Low-temperature studies of the simple variously substituted imidazole types 4-phenyl-1H-imidazole, C9H8N2, 1-benzyl-1H-imidazole, C10H10N2, and 1-mesityl-1H-imidazole, C12H14N2, extend comparisons between parent imidazole species and their derivatives, the pronounced double-bond localization opposite the substituted N atom common to simple neutral species being redistributed aromatically on protonation.
Supporting information
CCDC references: 248143; 248144; 248145
Crystals were obtained by recrystallization from CH2Cl2 [for (I) and (II)] and methanol [for (III)].
H atoms were located from difference Fourier maps, and were then placed at idealized positions [C—H = 0.95 Å and Uiso(H) = 1.5Ueq(C)]. All H-atom parameters were refined for (I) and (II) [C—H = 0.96 (2)–0.99 (2) Å and N—H = 85 (2) Å for (I), and C—H = 0.947 (18)–1.01 (2) Å for (II)] and fixed for (III) [C—H = 0.939–0.968 Å].
For all compounds, data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: Xtal3.5 (Hall et al., 1995). Program(s) used to refine structure: CRYLSQ in Xtal3.5 for (I), (III); CRYLSQin Xtal3.5 for (II). For all compounds, molecular graphics: Xtal3.5; software used to prepare material for publication: BONDLA and CIFIO in Xtal3.5.
Crystal data top
C9H8N2 | Dx = 1.221 Mg m−3 |
Mr = 144.19 | Mo Kα radiation, λ = 0.71073 Å |
Trigonal, R3c | Cell parameters from 8192 reflections |
Hall symbol: r 3 -2"c | θ = 2.4–28.6° |
a = 20.449 (2) Å | µ = 0.08 mm−1 |
c = 9.750 (1) Å | T = 150 K |
V = 3530.9 (6) Å3 | Slab, colourless |
Z = 18 | 0.4 × 0.35 × 0.14 mm |
F(000) = 1368 | |
Data collection top
Bruker SMART CCD diffractometer | 1043 independent reflections |
Radiation source: sealed tube | 1022 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.026 |
ω scans | θmax = 29.0°, θmin = 2.0° |
Absorption correction: multi-scan SADABS; Sheldrick, 1996 | h = −27→27 |
Tmin = 0.920, Tmax = 0.951 | k = −27→27 |
13318 measured reflections | l = −12→12 |
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)] = 0.028 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.056 | All H-atom parameters refined |
S = 1.08 | w = 1/(σ2(F) + 0.42F2) |
1043 reflections | (Δ/σ)max = 0.001 |
131 parameters | Δρmax = 0.16 e Å−3 |
0 restraints | Δρmin = −0.16 e Å−3 |
0 constraints | |
Crystal data top
C9H8N2 | Z = 18 |
Mr = 144.19 | Mo Kα radiation |
Trigonal, R3c | µ = 0.08 mm−1 |
a = 20.449 (2) Å | T = 150 K |
c = 9.750 (1) Å | 0.4 × 0.35 × 0.14 mm |
V = 3530.9 (6) Å3 | |
Data collection top
Bruker SMART CCD diffractometer | 1043 independent reflections |
Absorption correction: multi-scan SADABS; Sheldrick, 1996 | 1022 reflections with I > 2σ(I) |
Tmin = 0.920, Tmax = 0.951 | Rint = 0.026 |
13318 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.028 | 0 restraints |
wR(F2) = 0.056 | All H-atom parameters refined |
S = 1.08 | Δρmax = 0.16 e Å−3 |
1043 reflections | Δρmin = −0.16 e Å−3 |
131 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.20838 (8) | 0.57865 (8) | 0.2272 (2) | 0.0214 (6) | |
C2 | 0.21803 (9) | 0.61947 (9) | 0.1123 (2) | 0.0216 (6) | |
N3 | 0.20131 (8) | 0.57734 (8) | 0.00019 (18) | 0.0197 (5) | |
C4 | 0.17954 (9) | 0.50504 (9) | 0.0466 (2) | 0.0181 (6) | |
C41 | 0.15243 (9) | 0.43975 (9) | −0.0462 (2) | 0.0193 (6) | |
C42 | 0.17077 (11) | 0.38348 (10) | −0.0201 (2) | 0.0257 (7) | |
C43 | 0.14195 (12) | 0.31957 (11) | −0.1028 (2) | 0.0323 (8) | |
C44 | 0.09480 (12) | 0.31120 (11) | −0.2122 (2) | 0.0318 (8) | |
C45 | 0.07704 (11) | 0.36714 (11) | −0.2396 (2) | 0.0290 (7) | |
C46 | 0.10591 (10) | 0.43139 (10) | −0.1577 (2) | 0.0233 (7) | |
C5 | 0.18390 (9) | 0.50553 (9) | 0.1872 (2) | 0.0201 (6) | |
H1 | 0.2113 (13) | 0.5944 (13) | 0.309 (2) | 0.033 (6)* | |
H2 | 0.2330 (11) | 0.6726 (12) | 0.113 (2) | 0.028 (5)* | |
H5 | 0.1745 (13) | 0.4648 (14) | 0.249 (3) | 0.035 (6)* | |
H42 | 0.2025 (14) | 0.3892 (14) | 0.056 (2) | 0.034 (6)* | |
H43 | 0.1563 (14) | 0.2813 (14) | −0.085 (2) | 0.040 (6)* | |
H44 | 0.0754 (13) | 0.2663 (15) | −0.270 (2) | 0.038 (6)* | |
H45 | 0.0420 (14) | 0.3617 (14) | −0.314 (3) | 0.043 (7)* | |
H46 | 0.0919 (13) | 0.4699 (12) | −0.177 (2) | 0.027 (5)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0232 (7) | 0.0241 (7) | 0.0159 (6) | 0.0112 (6) | 0.0003 (5) | −0.0018 (5) |
C2 | 0.0225 (8) | 0.0216 (7) | 0.0204 (6) | 0.0108 (6) | 0.0004 (6) | −0.0004 (6) |
N3 | 0.0223 (6) | 0.0196 (6) | 0.0167 (6) | 0.0101 (6) | 0.0000 (5) | 0.0003 (5) |
C4 | 0.0174 (7) | 0.0194 (7) | 0.0178 (7) | 0.0094 (6) | 0.0000 (5) | 0.0002 (6) |
C41 | 0.0210 (7) | 0.0184 (7) | 0.0172 (7) | 0.0089 (6) | 0.0030 (6) | 0.0006 (6) |
C42 | 0.0319 (9) | 0.0258 (8) | 0.0238 (8) | 0.0176 (7) | −0.0010 (7) | −0.0002 (6) |
C43 | 0.0444 (11) | 0.0242 (9) | 0.0324 (10) | 0.0201 (9) | 0.0036 (8) | 0.0000 (7) |
C44 | 0.0411 (11) | 0.0234 (8) | 0.0250 (8) | 0.0116 (8) | 0.0042 (8) | −0.0052 (7) |
C45 | 0.0339 (10) | 0.0275 (9) | 0.0201 (8) | 0.0113 (8) | −0.0025 (7) | −0.0037 (7) |
C46 | 0.0273 (8) | 0.0238 (8) | 0.0191 (7) | 0.0130 (7) | −0.0009 (6) | −0.0009 (6) |
C5 | 0.0218 (7) | 0.0226 (7) | 0.0168 (7) | 0.0117 (6) | 0.0008 (6) | 0.0010 (6) |
Geometric parameters (Å, º) top
N1—C2 | 1.351 (2) | C42—C43 | 1.391 (3) |
N1—C5 | 1.375 (2) | C42—H42 | 0.96 (2) |
N1—H1 | 0.85 (2) | C43—C44 | 1.389 (3) |
C2—N3 | 1.326 (3) | C43—H43 | 0.98 (2) |
C2—H2 | 0.97 (2) | C44—C45 | 1.388 (3) |
N3—C4 | 1.389 (2) | C44—H44 | 0.98 (3) |
C4—C41 | 1.473 (3) | C45—C46 | 1.392 (3) |
C4—C5 | 1.374 (3) | C45—H45 | 0.99 (2) |
C41—C42 | 1.400 (2) | C46—H46 | 0.98 (2) |
C41—C46 | 1.398 (3) | C5—H5 | 0.96 (2) |
| | | |
C2—N1—C5 | 107.32 (13) | C42—C43—C44 | 120.2 (2) |
C2—N1—H1 | 125.7 (18) | C42—C43—H43 | 119.4 (13) |
C5—N1—H1 | 126.5 (17) | C44—C43—H43 | 120.4 (13) |
N1—C2—N3 | 111.81 (16) | C43—C44—C45 | 119.9 (2) |
N1—C2—H2 | 123.7 (14) | C43—C44—H44 | 119.2 (19) |
N3—C2—H2 | 124.4 (14) | C45—C44—H44 | 120.9 (19) |
C2—N3—C4 | 105.32 (17) | C44—C45—C46 | 120.3 (2) |
N3—C4—C41 | 122.67 (19) | C44—C45—H45 | 121.5 (17) |
N3—C4—C5 | 109.39 (17) | C46—C45—H45 | 118.1 (17) |
C41—C4—C5 | 127.85 (17) | C41—C46—C45 | 120.2 (2) |
C4—C41—C42 | 119.94 (19) | C41—C46—H46 | 120.4 (12) |
C4—C41—C46 | 120.9 (2) | C45—C46—H46 | 119.4 (12) |
C42—C41—C46 | 119.11 (18) | N1—C5—C4 | 106.15 (16) |
C41—C42—C43 | 120.3 (2) | N1—C5—H5 | 124.7 (15) |
C41—C42—H42 | 119.1 (18) | C4—C5—H5 | 129.1 (15) |
C43—C42—H42 | 120.6 (18) | | |
Crystal data top
C10H10N2 | F(000) = 336 |
Mr = 158.22 | Dx = 1.254 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -p 2yn | Cell parameters from 3206 reflections |
a = 8.222 (2) Å | θ = 2.9–29.0° |
b = 6.026 (1) Å | µ = 0.08 mm−1 |
c = 16.948 (4) Å | T = 150 K |
β = 93.283 (3)° | Blade, colourless |
V = 838.3 (3) Å3 | 0.6 × 0.2 × 0.1 mm |
Z = 4 | |
Data collection top
Bruker SMART CCD diffractometer | 2124 independent reflections |
Radiation source: sealed tube | 1533 reflections with I > 2 σ(I) |
Graphite monochromator | Rint = 0.055 |
ω scans | θmax = 29.0°, θmin = 2.4° |
Absorption correction: multi-scan SADABS; Sheldrick, 1996 | h = −11→10 |
Tmin = 0.94, Tmax = 0.96 | k = −8→8 |
9721 measured reflections | l = −22→22 |
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)] = 0.043 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.085 | All H-atom parameters refined |
S = 1.01 | w = 1/(σ2(F) + 0.092F2) |
2124 reflections | (Δ/σ)max = 0.013 |
149 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.23 e Å−3 |
0 constraints | |
Crystal data top
C10H10N2 | V = 838.3 (3) Å3 |
Mr = 158.22 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 8.222 (2) Å | µ = 0.08 mm−1 |
b = 6.026 (1) Å | T = 150 K |
c = 16.948 (4) Å | 0.6 × 0.2 × 0.1 mm |
β = 93.283 (3)° | |
Data collection top
Bruker SMART CCD diffractometer | 2124 independent reflections |
Absorption correction: multi-scan SADABS; Sheldrick, 1996 | 1533 reflections with I > 2 σ(I) |
Tmin = 0.94, Tmax = 0.96 | Rint = 0.055 |
9721 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.085 | All H-atom parameters refined |
S = 1.01 | Δρmax = 0.27 e Å−3 |
2124 reflections | Δρmin = −0.23 e Å−3 |
149 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | −0.10027 (14) | 0.1183 (2) | 0.15259 (7) | 0.0267 (6) | |
C2 | −0.16118 (18) | −0.0532 (3) | 0.19304 (9) | 0.0292 (7) | |
N3 | −0.23241 (15) | −0.2020 (2) | 0.14589 (8) | 0.0337 (7) | |
C4 | −0.2157 (2) | −0.1209 (3) | 0.07134 (10) | 0.0369 (8) | |
C5 | −0.1352 (2) | 0.0759 (3) | 0.07410 (9) | 0.0356 (8) | |
C1 | −0.0145 (2) | 0.3122 (3) | 0.18706 (10) | 0.0337 (8) | |
C11 | 0.15258 (18) | 0.3419 (2) | 0.15550 (8) | 0.0273 (7) | |
C12 | 0.26760 (19) | 0.1722 (3) | 0.16198 (9) | 0.0307 (7) | |
C13 | 0.42269 (19) | 0.2032 (3) | 0.13514 (9) | 0.0328 (8) | |
C14 | 0.46448 (19) | 0.4054 (3) | 0.10267 (9) | 0.0327 (8) | |
C15 | 0.3508 (2) | 0.5746 (3) | 0.09600 (10) | 0.0341 (8) | |
C16 | 0.1949 (2) | 0.5431 (3) | 0.12225 (9) | 0.0319 (8) | |
H2 | −0.1520 (19) | −0.057 (3) | 0.2512 (10) | 0.027 (4)* | |
H4 | −0.257 (2) | −0.194 (3) | 0.0249 (11) | 0.041 (5)* | |
H5 | −0.104 (2) | 0.170 (4) | 0.0324 (12) | 0.052 (6)* | |
H1a | −0.007 (2) | 0.289 (3) | 0.2471 (11) | 0.038 (5)* | |
H1b | −0.080 (2) | 0.446 (4) | 0.1723 (12) | 0.053 (6)* | |
H12 | 0.241 (2) | 0.032 (3) | 0.1873 (10) | 0.041 (5)* | |
H13 | 0.502 (2) | 0.084 (4) | 0.1401 (11) | 0.052 (6)* | |
H14 | 0.572 (2) | 0.430 (3) | 0.0827 (10) | 0.040 (5)* | |
H15 | 0.376 (2) | 0.719 (4) | 0.0697 (12) | 0.057 (6)* | |
H16 | 0.114 (2) | 0.661 (3) | 0.1150 (11) | 0.046 (5)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0251 (6) | 0.0266 (6) | 0.0290 (6) | 0.0000 (5) | 0.0064 (5) | 0.0013 (5) |
C2 | 0.0269 (7) | 0.0313 (8) | 0.0297 (7) | −0.0009 (6) | 0.0038 (6) | 0.0049 (6) |
N3 | 0.0287 (6) | 0.0335 (7) | 0.0390 (7) | −0.0036 (5) | 0.0026 (5) | −0.0001 (6) |
C4 | 0.0296 (8) | 0.0491 (10) | 0.0320 (8) | −0.0040 (7) | 0.0012 (6) | −0.0071 (7) |
C5 | 0.0346 (8) | 0.0439 (10) | 0.0288 (8) | −0.0007 (7) | 0.0063 (6) | 0.0056 (7) |
C1 | 0.0350 (8) | 0.0264 (8) | 0.0409 (9) | −0.0026 (6) | 0.0142 (7) | −0.0068 (7) |
C11 | 0.0300 (7) | 0.0248 (7) | 0.0274 (7) | −0.0032 (6) | 0.0046 (6) | −0.0030 (6) |
C12 | 0.0334 (7) | 0.0268 (7) | 0.0320 (8) | −0.0019 (6) | 0.0023 (6) | 0.0014 (6) |
C13 | 0.0293 (7) | 0.0338 (8) | 0.0348 (8) | 0.0023 (6) | −0.0024 (6) | −0.0001 (6) |
C14 | 0.0261 (7) | 0.0399 (9) | 0.0320 (8) | −0.0064 (6) | 0.0014 (6) | −0.0032 (7) |
C15 | 0.0387 (8) | 0.0279 (8) | 0.0360 (8) | −0.0067 (7) | 0.0058 (7) | 0.0019 (7) |
C16 | 0.0351 (8) | 0.0249 (7) | 0.0359 (8) | −0.0000 (6) | 0.0055 (6) | −0.0002 (6) |
Geometric parameters (Å, º) top
N1—C2 | 1.352 (2) | C11—C12 | 1.393 (2) |
N1—C5 | 1.369 (2) | C11—C16 | 1.389 (2) |
N1—C1 | 1.469 (2) | C12—C13 | 1.391 (2) |
C2—N3 | 1.316 (2) | C12—H12 | 0.98 (2) |
C2—H2 | 0.984 (16) | C13—C14 | 1.388 (2) |
N3—C4 | 1.369 (2) | C13—H13 | 0.97 (2) |
C4—C5 | 1.358 (3) | C14—C15 | 1.384 (2) |
C4—H4 | 0.947 (18) | C14—H14 | 0.974 (19) |
C5—H5 | 0.95 (2) | C15—C16 | 1.393 (2) |
C1—C11 | 1.513 (2) | C15—H15 | 1.01 (2) |
C1—H1a | 1.025 (18) | C16—H16 | 0.98 (2) |
C1—H1b | 1.00 (2) | | |
| | | |
C2—N1—C5 | 106.67 (13) | C1—C11—C12 | 120.75 (14) |
C2—N1—C1 | 126.14 (13) | C1—C11—C16 | 120.03 (14) |
C5—N1—C1 | 127.19 (14) | C12—C11—C16 | 119.18 (14) |
N1—C2—N3 | 112.19 (13) | C11—C12—C13 | 120.45 (15) |
N1—C2—H2 | 121.0 (10) | C11—C12—H12 | 120.2 (11) |
N3—C2—H2 | 126.8 (10) | C13—C12—H12 | 119.3 (11) |
C2—N3—C4 | 104.64 (14) | C12—C13—C14 | 120.00 (15) |
N3—C4—C5 | 110.77 (15) | C12—C13—H13 | 119.6 (12) |
N3—C4—H4 | 123.5 (12) | C14—C13—H13 | 120.4 (12) |
C5—C4—H4 | 125.7 (12) | C13—C14—C15 | 119.85 (15) |
N1—C5—C4 | 105.74 (14) | C13—C14—H14 | 121.3 (11) |
N1—C5—H5 | 124.1 (12) | C15—C14—H14 | 118.8 (11) |
C4—C5—H5 | 130.2 (12) | C14—C15—C16 | 120.18 (15) |
N1—C1—C11 | 112.25 (13) | C14—C15—H15 | 121.0 (12) |
N1—C1—H1a | 106.5 (10) | C16—C15—H15 | 118.7 (12) |
N1—C1—H1b | 107.7 (12) | C11—C16—C15 | 120.34 (14) |
C11—C1—H1a | 111.2 (10) | C11—C16—H16 | 119.9 (12) |
C11—C1—H1b | 107.8 (12) | C15—C16—H16 | 119.7 (12) |
H1a—C1—H1b | 111.3 (15) | | |
Crystal data top
C12H14N2 | F(000) = 400 |
Mr = 186.28 | Dx = 1.200 Mg m−3 |
Orthorhombic, Pna21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: p 2c -2n | Cell parameters from 2807 reflections |
a = 10.346 (1) Å | θ = 2.9–28.8° |
b = 9.222 (2) Å | µ = 0.07 mm−1 |
c = 10.803 (2) Å | T = 150 K |
V = 1030.7 (3) Å3 | Fragment, colourless |
Z = 4 | 0.35 × 0.22 × 0.16 mm |
Data collection top
Bruker SMART CCD diffractometer | 1281 reflections with I > 2 σ(I) |
Radiation source: sealed tube | Rint = 0.072 |
Graphite monochromator | θmax = 29.5°, θmin = 2.9° |
ω scans | h = −14→14 |
21713 measured reflections | k = −12→12 |
1503 independent reflections | l = −14→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)] = 0.055 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.067 | H-atom parameters not refined |
S = 1.07 | w = 1/(σ2(F) + 0.18F2) |
1503 reflections | (Δ/σ)max = 0.0004 |
126 parameters | Δρmax = 0.35 e Å−3 |
0 restraints | Δρmin = −0.30 e Å−3 |
0 constraints | |
Crystal data top
C12H14N2 | V = 1030.7 (3) Å3 |
Mr = 186.28 | Z = 4 |
Orthorhombic, Pna21 | Mo Kα radiation |
a = 10.346 (1) Å | µ = 0.07 mm−1 |
b = 9.222 (2) Å | T = 150 K |
c = 10.803 (2) Å | 0.35 × 0.22 × 0.16 mm |
Data collection top
Bruker SMART CCD diffractometer | 1281 reflections with I > 2 σ(I) |
21713 measured reflections | Rint = 0.072 |
1503 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.067 | H-atom parameters not refined |
S = 1.07 | Δρmax = 0.35 e Å−3 |
1503 reflections | Δρmin = −0.30 e Å−3 |
126 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.3675 (3) | 0.5624 (3) | 0.5000 (4) | 0.0265 (13) | |
C2 | 0.3457 (3) | 0.6013 (4) | 0.6204 (4) | 0.0291 (15) | |
N3 | 0.4481 (3) | 0.5826 (3) | 0.6901 (4) | 0.0329 (15) | |
C4 | 0.5418 (3) | 0.5285 (4) | 0.6113 (4) | 0.0341 (18) | |
C5 | 0.4929 (3) | 0.5150 (4) | 0.4937 (4) | 0.0323 (16) | |
C11 | 0.2750 (3) | 0.5710 (4) | 0.4010 (4) | 0.0243 (14) | |
C12 | 0.2439 (3) | 0.7071 (4) | 0.3540 (4) | 0.0264 (15) | |
C121 | 0.3078 (3) | 0.8431 (4) | 0.4011 (4) | 0.0326 (17) | |
C13 | 0.1515 (3) | 0.7133 (4) | 0.2591 (4) | 0.0290 (15) | |
C14 | 0.0929 (3) | 0.5898 (4) | 0.2140 (4) | 0.0289 (16) | |
C141 | −0.0072 (3) | 0.6003 (4) | 0.1138 (4) | 0.0366 (18) | |
C15 | 0.1277 (3) | 0.4557 (4) | 0.2624 (4) | 0.0273 (15) | |
C16 | 0.2206 (3) | 0.4436 (4) | 0.3567 (4) | 0.0249 (15) | |
C161 | 0.2589 (3) | 0.2975 (4) | 0.4036 (4) | 0.0318 (17) | |
H2 | 0.26596 | 0.63982 | 0.65028 | 0.03200* | |
H4 | 0.62838 | 0.50262 | 0.63466 | 0.03900* | |
H5 | 0.53679 | 0.47943 | 0.42174 | 0.03500* | |
H13 | 0.12935 | 0.80675 | 0.22453 | 0.03200* | |
H15 | 0.08757 | 0.36918 | 0.23150 | 0.03000* | |
H121a | 0.39829 | 0.83445 | 0.39811 | 0.04700* | |
H121b | 0.28184 | 0.85903 | 0.48611 | 0.04700* | |
H121c | 0.28122 | 0.92388 | 0.35376 | 0.04700* | |
H141a | −0.08966 | 0.60901 | 0.15290 | 0.05200* | |
H141b | −0.00553 | 0.51253 | 0.06719 | 0.05200* | |
H141c | 0.00818 | 0.68275 | 0.06348 | 0.05200* | |
H161a | 0.28212 | 0.30715 | 0.48945 | 0.04400* | |
H161b | 0.33079 | 0.26493 | 0.35850 | 0.04400* | |
H161c | 0.18769 | 0.23227 | 0.39759 | 0.04400* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0279 (13) | 0.0355 (14) | 0.0161 (11) | 0.0005 (12) | 0.0002 (11) | −0.0025 (12) |
C2 | 0.0336 (16) | 0.0344 (16) | 0.0193 (13) | 0.0008 (14) | 0.0018 (14) | −0.0015 (14) |
N3 | 0.0356 (15) | 0.0402 (15) | 0.0229 (14) | 0.0010 (13) | −0.0048 (13) | 0.0002 (13) |
C4 | 0.0304 (17) | 0.047 (2) | 0.0245 (16) | 0.0017 (15) | −0.0061 (14) | 0.0016 (17) |
C5 | 0.0275 (14) | 0.047 (2) | 0.0222 (14) | 0.0041 (14) | 0.0006 (13) | −0.0009 (16) |
C11 | 0.0239 (14) | 0.0322 (15) | 0.0169 (12) | −0.0002 (13) | 0.0004 (13) | −0.0018 (13) |
C12 | 0.0267 (16) | 0.0324 (17) | 0.0199 (13) | 0.0021 (13) | 0.0050 (13) | −0.0010 (13) |
C121 | 0.0360 (18) | 0.0322 (17) | 0.0294 (16) | −0.0023 (14) | 0.0014 (16) | −0.0009 (16) |
C13 | 0.0288 (15) | 0.0348 (17) | 0.0234 (14) | 0.0023 (14) | 0.0019 (13) | 0.0044 (13) |
C14 | 0.0230 (14) | 0.0427 (19) | 0.0210 (15) | 0.0029 (14) | −0.0000 (12) | 0.0003 (14) |
C141 | 0.0310 (17) | 0.051 (2) | 0.0277 (17) | −0.0002 (16) | −0.0084 (16) | 0.0018 (17) |
C15 | 0.0244 (15) | 0.0375 (17) | 0.0200 (13) | −0.0019 (13) | 0.0008 (13) | −0.0030 (13) |
C16 | 0.0237 (14) | 0.0332 (17) | 0.0179 (13) | 0.0018 (12) | 0.0035 (12) | −0.0003 (13) |
C161 | 0.0370 (18) | 0.0358 (17) | 0.0226 (14) | 0.0016 (15) | −0.0005 (16) | −0.0010 (15) |
Geometric parameters (Å, º) top
N1—C2 | 1.368 (4) | C121—H121c | 0.945 |
N1—C5 | 1.371 (5) | C13—C14 | 1.379 (5) |
N1—C11 | 1.437 (4) | C13—H13 | 0.967 |
C2—N3 | 1.311 (5) | C14—C141 | 1.502 (6) |
C2—H2 | 0.954 | C14—C15 | 1.390 (5) |
N3—C4 | 1.383 (5) | C141—H141a | 0.955 |
C4—C5 | 1.373 (6) | C141—H141b | 0.953 |
C4—H4 | 0.961 | C141—H141c | 0.948 |
C5—H5 | 0.959 | C15—C16 | 1.405 (5) |
C11—C12 | 1.391 (5) | C15—H15 | 0.959 |
C11—C16 | 1.388 (5) | C16—C161 | 1.493 (5) |
C12—C121 | 1.506 (5) | C161—H161a | 0.963 |
C12—C13 | 1.403 (5) | C161—H161b | 0.939 |
C121—H121a | 0.940 | C161—H161c | 0.953 |
C121—H121b | 0.968 | | |
| | | |
C2—N1—C5 | 106.7 (3) | C12—C13—C14 | 121.6 (3) |
C2—N1—C11 | 125.7 (3) | C12—C13—H13 | 118.7 |
C5—N1—C11 | 127.7 (2) | C14—C13—H13 | 119.7 |
N1—C2—N3 | 112.2 (3) | C13—C14—C141 | 120.3 (3) |
N1—C2—H2 | 124.2 | C13—C14—C15 | 119.2 (3) |
N3—C2—H2 | 123.6 | C141—C14—C15 | 120.5 (3) |
C2—N3—C4 | 105.1 (4) | C14—C141—H141a | 107.6 |
N3—C4—C5 | 110.1 (3) | C14—C141—H141b | 108.3 |
N3—C4—H4 | 125.6 | C14—C141—H141c | 110.4 |
C5—C4—H4 | 124.3 | H141a—C141—H141b | 108.8 |
N1—C5—C4 | 105.9 (3) | H141a—C141—H141c | 109.6 |
N1—C5—H5 | 126.7 | H141b—C141—H141c | 112.0 |
C4—C5—H5 | 127.4 | C14—C15—C16 | 121.3 (3) |
N1—C11—C12 | 118.4 (3) | C14—C15—H15 | 119.8 |
N1—C11—C16 | 118.6 (3) | C16—C15—H15 | 118.8 |
C12—C11—C16 | 123.0 (4) | C11—C16—C15 | 117.4 (3) |
C11—C12—C121 | 121.7 (3) | C11—C16—C161 | 122.7 (3) |
C11—C12—C13 | 117.4 (3) | C15—C16—C161 | 119.9 (3) |
C121—C12—C13 | 120.8 (3) | C16—C161—H161a | 108.0 |
C12—C121—H121a | 110.8 | C16—C161—H161b | 108.9 |
C12—C121—H121b | 109.0 | C16—C161—H161c | 110.0 |
C12—C121—H121c | 110.2 | H161a—C161—H161b | 109.4 |
H121a—C121—H121b | 108.8 | H161a—C161—H161c | 108.5 |
H121a—C121—H121c | 109.8 | H161b—C161—H161c | 112.0 |
H121b—C121—H121c | 108.2 | | |
Experimental details
| (I) | (II) | (III) |
Crystal data |
Chemical formula | C9H8N2 | C10H10N2 | C12H14N2 |
Mr | 144.19 | 158.22 | 186.28 |
Crystal system, space group | Trigonal, R3c | Monoclinic, P21/n | Orthorhombic, Pna21 |
Temperature (K) | 150 | 150 | 150 |
a, b, c (Å) | 20.449 (2), 20.449 (2), 9.750 (1) | 8.222 (2), 6.026 (1), 16.948 (4) | 10.346 (1), 9.222 (2), 10.803 (2) |
α, β, γ (°) | 90, 90, 120 | 90, 93.283 (3), 90 | 90, 90, 90 |
V (Å3) | 3530.9 (6) | 838.3 (3) | 1030.7 (3) |
Z | 18 | 4 | 4 |
Radiation type | Mo Kα | Mo Kα | Mo Kα |
µ (mm−1) | 0.08 | 0.08 | 0.07 |
Crystal size (mm) | 0.4 × 0.35 × 0.14 | 0.6 × 0.2 × 0.1 | 0.35 × 0.22 × 0.16 |
|
Data collection |
Diffractometer | Bruker SMART CCD diffractometer | Bruker SMART CCD diffractometer | Bruker SMART CCD diffractometer |
Absorption correction | Multi-scan SADABS; Sheldrick, 1996 | Multi-scan SADABS; Sheldrick, 1996 | – |
Tmin, Tmax | 0.920, 0.951 | 0.94, 0.96 | – |
No. of measured, independent and observed reflections | 13318, 1043, 1022 [I > 2σ(I)] | 9721, 2124, 1533 [I > 2 σ(I)] | 21713, 1503, 1281 [I > 2 σ(I)] |
Rint | 0.026 | 0.055 | 0.072 |
(sin θ/λ)max (Å−1) | 0.682 | 0.682 | 0.692 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.056, 1.08 | 0.043, 0.085, 1.01 | 0.055, 0.067, 1.07 |
No. of reflections | 1043 | 2124 | 1503 |
No. of parameters | 131 | 149 | 126 |
H-atom treatment | All H-atom parameters refined | All H-atom parameters refined | H-atom parameters not refined |
Δρmax, Δρmin (e Å−3) | 0.16, −0.16 | 0.27, −0.23 | 0.35, −0.30 |
Selected geometric parameters (Å, º) for (I) topN1—C2 | 1.351 (2) | N3—C4 | 1.389 (2) |
N1—C5 | 1.375 (2) | C4—C41 | 1.473 (3) |
C2—N3 | 1.326 (3) | C4—C5 | 1.374 (3) |
| | | |
C2—N1—C5 | 107.32 (13) | N3—C4—C5 | 109.39 (17) |
N1—C2—N3 | 111.81 (16) | C41—C4—C5 | 127.85 (17) |
C2—N3—C4 | 105.32 (17) | N1—C5—C4 | 106.15 (16) |
N3—C4—C41 | 122.67 (19) | | |
Selected geometric parameters (Å, º) for (II) topN1—C2 | 1.352 (2) | N3—C4 | 1.369 (2) |
N1—C5 | 1.369 (2) | C4—C5 | 1.358 (3) |
N1—C1 | 1.469 (2) | C1—C11 | 1.513 (2) |
C2—N3 | 1.316 (2) | | |
| | | |
C2—N1—C5 | 106.67 (13) | C2—N3—C4 | 104.64 (14) |
C2—N1—C1 | 126.14 (13) | N3—C4—C5 | 110.77 (15) |
C5—N1—C1 | 127.19 (14) | N1—C5—C4 | 105.74 (14) |
N1—C2—N3 | 112.19 (13) | N1—C1—C11 | 112.25 (13) |
Selected geometric parameters (Å, º) for (III) topN1—C2 | 1.368 (4) | C2—N3 | 1.311 (5) |
N1—C5 | 1.371 (5) | N3—C4 | 1.383 (5) |
N1—C11 | 1.437 (4) | C4—C5 | 1.373 (6) |
| | | |
C2—N1—C5 | 106.7 (3) | C2—N3—C4 | 105.1 (4) |
C2—N1—C11 | 125.7 (3) | N3—C4—C5 | 110.1 (3) |
C5—N1—C11 | 127.7 (2) | N1—C5—C4 | 105.9 (3) |
N1—C2—N3 | 112.2 (3) | | |
Comparative geometries (Å,°) topCpdRef | a | b | c | d | e | α | β | γ | δ | ε |
| | | | | Neutral | Molecules | | | | |
imHa | 1.340 (3) | 1.316 (3) | 1.369 (3) | 1.353 (3) | 1.351 (3) | 107.3 (2) | 111.7 (2) | 104.9 (2) | 109.9 (2) | 106.3 (2) |
imMeb | 1.334 | 1.288 | 1.363 | 1.335 | 1.347 | 106.6 | 112.2 | 104.9 | 110.1 | 106.2 |
imBnc | 1.352 (2) | 1.316 (2) | 1.369 (3) | 1.358 (3) | 1.369 (2) | 106.7 (1) | 112.3 (1) | 104.6 (1) | 110.8 (2) | 105.7 (1) |
imMesc | 1.368 (4) | 1.311 (5) | 1.383 (5) | 1.373 (6) | 1.371 (5) | 106.7 (3) | 112.2 (3) | 105.1 (3) | 110.1 (3) | 105.8 (3) |
4Ph-imHc | 1.351 (2) | 1.326 (3) | 1.389 (2) | 1.374 (3) | 1.375 (2) | 107.3 (1) | 111.8 (2) | 105.3 (1) | 109.4 (2) | 106.2 (2) |
d | 1.343 (6) | 1.305 (7) | 1.384 (5) | 1.370 (8) | 1.368 (6) | 105.8 (3) | 113.6 (3) | 104.9 (3) | 108.9 (4) | 106.9 (4) |
4-(2NH2-C6H4-)imHe | 1.343 (5) | 1.319 (5) | 1.362 (6) | 1.362 (6) | 1.356 (6) | 107.3 (3) | 111.3 (3) | 105.8 (3) | 108.8 (4) | 106.8 (4) |
| | | | | Cationic | Species | | | | |
imH2+ f | 1.320 (2) | 1.313 (2) | 1.372 (2) | 1.344 (2) | 1.365 (2) | 108.5 (1) | 108.9 (1) | 108.6 (1) | 106.8 (1) | 107.2 (1) |
g | 1.319 (4) | 1.324 (4) | 1.353 (4) | 1.350 (4) | 1.374 (4) | 108.5 (3) | 108.5 (3) | 109.1 (3) | 107.2 (3) | 106.7 (3) |
| 1.315 (4) | 1.323 (4) | 1.372 (4) | 1.340 (4) | 1.372 (4) | 108.6 (3) | 108.9 (3) | 108.3 (3) | 107.1 (3) | 107.0 (3) |
imMe2+ h | 1.324 (2) | 1.335 (3) | 1.380 (2) | 1.346 (3) | 1.376 (3) | 109.0 (2) | 108.3 (2) | 108.5 (2) | 107.1 (2) | 107.1 (2) |
Notes:
a Bolte and Lemke, 1999 (173 K); b Wang and Craven,1979 in its cocrystallized 1:1 barbital adduct 295 K; c this work (ca 150 K); d Claramunt et al., 2002 (293 K); e Ishida et al., 1990 (295 K); f Hsu and Schlemper, 1980 (X-ray study, 295 K); g Blessing, 1986 (293 K) (2 molecules); h Arduengo et al., 1992 (203 K). |
The wide relevance of imidazole, imH, and derivative systems in biological arrays, mono- and oligo-dentate ligand coordination complexes, and catalytically relevant carbenes has led to experimental and theoretical studies of electron distributions therein (e.g. Hsu & Schlemper, 1980; Arduengo et al., 1972). Many structural data are available, some of the more recent of good precision, but interspecies comparisons and studies of associated structural progressions and evolutions among simple species are relatively sparse. The present study of the title compounds, (I), (II) and (III), respectively, comprises additional contributions to the known data; in each case, one molecule, with H-atom positions well defined, comprises the asymmetric unit of the structure. Selected geometric parameters for the non-H atoms are presented in Tables 1–3, and the individual molecules are depicted, normal to their C3N2 im planes, in Figs. 1–3.
Recently, an independent study of (I) was published by Claramunt et al. (2002); although the temperature of the experiment is not cited in the paper, it would appear from the cell volume and CCDC deposition to have been executed at room temperature. The present determination at a lower temperature offers a more extensive data set, with s.u. values for the bond lengths of the ring reduced generally by a factor of 3. The hydrogen associations and hydrogen-bonding linking successive molecules in a spiral about the major axis are essentially as described and depicted in the earlier report, but the differences in the geometric parameters are substantial and significant.
Table 4 presents the geometric parameters of all of the im rings presented comparatively, together with those of related structures. Although these structure determinations are variable in precision and temperature of execution, a number of useful general comments are possible. The geometric parameters within the im rings of the neutral molecules are generally similar, regardless of replacement of the imine H atom by other substituents or the presence of substituents at other sites in the ring. In respect of the latter, it appears to be widespread that, because of steric and/or electronic and/or lattice force imperatives, the imine H atom tends to lie `trans' to any substituent at atoms C4 or C5, so that sites 1 and 4 tend to be occupied, as is the case in (I). Given that disposition, bond b is short, as is bond d (relative to typical aromatic N—C and C—C bonds), with angles β and γ correspondingly enlarged. With protonation of the second ring N atom, the imH2+ array becomes more symmetrical, approximating mm symmetry, with bonding parameters more evenly aromatic and little altered on passing from imH2+ to the imMe2+ species that are recorded with comparable precision. A system of particular interest in this context is the 4-(2-NH2—C6H4) imH array. In this species, the NH2 substituent of the phenyl ring lies adjacent to the unprotonated imH N atom [N···H = 2.11 (4) Å], incipiently protonating it. The torsion angle about the bond between the two rings is −50.3 (6)°, and there is a considerable exocyclic asymmetry at the substituted im C atom [121.2 (4), cf. 129.4 (4)°], the smaller angle being? enclosed by the NH2 substituent. This situation parallels the substituent disposition in (I) (Table 1), where the equivalent torsion angle is −38.6 (2)°. The difference between the pendant N—C(substituent) bond lengths in (II) and (III) is substantial and interesting, reflecting the differences in the electronic characteristics of benzyl and mesityl. The dihedral angle between the two aromatic planes in (III) is 73.7 (1)°.