Buy article online - an online subscription or single-article purchase is required to access this article.
The title compound, C18H15N3, was synthesized by the reaction of 2-phenylmethylidene-3,4-dihydronaphthalen-1(2H)-one with guanidine carbonate in ethylene glycol under microwave irradiation. X-ray analysis revealed the formation of a pyrimidine ring. The partially saturated six-membered ring adopts a distorted boat conformation.
Supporting information
CCDC reference: 209920
Key indicators
- Single-crystal X-ray study
- T = 296 K
- Mean (C-C) = 0.002 Å
- R factor = 0.038
- wR factor = 0.102
- Data-to-parameter ratio = 12.3
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
The title compound, (I), was prepared by the reaction of 2-phenylmethylidene-3,4-dihydronaphthalen-1(2H)-one with guanidine carbonate in ethylene glycol under microwave irradiation (m.p. 447–448 K). Single crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of a acetone and petroleum ether solution.
Atoms H3A and H3B were refined isotropically. The positions of the other H atoms were fixed geometrically with C—H distances of 0.93 (CH) or 0.97 Å (CH2).
Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 1997); program(s) used to solve structure: SHELXTL; program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
2-amino-4-phenyl-5,6-dihydrobenzo[
h]quinazoline
top
Crystal data top
C18H15N3 | F(000) = 576 |
Mr = 273.33 | Dx = 1.303 Mg m−3 |
Monoclinic, P21/c | Melting point = 447–448 K |
Hall symbol: -P 2ybc | Mo Kα radiation, λ = 0.71073 Å |
a = 10.902 (2) Å | Cell parameters from 25 reflections |
b = 6.906 (1) Å | θ = 3.0–12.6° |
c = 18.577 (3) Å | µ = 0.08 mm−1 |
β = 94.85 (1)° | T = 296 K |
V = 1393.6 (4) Å3 | Block, yellow |
Z = 4 | 0.58 × 0.54 × 0.24 mm |
Data collection top
Siemens P4 diffractometer | Rint = 0.022 |
Radiation source: normal-focus sealed tube | θmax = 25.0°, θmin = 1.9° |
Graphite monochromator | h = 0→12 |
ω scans | k = 0→8 |
2919 measured reflections | l = −22→22 |
2448 independent reflections | 3 standard reflections every 97 reflections |
1810 reflections with I > 2σ(I) | intensity decay: 1.0% |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.038 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.102 | w = 1/[σ2(Fo2) + (0.0602P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.01 | (Δ/σ)max = 0.001 |
2448 reflections | Δρmax = 0.15 e Å−3 |
199 parameters | Δρmin = −0.18 e Å−3 |
2 restraints | Extinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.043 (3) |
Crystal data top
C18H15N3 | V = 1393.6 (4) Å3 |
Mr = 273.33 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 10.902 (2) Å | µ = 0.08 mm−1 |
b = 6.906 (1) Å | T = 296 K |
c = 18.577 (3) Å | 0.58 × 0.54 × 0.24 mm |
β = 94.85 (1)° | |
Data collection top
Siemens P4 diffractometer | Rint = 0.022 |
2919 measured reflections | 3 standard reflections every 97 reflections |
2448 independent reflections | intensity decay: 1.0% |
1810 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | 2 restraints |
wR(F2) = 0.102 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | Δρmax = 0.15 e Å−3 |
2448 reflections | Δρmin = −0.18 e Å−3 |
199 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. |
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 (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.81730 (11) | 0.17629 (17) | 0.71624 (6) | 0.0400 (3) | |
N2 | 0.89605 (10) | 0.45988 (18) | 0.66146 (6) | 0.0394 (3) | |
N3 | 0.98173 (14) | 0.3452 (2) | 0.77085 (8) | 0.0564 (4) | |
C1 | 0.89514 (13) | 0.3265 (2) | 0.71412 (8) | 0.0386 (4) | |
C2 | 0.72585 (12) | 0.1698 (2) | 0.66278 (7) | 0.0362 (4) | |
C3 | 0.63317 (13) | 0.0136 (2) | 0.66516 (7) | 0.0382 (4) | |
C4 | 0.65687 (15) | −0.1548 (2) | 0.70558 (8) | 0.0457 (4) | |
H4 | 0.7331 | −0.1717 | 0.7313 | 0.055* | |
C5 | 0.56794 (17) | −0.2965 (2) | 0.70770 (9) | 0.0545 (5) | |
H5 | 0.5850 | −0.4098 | 0.7337 | 0.065* | |
C6 | 0.45352 (17) | −0.2697 (3) | 0.67108 (9) | 0.0554 (5) | |
H6 | 0.3929 | −0.3637 | 0.6733 | 0.066* | |
C7 | 0.42935 (15) | −0.1043 (3) | 0.63135 (8) | 0.0493 (4) | |
H7 | 0.3518 | −0.0873 | 0.6072 | 0.059* | |
C8 | 0.51843 (13) | 0.0382 (2) | 0.62648 (8) | 0.0410 (4) | |
C9 | 0.49366 (14) | 0.2206 (3) | 0.58360 (9) | 0.0522 (5) | |
H9A | 0.4671 | 0.3217 | 0.6150 | 0.063* | |
H9B | 0.4279 | 0.1978 | 0.5460 | 0.063* | |
C10 | 0.60837 (15) | 0.2862 (3) | 0.54961 (8) | 0.0506 (4) | |
H10A | 0.6276 | 0.1942 | 0.5127 | 0.061* | |
H10B | 0.5933 | 0.4111 | 0.5267 | 0.061* | |
C11 | 0.71635 (13) | 0.3018 (2) | 0.60602 (8) | 0.0371 (4) | |
C12 | 0.80931 (12) | 0.4404 (2) | 0.60587 (7) | 0.0364 (4) | |
C13 | 0.82260 (13) | 0.5716 (2) | 0.54317 (8) | 0.0397 (4) | |
C14 | 0.84315 (14) | 0.7687 (2) | 0.55284 (9) | 0.0474 (4) | |
H14 | 0.8449 | 0.8221 | 0.5989 | 0.057* | |
C15 | 0.86105 (15) | 0.8857 (3) | 0.49434 (11) | 0.0599 (5) | |
H15 | 0.8733 | 1.0179 | 0.5012 | 0.072* | |
C16 | 0.86099 (16) | 0.8083 (3) | 0.42585 (11) | 0.0657 (6) | |
H16 | 0.8744 | 0.8875 | 0.3868 | 0.079* | |
C17 | 0.84098 (15) | 0.6137 (3) | 0.41569 (10) | 0.0624 (5) | |
H17 | 0.8409 | 0.5609 | 0.3696 | 0.075* | |
C18 | 0.82096 (14) | 0.4958 (3) | 0.47366 (8) | 0.0509 (4) | |
H18 | 0.8062 | 0.3644 | 0.4661 | 0.061* | |
H3A | 0.9949 (16) | 0.2419 (19) | 0.7981 (8) | 0.061 (5)* | |
H3B | 1.0409 (13) | 0.430 (2) | 0.7671 (10) | 0.069 (6)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0399 (7) | 0.0390 (7) | 0.0396 (7) | −0.0008 (6) | −0.0051 (6) | 0.0016 (6) |
N2 | 0.0369 (7) | 0.0391 (7) | 0.0411 (7) | 0.0003 (5) | −0.0036 (5) | 0.0011 (6) |
N3 | 0.0581 (10) | 0.0503 (9) | 0.0560 (9) | −0.0122 (8) | −0.0230 (8) | 0.0111 (8) |
C1 | 0.0369 (8) | 0.0371 (8) | 0.0403 (8) | 0.0012 (7) | −0.0051 (7) | −0.0014 (7) |
C2 | 0.0350 (8) | 0.0377 (8) | 0.0355 (8) | 0.0029 (6) | 0.0011 (6) | −0.0025 (6) |
C3 | 0.0414 (8) | 0.0401 (9) | 0.0334 (7) | −0.0026 (7) | 0.0052 (6) | −0.0036 (7) |
C4 | 0.0504 (10) | 0.0456 (10) | 0.0413 (9) | −0.0026 (8) | 0.0054 (7) | 0.0029 (7) |
C5 | 0.0724 (12) | 0.0439 (10) | 0.0483 (10) | −0.0095 (9) | 0.0115 (9) | 0.0041 (8) |
C6 | 0.0619 (11) | 0.0535 (11) | 0.0518 (10) | −0.0221 (9) | 0.0104 (8) | −0.0061 (9) |
C7 | 0.0448 (9) | 0.0581 (11) | 0.0449 (9) | −0.0111 (8) | 0.0036 (7) | −0.0085 (8) |
C8 | 0.0407 (8) | 0.0453 (9) | 0.0370 (8) | −0.0042 (7) | 0.0039 (6) | −0.0073 (7) |
C9 | 0.0392 (9) | 0.0560 (11) | 0.0590 (10) | −0.0046 (8) | −0.0103 (8) | 0.0031 (9) |
C10 | 0.0466 (9) | 0.0557 (10) | 0.0473 (9) | −0.0079 (8) | −0.0096 (7) | 0.0108 (8) |
C11 | 0.0345 (8) | 0.0387 (8) | 0.0374 (8) | 0.0000 (7) | −0.0007 (6) | 0.0002 (7) |
C12 | 0.0353 (8) | 0.0350 (8) | 0.0387 (8) | 0.0039 (6) | 0.0013 (6) | −0.0001 (6) |
C13 | 0.0308 (8) | 0.0452 (9) | 0.0426 (9) | 0.0013 (7) | −0.0004 (6) | 0.0061 (7) |
C14 | 0.0410 (9) | 0.0456 (10) | 0.0546 (10) | −0.0010 (7) | −0.0009 (7) | 0.0059 (8) |
C15 | 0.0467 (10) | 0.0495 (10) | 0.0836 (14) | −0.0020 (8) | 0.0064 (9) | 0.0214 (10) |
C16 | 0.0471 (11) | 0.0805 (15) | 0.0706 (13) | 0.0016 (10) | 0.0123 (9) | 0.0361 (11) |
C17 | 0.0540 (11) | 0.0865 (15) | 0.0478 (10) | 0.0040 (10) | 0.0096 (8) | 0.0133 (10) |
C18 | 0.0500 (10) | 0.0549 (10) | 0.0477 (9) | 0.0008 (8) | 0.0049 (7) | 0.0039 (8) |
Geometric parameters (Å, º) top
N1—C1 | 1.3431 (19) | C9—C10 | 1.517 (2) |
N1—C2 | 1.3471 (17) | C9—H9A | 0.9700 |
N2—C1 | 1.3442 (18) | C9—H9B | 0.9700 |
N2—C12 | 1.3469 (17) | C10—C11 | 1.512 (2) |
N3—C1 | 1.3603 (19) | C10—H10A | 0.9700 |
N3—H3A | 0.880 (9) | C10—H10B | 0.9700 |
N3—H3B | 0.876 (9) | C11—C12 | 1.394 (2) |
C2—C11 | 1.392 (2) | C12—C13 | 1.492 (2) |
C2—C3 | 1.481 (2) | C13—C14 | 1.389 (2) |
C3—C4 | 1.397 (2) | C13—C18 | 1.392 (2) |
C3—C8 | 1.399 (2) | C14—C15 | 1.381 (2) |
C4—C5 | 1.380 (2) | C14—H14 | 0.9300 |
C4—H4 | 0.9300 | C15—C16 | 1.380 (3) |
C5—C6 | 1.382 (2) | C15—H15 | 0.9300 |
C5—H5 | 0.9300 | C16—C17 | 1.372 (3) |
C6—C7 | 1.373 (2) | C16—H16 | 0.9300 |
C6—H6 | 0.9300 | C17—C18 | 1.382 (2) |
C7—C8 | 1.391 (2) | C17—H17 | 0.9300 |
C7—H7 | 0.9300 | C18—H18 | 0.9300 |
C8—C9 | 1.503 (2) | | |
| | | |
C1—N1—C2 | 115.74 (12) | C10—C9—H9B | 109.5 |
C1—N2—C12 | 116.21 (12) | H9A—C9—H9B | 108.1 |
C1—N3—H3A | 116.0 (12) | C11—C10—C9 | 110.71 (13) |
C1—N3—H3B | 118.0 (12) | C11—C10—H10A | 109.5 |
H3A—N3—H3B | 119.9 (17) | C9—C10—H10A | 109.5 |
N1—C1—N2 | 126.45 (12) | C11—C10—H10B | 109.5 |
N1—C1—N3 | 116.72 (13) | C9—C10—H10B | 109.5 |
N2—C1—N3 | 116.83 (14) | H10A—C10—H10B | 108.1 |
N1—C2—C11 | 122.67 (13) | C2—C11—C12 | 116.35 (13) |
N1—C2—C3 | 117.81 (12) | C2—C11—C10 | 118.82 (13) |
C11—C2—C3 | 119.52 (13) | C12—C11—C10 | 124.83 (13) |
C4—C3—C8 | 119.60 (14) | N2—C12—C11 | 122.05 (13) |
C4—C3—C2 | 121.79 (13) | N2—C12—C13 | 115.43 (13) |
C8—C3—C2 | 118.60 (13) | C11—C12—C13 | 122.48 (12) |
C5—C4—C3 | 120.48 (15) | C14—C13—C18 | 118.54 (15) |
C5—C4—H4 | 119.8 | C14—C13—C12 | 121.31 (14) |
C3—C4—H4 | 119.8 | C18—C13—C12 | 120.07 (14) |
C4—C5—C6 | 119.86 (16) | C15—C14—C13 | 120.24 (17) |
C4—C5—H5 | 120.1 | C15—C14—H14 | 119.9 |
C6—C5—H5 | 120.1 | C13—C14—H14 | 119.9 |
C7—C6—C5 | 120.01 (16) | C16—C15—C14 | 120.64 (18) |
C7—C6—H6 | 120.0 | C16—C15—H15 | 119.7 |
C5—C6—H6 | 120.0 | C14—C15—H15 | 119.7 |
C6—C7—C8 | 121.35 (15) | C17—C16—C15 | 119.61 (17) |
C6—C7—H7 | 119.3 | C17—C16—H16 | 120.2 |
C8—C7—H7 | 119.3 | C15—C16—H16 | 120.2 |
C7—C8—C3 | 118.63 (15) | C16—C17—C18 | 120.24 (19) |
C7—C8—C9 | 122.18 (14) | C16—C17—H17 | 119.9 |
C3—C8—C9 | 119.14 (13) | C18—C17—H17 | 119.9 |
C8—C9—C10 | 110.69 (13) | C17—C18—C13 | 120.71 (17) |
C8—C9—H9A | 109.5 | C17—C18—H18 | 119.6 |
C10—C9—H9A | 109.5 | C13—C18—H18 | 119.6 |
C8—C9—H9B | 109.5 | | |
| | | |
C2—N1—C1—N2 | −5.6 (2) | N1—C2—C11—C12 | 1.8 (2) |
C2—N1—C1—N3 | 174.53 (13) | C3—C2—C11—C12 | −177.68 (13) |
C12—N2—C1—N1 | 0.6 (2) | N1—C2—C11—C10 | −178.31 (13) |
C12—N2—C1—N3 | −179.57 (13) | C3—C2—C11—C10 | 2.2 (2) |
C1—N1—C2—C11 | 4.2 (2) | C9—C10—C11—C2 | 35.1 (2) |
C1—N1—C2—C3 | −176.37 (12) | C9—C10—C11—C12 | −144.99 (15) |
N1—C2—C3—C4 | −20.1 (2) | C1—N2—C12—C11 | 6.1 (2) |
C11—C2—C3—C4 | 159.39 (13) | C1—N2—C12—C13 | −171.58 (12) |
N1—C2—C3—C8 | 158.98 (13) | C2—C11—C12—N2 | −7.2 (2) |
C11—C2—C3—C8 | −21.5 (2) | C10—C11—C12—N2 | 172.89 (14) |
C8—C3—C4—C5 | −0.1 (2) | C2—C11—C12—C13 | 170.33 (13) |
C2—C3—C4—C5 | 178.94 (13) | C10—C11—C12—C13 | −9.6 (2) |
C3—C4—C5—C6 | −1.6 (2) | N2—C12—C13—C14 | −48.08 (19) |
C4—C5—C6—C7 | 1.5 (2) | C11—C12—C13—C14 | 134.24 (15) |
C5—C6—C7—C8 | 0.5 (2) | N2—C12—C13—C18 | 128.54 (15) |
C6—C7—C8—C3 | −2.2 (2) | C11—C12—C13—C18 | −49.1 (2) |
C6—C7—C8—C9 | −179.69 (14) | C18—C13—C14—C15 | 0.2 (2) |
C4—C3—C8—C7 | 2.0 (2) | C12—C13—C14—C15 | 176.87 (13) |
C2—C3—C8—C7 | −177.07 (13) | C13—C14—C15—C16 | −1.2 (2) |
C4—C3—C8—C9 | 179.58 (14) | C14—C15—C16—C17 | 1.0 (3) |
C2—C3—C8—C9 | 0.5 (2) | C15—C16—C17—C18 | 0.0 (3) |
C7—C8—C9—C10 | −145.78 (15) | C16—C17—C18—C13 | −1.0 (3) |
C3—C8—C9—C10 | 36.76 (19) | C14—C13—C18—C17 | 0.9 (2) |
C8—C9—C10—C11 | −52.98 (18) | C12—C13—C18—C17 | −175.85 (14) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3B···N1i | 0.88 (1) | 2.30 (1) | 3.162 (2) | 166 (2) |
N3—H3A···N2ii | 0.88 (1) | 2.37 (1) | 3.1868 (19) | 154 (2) |
Symmetry codes: (i) −x+2, y+1/2, −z+3/2; (ii) −x+2, y−1/2, −z+3/2. |
Experimental details
Crystal data |
Chemical formula | C18H15N3 |
Mr | 273.33 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 296 |
a, b, c (Å) | 10.902 (2), 6.906 (1), 18.577 (3) |
β (°) | 94.85 (1) |
V (Å3) | 1393.6 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.58 × 0.54 × 0.24 |
|
Data collection |
Diffractometer | Siemens P4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2919, 2448, 1810 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.594 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.102, 1.01 |
No. of reflections | 2448 |
No. of parameters | 199 |
No. of restraints | 2 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.15, −0.18 |
Selected geometric parameters (Å, º) topN1—C1 | 1.3431 (19) | N3—C1 | 1.3603 (19) |
N1—C2 | 1.3471 (17) | C2—C11 | 1.392 (2) |
N2—C1 | 1.3442 (18) | C9—C10 | 1.517 (2) |
N2—C12 | 1.3469 (17) | C11—C12 | 1.394 (2) |
| | | |
C1—N1—C2 | 115.74 (12) | N1—C2—C11 | 122.67 (13) |
C1—N2—C12 | 116.21 (12) | N1—C2—C3 | 117.81 (12) |
N1—C1—N2 | 126.45 (12) | N2—C12—C11 | 122.05 (13) |
N1—C1—N3 | 116.72 (13) | N2—C12—C13 | 115.43 (13) |
N2—C1—N3 | 116.83 (14) | | |
| | | |
C11—C2—C3—C8 | −21.5 (2) | C8—C9—C10—C11 | −52.98 (18) |
C2—C3—C8—C9 | 0.5 (2) | C3—C2—C11—C10 | 2.2 (2) |
C3—C8—C9—C10 | 36.76 (19) | C9—C10—C11—C2 | 35.1 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3B···N1i | 0.876 (9) | 2.304 (10) | 3.162 (2) | 166.2 (17) |
N3—H3A···N2ii | 0.880 (9) | 2.370 (12) | 3.1868 (19) | 154.4 (15) |
Symmetry codes: (i) −x+2, y+1/2, −z+3/2; (ii) −x+2, y−1/2, −z+3/2. |
Subscribe to Acta Crystallographica Section E: Crystallographic Communications
The full text of this article is available to subscribers to the journal.
If you have already registered and are using a computer listed in your registration details, please email
support@iucr.org for assistance.
Pyrimidine derivatives occupy a unique position as dynamic agents, both as esential components of nucleic acids and therapeutic agents (Mochida, 1982). Since microwave heating resulting the mass heating effect, much faster temperature increasing, achieving high temperatures required for reactions was used for organic synthesis by Gedye et al. (1986), the microwave chemistry has been a topic of continuing interest. Rate enhancement in many reactions has been reported in recent years. We report here the crystal structure of the title compound, (I), which was synthesized by the reaction of 2-phenylmethylidene-3,4-dihydronaphthalen-1(2H)-one with guanidine carbonate in ethylene glycol under microwave irradiation.
In (I), atoms C1, C2, N1, N2, C11 and C12 form a pyrimidine ring (Fig. 1). The N1—C1, N1—C2, N2—C1 and N2—C12 bond lengths of 1.3431 (19), 1.3471 (17), 1.3442 (18) and 1.3469 (17) Å are slightly longer than those of ethyl 2-amino-4-(3-nitrophenyl)-1,4-dihydro-2H-pyrano[3,2-h]quinoline-3-carboxylate (Wang et al., 2003). In addition, the N3—C1 bond lenth of 1.3603 (19) Å is shorter than the typical Csp2—N bond distance (Lorente et al., 1995). The six-membered ring C2/C3/C8/C9/C10/C11 adopts a distorted boat conformation; atoms C2, C3, C8 and C9 are on one plane, while C10 and C11 deviate from the plane by 0.857 (3) and 0.437 (3) Å, respectively. The torsion angle C8—C9—-C10–C11 is −52.98 (18)°. The dihedral angles between this plane and the C3–C8 phenyl ring, the C13–C18 phenyl ring and the pyrimidine ring are 1.6 (1), 68.39 (6) and 22.6 (1)°, respectively.
In the crystal, the molecules are linked by the N—H···N hydrogen bonds, forming polymers (Fig. 2 and Table 2). The hydrogen bonds are formed between the amino group and atoms N1 and N2 of the pyrimidine ring of adjacent molecules.