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organic compounds
Acta Crystallographica Section E

Experimental
Crystal data
C12H6F6N2O3 Mr = 340.19 Monoclinic, P21 =c ° a = 5.7996 (5) A ° b = 20.838 (2) A ° c = 10.4259 (8) A  = 91.100 (7) ° V = 1259.76 (19) A3 Z=4 Mo K radiation = 0.19 mmþ1 T = 100 (2) K 0.6 á 0.2 á 0.1 mm

Structure Reports Online
ISSN 1600-5368

7-Methyl-3,N-bis(trifluoroacetyl)oxazolo[3,2-a]pyridinium-2-imidate
Victor B. Rybakov,a* Alexander A. Bush,a Sergei I. Troyanov,a Eugene V. Babaeva and Erhard Kemnitz
b

Data collection
Stoe IPDS diffractometer Absorption correction: none 3851 measured reflections 3776 independent reflections 3247 reflections with I > 2 (I) Rint = 0.026

a Department of Chemistry, Moscow State University, 119992 Moscow, Russian Federation, and bInstitut fur Chemie, Mathematisch-Naturwissenshaftliche Fakultat, Humboldt-Universitat zu Berlin, D­12489 Berlin, Germany Correspondence e-mail: rybakov20021@yandex.ru

Refinement
R[F 2 > 2 (F 2)] = 0.048 wR(F 2) = 0.131 S = 1.01 3776 reflections 236 parameters 12 restraints H-atom parameters constrained ° àmax = 0.41 e Aþ3 ° àmin = þ0.40 e Aþ3

Received 17 July 2007; accepted 20 July 2007 ° Key indicators: single-crystal X-ray study; T = 100 K; mean (C­C) = 0.001 A; disorder in main residue; R factor = 0.048; wR factor = 0.131; data-to-parameter ratio = 16.0.

The title compound, C12H6F6N2O3, belongs to a class of mesoionic compounds. The crystal packing exhibits a short intermolecular N(heterobicycle)àààO(N trifluoroacetyl) ° contact of 2.8689 (11) A, which indicates that the principal location of the negative charge is near the chain C and O atoms of the N trifluoroacetyl group. The F atoms of one trifluoromethyl group are disordered over two positions, the site occupancy ratio being ca 3:2.

Data collection: X AREA (Stoe & Cie, 2002); cell refinement: X AREA; data reduction: X RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP 3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

The authors are indebted to the Russian Foundation for Basic Research for funding the licence fee for the use of the Cambridge Structural Database (Version 5.28; Allen, 2002).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CV2281).

Related literature
For the crystal structures of related mesoionic compounds, see: Rybakov et al. (2002, 2006); Babaev et al. (2004, 2005).

References
Allen, F. H. (2002). Acta Cryst. B58, 380 388. Babaev, E. V., Bush, A. A., Orlova, I. A., Rybakov, V. B. & Iwataki, I. (2005). Russ. Chem. Bull. 54, 231 237. Babaev, E. V., Rybakov, V. B., Orlova, I. A., Bush, A. A., Maerle, K. V. & Nasonov, A. F. (2004). Russ. Chem. Bull. 53, 176 180. Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837 838. Rybakov, V. B., Babaev, E. V., Pasechnichenko, K. Yu. & Sonneveld, E. (2002). Crystallogr. Rep. 47, 76 81. Rybakov, V. B., Bush, A. A., Troyanov, S. I., Babaev, E. V. & Kemnitz, E. (2006). Acta Cryst. E62, o1673 o1675. Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of ¨ Gottingen, Germany. Stoe & Cie (2002). X-AREA (Version 1.18) and X-RED32 (Version 1.04). Stoe & Cie, Darmstadt, Germany.

Acta Cryst. (2007). E63, o3619

doi:10.1107/S1600536807035611

# 2007 International Union of Crystallography

o3619


supplementary materials


supplementary materials
Acta Cryst. (2007). E63, o3619 [ doi:10.1107/S1600536807035611 ]

7-Methyl-3,N-bis(trifluoroacetyl)oxazolo[3,2-a]pyridinium-2-imidate V. B. Rybakov, A. A. Bush, S. I. Troyanov, E. V. Babaev and E. Kemnitz
Comment Earlier (Rybakov et al., 2002, 2006; Babaev et al., 2004, 2005), we described successful synthesis of previously unknown class of mesoionic compounds. Now we synthesized a new (Allen, 2002) one - see Scheme 1. The structure of the title compound is shown on Fig. 1. The main structural feature of this molecule is the difference in lengths of two C--O bonds in the oxazole ring, C3--O4 and C5--O4 of 1.3926 (11) and 1.3467 (10) å, respectively. Additionally, the bond N1--C2 is longer than other two C--N bonds in the bicycle. These facts may demonstrate the separation of charges in the mesoionic system into two parts: N1 atom of the pyridine-2-one-like positively charged fragment and a negatively charged C2--C3--N30--C30--O30 unit. This conclusion also confirmed by relatively short interatomic contacts C2···O30i = 3.2066 (11) å, N1···O30i = 2.8689 (11) å and C5···O30i = 2.9258 (12) å [symmetry code: (i) -x + 1, -y + 1, -z + 2]. Interestingly, the group C10O10 seems to make a smaller contribution to the delocalization of the negative charge, since the C10--O10 distance are relatively long [1.2269 (11) å]. Experimental The slurry of 4-methyl-N-(cyanomethyl)pyrid-2-one (3 g, 20.3 mmol) in 10 ml of acetonitrile was chilled to 228 K and then trifluoroacetic anhydride (10 ml, 15.1 g, 71.9 mmol) was added. [Scheme 2] Immediately after addition the temperature of reaction mixture has risen to 263 K and then slowly decreased to 253 K. Reaction mixture was allowed to warm to RT. The formation of new precipitate was observed at 283 K. New precipitate was filtered off, washed with ether and dried. Mother liquor and ether washings were combined and, after staying overnight, new portion of product with identical mp was harvested. 7.63 g of 3,N-bis(trifluoroacetyl)-7-methyloxazolo[3,2-a]pyridinium2-imidate was obtained. Yield 83%. M.p. 508­510 K (decomp.).
1

H-NMR spectrum: 9.61 (d, 1H, H5, J56 = 6.6 Hz), 8.05 (s, 1H, H8), 7.68 (d, 1H, H6, J56 = 6.6 Hz), 2.67 (s, 3H, 7­CH3).

Refinement C-bound H-atoms were placed in calculated positions (C--H 0.95­0.99 å) and refined as riding, with Uiso(H) = 1.2­1.5Ueq(C). One CF3-group (at C31) was treated as rotationally disordered between two orientations with the refined occupancies of 0.61 (1) and 0.39 (1), respectively. For this group, the bond restraints for the equality of C--F bond lengths and F···F distances have been applied using SADI option.

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supplementary materials
Figures Fig. 1. The molecular structure of the title compound showing the atom­numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms presented as spheres with arbitrary radius. Only major part of the disordered CF3­group is shown.

Fig. 2. Reaction scheme.

3,N-Bis(trifluoroacetyl)-7-methyloxazolo[3,2-a]pyridinium-2-imidate Crystal data
C12H6F6N2O3 Mr = 340.19 Monoclinic, P21/c Hall symbol: -P 2ybc a = 5.7996 (5) å b = 20.838 (2) å c = 10.4259 (8) å = 91.100 (7)º V = 1259.76 (19) å Z=4
3

F

000

= 680

Dx = 1.794 Mg m-3 Melting point: 509 K Mo K radiation = 0.71073 å Cell parameters from 429 reflections = 3.0­29.5º µ = 0.19 mm-1 T = 100 (2) K Needle, colourless 0.6 â 0.2 â 0.1 mm

Data collection
Stoe IPDS diffractometer Radiation source: fine-focus sealed tube Monochromator: graphite T = 100(2) K scans Absorption correction: none 3851 measured reflections 3776 independent reflections 3247 reflections with I > 2(I) R
int

= 0.026 = 30.4º = 2.0º

max min

h = -88 k = 029 l = 014

Refinement
Refinement on F2 Least-squares matrix: full R[F2 > 2(F2)] = 0.048 wR(F2) = 0.131 Secondary atom site location: difference Fourier map Hydrogen site location: inferred from neighbouring sites H-atom parameters constrained w = 1/[2(Fo2) + (0.0989P)2]

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supplementary materials
where P = (F S = 1.01 3776 reflections 236 parameters (/)
max o 2

+ 2Fc2)/3
-3

= 0.008

max = 0.41 e å

min = -0.40 e å-3

12 restraints Extinction correction: none Primary atom site location: structure-invariant direct methods

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (å2)
x N1 C2 C3 O4 C5 C6 H6 C7 C8 H8 C9 H9 C71 H711 H712 H713 C10 O10 C11 F11 F12 F13 N30 C30 O30 C31 F31 F31A F32 F32A F33 F33A 0.44604 (14) 0.35449 (16) 0.50625 (16) 0.68186 (12) 0.64170 (15) 0.77826 (15) 0.9158 0.70315 (17) 0.49988 (17) 0.4502 0.37070 (16) 0.2323 0.84132 (19) 1.0047 0.7868 0.8223 0.14649 (15) 0.02315 (13) 0.06580 (18) 0.03658 (13) -0.13470 (12) 0.21923 (13) 0.50521 (14) 0.64171 (15) 0.73421 (13) 0.66604 (13) 0.6495 (3) 0.7273 (4) 0.5059 (3) 0.4601 (4) 0.8673 (3) 0.8216 (5) y 0.48860 0.54599 0.56442 0.51893 0.47454 0.42148 0.4130 0.38161 0.39605 0.3683 0.44916 0.4583 0.32277 0.3343 0.3057 0.2902 0.57336 0.54843 0.63848 0.63791 0.65525 0.68456 0.61598 0.62233 0.58246 0.69364 0.73418 0.73278 0.71061 0.71272 0.70461 0.69982 (4) (4) (4) (3) (4) (4) (4) (5) (4) (5) z 0.69681 (7) 0.74712 (9) 0.84737 (9) 0.85528 (7) 0.76367 (8) 0.73918 (9) 0.7872 0.64112 (9) 0.57260 (9) 0.5052 0.60035 (9) 0.5536 0.60798 (10) 0.6025 0.5253 0.6747 0.69798 (8) 0.61505 (7) 0.75063 (10) 0.87753 (7) 0.69530 (7) 0.72526 (7) 0.91787 (8) 1.02203 (8) 1.09181 (7) 1.06253 (7) 0.96520 (19) 0.9667 (3) 1.14445 (15) 1.1051 (2) 1.11975 (15) 1.1588 (2) Uiso*/Ueq 0.01393 (16) 0.01340 (17) 0.01458 (18) 0.01510 (15) 0.01303 (17) 0.01475 (17) 0.018* 0.01577 (18) 0.01844 (19) 0.022* 0.01550 (18) 0.019* 0.0215 (2) 0.032* 0.032* 0.032* 0.01288 (17) 0.02110 (17) 0.0195 (2) 0.02487 (16) 0.02538 (16) 0.02507 (16) 0.01664 (17) 0.01487 (17) 0.01776 (16) 0.0247 (2) 0.0263 (4) 0.0281 (6) 0.0280 (4) 0.0294 (6) 0.0290 (4) 0.0323 (6) Occ. (<1)

(4) (4) (4) (3) (3) (3) (4) (5) (3) (5) (11) (16) (10) (16) (11) (17)

0.61 0.39 0.61 0.39 0.61 0.39

(1) (1) (1) (1) (1) (1)

Atomic displacement parameters (å2)
N1 U11 0.0168 (3) U22 0.0119 (3) U33 0.0130 (3) U12 -0.0028 (2) U13 -0.0008 (3) U23 0.0015 (2)

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supplementary materials
C2 C3 O4 C5 C6 C7 C8 C9 C71 C10 O10 C11 F11 F12 F13 N30 C30 O30 C31 F31 F31A F32 F32A F33 F33A 0.0163 0.0181 0.0161 0.0158 0.0136 0.0220 0.0227 0.0176 0.0282 0.0132 0.0216 0.0208 0.0279 0.0275 0.0295 0.0194 0.0135 0.0227 0.0335 0.0327 0.0301 0.0322 0.0287 0.0347 0.0375 (4) (4) (3) (4) (4) (4) (4) (4) (5) (4) (3) (4) (3) (3) (3) (4) (4) (3) (6) (10) (14) (8) (12) (9) (14) 0.0098 0.0096 0.0110 0.0092 0.0118 0.0094 0.0135 0.0133 0.0160 0.0135 0.0195 0.0125 0.0207 0.0199 0.0178 0.0132 0.0181 0.0138 0.0145 0.0164 0.0181 0.0193 0.0245 0.0193 0.0210 (3) (4) (3) (3) (3) (3) (4) (4) (4) (4) (3) (4) (3) (3) (3) (3) (4) (3) (4) (6) (9) (6) (10) (7) (10) 0.0141 0.0160 0.0181 0.0140 0.0187 0.0159 0.0191 0.0155 0.0203 0.0119 0.0219 0.0251 0.0259 0.0286 0.0278 0.0171 0.0130 0.0167 0.0258 0.0297 0.0360 0.0323 0.0351 0.0329 0.0380 (3) (4) (3) (4) (4) (4) (4) (4) (4) (3) (3) (5) (3) (3) (3) (4) (4) (3) (5) (7) (11) (9) (15) (9) (16) -0.0003 (3) -0.0024 (3) 0.0005 (2) -0.0021 (3) -0.0007 (3) -0.0016 (3) -0.0028 (3) -0.0034 (3) 0.0028 (3) -0.0005 (3) 0.0003 (3) 0.0039 (3) 0.0021 (2) 0.0035 (2) 0.0029 (2) -0.0020 (3) -0.0021 (3) 0.0002 (2) 0.0068 (4) 0.0029 (8) 0.0028 (11) 0.0046 (6) 0.0085 (9) 0.0020 (6) -0.0007 (9) -0.0017 (3) -0.0028 (3) -0.0032 (2) -0.0012 (3) -0.0025 (3) 0.0005 (3) -0.0008 (3) -0.0021 (3) -0.0003 (4) -0.0017 (3) -0.0083 (3) -0.0062 (3) -0.0035 (3) -0.0041 (3) -0.0030 (3) -0.0039 (3) -0.0013 (3) -0.0034 (2) -0.0095 (4) 0.0008 (7) -0.0014 (11) -0.0026 (6) 0.0029 (10) -0.0064 (7) -0.0095 (11) 0.0007 (3) 0.0008 (3) -0.0012 (2) -0.0007 (3) 0.0004 (3) -0.0004 (3) -0.0023 (3) 0.0002 (3) -0.0025 (3) -0.0010 (3) -0.0024 (3) -0.0038 (3) -0.0020 (2) -0.0015 (2) -0.0008 (2) -0.0033 (3) -0.0033 (3) 0.0021 (2) -0.0071 (3) 0.0000 (5) -0.0019 (7) -0.0001 (7) 0.0041 (11) -0.0016 (7) 0.0006 (12)

Geometric parameters (å, °)
N1--C5 N1--C9 N1--C2 C2--C3 C2--C10 C3--N30 C3--O4 O4--C5 C5--C6 C6--C7 C6--H6 C7--C8 C7--C71 C8--C9 C8--H8 C9--H9 C71--H711 C5--N1--C9 C5--N1--C2 C9--N1--C2 C3--C2--N1 1.3524 1.3641 1.4135 1.4068 1.4210 1.3018 1.3926 1.3467 1.3868 1.3813 0.9500 1.3994 1.5085 1.3705 0.9500 0.9500 0.9800 120.21 108.02 131.76 105.82 (11) (11) (11) (12) (12) (11) (11) (10) (12) (12) (13) (14) (13) C71--H712 C71--H713 C10--O10 C10--C11 C11--F12 C11--F11 C11--F13 N30--C30 C30--O30 C30--C31 C31--F33 C31--F31 C31--F32 C31--F32A C31--F33A C31--F31A C7--C71--H713 H711--C71--H713 H712--C71--H713 O10--C10--C2 0.9800 0.9800 1.2269 (11) 1.5401 (13) 1.3346 (11) 1.3371 (13) 1.3389 (13) 1.3380 (11) 1.2215 (12) 1.5506 (13) 1.3205 (18) 1.3223 (17) 1.3218 (18) 1.342 (3) 1.343 (3) 1.342 (3) 109.5 109.5 109.5 124.31 (9)

(8) (7) (8) (8)

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supplementary materials
C3--C2--C10 N1--C2--C10 N30--C3--O4 N30--C3--C2 O4--C3--C2 C5--O4--C3 O4--C5--N1 O4--C5--C6 N1--C5--C6 C7--C6--C5 C7--C6--H6 C5--C6--H6 C6--C7--C8 C6--C7--C71 C8--C7--C71 C9--C8--C7 C9--C8--H8 C7--C8--H8 N1--C9--C8 N1--C9--H9 C8--C9--H9 C7--C71--H711 C7--C71--H712 H711--C71--H712 C5--N1--C2--C3 C9--N1--C2--C3 C5--N1--C2--C10 C9--N1--C2--C10 N1--C2--C3--N30 C10--C2--C3--N30 N1--C2--C3--O4 C10--C2--C3--O4 N30--C3--O4--C5 C2--C3--O4--C5 C3--O4--C5--N1 C3--O4--C5--C6 C9--N1--C5--O4 C2--N1--C5--O4 C9--N1--C5--C6 C2--N1--C5--C6 O4--C5--C6--C7 N1--C5--C6--C7 C5--C6--C7--C8 C5--C6--C7--C71 C6--C7--C8--C9 C71--C7--C8--C9 C5--N1--C9--C8 C2--N1--C9--C8 C7--C8--C9--N1 132.30 121.87 122.66 129.43 107.73 108.01 110.41 125.92 123.66 116.28 121.9 121.9 119.94 119.80 120.26 121.63 119.2 119.2 118.26 120.9 120.9 109.5 109.5 109.5 (8) (8) (8) (9) (7) (7) (7) (8) (8) (8) O10--C10--C11 C2--C10--C11 F12--C11--F11 F12--C11--F13 F11--C11--F13 F12--C11--C10 F11--C11--C10 F13--C11--C10 C3--N30--C30 O30--C30--N30 O30--C30--C31 N30--C30--C31 F33--C31--F31 F33--C31--F32 F31--C31--F32 F32A--C31--F33A F32A--C31--F31A F33A--C31--F31A F33--C31--C30 F31--C31--C30 F32--C31--C30 F32A--C31--C30 F33A--C31--C30 F31A--C31--C30 N1--C2--C10--O10 C3--C2--C10--C11 N1--C2--C10--C11 O10--C10--C11--F12 C2--C10--C11--F12 O10--C10--C11--F11 C2--C10--C11--F11 O10--C10--C11--F13 C2--C10--C11--F13 O4--C3--N30--C30 C2--C3--N30--C30 C3--N30--C30--O30 C3--N30--C30--C31 O30--C30--C31--F33 N30--C30--C31--F33 O30--C30--C31--F31 N30--C30--C31--F31 O30--C30--C31--F32 N30--C30--C31--F32 O30--C30--C31--F32A N30--C30--C31--F32A O30--C30--C31--F33A N30--C30--C31--F33A O30--C30--C31--F31A N30--C30--C31--F31A 116.56 119.13 107.71 107.68 107.41 110.17 112.96 110.72 122.05 131.48 116.93 111.41 106.66 106.71 106.47 108.30 108.42 108.32 111.34 113.47 111.77 107.27 110.59 113.80 (8) (8) (9) (8) (8) (8) (8) (8) (9) (9) (8) (8) (10) (10) (10) (13) (13) (13) (12) (13) (12) (16) (17) (17)

(8) (9) (8) (9)

(9)

-0.38 (10) 179.12 (9) -179.35 (8) 0.14 (15) 175.15 (10) -6.03 (17) 0.01 (10) 178.83 (9) -175.19 (9) 0.36 (10) -0.61 (10) 179.43 (9) -178.94 (8) 0.62 (10) 1.02 (13) -179.42 (8) 179.30 (8) -0.65 (14) 0.23 (13) 179.99 (9) -0.19 (14) -179.95 (9) -0.92 (13) 179.64 (9) 0.53 (14)

4.53 (14) 5.72 (15) -175.62 (8) 1.46 (13) -178.40 (8) 121.96 (10) -57.91 (12) -117.54 (9) 62.60 (11) -15.46 (14) 170.04 (9) -23.29 (16) 161.80 (8) 33.75 (11) -150.53 (9) 154.09 (9) -30.19 (11) -85.50 (10) 90.23 (10) -107.33 (12) 68.40 (12) 10.58 (13) -173.70 (12) 132.76 (12) -51.51 (12)

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supplementary materials
C3--C2--C10--O10 -174.13 (10)

Fig. 1

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supplementary materials
Fig. 2

sup-7