Fig. 1). The angle which the –C(CN)2 group makes with the five-membered ring is 4.1 (1)°, demonstrating a small twist from planarity about the C4—C7 bond.