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The two title compounds, C
13H
18N
8 and C
17H
20N
8·0.5H
2O, possess similar molecular shapes, with the pyrazoline moiety and
s-triazine ring located approximately in one plane, and the imidazole or benzimidazole ring nearly perpendicular to the
s-triazine nucleus. In both crystal structures, despite there being a large number of accessible hydrogen-bond acceptor sites, only one H atom from the NH
2 group is involved in hydrogen bonding; the molecules are assembled into discrete centrosymmetric dimers
via a pair of nearly linear N—H
N hydrogen bonds.
Supporting information
CCDC references: 229108; 229109
Compound (I) was prepared according to the procedure described by Brzozowski & S\,aczewski (2002). For the preparation of (II), to a solution of benzimidazole (2.36 g, 0.02 mol) in dimethyl sulfoxide (10 ml) were added successively finely powdered NaOH (1.6 g, 0.04 mol) and 4-bromomethyl-6-(3,5,5-trimethyl-4,5-dihydro-1H-pyrazolyl)-1,3,5-triazin- 2-amine [6] (3.0 g, 0.01 mol). The reaction mixture was stirred vigorously at 308–313 K for 2 h and then poured into cold water (50 ml). The crude product that precipitated was separated by suction and purified by crystallization from methanol/water to give (II) in 76% yield (m.p. 402–404 K). IR (cm−1): 3424, 1664, 1544, 1472, 1440, 1376, 1196. 1H-NMR (DMSO-d6): δ 0.92 (s, 6H, CH3), 1.87 (s, 3H, CH3), 2.62 (s, 2H, CH2), 5.26 (s, 2H, CH2), 6.9 (s, 2H, NH2), 7.1–7.25 (m, 2H, aromat.), 7.4–7.5 (m, 1H, aromat.), 7.6–7.7 (m, 1H, aromat.), 8.24 (s, 1H, CH). The single-crystal used for X-ray analysis was obtained by slow evaporation of a toluene solution of (II).
In both (I) and (II), all H atoms were located from difference Fourier maps. In (I), they were refined freely, with isotropic displacement parameters. In (II), they were placed in positions calculated from the standarization of C—H, N—H and O—H bond lengths (0.96, 0.90 and 0.85 Å, respectively) and during refinement were constrained to ride on their parent atoms. The Uiso value of the unique H atom of the water molecule was set equal to 1.2Ueq(O1W); isotropic displacement parameters of the remaining H atoms were refined.
For both compounds, data collection: CrysAlis (Oxford Diffraction, 2000); cell refinement: CrysAlis; data reduction: CrysAlis; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation (Siemens, 1989); software used to prepare material for publication: SHELXL97.
(I) 2-Amino-6-(1-imidazolylmethyl)-4-(3,5,5-trimethyl-2-pyrazolin-1-yl)- 1,3,5-triazine
top
Crystal data top
C13H18N8 | Z = 2 |
Mr = 286.35 | F(000) = 304 |
Triclinic, P1 | Dx = 1.370 Mg m−3 |
Hall symbol: -P1 | Melting point = 239–241 K |
a = 8.2493 (7) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 9.4564 (7) Å | Cell parameters from 3986 reflections |
c = 9.7050 (8) Å | θ = 4–25° |
α = 93.221 (5)° | µ = 0.09 mm−1 |
β = 105.342 (5)° | T = 110 K |
γ = 106.191 (6)° | Block, colorless |
V = 694.20 (10) Å3 | 0.40 × 0.40 × 0.30 mm |
Data collection top
Kuma CCD diffractometer | 2275 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.017 |
Graphite monochromator | θmax = 25.0°, θmin = 2.2° |
ω scan | h = −9→6 |
5098 measured reflections | k = −11→11 |
2448 independent reflections | l = −10→11 |
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: difference Fourier map |
wR(F2) = 0.096 | All H-atom parameters refined |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0495P)2 + 0.2587P] where P = (Fo2 + 2Fc2)/3 |
2834 reflections | (Δ/σ)max = 0.015 |
262 parameters | Δρmax = 0.26 e Å−3 |
0 restraints | Δρmin = −0.29 e Å−3 |
Crystal data top
C13H18N8 | γ = 106.191 (6)° |
Mr = 286.35 | V = 694.20 (10) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.2493 (7) Å | Mo Kα radiation |
b = 9.4564 (7) Å | µ = 0.09 mm−1 |
c = 9.7050 (8) Å | T = 110 K |
α = 93.221 (5)° | 0.40 × 0.40 × 0.30 mm |
β = 105.342 (5)° | |
Data collection top
Kuma CCD diffractometer | 2275 reflections with I > 2σ(I) |
5098 measured reflections | Rint = 0.017 |
2448 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.096 | All H-atom parameters refined |
S = 1.08 | Δρmax = 0.26 e Å−3 |
2834 reflections | Δρmin = −0.29 e Å−3 |
262 parameters | |
Special details top
Experimental. The following instruments and parameters were used: Melting points, Būchi 535 apparatus; IR spectra (KBr pellets, 400–4000 cm−1) were taken on a Perkin-Elmer 1600 FTIR spectrometer; 1H-NMR spectra were run on a Varian Gemini 200 apparatus at 200 MHz (chemical shifts are expressed as δ values relative to Me4Si as standard). Analyses of C, H, N were within ±0.4% of the theoretical values. |
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | −0.26991 (12) | 0.56010 (10) | 0.10088 (10) | 0.0158 (2) | |
C2 | −0.34077 (15) | 0.67102 (13) | 0.11629 (13) | 0.0195 (2) | |
H2 | −0.3715 (19) | 0.6915 (16) | 0.2021 (16) | 0.024 (4)* | |
N3 | −0.36353 (14) | 0.73997 (11) | 0.00153 (11) | 0.0234 (2) | |
C8 | −0.24288 (15) | 0.55953 (13) | −0.03304 (12) | 0.0196 (2) | |
H8 | −0.192 (2) | 0.4899 (17) | −0.0665 (16) | 0.025 (4)* | |
C9 | −0.30161 (16) | 0.66924 (13) | −0.09244 (13) | 0.0216 (3) | |
H9 | −0.308 (2) | 0.6976 (17) | −0.1889 (17) | 0.029 (4)* | |
C10 | −0.21857 (14) | 0.46810 (12) | 0.20834 (12) | 0.0166 (2) | |
H10A | −0.2778 (18) | 0.4747 (15) | 0.2816 (15) | 0.019 (3)* | |
H10B | −0.258 (2) | 0.3644 (17) | 0.1640 (16) | 0.025 (4)* | |
C11 | −0.02085 (14) | 0.51495 (12) | 0.27983 (11) | 0.0147 (2) | |
N12 | 0.07247 (12) | 0.64972 (10) | 0.26682 (10) | 0.0158 (2) | |
C13 | 0.24811 (14) | 0.68346 (12) | 0.33291 (11) | 0.0141 (2) | |
N14 | 0.32704 (12) | 0.59229 (10) | 0.40704 (10) | 0.0157 (2) | |
C15 | 0.21596 (15) | 0.45886 (12) | 0.41085 (12) | 0.0160 (2) | |
N16 | 0.03863 (12) | 0.41319 (10) | 0.34899 (10) | 0.0175 (2) | |
N17 | 0.34780 (12) | 0.82098 (10) | 0.32232 (10) | 0.0150 (2) | |
N18 | 0.53309 (12) | 0.85415 (10) | 0.36745 (10) | 0.0154 (2) | |
C19 | 0.59850 (14) | 0.98209 (12) | 0.33292 (11) | 0.0158 (2) | |
C20 | 0.46406 (14) | 1.05579 (12) | 0.26466 (12) | 0.0173 (2) | |
H20B | 0.4640 (19) | 1.1338 (17) | 0.3380 (16) | 0.025 (4)* | |
H20A | 0.486 (2) | 1.1052 (17) | 0.1814 (16) | 0.026 (4)* | |
C21 | 0.29122 (14) | 0.92608 (12) | 0.22165 (12) | 0.0151 (2) | |
N22 | 0.28486 (14) | 0.36140 (12) | 0.48171 (11) | 0.0207 (2) | |
H22A | 0.402 (2) | 0.3760 (17) | 0.5164 (17) | 0.029 (4)* | |
H22B | 0.213 (2) | 0.272 (2) | 0.4791 (17) | 0.031 (4)* | |
C23 | 0.24984 (16) | 0.85702 (14) | 0.06468 (12) | 0.0209 (3) | |
H23C | 0.143 (2) | 0.7707 (17) | 0.0389 (16) | 0.022 (3)* | |
H23A | 0.350 (2) | 0.8280 (17) | 0.0501 (17) | 0.030 (4)* | |
H23B | 0.231 (2) | 0.9330 (17) | 0.0028 (17) | 0.028 (4)* | |
C24 | 0.13763 (15) | 0.97313 (13) | 0.24606 (13) | 0.0197 (2) | |
H24C | 0.1624 (19) | 1.0129 (17) | 0.3484 (17) | 0.027 (4)* | |
H24B | 0.029 (2) | 0.8896 (18) | 0.2166 (17) | 0.031 (4)* | |
H24A | 0.1239 (19) | 1.0538 (16) | 0.1864 (15) | 0.022 (3)* | |
C25 | 0.79186 (15) | 1.05026 (14) | 0.36078 (14) | 0.0227 (3) | |
H25C | 0.835 (2) | 1.1468 (19) | 0.4246 (18) | 0.034 (4)* | |
H25B | 0.855 (2) | 0.9820 (18) | 0.4030 (17) | 0.029 (4)* | |
H25A | 0.819 (2) | 1.0740 (18) | 0.2710 (18) | 0.032 (4)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0135 (4) | 0.0161 (5) | 0.0164 (4) | 0.0042 (4) | 0.0023 (3) | 0.0032 (4) |
C2 | 0.0183 (5) | 0.0205 (6) | 0.0209 (6) | 0.0085 (4) | 0.0051 (4) | 0.0031 (4) |
N3 | 0.0234 (5) | 0.0228 (5) | 0.0257 (5) | 0.0105 (4) | 0.0055 (4) | 0.0069 (4) |
C8 | 0.0203 (5) | 0.0208 (6) | 0.0182 (5) | 0.0069 (5) | 0.0056 (4) | 0.0030 (4) |
C9 | 0.0212 (6) | 0.0227 (6) | 0.0202 (6) | 0.0054 (5) | 0.0052 (5) | 0.0068 (5) |
C10 | 0.0155 (5) | 0.0158 (5) | 0.0178 (5) | 0.0046 (4) | 0.0036 (4) | 0.0048 (4) |
C11 | 0.0160 (5) | 0.0155 (5) | 0.0131 (5) | 0.0057 (4) | 0.0040 (4) | 0.0020 (4) |
N12 | 0.0147 (4) | 0.0157 (5) | 0.0166 (4) | 0.0052 (4) | 0.0034 (4) | 0.0034 (3) |
C13 | 0.0155 (5) | 0.0151 (5) | 0.0126 (5) | 0.0063 (4) | 0.0041 (4) | 0.0021 (4) |
N14 | 0.0161 (4) | 0.0152 (5) | 0.0162 (4) | 0.0056 (4) | 0.0036 (4) | 0.0043 (4) |
C15 | 0.0187 (5) | 0.0159 (5) | 0.0145 (5) | 0.0063 (4) | 0.0051 (4) | 0.0030 (4) |
N16 | 0.0160 (5) | 0.0160 (5) | 0.0198 (5) | 0.0051 (4) | 0.0033 (4) | 0.0052 (4) |
N17 | 0.0121 (4) | 0.0146 (5) | 0.0181 (4) | 0.0053 (3) | 0.0023 (3) | 0.0057 (3) |
N18 | 0.0118 (4) | 0.0183 (5) | 0.0162 (4) | 0.0056 (4) | 0.0030 (3) | 0.0026 (4) |
C19 | 0.0162 (5) | 0.0168 (5) | 0.0148 (5) | 0.0057 (4) | 0.0045 (4) | 0.0028 (4) |
C20 | 0.0165 (5) | 0.0157 (5) | 0.0201 (5) | 0.0054 (4) | 0.0046 (4) | 0.0055 (4) |
C21 | 0.0156 (5) | 0.0139 (5) | 0.0168 (5) | 0.0060 (4) | 0.0040 (4) | 0.0062 (4) |
N22 | 0.0179 (5) | 0.0172 (5) | 0.0263 (5) | 0.0061 (4) | 0.0033 (4) | 0.0087 (4) |
C23 | 0.0232 (6) | 0.0211 (6) | 0.0176 (6) | 0.0072 (5) | 0.0039 (5) | 0.0041 (4) |
C24 | 0.0168 (5) | 0.0174 (5) | 0.0274 (6) | 0.0079 (4) | 0.0072 (5) | 0.0064 (5) |
C25 | 0.0159 (6) | 0.0246 (6) | 0.0279 (6) | 0.0054 (5) | 0.0068 (5) | 0.0093 (5) |
Geometric parameters (Å, º) top
N1—C2 | 1.3545 (15) | N17—C21 | 1.5121 (13) |
N1—C8 | 1.3756 (15) | N18—C19 | 1.2823 (15) |
N1—C10 | 1.4484 (14) | C19—C25 | 1.4872 (15) |
C2—N3 | 1.3191 (16) | C19—C20 | 1.4996 (15) |
C2—H2 | 0.957 (15) | C20—C21 | 1.5375 (15) |
N3—C9 | 1.3815 (16) | C20—H20B | 0.996 (15) |
C8—C9 | 1.3577 (17) | C20—H20A | 0.988 (15) |
C8—H8 | 0.959 (15) | C21—C24 | 1.5234 (15) |
C9—H9 | 0.980 (16) | C21—C23 | 1.5337 (16) |
C10—C11 | 1.5171 (15) | N22—H22A | 0.905 (17) |
C10—H10A | 0.971 (14) | N22—H22B | 0.881 (18) |
C10—H10B | 0.976 (15) | C23—H23C | 0.980 (15) |
C11—N12 | 1.3248 (14) | C23—H23A | 0.984 (16) |
C11—N16 | 1.3338 (14) | C23—H23B | 0.980 (16) |
N12—C13 | 1.3565 (14) | C24—H24C | 0.988 (15) |
C13—N14 | 1.3489 (14) | C24—H24B | 0.974 (17) |
C13—N17 | 1.3570 (14) | C24—H24A | 0.997 (15) |
N14—C15 | 1.3459 (14) | C25—H25C | 0.991 (17) |
C15—N22 | 1.3424 (15) | C25—H25B | 0.982 (16) |
C15—N16 | 1.3567 (15) | C25—H25A | 0.977 (17) |
N17—N18 | 1.4105 (12) | | |
| | | |
C2—N1—C8 | 106.52 (9) | N18—C19—C20 | 114.27 (10) |
C2—N1—C10 | 126.95 (10) | C25—C19—C20 | 123.69 (10) |
C8—N1—C10 | 126.34 (9) | C19—C20—C21 | 102.50 (9) |
N3—C2—N1 | 112.49 (10) | C19—C20—H20B | 108.7 (8) |
N3—C2—H2 | 126.4 (9) | C21—C20—H20B | 112.0 (9) |
N1—C2—H2 | 121.1 (9) | C19—C20—H20A | 114.4 (9) |
C2—N3—C9 | 104.38 (10) | C21—C20—H20A | 112.3 (9) |
C9—C8—N1 | 105.95 (10) | H20B—C20—H20A | 107.0 (12) |
C9—C8—H8 | 133.2 (9) | N17—C21—C24 | 113.65 (9) |
N1—C8—H8 | 120.9 (9) | N17—C21—C23 | 109.68 (9) |
C8—C9—N3 | 110.64 (10) | C24—C21—C23 | 111.33 (9) |
C8—C9—H9 | 128.5 (9) | N17—C21—C20 | 99.27 (8) |
N3—C9—H9 | 120.9 (9) | C24—C21—C20 | 112.11 (9) |
N1—C10—C11 | 112.83 (9) | C23—C21—C20 | 110.21 (9) |
N1—C10—H10A | 108.2 (8) | C15—N22—H22A | 123.3 (10) |
C11—C10—H10A | 109.1 (8) | C15—N22—H22B | 117.6 (10) |
N1—C10—H10B | 109.8 (9) | H22A—N22—H22B | 117.9 (14) |
C11—C10—H10B | 109.0 (9) | C21—C23—H23C | 110.3 (8) |
H10A—C10—H10B | 107.8 (12) | C21—C23—H23A | 110.5 (9) |
N12—C11—N16 | 127.53 (10) | H23C—C23—H23A | 110.4 (13) |
N12—C11—C10 | 117.39 (9) | C21—C23—H23B | 107.9 (9) |
N16—C11—C10 | 115.08 (9) | H23C—C23—H23B | 110.0 (12) |
C11—N12—C13 | 114.03 (9) | H23A—C23—H23B | 107.7 (13) |
N14—C13—N17 | 119.25 (10) | C21—C24—H24C | 111.1 (9) |
N14—C13—N12 | 125.10 (10) | C21—C24—H24B | 110.6 (9) |
N17—C13—N12 | 115.65 (9) | H24C—C24—H24B | 109.6 (13) |
C15—N14—C13 | 114.31 (9) | C21—C24—H24A | 107.1 (8) |
N22—C15—N14 | 117.84 (10) | H24C—C24—H24A | 108.5 (12) |
N22—C15—N16 | 116.46 (10) | H24B—C24—H24A | 109.9 (12) |
N14—C15—N16 | 125.69 (10) | C19—C25—H25C | 111.1 (10) |
C11—N16—C15 | 113.34 (9) | C19—C25—H25B | 110.4 (9) |
C13—N17—N18 | 118.38 (9) | H25C—C25—H25B | 110.5 (13) |
C13—N17—C21 | 126.74 (9) | C19—C25—H25A | 110.3 (10) |
N18—N17—C21 | 111.18 (8) | H25C—C25—H25A | 105.1 (13) |
C19—N18—N17 | 107.50 (9) | H25B—C25—H25A | 109.4 (13) |
N18—C19—C25 | 122.03 (10) | | |
| | | |
N16—C11—C10—N1 | −162.58 (9) | N18—C19—C20—C21 | −16.22 (13) |
N12—C11—C10—N1 | 17.25 (14) | C19—C20—C21—N17 | 20.89 (10) |
C11—C10—N1—C2 | −101.91 (12) | C20—C21—N17—N18 | −21.73 (11) |
C11—C10—N1—C8 | 72.46 (14) | C21—N17—N18—C19 | 13.10 (12) |
N17—N18—C19—C20 | 2.52 (13) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N22—H22A···N14i | 0.905 (17) | 2.085 (17) | 2.9906 (14) | 179.0 (15) |
N22—H22A···N18i | 0.905 (17) | 2.626 (16) | 3.0712 (14) | 111.2 (12) |
C2—H2···N18ii | 0.957 (15) | 2.574 (15) | 3.4491 (15) | 152.1 (12) |
C20—H20A···N3iii | 0.988 (15) | 2.547 (15) | 3.3782 (15) | 141.6 (11) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1, y, z; (iii) −x, −y+2, −z. |
(II) 2-Amino-6-(1-benzimidazolylmethyl)-4-(3,5,5-trimethyl-2-pyrazolin-1-yl)- 1,3,5-triazine hemihydrate
top
Crystal data top
C17H20N8·0.5H2O | F(000) = 1464 |
Mr = 345.42 | Dx = 1.334 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C2yc | Cell parameters from 4283 reflections |
a = 22.5030 (14) Å | θ = 4–50° |
b = 8.3217 (6) Å | µ = 0.09 mm−1 |
c = 18.4269 (12) Å | T = 100 K |
β = 94.667 (5)° | Needle, colorless |
V = 3439.2 (4) Å3 | 0.35 × 0.10 × 0.05 mm |
Z = 8 | |
Data collection top
Kuma CCD diffractometer | 1805 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.048 |
Graphite monochromator | θmax = 25.1°, θmin = 1.8° |
ω scan | h = −26→26 |
8348 measured reflections | k = −9→9 |
3035 independent reflections | l = −20→21 |
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)] = 0.045 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.093 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.93 | w = 1/[σ2(Fo2) + (0.0337P)2] where P = (Fo2 + 2Fc2)/3 |
3035 reflections | (Δ/σ)max < 0.001 |
251 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.27 e Å−3 |
Crystal data top
C17H20N8·0.5H2O | V = 3439.2 (4) Å3 |
Mr = 345.42 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 22.5030 (14) Å | µ = 0.09 mm−1 |
b = 8.3217 (6) Å | T = 100 K |
c = 18.4269 (12) Å | 0.35 × 0.10 × 0.05 mm |
β = 94.667 (5)° | |
Data collection top
Kuma CCD diffractometer | 1805 reflections with I > 2σ(I) |
8348 measured reflections | Rint = 0.048 |
3035 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.093 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.93 | Δρmax = 0.27 e Å−3 |
3035 reflections | Δρmin = −0.27 e Å−3 |
251 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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.08659 (8) | 0.5875 (2) | 0.03456 (10) | 0.0194 (5) | |
C2 | 0.09610 (11) | 0.4873 (3) | 0.09316 (12) | 0.0234 (6) | |
H2 | 0.1320 | 0.4246 | 0.0995 | 0.022 (6)* | |
N3 | 0.05246 (8) | 0.4842 (2) | 0.13650 (10) | 0.0242 (5) | |
C4 | −0.04410 (10) | 0.6411 (3) | 0.12707 (14) | 0.0272 (6) | |
H4 | −0.0563 | 0.5902 | 0.1702 | 0.033 (7)* | |
C5 | −0.07615 (11) | 0.7543 (3) | 0.08465 (14) | 0.0300 (6) | |
H5 | −0.1144 | 0.7880 | 0.0987 | 0.042 (8)* | |
C6 | −0.05419 (11) | 0.8198 (3) | 0.02229 (14) | 0.0287 (6) | |
H6 | −0.0772 | 0.8989 | −0.0055 | 0.031 (7)* | |
C7 | 0.00023 (10) | 0.7739 (3) | −0.00065 (13) | 0.0236 (6) | |
H7 | 0.0148 | 0.8161 | −0.0443 | 0.022 (6)* | |
C8 | 0.03180 (10) | 0.6596 (3) | 0.04147 (12) | 0.0206 (6) | |
C9 | 0.01079 (10) | 0.5934 (3) | 0.10454 (12) | 0.0216 (6) | |
C10 | 0.12992 (10) | 0.6372 (3) | −0.01543 (12) | 0.0211 (6) | |
H10A | 0.1600 | 0.5555 | −0.0158 | 0.030 (7)* | |
H10B | 0.1110 | 0.6456 | −0.0639 | 0.015 (6)* | |
C11 | 0.15971 (9) | 0.7951 (3) | 0.00663 (12) | 0.0172 (5) | |
N12 | 0.15224 (8) | 0.8482 (2) | 0.07301 (10) | 0.0193 (5) | |
C13 | 0.17822 (10) | 0.9925 (3) | 0.08882 (12) | 0.0181 (5) | |
N14 | 0.21043 (8) | 1.0774 (2) | 0.04389 (10) | 0.0187 (5) | |
C15 | 0.21467 (10) | 1.0078 (3) | −0.02164 (12) | 0.0192 (6) | |
N16 | 0.18992 (8) | 0.8655 (2) | −0.04408 (10) | 0.0196 (5) | |
N17 | 0.16971 (8) | 1.0520 (2) | 0.15563 (10) | 0.0191 (5) | |
N18 | 0.19151 (8) | 1.2062 (2) | 0.17559 (10) | 0.0195 (5) | |
C19 | 0.17251 (10) | 1.2412 (3) | 0.23716 (13) | 0.0225 (6) | |
C20 | 0.13471 (11) | 1.1149 (3) | 0.26857 (13) | 0.0281 (6) | |
H20A | 0.0971 | 1.1568 | 0.2808 | 0.042 (8)* | |
H20B | 0.1556 | 1.0734 | 0.3121 | 0.031 (7)* | |
C21 | 0.12614 (11) | 0.9891 (3) | 0.20701 (13) | 0.0234 (6) | |
N22 | 0.24601 (8) | 1.0862 (2) | −0.06972 (10) | 0.0235 (5) | |
H22B | 0.2462 | 1.0466 | −0.1151 | 0.035 (8)* | |
H22A | 0.2587 | 1.1877 | −0.0617 | 0.048 (9)* | |
C23 | 0.06302 (11) | 0.9985 (3) | 0.17062 (14) | 0.0329 (7) | |
H23A | 0.0526 | 1.1079 | 0.1590 | 0.050 (9)* | |
H23B | 0.0364 | 0.9682 | 0.2064 | 0.049 (8)* | |
H23C | 0.0583 | 0.9295 | 0.1288 | 0.041 (8)* | |
C24 | 0.14255 (13) | 0.8205 (3) | 0.23364 (14) | 0.0359 (7) | |
H24A | 0.1829 | 0.8136 | 0.2548 | 0.043 (8)* | |
H24B | 0.1158 | 0.7984 | 0.2704 | 0.048 (8)* | |
H24C | 0.1362 | 0.7474 | 0.1935 | 0.045 (8)* | |
C25 | 0.18686 (12) | 1.3969 (3) | 0.27468 (15) | 0.0322 (7) | |
H25A | 0.2060 | 1.3773 | 0.3224 | 0.056 (9)* | |
H25B | 0.2129 | 1.4576 | 0.2463 | 0.054 (9)* | |
H25C | 0.1509 | 1.4562 | 0.2799 | 0.053 (9)* | |
O1W | 0.0000 | 0.3058 (3) | 0.2500 | 0.0894 (12) | |
H1W | 0.0156 | 0.3618 | 0.2180 | 0.107* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0178 (11) | 0.0190 (11) | 0.0219 (12) | −0.0020 (9) | 0.0038 (9) | −0.0004 (9) |
C2 | 0.0223 (14) | 0.0221 (14) | 0.0262 (15) | −0.0024 (13) | 0.0038 (12) | 0.0014 (12) |
N3 | 0.0230 (12) | 0.0257 (12) | 0.0245 (12) | −0.0028 (10) | 0.0062 (10) | 0.0007 (10) |
C4 | 0.0228 (14) | 0.0311 (15) | 0.0291 (16) | −0.0066 (12) | 0.0099 (13) | −0.0048 (13) |
C5 | 0.0186 (14) | 0.0368 (16) | 0.0348 (17) | 0.0015 (12) | 0.0026 (13) | −0.0103 (13) |
C6 | 0.0265 (15) | 0.0307 (16) | 0.0287 (16) | 0.0009 (13) | 0.0002 (13) | −0.0030 (13) |
C7 | 0.0240 (14) | 0.0232 (14) | 0.0234 (14) | −0.0032 (12) | 0.0017 (12) | −0.0012 (12) |
C8 | 0.0207 (14) | 0.0187 (13) | 0.0222 (14) | −0.0030 (11) | 0.0008 (11) | −0.0061 (11) |
C9 | 0.0214 (14) | 0.0223 (14) | 0.0217 (14) | −0.0049 (12) | 0.0042 (12) | −0.0018 (11) |
C10 | 0.0192 (13) | 0.0241 (14) | 0.0203 (15) | −0.0031 (12) | 0.0032 (11) | 0.0000 (11) |
C11 | 0.0125 (12) | 0.0184 (13) | 0.0206 (14) | 0.0011 (10) | 0.0014 (11) | 0.0012 (11) |
N12 | 0.0185 (11) | 0.0196 (11) | 0.0199 (11) | −0.0031 (9) | 0.0021 (9) | −0.0008 (9) |
C13 | 0.0155 (13) | 0.0204 (13) | 0.0182 (14) | 0.0024 (11) | −0.0007 (11) | 0.0029 (11) |
N14 | 0.0186 (11) | 0.0237 (11) | 0.0141 (11) | −0.0043 (9) | 0.0041 (9) | 0.0027 (9) |
C15 | 0.0148 (12) | 0.0228 (14) | 0.0201 (14) | 0.0003 (11) | 0.0028 (11) | 0.0065 (12) |
N16 | 0.0179 (10) | 0.0227 (11) | 0.0188 (11) | −0.0038 (9) | 0.0045 (9) | 0.0007 (9) |
N17 | 0.0218 (11) | 0.0201 (11) | 0.0158 (11) | −0.0069 (9) | 0.0044 (10) | 0.0003 (9) |
N18 | 0.0189 (11) | 0.0174 (11) | 0.0222 (12) | −0.0012 (9) | 0.0024 (9) | 0.0001 (9) |
C19 | 0.0213 (13) | 0.0254 (14) | 0.0207 (14) | −0.0014 (11) | 0.0006 (12) | −0.0010 (11) |
C20 | 0.0284 (16) | 0.0379 (16) | 0.0182 (15) | −0.0080 (13) | 0.0026 (13) | −0.0014 (12) |
C21 | 0.0251 (14) | 0.0292 (15) | 0.0168 (14) | −0.0060 (12) | 0.0076 (12) | −0.0013 (12) |
N22 | 0.0263 (12) | 0.0256 (13) | 0.0197 (13) | −0.0087 (10) | 0.0088 (10) | −0.0003 (10) |
C23 | 0.0279 (16) | 0.046 (2) | 0.0260 (16) | −0.0086 (14) | 0.0079 (13) | −0.0143 (14) |
C24 | 0.051 (2) | 0.0336 (17) | 0.0240 (16) | −0.0140 (14) | 0.0083 (15) | 0.0048 (14) |
C25 | 0.0323 (16) | 0.0307 (15) | 0.0347 (18) | −0.0071 (14) | 0.0102 (14) | −0.0076 (13) |
O1W | 0.152 (3) | 0.0356 (18) | 0.094 (3) | 0.000 | 0.088 (3) | 0.000 |
Geometric parameters (Å, º) top
N1—C2 | 1.367 (3) | C15—N22 | 1.345 (3) |
N1—C8 | 1.386 (3) | C15—N16 | 1.359 (3) |
N1—C10 | 1.455 (3) | N17—N18 | 1.412 (2) |
C2—N3 | 1.316 (3) | N17—C21 | 1.511 (3) |
C2—H2 | 0.96 | N18—C19 | 1.278 (3) |
N3—C9 | 1.401 (3) | C19—C25 | 1.491 (3) |
C4—C5 | 1.388 (3) | C19—C20 | 1.498 (3) |
C4—C9 | 1.392 (3) | C20—C21 | 1.544 (3) |
C4—H4 | 0.96 | C20—H20A | 0.96 |
C5—C6 | 1.398 (3) | C20—H20B | 0.96 |
C5—H5 | 0.96 | C21—C24 | 1.522 (3) |
C6—C7 | 1.381 (3) | C21—C23 | 1.523 (3) |
C6—H6 | 0.96 | N22—H22B | 0.90 |
C7—C8 | 1.386 (3) | N22—H22A | 0.90 |
C7—H7 | 0.96 | C23—H23A | 0.96 |
C8—C9 | 1.403 (3) | C23—H23B | 0.96 |
C10—C11 | 1.515 (3) | C23—H23C | 0.96 |
C10—H10A | 0.96 | C24—H24A | 0.96 |
C10—H10B | 0.96 | C24—H24B | 0.96 |
C11—N12 | 1.324 (3) | C24—H24C | 0.96 |
C11—N16 | 1.335 (3) | C25—H25A | 0.96 |
N12—C13 | 1.357 (3) | C25—H25B | 0.96 |
C13—N14 | 1.344 (3) | C25—H25C | 0.96 |
C13—N17 | 1.355 (3) | O1W—H1W | 0.85 |
N14—C15 | 1.349 (3) | | |
| | | |
C2—N1—C8 | 105.94 (19) | C11—N16—C15 | 112.91 (19) |
C2—N1—C10 | 127.14 (19) | C13—N17—N18 | 119.80 (18) |
C8—N1—C10 | 125.57 (19) | C13—N17—C21 | 126.15 (19) |
N3—C2—N1 | 114.5 (2) | N18—N17—C21 | 112.39 (17) |
N3—C2—H2 | 125.2 | C19—N18—N17 | 107.71 (18) |
N1—C2—H2 | 120.3 | N18—C19—C25 | 122.3 (2) |
C2—N3—C9 | 103.82 (19) | N18—C19—C20 | 115.1 (2) |
C5—C4—C9 | 117.3 (2) | C25—C19—C20 | 122.6 (2) |
C5—C4—H4 | 126.5 | C19—C20—C21 | 103.47 (19) |
C9—C4—H4 | 116.2 | C19—C20—H20A | 112.1 |
C4—C5—C6 | 121.7 (2) | C21—C20—H20A | 111.1 |
C4—C5—H5 | 118.8 | C19—C20—H20B | 108.7 |
C6—C5—H5 | 119.5 | C21—C20—H20B | 113.2 |
C7—C6—C5 | 121.7 (3) | H20A—C20—H20B | 108.4 |
C7—C6—H6 | 118.7 | N17—C21—C24 | 111.6 (2) |
C5—C6—H6 | 119.6 | N17—C21—C23 | 109.63 (19) |
C6—C7—C8 | 116.4 (2) | C24—C21—C23 | 112.5 (2) |
C6—C7—H7 | 121.8 | N17—C21—C20 | 100.19 (18) |
C8—C7—H7 | 121.7 | C24—C21—C20 | 112.1 (2) |
C7—C8—N1 | 131.7 (2) | C23—C21—C20 | 110.2 (2) |
C7—C8—C9 | 122.8 (2) | C15—N22—H22B | 118.5 |
N1—C8—C9 | 105.6 (2) | C15—N22—H22A | 121.5 |
C4—C9—N3 | 129.7 (2) | H22B—N22—H22A | 118.1 |
C4—C9—C8 | 120.1 (2) | C21—C23—H23A | 110.4 |
N3—C9—C8 | 110.1 (2) | C21—C23—H23B | 107.2 |
N1—C10—C11 | 112.42 (18) | H23A—C23—H23B | 104.3 |
N1—C10—H10A | 108.2 | C21—C23—H23C | 111.2 |
C11—C10—H10A | 108.6 | H23A—C23—H23C | 112.3 |
N1—C10—H10B | 109.8 | H23B—C23—H23C | 111.1 |
C11—C10—H10B | 109.9 | C21—C24—H24A | 112.5 |
H10A—C10—H10B | 107.8 | C21—C24—H24B | 104.7 |
N12—C11—N16 | 127.6 (2) | H24A—C24—H24B | 109.2 |
N12—C11—C10 | 116.8 (2) | C21—C24—H24C | 108.5 |
N16—C11—C10 | 115.6 (2) | H24A—C24—H24C | 110.6 |
C11—N12—C13 | 114.1 (2) | H24B—C24—H24C | 111.1 |
N14—C13—N17 | 119.4 (2) | C19—C25—H25A | 109.9 |
N14—C13—N12 | 125.2 (2) | C19—C25—H25B | 108.9 |
N17—C13—N12 | 115.4 (2) | H25A—C25—H25B | 109.9 |
C13—N14—C15 | 114.01 (19) | C19—C25—H25C | 110.0 |
N22—C15—N14 | 117.4 (2) | H25A—C25—H25C | 108.3 |
N22—C15—N16 | 116.5 (2) | H25B—C25—H25C | 109.9 |
N14—C15—N16 | 126.1 (2) | | |
| | | |
N16—C11—C10—N1 | −166.01 (19) | N18—C19—C20—C21 | −6.6 (3) |
N12—C11—C10—N1 | 13.1 (3) | C19—C20—C21—N17 | 9.4 (2) |
C11—C10—N1—C2 | −93.8 (3) | C20—C21—N17—N18 | −10.4 (2) |
C11—C10—N1—C8 | 71.0 (3) | C21—N17—N18—C19 | 7.0 (2) |
N17—N18—C19—C20 | 0.1 (3) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1W···N3 | 0.85 | 2.04 | 2.894 (2) | 176 |
N22—H22A···N14i | 0.90 | 2.09 | 2.991 (3) | 179 |
N22—H22A···N18i | 0.90 | 2.61 | 3.035 (3) | 110 |
C20—H20A···O1Wii | 0.96 | 2.54 | 3.415 (3) | 152 |
C2—H2···N18iii | 0.96 | 2.60 | 3.443 (3) | 147 |
Symmetry codes: (i) −x+1/2, −y+5/2, −z; (ii) x, y+1, z; (iii) x, y−1, z. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C13H18N8 | C17H20N8·0.5H2O |
Mr | 286.35 | 345.42 |
Crystal system, space group | Triclinic, P1 | Monoclinic, C2/c |
Temperature (K) | 110 | 100 |
a, b, c (Å) | 8.2493 (7), 9.4564 (7), 9.7050 (8) | 22.5030 (14), 8.3217 (6), 18.4269 (12) |
α, β, γ (°) | 93.221 (5), 105.342 (5), 106.191 (6) | 90, 94.667 (5), 90 |
V (Å3) | 694.20 (10) | 3439.2 (4) |
Z | 2 | 8 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.09 | 0.09 |
Crystal size (mm) | 0.40 × 0.40 × 0.30 | 0.35 × 0.10 × 0.05 |
|
Data collection |
Diffractometer | Kuma CCD diffractometer | Kuma CCD diffractometer |
Absorption correction | – | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5098, 2448, 2275 | 8348, 3035, 1805 |
Rint | 0.017 | 0.048 |
(sin θ/λ)max (Å−1) | 0.595 | 0.596 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.096, 1.08 | 0.045, 0.093, 0.93 |
No. of reflections | 2834 | 3035 |
No. of parameters | 262 | 251 |
H-atom treatment | All H-atom parameters refined | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.26, −0.29 | 0.27, −0.27 |
Selected geometric parameters (Å, º) for (I) topC11—N12 | 1.3248 (14) | N14—C15 | 1.3459 (14) |
C11—N16 | 1.3338 (14) | C15—N22 | 1.3424 (15) |
N12—C13 | 1.3565 (14) | C15—N16 | 1.3567 (15) |
C13—N14 | 1.3489 (14) | N17—N18 | 1.4105 (12) |
C13—N17 | 1.3570 (14) | N18—C19 | 1.2823 (15) |
| | | |
N12—C11—N16 | 127.53 (10) | C15—N14—C13 | 114.31 (9) |
C11—N12—C13 | 114.03 (9) | N14—C15—N16 | 125.69 (10) |
N14—C13—N12 | 125.10 (10) | C11—N16—C15 | 113.34 (9) |
| | | |
N12—C11—C10—N1 | 17.25 (14) | C19—C20—C21—N17 | 20.89 (10) |
C11—C10—N1—C2 | −101.91 (12) | C20—C21—N17—N18 | −21.73 (11) |
N17—N18—C19—C20 | 2.52 (13) | C21—N17—N18—C19 | 13.10 (12) |
N18—C19—C20—C21 | −16.22 (13) | | |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
N22—H22A···N14i | 0.905 (17) | 2.085 (17) | 2.9906 (14) | 179.0 (15) |
N22—H22A···N18i | 0.905 (17) | 2.626 (16) | 3.0712 (14) | 111.2 (12) |
C2—H2···N18ii | 0.957 (15) | 2.574 (15) | 3.4491 (15) | 152.1 (12) |
C20—H20A···N3iii | 0.988 (15) | 2.547 (15) | 3.3782 (15) | 141.6 (11) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1, y, z; (iii) −x, −y+2, −z. |
Selected geometric parameters (Å, º) for (II) topC11—N12 | 1.324 (3) | N14—C15 | 1.349 (3) |
C11—N16 | 1.335 (3) | C15—N22 | 1.345 (3) |
N12—C13 | 1.357 (3) | C15—N16 | 1.359 (3) |
C13—N14 | 1.344 (3) | N17—N18 | 1.412 (2) |
C13—N17 | 1.355 (3) | N18—C19 | 1.278 (3) |
| | | |
N12—C11—N16 | 127.6 (2) | C13—N14—C15 | 114.01 (19) |
C11—N12—C13 | 114.1 (2) | N14—C15—N16 | 126.1 (2) |
N14—C13—N12 | 125.2 (2) | C11—N16—C15 | 112.91 (19) |
| | | |
N12—C11—C10—N1 | 13.1 (3) | C19—C20—C21—N17 | 9.4 (2) |
C11—C10—N1—C2 | −93.8 (3) | C20—C21—N17—N18 | −10.4 (2) |
N17—N18—C19—C20 | 0.1 (3) | C21—N17—N18—C19 | 7.0 (2) |
N18—C19—C20—C21 | −6.6 (3) | | |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1W···N3 | 0.85 | 2.04 | 2.894 (2) | 176.3 |
N22—H22A···N14i | 0.90 | 2.09 | 2.991 (3) | 179.1 |
N22—H22A···N18i | 0.90 | 2.61 | 3.035 (3) | 109.6 |
C20—H20A···O1Wii | 0.96 | 2.54 | 3.415 (3) | 152.3 |
C2—H2···N18iii | 0.96 | 2.60 | 3.443 (3) | 146.8 |
Symmetry codes: (i) −x+1/2, −y+5/2, −z; (ii) x, y+1, z; (iii) x, y−1, z. |
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Molecules with 2,4-diamino-1,3,5-triazine skeletons are known to possess diverse biological activities. Recently, it has been demonstrated that some 2-amino-4-(3,5,5-trimethyl-2-pyrazolino) −1,3,5-triazine derivatives caused considerable growth inhibition in distinct tumor cell lines, showing that these compounds may be useful in the development of new chemotherapeutic agents (Brzozowski et al., 2000; Brzozowski & S\,aczewski, 2002).
The present structure determinations of 2-amino-6-(1-imidazolylmethyl)-4-(3,5,5- trimethyl-2-pyrazolino)-1,3,5-triazine, (I), and 2-amino-6-(1-benzimidazolylmethyl)-4-(3,5,5- trimethyl-2-pyrazolino)-1,3,5-triazine hemihydrate, (II), are part of our research program on structure–activity relationships for this series of compounds. So far, only the crystal structure of one derivative, 2-amino-4-(3,5,5-trimethyl-2-pyrazolino)-6-chloromethyl-1,3,5-triazine, has been reported (Brzozowski et al., 2000).
The molecular structures of (I) and (II) are shown in Fig. 1. Bond lengths and bond angles for (I) and (II) (Tables 1 and 3) show good agreement. The s-triazine moiety exhibits a typical pattern of bond angles with N—C—N angles greater than 125° and C—N—C angles less than 115°. In both compounds, the C11—N12 and C11—N16 bonds are the shortest in the s-triazine ring, and the C15—N16 and C13—N12 bonds are the longest. The s-triazine ring geometry compares well with some other 2,4-diamino-1,3,5-triazine derivatives (Perrakis et al., 1993; Brzozowski et al., 2000; Gidaspov et al., 2002). The triazine rings, including atoms N22, C10 and N17 of the substituents, are virtually flat, the maximum deviation from planarity being 0.0041 (7) and 0.0252 (16) Å in (I) and (II), respectively, when all these atoms are included in the calculation of the best plane.
The conformational features of (I) and (II) are generally very similar (Tables 1 and 3). As in 2-amino-4-(3,5,5-trimethyl-2-pyrazolino)-6-chloromethyl-1,3,5-triazine (Brzozowski et al., 2000), the molecules show a Z configuration at the partially double C13—N17 bond. The pyrazoline moiety and s-triazine ring lie approximately in one plane, whereas the benzimidazole and imidazole rings are nearly perpendicular to the s-triazine nucleus [the dihedral angles are 87.10 (4) and 80.09 (5)° for (I) and (II), respectively]. Interaction of these heteroaromatic substituents with the two methyl groups bound to atom C21 of the pyrazoline fragment results, most probably, in a characteristic bent shape of the molecules, with the dihedral angle between the pyrazoline and the imidazolyl planes equal to 76.71 (5) and 77.87 (8)°, and N12—C11—C10—N1 torsion angles of 17.25 (14) and 13.1 (3)°, in (I) and (II), respectively. The bonds to pyrazoline atom N17 are not strictly coplanar, and atom N17 deviates 0.1582 (11) Å from the plane defined by atoms C13, N18 and C21 in (I), whereas this deviation is 0.106 (2) Å in (II). The endocyclic torsion angles of the 3,5,5-trimethylpyrazoline moiety indicate an envelope conformation of the five-membered ring in (I) (Table 1) and a strongly flattened envelope in (II) (Table 3).
Compounds (I) and (II) have practically identical abilities to form classical hydrogen bonds. Each molecule contains one NH2 group, which may act as a twofold hydrogen-bond donor, and five potentially good hydrogen-bond acceptors (atoms N3, N12, N14, N16 and N18; however, atom N12 can be excluded from this list, as access to the lone pair in its sp2 orbital is hindered by the bulky substituents on atoms C11 and C13 of the s-triazine ring). The number of hydrogen-bond acceptors in these molecules strongly exceeds that of donors. In the crystal structure of the analogue of (I) and (II), 2-amino-4-(3,5,5-trimethyl-2-pyrazolino)- 6-chloromethyl-1,3,5-triazine, which lacks one N-acceptor site when compared with the title compounds, the molecules are assembled into tapes via R22(8) hydrogen-bond motifs generated by N—H···N interactions between the NH2 group and the triazine atoms N14 and N16 (Brzozowski et al., 2000). Such one-dimensional assemblies are a characteristic supramolecular feature of many 2-aminopyrimidines (Aäkeroy et al., 1998; Krische et al., 1998; Krische et al., 2000). However, no such tapes were found in the crystal structures of (I) and (II). The molecules of (I) form centrosymmetric dimers via a pair of nearly linear N22—H22A···N14i hydrogen bonds (Fig. 2 and Table 2, symmetry codes defined in Table 2), and this is the only conventional hydrogen bond in this structure. The amine group interacts only very weakly with pyrazoline atom N18 in the same dimer. C20—H20A···N3iii interactions join the dimers into one-dimensional networks, which are further organized into closely packed layers, parallel to the (211) plane, via π-π stacking interactions between the imidazole moieties [interplanar distance 3.305 (5) Å; Fig. 2]. Neighbouring layers are further connected via weak C2—H2···N18ii interactions between the imidazole and pyrazoline moieties. Interestingly, the C2···N18ii vector is oriented nearly perpendicular to the pyrazoline ring plane, indicating that this weak hydrogen bond is accepted by the lone pair in the p orbital and not by that of the sp2 orbital of the atom N18.
We were unable to obtain (II) in the anhydrous form. When recrystallized from a hot saturated toluene solution, (II) formed a hemihydrate. The water molecules lie in special positions of twofold symmetry and act as double proton donors in O—H···N hydrogen bonds and as double proton acceptors in C—H···O hydrogen bonds (Table 4). It is interesting that, despite the presence of water molecules and differences in the overall molecular packing, the molecules of (II) are joined together by a set of weak and strong interactions that are similar to those observed in (I). Molecules of (II) are connected into centrosymetric dimers via pairs of nearly linear N22—H22A···N14i hydrogen bonds (Fig. 3 and Table 4, symmetry codes defined in Table 4). Furthermore, π-π stacking interactions between the benzimidazole rings [interplanar distance 3.323 (2) Å] and weak C2—H2···N18iii interactions between benzimidazole and pyrazoline rings can be observed. When compared with (I), the missing C20—H20A···N3 interaction is replaced in (II) by two hydrogen bonds involving the water molecule, viz. C20—H20A···O1Wii and O1W—H1W···N3. Thus, as in (I), despite there being a large number of potential hydrogen-bonding sites, only one amine H atom is involved in hydrogen bonding.