organic compounds
4,5,6-Triamino-2-(methylsulfanyl)pyrimidine: π-stacked hydrogen-bonded sheets of R22(8), R22(10) and R66(32) rings
aDepartamento de Química Inorgánica y Orgánica, Universidad de Jaén, 23071 Jaén, Spain, bDepartment of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB24 3UE, Scotland, and cSchool of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland
*Correspondence e-mail: cg@st-andrews.ac.uk
In the title compound, C5H9N5S, the three independent C—NH2 units are all somewhat pyramidal. The molecules are linked by a combination of one N—H⋯S and two N—H⋯N hydrogen bonds into sheets containing three types of ring motif, viz. R22(8), R22(10) and R66(32), all of them centrosymmetric. Adjacent sheets are linked by a single π–π stacking interaction.
Comment
The title compound, (I), was prepared following a published procedure (Baddiley et al., 1943) for use as an intermediate in the synthesis of fused pyrimidine derivatives of potential biological interest.
Within the heterocyclic ring in the molecule of (I), the bond distances (Table 1) provide evidence for aromatic delocalization. The internal bond angles at atoms N1, N3 and C5 are all significantly less than the idealized value of 120°; those at N1 and N3 reflect the stereochemical influence of the lone pairs of electrons on these atoms, while that at C5 is influenced by the behaviour of the exocyclic amino group.
Each of the three independent C—NH2 units is, to a greater or lesser extent, pyramidal, and this is least marked for atom N6 and most marked for atom N5. The sums of the interbond angles at atoms N4, N5 and N6 deviate by 12, 26 and 3°, respectively, from 360°. Closely associated with the degree of pyramidalization at the amino N atoms is the variation in the exocyclic C—N bond distances (Table 1), with C5—N5 the longest of these and C6—N6 the shortest. The very long C5—N5 bond is also doubtless influenced by the rotation of the lone pair at N5 to be almost coplanar with the pyrimidine ring (Table 1 and Fig. 1). The mean values (Allen et al., 1987) for C—S bonds of the types found in (I) are 1.773 and 1.789 Å, so that the difference between the S2—C2 and S2—C21 distances is larger than expected.
Amino atoms N4 and N5 are, therefore, potential acceptors of hydrogen bonds, in addition to ring atoms N1 and N3 and sulfanyl atom S2, while each amino group is potentially a double donor of hydrogen bonds. In practice, there is one intramolecular N—H⋯N hydrogen bond (Table 2), with the highly pyramidal N5 atom as the acceptor, and each amino group acts as a single donor in intermolecular hydrogen bonds, with one ring N atom, one amino N atom and the S atom as the three acceptors (Table 2). Hence, two of the N—H bonds do not participate in any hydrogen-bond formation.
The three intermolecular hydrogen bonds generate a sheet containing three distinct types of ring, all centrosymmetric, but the formation of this rather complex sheet is readily analysed in terms of two straightforward one-dimensional substructures, one built from two independent N—H⋯N hydrogen bonds and the other built using only N—H⋯S hydrogen bonds.
Amino atom N5 in the molecule at (x, y, z) acts as hydrogen-bond donor to the pyramidal amino N4 atom in the molecule at (−x, −y, 1 − z), so forming a centrosymmetric R22(10) (Bernstein et al., 1995) ring centred at (0, 0, ). Similarly, amino atom N6 at (x, y, z) acts as hydrogen-bond donor to ring atom N1 in the molecule at (1 − x, 1 − y, 1 − z), so forming a second ring motif, this time of R22(8) type, centred at (, , ). Propagation by inversion of these two hydrogen bonds then generates a chain of centrosymmetric rings running parallel to the [110] direction, with R22(8) rings centred at (n + , n + , ) (n = zero or integer) and R22(10) rings centred at (n, n, ) (n = zero or integer) (Fig. 2).
In the second one-dimensional x, y, z) acts as hydrogen-bond donor to the S atom in the molecule at (− + x, − y, − + z), thereby forming a C(6) chain running parallel to the [101] direction and generated by the n-glide plane at y = (Fig. 3).
amino atom N4 in the molecule at (The combination of the [110] and [101] chains generates a (11) sheet built from R22(8), R22(10) and R66(32) rings, all of them centrosymmetric (Fig. 4), and these sheets are linked by a centrosymmetric π–π stacking interaction. The pyrimidine rings of the molecules at (x, y, z) and (−x, 1 − y, 1 − z) are strictly parallel, with an interplanar spacing of 3.337 (2) Å. The ring-centroid separation is 3.649 (2) Å, corresponding to a near-ideal ring offset of 1.476 (2) Å. The combination of this interaction with the R22(8) rings generates a chain running parallel to the [100] direction, while the combination of the π-stacking interaction with the R22(10) rings generates a chain parallel to the [010] direction. In this manner, the (11) sheets are linked into a single three-dimensional structure.
Experimental
Crystals of the title compound, (I), were prepared according to the procedure of Baddiley et al. (1943).
Crystal data
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Data collection
Refinement
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The P21/n was uniquely assigned from the All H atoms were located from difference maps and then treated as riding atoms. The H atoms of the methyl group were assigned C—H distances of 0.98 Å, with Uiso(H) = 1.5Ueq(C). The amino H atoms were allowed to ride at the locations deduced from the difference maps, with N—H = 0.88 Å and Uiso(H) = 1.2Ueq(N).
Data collection: COLLECT (Nonius, 1999); cell DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
Supporting information
10.1107/S0108270106003805/sk1899sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S0108270106003805/sk1899Isup2.hkl
Crystals of the title compound, (I), were prepared according to the published procedure of Baddiley et al. (1943).
The
P21/n was uniquely assigned from the All H atoms were located from difference maps and then treated as riding atoms. The H atoms of the methyl group were assigned C—H distances of 0.98 Å, with Uiso(H) = 1.5Ueq(C). The H atoms bonded to N atoms were permitted to ride at the locations deduced from the difference maps, with N—H = 0.88 Å and Uiso(H) = 1.2Ueq(N).Data collection: COLLECT (Nonius, 1999); cell
DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).C5H9N5S | F(000) = 360 |
Mr = 171.23 | Dx = 1.558 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 1659 reflections |
a = 7.7824 (2) Å | θ = 3.9–27.5° |
b = 8.9623 (3) Å | µ = 0.38 mm−1 |
c = 10.5078 (4) Å | T = 120 K |
β = 95.261 (2)° | Rod, yellow |
V = 729.81 (4) Å3 | 0.40 × 0.20 × 0.10 mm |
Z = 4 |
Bruker Nonius KappaCCD area-detector diffractometer | 1659 independent reflections |
Radiation source: Bruker Nonius FR591 rotating anode | 1533 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.024 |
Detector resolution: 9.091 pixels mm-1 | θmax = 27.5°, θmin = 3.9° |
ϕ and ω scans | h = −9→10 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −11→11 |
Tmin = 0.863, Tmax = 0.963 | l = −13→13 |
9338 measured reflections |
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)] = 0.029 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.073 | H-atom parameters constrained |
S = 1.11 | w = 1/[σ2(Fo2) + (0.0279P)2 + 0.4621P] where P = (Fo2 + 2Fc2)/3 |
1659 reflections | (Δ/σ)max = 0.001 |
101 parameters | Δρmax = 0.32 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
C5H9N5S | V = 729.81 (4) Å3 |
Mr = 171.23 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 7.7824 (2) Å | µ = 0.38 mm−1 |
b = 8.9623 (3) Å | T = 120 K |
c = 10.5078 (4) Å | 0.40 × 0.20 × 0.10 mm |
β = 95.261 (2)° |
Bruker Nonius KappaCCD area-detector diffractometer | 1659 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 1533 reflections with I > 2σ(I) |
Tmin = 0.863, Tmax = 0.963 | Rint = 0.024 |
9338 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.073 | H-atom parameters constrained |
S = 1.11 | Δρmax = 0.32 e Å−3 |
1659 reflections | Δρmin = −0.25 e Å−3 |
101 parameters |
x | y | z | Uiso*/Ueq | ||
S2 | 0.20359 (4) | 0.56815 (4) | 0.76430 (3) | 0.01392 (11) | |
N1 | 0.29835 (13) | 0.43416 (12) | 0.56444 (10) | 0.0127 (2) | |
N3 | 0.02044 (13) | 0.36293 (12) | 0.62592 (10) | 0.0123 (2) | |
N4 | −0.14454 (14) | 0.18287 (13) | 0.51618 (11) | 0.0160 (2) | |
N5 | 0.11872 (15) | 0.14725 (13) | 0.33624 (11) | 0.0181 (2) | |
N6 | 0.41062 (14) | 0.32976 (13) | 0.38935 (11) | 0.0166 (2) | |
C2 | 0.16664 (15) | 0.43941 (13) | 0.63708 (12) | 0.0114 (2) | |
C4 | 0.00458 (16) | 0.26619 (14) | 0.52615 (12) | 0.0122 (3) | |
C5 | 0.13097 (16) | 0.24760 (13) | 0.44239 (12) | 0.0121 (3) | |
C6 | 0.27909 (15) | 0.33792 (14) | 0.46462 (12) | 0.0121 (3) | |
C21 | 0.00427 (17) | 0.55706 (15) | 0.83815 (13) | 0.0167 (3) | |
H4A | −0.1695 | 0.1400 | 0.4415 | 0.019* | |
H4B | −0.2280 | 0.2287 | 0.5516 | 0.019* | |
H5A | 0.1231 | 0.0533 | 0.3608 | 0.022* | |
H5B | 0.0248 | 0.1595 | 0.2839 | 0.022* | |
H6A | 0.4913 | 0.3987 | 0.3987 | 0.020* | |
H6B | 0.3970 | 0.2779 | 0.3180 | 0.020* | |
H21A | −0.0930 | 0.5695 | 0.7729 | 0.025* | |
H21B | 0.0012 | 0.6361 | 0.9024 | 0.025* | |
H21C | −0.0039 | 0.4596 | 0.8794 | 0.025* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S2 | 0.01338 (18) | 0.01476 (18) | 0.01352 (18) | −0.00151 (11) | 0.00070 (12) | −0.00268 (11) |
N1 | 0.0116 (5) | 0.0127 (5) | 0.0136 (5) | −0.0009 (4) | 0.0007 (4) | −0.0007 (4) |
N3 | 0.0122 (5) | 0.0121 (5) | 0.0123 (5) | −0.0003 (4) | 0.0004 (4) | 0.0012 (4) |
N4 | 0.0142 (5) | 0.0172 (6) | 0.0169 (6) | −0.0054 (4) | 0.0026 (4) | −0.0017 (4) |
N5 | 0.0189 (6) | 0.0155 (6) | 0.0196 (6) | −0.0011 (4) | 0.0009 (4) | −0.0030 (4) |
N6 | 0.0150 (5) | 0.0175 (6) | 0.0180 (6) | −0.0040 (4) | 0.0056 (4) | −0.0048 (4) |
C2 | 0.0117 (6) | 0.0108 (6) | 0.0113 (6) | 0.0009 (4) | −0.0009 (4) | 0.0019 (4) |
C4 | 0.0122 (6) | 0.0109 (6) | 0.0132 (6) | −0.0004 (4) | −0.0010 (5) | 0.0036 (5) |
C5 | 0.0136 (6) | 0.0101 (6) | 0.0123 (6) | 0.0002 (4) | −0.0003 (5) | 0.0012 (5) |
C6 | 0.0124 (6) | 0.0111 (6) | 0.0128 (6) | 0.0016 (4) | 0.0006 (4) | 0.0027 (5) |
C21 | 0.0191 (7) | 0.0176 (6) | 0.0142 (6) | −0.0021 (5) | 0.0050 (5) | −0.0017 (5) |
N1—C2 | 1.3337 (16) | S2—C21 | 1.7997 (13) |
C2—N3 | 1.3242 (16) | C21—H21A | 0.98 |
N3—C4 | 1.3573 (17) | C21—H21B | 0.98 |
C4—C5 | 1.3888 (18) | C21—H21C | 0.98 |
C5—C6 | 1.4104 (17) | N4—H4A | 0.88 |
C6—N1 | 1.3557 (16) | N4—H4B | 0.88 |
C4—N4 | 1.3759 (16) | N5—H5A | 0.88 |
C5—N5 | 1.4292 (16) | N5—H5B | 0.88 |
C6—N6 | 1.3518 (16) | N6—H6A | 0.88 |
C2—S2 | 1.7694 (13) | N6—H6B | 0.88 |
C6—N1—C2 | 115.40 (11) | C4—N4—H4A | 114.9 |
N1—C2—N3 | 129.07 (11) | C4—N4—H4B | 111.4 |
C2—N3—C4 | 114.55 (11) | H4A—N4—H4B | 118.1 |
N3—C4—C5 | 123.14 (11) | C5—N5—H5A | 112.1 |
C4—C5—C6 | 116.22 (11) | C5—N5—H5B | 113.7 |
C5—C6—N1 | 121.60 (11) | H5A—N5—H5B | 108.0 |
N3—C4—N4 | 114.95 (11) | C6—N6—H6A | 117.9 |
C5—C4—N4 | 121.88 (12) | C6—N6—H6B | 119.2 |
C4—C5—N5 | 124.73 (11) | H6A—N6—H6B | 119.7 |
C6—C5—N5 | 119.04 (11) | S2—C21—H21A | 109.5 |
C5—C6—N6 | 121.56 (11) | S2—C21—H21B | 109.5 |
N1—C6—N6 | 116.82 (11) | H21A—C21—H21B | 109.5 |
N1—C2—S2 | 112.03 (9) | S2—C21—H21C | 109.5 |
N3—C2—S2 | 118.90 (9) | H21A—C21—H21C | 109.5 |
C2—S2—C21 | 101.71 (6) | H21B—C21—H21C | 109.5 |
C6—N1—C2—N3 | 0.61 (19) | C2—N1—C6—N6 | −179.84 (11) |
C6—N1—C2—S2 | −179.87 (8) | C2—N1—C6—C5 | −1.53 (17) |
N3—C2—S2—C21 | −3.12 (11) | C4—C5—C6—N6 | −179.96 (11) |
N1—C2—S2—C21 | 177.30 (9) | N5—C5—C6—N6 | −1.20 (18) |
N1—C2—N3—C4 | 0.02 (19) | C4—C5—C6—N1 | 1.81 (18) |
S2—C2—N3—C4 | −179.47 (9) | N5—C5—C6—N1 | −179.43 (11) |
C2—N3—C4—N4 | 178.05 (11) | N3—C4—N4—H4A | 163 |
C2—N3—C4—C5 | 0.28 (18) | C4—C5—N5—H5A | −69 |
N3—C4—C5—C6 | −1.16 (18) | C5—C6—N6—H6A | 170 |
N4—C4—C5—C6 | −178.78 (11) | N3—C4—N4—H4B | 26 |
N3—C4—C5—N5 | −179.84 (11) | C4—C5—N5—H5B | 54 |
N4—C4—C5—N5 | 2.5 (2) | C5—C6—N6—H6B | 10 |
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H4A···S2i | 0.88 | 2.75 | 3.5902 (12) | 159 |
N5—H5A···N4ii | 0.88 | 2.48 | 3.3379 (16) | 166 |
N6—H6A···N1iii | 0.88 | 2.23 | 3.1049 (15) | 176 |
N6—H6B···N5 | 0.88 | 2.48 | 2.8134 (16) | 103 |
Symmetry codes: (i) x−1/2, −y+1/2, z−1/2; (ii) −x, −y, −z+1; (iii) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C5H9N5S |
Mr | 171.23 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 120 |
a, b, c (Å) | 7.7824 (2), 8.9623 (3), 10.5078 (4) |
β (°) | 95.261 (2) |
V (Å3) | 729.81 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.38 |
Crystal size (mm) | 0.40 × 0.20 × 0.10 |
Data collection | |
Diffractometer | Bruker Nonius KappaCCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.863, 0.963 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9338, 1659, 1533 |
Rint | 0.024 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.073, 1.11 |
No. of reflections | 1659 |
No. of parameters | 101 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.32, −0.25 |
Computer programs: COLLECT (Nonius, 1999), DENZO (Otwinowski & Minor, 1997) and COLLECT, DENZO and COLLECT, OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997), OSCAIL and SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003), SHELXL97 and PRPKAPPA (Ferguson, 1999).
N1—C2 | 1.3337 (16) | C4—N4 | 1.3759 (16) |
C2—N3 | 1.3242 (16) | C5—N5 | 1.4292 (16) |
N3—C4 | 1.3573 (17) | C6—N6 | 1.3518 (16) |
C4—C5 | 1.3888 (18) | C2—S2 | 1.7694 (13) |
C5—C6 | 1.4104 (17) | S2—C21 | 1.7997 (13) |
C6—N1 | 1.3557 (16) | ||
C6—N1—C2 | 115.40 (11) | N1—C2—S2 | 112.03 (9) |
N1—C2—N3 | 129.07 (11) | N3—C2—S2 | 118.90 (9) |
C2—N3—C4 | 114.55 (11) | C2—S2—C21 | 101.71 (6) |
N3—C4—C5 | 123.14 (11) | C4—N4—H4A | 114.9 |
C4—C5—C6 | 116.22 (11) | C4—N4—H4B | 111.4 |
C5—C6—N1 | 121.60 (11) | H4A—N4—H4B | 118.1 |
N3—C4—N4 | 114.95 (11) | C5—N5—H5A | 112.1 |
C5—C4—N4 | 121.88 (12) | C5—N5—H5B | 113.7 |
C4—C5—N5 | 124.73 (11) | H5A—N5—H5B | 108.0 |
C6—C5—N5 | 119.04 (11) | C6—N6—H6A | 117.9 |
C5—C6—N6 | 121.56 (11) | C6—N6—H6B | 119.2 |
N1—C6—N6 | 116.82 (11) | H6A—N6—H6B | 119.7 |
N3—C4—N4—H4A | 163 | N3—C4—N4—H4B | 26 |
C4—C5—N5—H5A | −69 | C4—C5—N5—H5B | 54 |
C5—C6—N6—H6A | 170 | C5—C6—N6—H6B | 10 |
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H4A···S2i | 0.88 | 2.75 | 3.5902 (12) | 159 |
N5—H5A···N4ii | 0.88 | 2.48 | 3.3379 (16) | 166 |
N6—H6A···N1iii | 0.88 | 2.23 | 3.1049 (15) | 176 |
N6—H6B···N5 | 0.88 | 2.48 | 2.8134 (16) | 103 |
Symmetry codes: (i) x−1/2, −y+1/2, z−1/2; (ii) −x, −y, −z+1; (iii) −x+1, −y+1, −z+1. |
Acknowledgements
The X-ray data were collected at the EPSRC X-ray Crystallographic Service, University of Southampton, England. JC, ASR and MNM thank the Consejería de Innovación, Ciencia y Empresa (Junta de Andalucía, Spain) and the Universidad de Jaén for financial support.
References
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The title compound, (I), was prepared following a published procedure (Baddiley et al., 1943) for use as an intermediate in the synthesis of fused pyrimidine derivatives of potential biological interest.
Within the heterocyclic ring in the molecule of (I), the bond distances (Table 1) provide evidence for aromatic delocalization. The internal bond angles at atoms N1, N3 and C5 are all significantly less than the idealized value of 120°; those at N1 and N3 reflect the stereochemical influence of the lone pairs of electrons on these atoms, while that at C5 is influenced by the behaviour of the exocyclic amino group.
Each of the three independent C—NH2 units is, to a greater or lesser extent, pyramidal, and this is least marked for atom N6 and most marked for atom N5. The sums of the interbond angles at atoms N4, N5 and N6 deviate by 12, 26 and 3°, respectively, from 360°. Closely associated with the degree of pyramidalization at the amino N atoms is the variation in the exocyclic C—N bond distances (Table 1), with C5—N5 the longest of these and C6—N6 the shortest. The very long C5—N5 bond is also doubtless influenced by the rotation of the lone pair at N5 to be almost coplanar with the pyrimidine ring (Table 1, Fig. 1). The mean values (Allen et al., 1987) for C—S bonds of the types found in (I) are 1.773 and 1.789 Å, so that the difference between the C2—C2 and S2—C21 distances is larger than expected.
Both amino atoms N4 an N5 are, therefore, potential acceptors of hydrogen bonds, in addition to the ring atoms N1 and N3 and the sulfanyl atom S2, while each amino group is potentially a double donor of hydrogen bonds. In practice, there is one intramolecular N—H···N hydrogen bond (Table 2), with the highly pyramidal atom N5 as the acceptor, and each amino group acts as a single donor in intermolecular hydrogen bonds, with one ring N atom, one amino N atom and the S atom as the three acceptors (Table 2). Hence, two of the N—H bonds do not participate in any hydrogen-bond formation.
The three intermolecular hydrogen bonds generate a sheet containing three distinct types of ring, all centrosymmetric, but the formation of this rather complex sheet is readily analysed in terms of two straightforward one-dimensional substructures, one of then built from two independent N—H···N hydrogen bonds and the other built using only N—H···S hydrogen bonds.
Amino atom N5 in the molecule at (x, y, z) acts as hydrogen-bond donor to the pyramidal amino atom N4 in the molecule at (−x, −y, 1 − z), so forming a centrosymmetric R22(10) (Bernstein et al., 1995) ring centred at (0,0,1/2). Similarly, amino atom N6 at (x, y, z) acts as hydrogen-bond donor to ring atom N1 in the molecule at (1 − x, 1 − y, 1 − z), so forming a second ring motif, this time of R22(8) type, centred at (1/2, 1/2, 1/2). Propagation by inversion of these two hydrogen bonds then generates a chain of centrosymmetric rings running parallel to the [110] direction, with R22(8) rings centred at (n + 1/2, n + 1/2, 1/2) (n = zero or integer) and R22(10) rings centred at (n, n, 1/2) (n = zero or integer) (Fig. 2).
In the second one-dimensional substructure, amino atom N4 in the molecule at (x, y, z) acts as hydrogen-bond donor to the S atom in the molecule at (−1/2 + x, 1/2 − y, −1/2 + z), thereby forming a C(6) chain running parallel to the [101] direction and generated by the n-glide plane at y = 1/4 (Fig. 3).
The combination of the [110] and [101] chains generates a (111) sheet built from R22(8), R22(10) and R66(32) rings, all of them centrosymmetric (Fig. 4), and these sheets are linked by a centrosymmetric π–π stacking interaction. The pyrimidine rings of the molecules at (x, y, z) and (−x, 1 − y, 1 − z) are strictly parallel, with an interplanar spacing of 3.337 (2) Å. The ring-centroid separation is 3.649 (2) Å, corresponding to a near-ideal ring offset of 1.476 (2) Å. The combination of this interaction with the R22(8) rings generates a chain running parallel to the [100] direction, while the combination of the π-stacking interaction with the R22(10) rings generates a chain parallel to the [010] direction. In this manner, the (111) sheets are linked into a single three-dimensional structure.