Relationship between structure and photoinitiating abilities of selected bromide salts of 2-oxo-2,3-dihydro-1H-imidazo[1,2-a]pyridine (IMP): influence of the solvent and the substitution in benzaldehyde on the course of its reaction with IMP

2-Oxo-2,3-dihydro-1H-imidazo[1,2-a]pyridinium bromide and its C3-substituted derivatives have been synthesized and structurally characterized by X-ray crystallography and quantum chemical calculations. Their potential as photoinitiators for free-radical polymerization has been investigated experimentally and compared with theoretical results. It has been established that the course of the reaction that introduces the substituted benzylidene group to the imidazole ring is different in the protic and dipolar aprotic solvents, and also depends on the character of the substituent, as the energy change in the reaction favours either R¹R²C=CHR³ or R¹R²CH-CH(OCH₃)R³ formation.

Computing details

For all compounds, data collection: CrysAlisCCDv.1.171(Oxford Diffraction,2000); cell refinement: CrysAlisREDv.1.171(Oxford Diffraction,2000); data reduction: CrysAlisREDv.1.171(Oxford Diffraction,2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Simens Analytical X-Ray Instruments (1989); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

(1) '2-oxo-2,3-dihydro-1H-imidazo[1,2-a]pyridinium bromide'

Crystal data

C7H7N2O·Br	Z = 2
Mr = 215.06	F(000) = 212
Triclinic, P1	Dx = 1.810 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.269 (1) Å	Cell parameters from 2054 reflections
b = 7.709 (2) Å	θ = 2.9–27.1°
c = 8.403 (2) Å	µ = 5.15 mm^−1
α = 67.01 (3)°	T = 295 K
β = 68.03 (3)°	Planar, light brown
γ = 72.00 (3)°	0.4 × 0.25 × 0.1 mm
V = 394.61 (19) Å^3

Data collection

Kuma KM4CCD κ-geometry diffractometer	1707 independent reflections
Radiation source: fine-focus sealed tube	1527 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
ω scans	θmax = 27.1°, θmin = 2.9°
Absorption correction: multi-scan XEMP.Siemens Analytical Xray, 1990	h = −7→9
Tmin = 0.234, Tmax = 0.592	k = −9→9
4519 measured reflections	l = −10→10

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.020	H-atom parameters constrained
wR(F^2) = 0.050	w = 1/[σ^2(Fo^2) + (0.0288P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max = 0.001
1707 reflections	Δρmax = 0.25 e Å^−3
101 parameters	Δρmin = −0.37 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.022 (3)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.83766 (3)	0.63871 (2)	0.30079 (2)	0.04169 (10)
N1	0.6947 (2)	0.1722 (2)	0.72772 (19)	0.0311 (3)
C1	0.7598 (2)	0.0053 (2)	0.8456 (2)	0.0326 (4)
C2	0.8188 (3)	−0.1648 (3)	0.8048 (3)	0.0423 (4)
H2	0.8678	−0.2838	0.8855	0.051*
C3	0.8039 (3)	−0.1581 (3)	0.6449 (3)	0.0433 (4)
H3	0.8446	−0.2739	0.6129	0.052*
C4	0.7337 (3)	0.0142 (3)	0.5263 (3)	0.0422 (4)
H4	0.7216	0.0152	0.4160	0.051*
C5	0.6801 (3)	0.1803 (3)	0.5700 (2)	0.0374 (4)
H5A	0.6326	0.3004	0.4896	0.045*
C6	0.6406 (3)	0.3314 (3)	0.8016 (3)	0.0379 (4)
H6A	0.7222	0.4269	0.7256	0.045*
H6B	0.5006	0.3904	0.8166	0.045*
C7	0.6842 (3)	0.2318 (3)	0.9828 (3)	0.0404 (4)
N2	0.7529 (2)	0.0405 (2)	0.9946 (2)	0.0413 (4)
H2A	0.7849	−0.0434	1.0784	0.050*
O1	0.6626 (2)	0.3017 (2)	1.0954 (2)	0.0578 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.04512 (14)	0.03459 (13)	0.04192 (13)	−0.00235 (8)	−0.01894 (9)	−0.00642 (8)
N1	0.0300 (7)	0.0268 (7)	0.0354 (8)	−0.0041 (6)	−0.0111 (6)	−0.0079 (6)
C1	0.0305 (8)	0.0287 (9)	0.0355 (9)	−0.0050 (7)	−0.0112 (7)	−0.0060 (7)
C2	0.0428 (10)	0.0279 (9)	0.0498 (11)	−0.0023 (8)	−0.0133 (9)	−0.0090 (8)
C3	0.0432 (10)	0.0364 (11)	0.0531 (12)	−0.0077 (8)	−0.0099 (9)	−0.0206 (9)
C4	0.0390 (10)	0.0500 (12)	0.0425 (10)	−0.0095 (9)	−0.0116 (8)	−0.0188 (9)
C5	0.0353 (9)	0.0390 (10)	0.0355 (9)	−0.0074 (8)	−0.0140 (8)	−0.0052 (8)
C6	0.0403 (10)	0.0276 (9)	0.0463 (11)	−0.0027 (7)	−0.0158 (8)	−0.0120 (8)
C7	0.0392 (10)	0.0402 (10)	0.0435 (10)	−0.0055 (8)	−0.0133 (8)	−0.0152 (8)
N2	0.0499 (9)	0.0350 (8)	0.0379 (9)	−0.0014 (7)	−0.0220 (7)	−0.0064 (7)
O1	0.0712 (10)	0.0564 (10)	0.0567 (9)	−0.0014 (8)	−0.0254 (8)	−0.0304 (8)

Geometric parameters (Å, º)

N1—C5	1.345 (2)	C4—C5	1.370 (3)
N1—C1	1.356 (2)	C4—H4	0.9600
N1—C6	1.470 (2)	C5—H5A	0.9600
C1—N2	1.361 (2)	C6—C7	1.519 (3)
C1—C2	1.384 (3)	C6—H6A	0.9601
C2—C3	1.368 (3)	C6—H6B	0.9600
C2—H2	0.9600	C7—O1	1.202 (2)
C3—C4	1.395 (3)	C7—N2	1.379 (2)
C3—H3	0.9600	N2—H2A	0.8010
C5—N1—C1	122.36 (15)	N1—C5—C4	118.89 (17)
C5—N1—C6	127.48 (15)	N1—C5—H5A	120.5
C1—N1—C6	110.14 (15)	C4—C5—H5A	120.6
N1—C1—N2	109.19 (15)	N1—C6—C7	102.57 (14)
N1—C1—C2	120.44 (17)	N1—C6—H6A	111.4
N2—C1—C2	130.36 (17)	C7—C6—H6A	111.1
C3—C2—C1	117.61 (17)	N1—C6—H6B	111.2
C3—C2—H2	120.8	C7—C6—H6B	111.2
C1—C2—H2	121.6	H6A—C6—H6B	109.3
C2—C3—C4	121.25 (17)	O1—C7—N2	126.17 (19)
C2—C3—H3	119.3	O1—C7—C6	128.11 (19)
C4—C3—H3	119.4	N2—C7—C6	105.71 (15)
C5—C4—C3	119.43 (18)	C1—N2—C7	112.38 (15)
C5—C4—H4	120.7	C1—N2—H2A	122.0
C3—C4—H4	119.9	C7—N2—H2A	125.6
C5—N1—C1—N2	−178.23 (14)	C3—C4—C5—N1	−0.7 (3)
C6—N1—C1—N2	0.18 (19)	C5—N1—C6—C7	178.32 (15)
C5—N1—C1—C2	1.5 (2)	C1—N1—C6—C7	0.01 (18)
C6—N1—C1—C2	179.88 (16)	N1—C6—C7—O1	−179.5 (2)
N1—C1—C2—C3	−1.6 (3)	N1—C6—C7—N2	−0.19 (18)
N2—C1—C2—C3	178.00 (18)	N1—C1—N2—C7	−0.3 (2)
C1—C2—C3—C4	0.7 (3)	C2—C1—N2—C7	−179.98 (18)
C2—C3—C4—C5	0.5 (3)	O1—C7—N2—C1	179.60 (19)
C1—N1—C5—C4	−0.2 (2)	C6—C7—N2—C1	0.3 (2)
C6—N1—C5—C4	−178.37 (16)

(2a) '3-[Methoxy-(2-nitro-phenyl)-methyl]-2-oxo- 3H-imidazo[1,2-a]pyridinium bromide'

Crystal data

C15H14N3O4·Br	F(000) = 384
Mr = 380.20	Dx = 1.684 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 2950 reflections
a = 7.359 (1) Å	θ = 5.2–25.0°
b = 12.987 (3) Å	µ = 2.77 mm^−1
c = 8.159 (2) Å	T = 150 K
β = 105.95 (3)°	Plate, yellow
V = 749.7 (3) Å^3	0.4 × 0.3 × 0.08 mm
Z = 2

Data collection

Kuma KM4CCD κ-geometry diffractometer	1957 independent reflections
Radiation source: fine-focus sealed tube	1759 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
ω scans	θmax = 25.0°, θmin = 5.2°
Absorption correction: multi-scan XEMP.Siemens Analytical Xray, 1990	h = −8→8
Tmin = 0.381, Tmax = 0.801	k = −15→12
3720 measured reflections	l = −7→9

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.028	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.052	w = 1/[σ^2(Fo^2) + (0.0242P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.96	(Δ/σ)max < 0.001
1957 reflections	Δρmax = 0.42 e Å^−3
244 parameters	Δρmin = −0.33 e Å^−3
1 restraint	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.001 (9)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.52232 (5)	0.59404 (4)	0.64410 (5)	0.02241 (12)
N1	0.8597 (4)	0.4599 (2)	0.4622 (4)	0.0151 (7)
N2	0.7282 (5)	0.3063 (3)	0.4612 (5)	0.0241 (9)
N3	1.2337 (5)	0.6138 (2)	0.9261 (4)	0.0209 (9)
O1	0.7878 (4)	0.2730 (3)	0.7472 (5)	0.0283 (9)
O3	1.1039 (4)	0.6337 (2)	0.7973 (4)	0.0286 (7)
O2	1.3690 (5)	0.6700 (2)	0.9850 (4)	0.0333 (8)
C1	0.7588 (6)	0.3847 (3)	0.3608 (6)	0.0175 (10)
C2	0.7016 (6)	0.3983 (4)	0.1852 (6)	0.0252 (11)
C3	0.7440 (6)	0.4903 (4)	0.1217 (6)	0.0281 (11)
C4	0.8432 (7)	0.5674 (3)	0.2300 (6)	0.0281 (13)
C5	0.8992 (6)	0.5506 (3)	0.4008 (6)	0.0233 (10)
C6	0.9020 (5)	0.4302 (3)	0.6448 (5)	0.0153 (9)
H6	0.8469	0.4753	0.7112	0.018*
C7	0.8015 (5)	0.3263 (3)	0.6314 (6)	0.0188 (9)
C8	1.1146 (6)	0.4193 (3)	0.7263 (5)	0.0149 (9)
C9	1.1631 (5)	0.4253 (3)	0.9213 (5)	0.0150 (9)
C10	1.2269 (6)	0.5152 (3)	1.0144 (5)	0.0183 (9)
C13	1.2089 (6)	0.3399 (4)	1.1941 (6)	0.0235 (10)
C12	1.2705 (7)	0.4314 (4)	1.2792 (7)	0.0255 (12)
C11	1.2810 (5)	0.5189 (3)	1.1893 (5)	0.0213 (10)
H11	1.3299	0.5823	1.2444	0.026*
C14	1.1585 (6)	0.3377 (3)	1.0173 (5)	0.0220 (10)
O1R	1.1646 (4)	0.3228 (2)	0.6671 (3)	0.0172 (7)
C1R	1.3636 (6)	0.3069 (3)	0.7045 (6)	0.0222 (10)
H1R	1.3759	0.2554	0.6200	0.029*
H2R	1.4202	0.3658	0.6785	0.029*
H3R	1.4156	0.2855	0.8136	0.029*
H2	0.636 (6)	0.342 (3)	0.126 (5)	0.031 (12)*
H2A	0.669 (6)	0.255 (3)	0.423 (5)	0.022 (13)*
H3	0.699 (6)	0.499 (3)	0.010 (6)	0.028 (13)*
H4	0.870 (6)	0.630 (3)	0.181 (5)	0.021 (13)*
H5	0.962 (5)	0.591 (5)	0.487 (4)	0.013 (9)*
H8	1.169 (5)	0.475 (3)	0.684 (4)	0.003 (9)*
H12	1.297 (5)	0.432 (3)	1.403 (5)	0.022 (11)*
H13	1.198 (5)	0.279 (3)	1.253 (5)	0.014 (10)*
H14	1.128 (5)	0.278 (3)	0.964 (5)	0.021 (12)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.02165 (19)	0.01693 (18)	0.0283 (2)	0.0035 (2)	0.00623 (14)	−0.0001 (3)
N1	0.0140 (17)	0.0151 (17)	0.0163 (18)	0.0020 (14)	0.0043 (15)	0.0012 (14)
N2	0.021 (2)	0.018 (2)	0.030 (2)	−0.0085 (17)	−0.0009 (18)	−0.0001 (18)
N3	0.0252 (18)	0.016 (3)	0.0228 (19)	−0.0043 (16)	0.0094 (15)	−0.0050 (16)
O1	0.0205 (18)	0.029 (2)	0.035 (2)	−0.0052 (15)	0.0071 (16)	0.0122 (18)
O3	0.0318 (17)	0.0189 (15)	0.0325 (19)	0.0066 (13)	0.0044 (15)	0.0039 (13)
O2	0.043 (2)	0.0255 (17)	0.0313 (19)	−0.0171 (16)	0.0109 (16)	−0.0100 (14)
C1	0.010 (2)	0.017 (2)	0.026 (3)	0.0041 (19)	0.007 (2)	0.003 (2)
C2	0.020 (2)	0.029 (3)	0.023 (3)	0.000 (2)	0.001 (2)	−0.006 (2)
C3	0.028 (3)	0.040 (3)	0.015 (3)	0.011 (2)	0.004 (2)	0.002 (2)
C4	0.033 (3)	0.025 (4)	0.028 (3)	0.0049 (19)	0.010 (2)	0.007 (2)
C5	0.024 (2)	0.017 (2)	0.028 (3)	−0.0002 (19)	0.008 (2)	−0.002 (2)
C6	0.018 (2)	0.015 (2)	0.012 (2)	0.0051 (17)	0.0049 (17)	0.0003 (17)
C7	0.010 (2)	0.019 (2)	0.026 (3)	0.0005 (17)	0.0023 (18)	0.004 (2)
C8	0.016 (2)	0.008 (2)	0.021 (2)	−0.0004 (16)	0.0049 (18)	−0.0024 (18)
C9	0.013 (2)	0.014 (2)	0.017 (2)	0.0022 (16)	0.0023 (17)	−0.0029 (17)
C10	0.018 (2)	0.017 (2)	0.021 (2)	0.0032 (18)	0.0068 (19)	0.0043 (18)
C13	0.029 (3)	0.019 (3)	0.024 (3)	0.003 (2)	0.008 (2)	0.005 (2)
C12	0.024 (3)	0.031 (3)	0.020 (3)	0.004 (2)	0.003 (2)	0.000 (2)
C11	0.017 (2)	0.021 (2)	0.024 (3)	0.0018 (18)	0.0033 (19)	−0.0069 (19)
C14	0.026 (2)	0.014 (2)	0.026 (3)	−0.0047 (19)	0.008 (2)	−0.004 (2)
O1R	0.0125 (15)	0.0150 (15)	0.0216 (16)	0.0019 (12)	0.0006 (13)	−0.0053 (12)
C1R	0.015 (2)	0.023 (2)	0.028 (3)	0.006 (2)	0.006 (2)	0.004 (2)

Geometric parameters (Å, º)

N1—C5	1.342 (5)	C6—C8	1.529 (5)
N1—C1	1.361 (5)	C6—H6	0.9599
N1—C6	1.487 (5)	C8—O1R	1.427 (5)
N2—C1	1.365 (6)	C8—C9	1.533 (5)
N2—C7	1.369 (5)	C8—H8	0.93 (4)
N2—H2A	0.81 (4)	C9—C14	1.387 (5)
N3—O2	1.221 (4)	C9—C10	1.402 (5)
N3—O3	1.238 (4)	C10—C11	1.372 (6)
N3—C10	1.477 (5)	C13—C14	1.387 (6)
O1—C7	1.198 (5)	C13—C12	1.388 (6)
C1—C2	1.389 (6)	C13—H13	0.93 (4)
C2—C3	1.372 (6)	C12—C11	1.366 (6)
C2—H2	0.94 (4)	C12—H12	0.97 (4)
C3—C4	1.400 (7)	C11—H11	0.9600
C3—H3	0.89 (4)	C14—H14	0.89 (4)
C4—C5	1.358 (6)	O1R—C1R	1.427 (5)
C4—H4	0.96 (4)	C1R—H1R	0.9820
C5—H5	0.90 (4)	C1R—H2R	0.9224
C6—C7	1.528 (5)	C1R—H3R	0.9110
C5—N1—C1	122.7 (4)	N2—C7—C6	106.8 (4)
C5—N1—C6	126.5 (3)	O1R—C8—C6	105.2 (3)
C1—N1—C6	110.6 (3)	O1R—C8—C9	112.8 (3)
C1—N2—C7	112.5 (4)	C6—C8—C9	111.4 (3)
C1—N2—H2A	123 (3)	O1R—C8—H8	112 (2)
C7—N2—H2A	124 (3)	C6—C8—H8	105 (2)
O2—N3—O3	124.3 (3)	C9—C8—H8	110 (2)
O2—N3—C10	117.4 (3)	C14—C9—C10	115.7 (4)
O3—N3—C10	118.3 (3)	C14—C9—C8	120.6 (4)
N1—C1—N2	108.9 (4)	C10—C9—C8	123.5 (4)
N1—C1—C2	119.8 (4)	C11—C10—C9	123.4 (4)
N2—C1—C2	131.4 (4)	C11—C10—N3	116.0 (4)
C3—C2—C1	117.7 (4)	C9—C10—N3	120.6 (3)
C3—C2—H2	129 (3)	C14—C13—C12	119.7 (4)
C1—C2—H2	114 (3)	C14—C13—H13	119 (2)
C2—C3—C4	121.1 (4)	C12—C13—H13	122 (2)
C2—C3—H3	116 (3)	C11—C12—C13	120.2 (5)
C4—C3—H3	123 (3)	C11—C12—H12	121 (2)
C5—C4—C3	119.4 (4)	C13—C12—H12	118 (2)
C5—C4—H4	122 (3)	C12—C11—C10	119.1 (4)
C3—C4—H4	119 (3)	C12—C11—H11	122.1
N1—C5—C4	119.2 (4)	C10—C11—H11	118.8
N1—C5—H5	110 (3)	C13—C14—C9	121.9 (4)
C4—C5—H5	131 (3)	C13—C14—H14	119 (3)
N1—C6—C7	101.1 (3)	C9—C14—H14	119 (3)
N1—C6—C8	111.5 (3)	C1R—O1R—C8	113.5 (3)
C7—C6—C8	111.5 (3)	O1R—C1R—H1R	103.6
N1—C6—H6	113.7	O1R—C1R—H2R	109.5
C7—C6—H6	107.9	H1R—C1R—H2R	105.6
C8—C6—H6	110.6	O1R—C1R—H3R	112.6
O1—C7—N2	126.5 (4)	H1R—C1R—H3R	112.5
O1—C7—C6	126.7 (4)	H2R—C1R—H3R	112.5
C5—N1—C1—N2	−174.7 (4)	C7—C6—C8—O1R	35.5 (4)
C6—N1—C1—N2	0.4 (5)	N1—C6—C8—C9	160.7 (3)
C5—N1—C1—C2	3.6 (6)	C7—C6—C8—C9	−87.1 (4)
C6—N1—C1—C2	178.8 (4)	O1R—C8—C9—C14	−31.3 (5)
C7—N2—C1—N1	1.6 (5)	C6—C8—C9—C14	86.7 (4)
C7—N2—C1—C2	−176.5 (5)	O1R—C8—C9—C10	144.0 (4)
N1—C1—C2—C3	−2.6 (6)	C6—C8—C9—C10	−97.9 (4)
N2—C1—C2—C3	175.4 (5)	C14—C9—C10—C11	−0.4 (6)
C1—C2—C3—C4	0.6 (7)	C8—C9—C10—C11	−175.9 (4)
C2—C3—C4—C5	0.4 (7)	C14—C9—C10—N3	−178.6 (3)
C1—N1—C5—C4	−2.6 (6)	C8—C9—C10—N3	5.9 (6)
C6—N1—C5—C4	−176.9 (4)	O2—N3—C10—C11	40.9 (5)
C3—C4—C5—N1	0.5 (6)	O3—N3—C10—C11	−139.7 (4)
C5—N1—C6—C7	173.0 (4)	O2—N3—C10—C9	−140.8 (4)
C1—N1—C6—C7	−2.0 (4)	O3—N3—C10—C9	38.6 (5)
C5—N1—C6—C8	−68.4 (5)	C14—C13—C12—C11	0.2 (7)
C1—N1—C6—C8	116.7 (4)	C13—C12—C11—C10	1.1 (7)
C1—N2—C7—O1	176.5 (4)	C9—C10—C11—C12	−1.0 (6)
C1—N2—C7—C6	−2.9 (5)	N3—C10—C11—C12	177.3 (4)
N1—C6—C7—O1	−176.5 (4)	C12—C13—C14—C9	−1.6 (7)
C8—C6—C7—O1	64.8 (6)	C10—C9—C14—C13	1.7 (6)
N1—C6—C7—N2	2.8 (4)	C8—C9—C14—C13	177.4 (4)
C8—C6—C7—N2	−115.9 (4)	C6—C8—O1R—C1R	169.3 (3)
N1—C6—C8—O1R	−76.8 (4)	C9—C8—O1R—C1R	−69.1 (4)

(3) '3-(4-Methoxy-benzyliden)-2-oxo-2,3-dihydro- 1H-imidazo[1,2-a] pyridinium bromide'

Crystal data

C15H13N2O2·Br	F(000) = 672
Mr = 333.18	Dx = 1.571 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2956 reflections
a = 8.851 (2) Å	θ = 4.3–25.0°
b = 10.014 (2) Å	µ = 2.92 mm^−1
c = 15.895 (3) Å	T = 295 K
V = 1408.8 (5) Å^3	Cubic, light brown
Z = 4	0.4 × 0.1 × 0.1 mm

Data collection

Kuma KM4CCD κ-geometry diffractometer	2472 independent reflections
Radiation source: fine-focus sealed tube	1972 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.091
ω scans	θmax = 25.0°, θmin = 4.3°
Absorption correction: multi-scan XEMP.Siemens Analytical Xray, 1990	h = −10→7
Tmin = 0.543, Tmax = 0.750	k = −11→11
10831 measured reflections	l = −18→18

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.047	All H-atom parameters refined
wR(F^2) = 0.117	w = 1/[σ^2(Fo^2) + (0.0716P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.98	(Δ/σ)max = 0.001
2472 reflections	Δρmax = 0.56 e Å^−3
217 parameters	Δρmin = −0.89 e Å^−3
0 restraints	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.022 (18)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.99966 (6)	0.45159 (5)	0.78893 (3)	0.0583 (2)
O1	0.4740 (3)	0.1223 (4)	0.9604 (2)	0.0476 (8)
O2	0.2916 (5)	0.3075 (4)	0.5815 (2)	0.0639 (12)
N1	0.8659 (4)	0.1036 (4)	0.9472 (3)	0.0357 (10)
N2	0.6854 (4)	0.0797 (4)	1.0398 (3)	0.0409 (10)
H2N	0.6502	0.0714	1.0867	0.049*
C1	0.8371 (5)	0.0740 (5)	1.0279 (3)	0.0376 (11)
C2	0.9506 (6)	0.0475 (6)	1.0853 (4)	0.0449 (12)
H2	0.927 (5)	0.022 (5)	1.136 (3)	0.032 (13)*
C3	1.0966 (5)	0.0484 (6)	1.0555 (4)	0.0504 (14)
H3	1.176 (6)	0.018 (5)	1.099 (3)	0.059 (15)*
C4	1.1245 (6)	0.0753 (6)	0.9708 (4)	0.0547 (16)
H4	1.210 (6)	0.077 (5)	0.948 (3)	0.052 (15)*
C5	1.0139 (5)	0.1045 (5)	0.9172 (3)	0.0430 (11)
H5	1.025 (6)	0.145 (5)	0.862 (3)	0.046 (13)*
C6	0.7288 (5)	0.1297 (5)	0.9017 (3)	0.0341 (10)
C7	0.6118 (5)	0.1112 (5)	0.9667 (3)	0.0383 (11)
C8	0.7278 (6)	0.1737 (5)	0.8234 (3)	0.0410 (12)
H8	0.810 (6)	0.200 (5)	0.806 (3)	0.036 (13)*
C9	0.6066 (6)	0.2048 (5)	0.7640 (3)	0.0408 (12)
C10	0.6441 (6)	0.2786 (6)	0.6934 (4)	0.0512 (14)
H10	0.764 (7)	0.309 (6)	0.688 (4)	0.070 (17)*
C11	0.5375 (7)	0.3120 (6)	0.6347 (4)	0.0569 (16)
H11	0.558 (6)	0.360 (6)	0.590 (4)	0.060 (18)*
C12	0.3864 (6)	0.2720 (5)	0.6464 (4)	0.0477 (13)
C13	0.3482 (6)	0.1987 (6)	0.7150 (4)	0.0492 (13)
H13	0.240 (7)	0.156 (6)	0.712 (3)	0.066 (17)*
C14	0.4559 (5)	0.1659 (6)	0.7736 (3)	0.0458 (13)
H14	0.432 (6)	0.125 (6)	0.824 (4)	0.058 (17)*
C15	0.1371 (7)	0.2645 (7)	0.5892 (4)	0.0636 (17)
H15A	0.1027	0.3074	0.6369	0.083*
H15B	0.1272	0.1728	0.5920	0.083*
H15C	0.0854	0.3017	0.5444	0.083*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0526 (3)	0.0705 (4)	0.0519 (3)	−0.0055 (4)	−0.0138 (3)	0.0061 (3)
O1	0.0166 (18)	0.075 (2)	0.0514 (19)	0.0026 (16)	0.0005 (15)	−0.0008 (17)
O2	0.072 (3)	0.066 (3)	0.053 (2)	0.003 (2)	−0.026 (2)	0.010 (2)
N1	0.0160 (17)	0.042 (2)	0.049 (2)	−0.0018 (16)	−0.0011 (17)	−0.0078 (19)
N2	0.0226 (18)	0.060 (3)	0.040 (2)	−0.0029 (17)	0.0027 (16)	−0.003 (2)
C1	0.022 (2)	0.041 (3)	0.050 (3)	−0.001 (2)	0.000 (2)	−0.001 (2)
C2	0.039 (3)	0.043 (3)	0.053 (3)	0.002 (2)	−0.010 (2)	0.004 (3)
C3	0.029 (3)	0.048 (3)	0.074 (4)	0.003 (3)	−0.016 (2)	−0.005 (3)
C4	0.018 (2)	0.063 (4)	0.084 (5)	−0.002 (2)	−0.002 (3)	−0.012 (3)
C5	0.014 (2)	0.053 (3)	0.062 (3)	−0.004 (2)	0.012 (3)	−0.008 (2)
C6	0.015 (2)	0.046 (3)	0.042 (3)	0.0022 (19)	−0.0015 (18)	−0.001 (2)
C7	0.022 (2)	0.047 (3)	0.046 (3)	−0.007 (2)	0.004 (2)	−0.007 (2)
C8	0.027 (3)	0.043 (3)	0.053 (3)	−0.002 (2)	0.006 (2)	0.001 (2)
C9	0.034 (3)	0.046 (3)	0.042 (3)	−0.002 (2)	0.004 (2)	0.001 (2)
C10	0.044 (3)	0.059 (3)	0.051 (3)	−0.007 (3)	0.003 (3)	0.005 (3)
C11	0.068 (4)	0.055 (3)	0.048 (3)	−0.011 (3)	−0.005 (3)	0.015 (3)
C12	0.056 (3)	0.039 (3)	0.048 (3)	0.009 (3)	−0.009 (3)	−0.009 (3)
C13	0.037 (3)	0.065 (4)	0.046 (3)	0.002 (3)	0.000 (3)	0.004 (3)
C14	0.033 (3)	0.070 (4)	0.034 (3)	−0.002 (2)	0.000 (2)	0.006 (3)
C15	0.066 (4)	0.064 (4)	0.060 (4)	0.010 (3)	−0.025 (3)	0.000 (3)

Geometric parameters (Å, º)

O1—C7	1.229 (5)	C6—C8	1.320 (7)
O2—C12	1.376 (6)	C6—C7	1.475 (6)
O2—C15	1.439 (8)	C8—C9	1.462 (7)
N1—C1	1.342 (6)	C8—H8	0.82 (5)
N1—C5	1.394 (6)	C9—C10	1.384 (7)
N1—C6	1.437 (6)	C9—C14	1.398 (8)
N2—C1	1.357 (5)	C10—C11	1.368 (8)
N2—C7	1.369 (6)	C10—H10	1.11 (6)
N2—H2N	0.8118	C11—C12	1.408 (8)
C1—C2	1.382 (7)	C11—H11	0.87 (6)
C2—C3	1.376 (8)	C12—C13	1.357 (8)
C2—H2	0.87 (5)	C13—C14	1.374 (8)
C3—C4	1.395 (9)	C13—H13	1.05 (6)
C3—H3	1.03 (6)	C14—H14	0.92 (6)
C4—C5	1.330 (8)	C15—H15A	0.9240
C4—H4	0.84 (5)	C15—H15B	0.9240
C5—H5	0.98 (5)	C15—H15C	0.9241
C12—O2—C15	115.9 (5)	C6—C8—C9	133.2 (5)
C1—N1—C5	120.5 (4)	C6—C8—H8	115 (3)
C1—N1—C6	111.2 (4)	C9—C8—H8	111 (3)
C5—N1—C6	128.3 (4)	C10—C9—C14	117.8 (6)
C1—N2—C7	111.2 (4)	C10—C9—C8	117.5 (5)
C1—N2—H2N	120.2	C14—C9—C8	124.7 (5)
C7—N2—H2N	128.3	C11—C10—C9	121.2 (5)
N1—C1—N2	108.2 (4)	C11—C10—H10	123 (3)
N1—C1—C2	122.4 (4)	C9—C10—H10	116 (3)
N2—C1—C2	129.4 (5)	C10—C11—C12	119.7 (5)
C3—C2—C1	117.0 (5)	C10—C11—H11	123 (4)
C3—C2—H2	123 (3)	C12—C11—H11	118 (4)
C1—C2—H2	120 (3)	C13—C12—O2	126.2 (5)
C2—C3—C4	120.0 (5)	C13—C12—C11	119.7 (5)
C2—C3—H3	114 (3)	O2—C12—C11	114.0 (5)
C4—C3—H3	126 (3)	C12—C13—C14	120.2 (5)
C5—C4—C3	122.0 (5)	C12—C13—H13	114 (3)
C5—C4—H4	112 (4)	C14—C13—H13	124 (3)
C3—C4—H4	126 (4)	C13—C14—C9	121.4 (5)
C4—C5—N1	118.2 (5)	C13—C14—H14	122 (3)
C4—C5—H5	127 (3)	C9—C14—H14	116 (3)
N1—C5—H5	114 (3)	O2—C15—H15A	104.1
C8—C6—N1	122.8 (4)	O2—C15—H15B	113.1
C8—C6—C7	134.3 (4)	H15A—C15—H15B	113.0
N1—C6—C7	102.5 (4)	O2—C15—H15C	106.5
O1—C7—N2	124.2 (4)	H15A—C15—H15C	106.3
O1—C7—C6	128.9 (5)	H15B—C15—H15C	113.0
N2—C7—C6	106.9 (4)
C5—N1—C1—N2	−179.7 (4)	N1—C6—C7—O1	179.8 (5)
C6—N1—C1—N2	−0.5 (6)	C8—C6—C7—N2	−171.5 (6)
C5—N1—C1—C2	2.1 (8)	N1—C6—C7—N2	0.7 (5)
C6—N1—C1—C2	−178.6 (5)	N1—C6—C8—C9	178.6 (5)
C7—N2—C1—N1	1.0 (6)	C7—C6—C8—C9	−10.4 (10)
C7—N2—C1—C2	179.0 (5)	C6—C8—C9—C10	165.1 (6)
N1—C1—C2—C3	−2.1 (9)	C6—C8—C9—C14	−14.7 (9)
N2—C1—C2—C3	−179.9 (6)	C14—C9—C10—C11	−0.2 (9)
C1—C2—C3—C4	0.0 (10)	C8—C9—C10—C11	180.0 (5)
C2—C3—C4—C5	2.1 (10)	C9—C10—C11—C12	0.6 (10)
C3—C4—C5—N1	−2.1 (8)	C15—O2—C12—C13	1.5 (8)
C1—N1—C5—C4	0.0 (7)	C15—O2—C12—C11	177.8 (5)
C6—N1—C5—C4	−179.1 (5)	C10—C11—C12—C13	−1.2 (9)
C1—N1—C6—C8	173.2 (5)	C10—C11—C12—O2	−177.7 (5)
C5—N1—C6—C8	−7.6 (8)	O2—C12—C13—C14	177.4 (5)
C1—N1—C6—C7	−0.2 (5)	C11—C12—C13—C14	1.3 (9)
C5—N1—C6—C7	179.0 (4)	C12—C13—C14—C9	−0.8 (9)
C1—N2—C7—O1	179.8 (5)	C10—C9—C14—C13	0.3 (8)
C1—N2—C7—C6	−1.1 (6)	C8—C9—C14—C13	−179.9 (5)
C8—C6—C7—O1	7.5 (10)