7-Methyl-3,N-bis(trifluoro­acet­yl)­oxazolo[3,2-a]pyridinium-2-imidate

Rybakov, V.B.; Bush, A.A.; Troyanov, S.I.; Babaev, E.V.; Kemnitz, E.

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

The title compound, C₁₂H₆F₆N₂O₃, belongs to a class of mesoionic compounds. The crystal packing exhibits a short intermolecular N(heterobicycle)

O(N–trifluoroacetyl) contact of 2.8689 (11) Å, 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.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807035611/cv2281sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536807035611/cv2281Isup2.hkl Contains datablock I

CCDC reference: 657854

checkCIF report

Key indicators

Single-crystal X-ray study
T = 100 K
Mean (C-C) = 0.001 Å
Disorder in main residue
R factor = 0.048
wR factor = 0.131
Data-to-parameter ratio = 16.0

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT430_ALERT_2_B Short Inter D...A Contact  O30    ..  N1      ..       2.87 Ang.
PLAT432_ALERT_2_B Short Inter X...Y Contact  F11    ..  C30     ..       2.78 Ang.

Alert level C
PLAT301_ALERT_3_C Main Residue  Disorder .........................      12.00 Perc.
PLAT432_ALERT_2_C Short Inter X...Y Contact  O30    ..  C5      ..       2.93 Ang.

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         12

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

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

Comment top

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 C10═O10 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].

Related literature top

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

Experimental top

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]pyridinium-2-imidate was obtained. Yield 83%. M.p. 508–510 K (decomp.).

¹H-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, 7–CH₃).

Structure description top

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

Computing details top

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).

Figures top

	Fig. 1. The molecular structure of the title compound showing the atom–numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms presented as spheres with arbitrary radius. Only major part of the disordered CF₃–group is shown.
	Fig. 2. Reaction scheme.

3,N-Bis(trifluoroacetyl)-7-methyloxazolo[3,2-a]pyridinium-2-imidate top

Crystal data top

C₁₂H₆F₆N₂O₃	F(000) = 680
M_r = 340.19	D_x = 1.794 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 509 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 5.7996 (5) Å	Cell parameters from 429 reflections
b = 20.838 (2) Å	θ = 3.0–29.5°
c = 10.4259 (8) Å	µ = 0.19 mm⁻¹
β = 91.100 (7)°	T = 100 K
V = 1259.76 (19) Å³	Needle, colourless
Z = 4	0.6 × 0.2 × 0.1 mm

Data collection top

Stoe IPDS diffractometer	3247 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.026
Graphite monochromator	θ_max = 30.4°, θ_min = 2.0°
ω scans	h = −8→8
3851 measured reflections	k = 0→29
3776 independent reflections	l = 0→14

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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.131	H-atom parameters constrained
S = 1.01	w = 1/[σ²(F_o²) + (0.0989P)²] where P = (F_o² + 2F_c²)/3
3776 reflections	(Δ/σ)_max = 0.008
236 parameters	Δρ_max = 0.41 e Å⁻³
12 restraints	Δρ_min = −0.40 e Å⁻³

Crystal data top

C₁₂H₆F₆N₂O₃	V = 1259.76 (19) Å³
M_r = 340.19	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 5.7996 (5) Å	µ = 0.19 mm⁻¹
b = 20.838 (2) Å	T = 100 K
c = 10.4259 (8) Å	0.6 × 0.2 × 0.1 mm
β = 91.100 (7)°

Data collection top

Stoe IPDS diffractometer	3247 reflections with I > 2σ(I)
3851 measured reflections	R_int = 0.026
3776 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	12 restraints
wR(F²) = 0.131	H-atom parameters constrained
S = 1.01	Δρ_max = 0.41 e Å⁻³
3776 reflections	Δρ_min = −0.40 e Å⁻³
236 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
N1	0.44604 (14)	0.48860 (4)	0.69681 (7)	0.01393 (16)
C2	0.35449 (16)	0.54599 (4)	0.74712 (9)	0.01340 (17)
C3	0.50625 (16)	0.56442 (4)	0.84737 (9)	0.01458 (18)
O4	0.68186 (12)	0.51893 (3)	0.85528 (7)	0.01510 (15)
C5	0.64170 (15)	0.47454 (4)	0.76367 (8)	0.01303 (17)
C6	0.77826 (15)	0.42148 (4)	0.73918 (9)	0.01475 (17)
H6	0.9158	0.4130	0.7872	0.018*
C7	0.70315 (17)	0.38161 (4)	0.64112 (9)	0.01577 (18)
C8	0.49988 (17)	0.39605 (5)	0.57260 (9)	0.01844 (19)
H8	0.4502	0.3683	0.5052	0.022*
C9	0.37070 (16)	0.44916 (4)	0.60035 (9)	0.01550 (18)
H9	0.2323	0.4583	0.5536	0.019*
C71	0.84132 (19)	0.32277 (5)	0.60798 (10)	0.0215 (2)
H711	1.0047	0.3343	0.6025	0.032*
H712	0.7868	0.3057	0.5253	0.032*
H713	0.8223	0.2902	0.6747	0.032*
C10	0.14649 (15)	0.57336 (4)	0.69798 (8)	0.01288 (17)
O10	0.02315 (13)	0.54843 (4)	0.61505 (7)	0.02110 (17)
C11	0.06580 (18)	0.63848 (4)	0.75063 (10)	0.0195 (2)
F11	0.03658 (13)	0.63791 (3)	0.87753 (7)	0.02487 (16)
F12	−0.13470 (12)	0.65525 (3)	0.69530 (7)	0.02538 (16)
F13	0.21923 (13)	0.68456 (3)	0.72526 (7)	0.02507 (16)
N30	0.50521 (14)	0.61598 (4)	0.91787 (8)	0.01664 (17)
C30	0.64171 (15)	0.62233 (5)	1.02203 (8)	0.01487 (17)
O30	0.73421 (13)	0.58246 (3)	1.09181 (7)	0.01776 (16)
C31	0.66604 (13)	0.69364 (5)	1.06253 (7)	0.0247 (2)
F31	0.6495 (3)	0.73418 (11)	0.96520 (19)	0.0263 (4)	0.61 (1)
F31A	0.7273 (4)	0.73278 (16)	0.9667 (3)	0.0281 (6)	0.39 (1)
F32	0.5059 (3)	0.71061 (10)	1.14445 (15)	0.0280 (4)	0.61 (1)
F32A	0.4601 (4)	0.71272 (16)	1.1051 (2)	0.0294 (6)	0.39 (1)
F33	0.8673 (3)	0.70461 (11)	1.11975 (15)	0.0290 (4)	0.61 (1)
F33A	0.8216 (5)	0.69982 (17)	1.1588 (2)	0.0323 (6)	0.39 (1)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0168 (3)	0.0119 (3)	0.0130 (3)	−0.0028 (2)	−0.0008 (3)	0.0015 (2)
C2	0.0163 (4)	0.0098 (3)	0.0141 (3)	−0.0003 (3)	−0.0017 (3)	0.0007 (3)
C3	0.0181 (4)	0.0096 (4)	0.0160 (4)	−0.0024 (3)	−0.0028 (3)	0.0008 (3)
O4	0.0161 (3)	0.0110 (3)	0.0181 (3)	0.0005 (2)	−0.0032 (2)	−0.0012 (2)
C5	0.0158 (4)	0.0092 (3)	0.0140 (4)	−0.0021 (3)	−0.0012 (3)	−0.0007 (3)
C6	0.0136 (4)	0.0118 (3)	0.0187 (4)	−0.0007 (3)	−0.0025 (3)	0.0004 (3)
C7	0.0220 (4)	0.0094 (3)	0.0159 (4)	−0.0016 (3)	0.0005 (3)	−0.0004 (3)
C8	0.0227 (4)	0.0135 (4)	0.0191 (4)	−0.0028 (3)	−0.0008 (3)	−0.0023 (3)
C9	0.0176 (4)	0.0133 (4)	0.0155 (4)	−0.0034 (3)	−0.0021 (3)	0.0002 (3)
C71	0.0282 (5)	0.0160 (4)	0.0203 (4)	0.0028 (3)	−0.0003 (4)	−0.0025 (3)
C10	0.0132 (4)	0.0135 (4)	0.0119 (3)	−0.0005 (3)	−0.0017 (3)	−0.0010 (3)
O10	0.0216 (3)	0.0195 (3)	0.0219 (3)	0.0003 (3)	−0.0083 (3)	−0.0024 (3)
C11	0.0208 (4)	0.0125 (4)	0.0251 (5)	0.0039 (3)	−0.0062 (3)	−0.0038 (3)
F11	0.0279 (3)	0.0207 (3)	0.0259 (3)	0.0021 (2)	−0.0035 (3)	−0.0020 (2)
F12	0.0275 (3)	0.0199 (3)	0.0286 (3)	0.0035 (2)	−0.0041 (3)	−0.0015 (2)
F13	0.0295 (3)	0.0178 (3)	0.0278 (3)	0.0029 (2)	−0.0030 (3)	−0.0008 (2)
N30	0.0194 (4)	0.0132 (3)	0.0171 (4)	−0.0020 (3)	−0.0039 (3)	−0.0033 (3)
C30	0.0135 (4)	0.0181 (4)	0.0130 (4)	−0.0021 (3)	−0.0013 (3)	−0.0033 (3)
O30	0.0227 (3)	0.0138 (3)	0.0167 (3)	0.0002 (2)	−0.0034 (2)	0.0021 (2)
C31	0.0335 (6)	0.0145 (4)	0.0258 (5)	0.0068 (4)	−0.0095 (4)	−0.0071 (3)
F31	0.0327 (10)	0.0164 (6)	0.0297 (7)	0.0029 (8)	0.0008 (7)	0.0000 (5)
F31A	0.0301 (14)	0.0181 (9)	0.0360 (11)	0.0028 (11)	−0.0014 (11)	−0.0019 (7)
F32	0.0322 (8)	0.0193 (6)	0.0323 (9)	0.0046 (6)	−0.0026 (6)	−0.0001 (7)
F32A	0.0287 (12)	0.0245 (10)	0.0351 (15)	0.0085 (9)	0.0029 (10)	0.0041 (11)
F33	0.0347 (9)	0.0193 (7)	0.0329 (9)	0.0020 (6)	−0.0064 (7)	−0.0016 (7)
F33A	0.0375 (14)	0.0210 (10)	0.0380 (16)	−0.0007 (9)	−0.0095 (11)	0.0006 (12)

Geometric parameters (Å, º) top

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

C5—N1—C9	120.21 (8)	C7—C71—H713	109.5
C5—N1—C2	108.02 (7)	H711—C71—H713	109.5
C9—N1—C2	131.76 (8)	H712—C71—H713	109.5
C3—C2—N1	105.82 (8)	O10—C10—C2	124.31 (9)
C3—C2—C10	132.30 (8)	O10—C10—C11	116.56 (8)
N1—C2—C10	121.87 (8)	C2—C10—C11	119.13 (8)
N30—C3—O4	122.66 (8)	F12—C11—F11	107.71 (9)
N30—C3—C2	129.43 (9)	F12—C11—F13	107.68 (8)
O4—C3—C2	107.73 (7)	F11—C11—F13	107.41 (8)
C5—O4—C3	108.01 (7)	F12—C11—C10	110.17 (8)
O4—C5—N1	110.41 (7)	F11—C11—C10	112.96 (8)
O4—C5—C6	125.92 (8)	F13—C11—C10	110.72 (8)
N1—C5—C6	123.66 (8)	C3—N30—C30	122.05 (9)
C7—C6—C5	116.28 (8)	O30—C30—N30	131.48 (9)
C7—C6—H6	121.9	O30—C30—C31	116.93 (8)
C5—C6—H6	121.9	N30—C30—C31	111.41 (8)
C6—C7—C8	119.94 (8)	F33—C31—F31	106.66 (10)
C6—C7—C71	119.80 (9)	F33—C31—F32	106.71 (10)
C8—C7—C71	120.26 (8)	F31—C31—F32	106.47 (10)
C9—C8—C7	121.63 (9)	F32A—C31—F33A	108.30 (13)
C9—C8—H8	119.2	F32A—C31—F31A	108.42 (13)
C7—C8—H8	119.2	F33A—C31—F31A	108.32 (13)
N1—C9—C8	118.26 (9)	F33—C31—C30	111.34 (12)
N1—C9—H9	120.9	F31—C31—C30	113.47 (13)
C8—C9—H9	120.9	F32—C31—C30	111.77 (12)
C7—C71—H711	109.5	F32A—C31—C30	107.27 (16)
C7—C71—H712	109.5	F33A—C31—C30	110.59 (17)
H711—C71—H712	109.5	F31A—C31—C30	113.80 (17)

C5—N1—C2—C3	−0.38 (10)	N1—C2—C10—O10	4.53 (14)
C9—N1—C2—C3	179.12 (9)	C3—C2—C10—C11	5.72 (15)
C5—N1—C2—C10	−179.35 (8)	N1—C2—C10—C11	−175.62 (8)
C9—N1—C2—C10	0.14 (15)	O10—C10—C11—F12	1.46 (13)
N1—C2—C3—N30	175.15 (10)	C2—C10—C11—F12	−178.40 (8)
C10—C2—C3—N30	−6.03 (17)	O10—C10—C11—F11	121.96 (10)
N1—C2—C3—O4	0.01 (10)	C2—C10—C11—F11	−57.91 (12)
C10—C2—C3—O4	178.83 (9)	O10—C10—C11—F13	−117.54 (9)
N30—C3—O4—C5	−175.19 (9)	C2—C10—C11—F13	62.60 (11)
C2—C3—O4—C5	0.36 (10)	O4—C3—N30—C30	−15.46 (14)
C3—O4—C5—N1	−0.61 (10)	C2—C3—N30—C30	170.04 (9)
C3—O4—C5—C6	179.43 (9)	C3—N30—C30—O30	−23.29 (16)
C9—N1—C5—O4	−178.94 (8)	C3—N30—C30—C31	161.80 (8)
C2—N1—C5—O4	0.62 (10)	O30—C30—C31—F33	33.75 (11)
C9—N1—C5—C6	1.02 (13)	N30—C30—C31—F33	−150.53 (9)
C2—N1—C5—C6	−179.42 (8)	O30—C30—C31—F31	154.09 (9)
O4—C5—C6—C7	179.30 (8)	N30—C30—C31—F31	−30.19 (11)
N1—C5—C6—C7	−0.65 (14)	O30—C30—C31—F32	−85.50 (10)
C5—C6—C7—C8	0.23 (13)	N30—C30—C31—F32	90.23 (10)
C5—C6—C7—C71	179.99 (9)	O30—C30—C31—F32A	−107.33 (12)
C6—C7—C8—C9	−0.19 (14)	N30—C30—C31—F32A	68.40 (12)
C71—C7—C8—C9	−179.95 (9)	O30—C30—C31—F33A	10.58 (13)
C5—N1—C9—C8	−0.92 (13)	N30—C30—C31—F33A	−173.70 (12)
C2—N1—C9—C8	179.64 (9)	O30—C30—C31—F31A	132.76 (12)
C7—C8—C9—N1	0.53 (14)	N30—C30—C31—F31A	−51.51 (12)
C3—C2—C10—O10	−174.13 (10)

Experimental details

Crystal data
Chemical formula	C₁₂H₆F₆N₂O₃
M_r	340.19
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	5.7996 (5), 20.838 (2), 10.4259 (8)
β (°)	91.100 (7)
V (Å³)	1259.76 (19)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.19
Crystal size (mm)	0.6 × 0.2 × 0.1

Data collection
Diffractometer	Stoe IPDS
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	3851, 3776, 3247
R_int	0.026
(sin θ/λ)_max (Å⁻¹)	0.711

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.131, 1.01
No. of reflections	3776
No. of parameters	236
No. of restraints	12
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.41, −0.40

Computer programs: X-AREA (Stoe & Cie, 2002), X-AREA, X-RED32 (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

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7-Methyl-3,N-bis(trifluoro­acet­yl)­oxazolo[3,2-a]pyridinium-2-imidate

Supporting information

Key indicators

checkCIF/PLATON results

7-Methyl-3,N-bis(trifluoroacetyl)oxazolo[3,2-a]pyridinium-2-imidate