organic compounds
3-(2-Chloroethyl)-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one
aDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA, bDepartment of Chemistry, Howard University, 525 College Street NW, Washington DC 20059, USA, cDepartment of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India, and dDepartment of Studies in Chemistry, Mangalore University, Mangalagangotri 574 199, India
*Correspondence e-mail: rbutcher99@yahoo.com
In the title molecule, C11H11ClN2O, the pyrido[1,2-a]pyrimidine ring system is planar (maximum deviation = 0.0148 Å) and the methyl C and carbonyl O atoms are nearly coplanar to it. The chloroethyl side chain is in a synclinal conformation, nearly orthogonal to the pyrimidine ring, with a dihedral angle between the chloroethyl side chain and the pyrimidine ring of 88.5 (1)°. Weak intermolecular C—H⋯N and C—H⋯Cl hydrogen bonds along with π–π interactions between the pyrimidine and pyridine rings [centroid–centroid distance is 3.538 (2) Å] form a three-dimensional network. The crystal is a racemic twin with a 0.68 (12):0.32 (12) domain ratio. MOPAC AM1 and density functional theory (DFT) theoretical calculations at the B3-LYP/6–311+G(d,p) level support these observations.
Related literature
For related structures, see: Blaton et al. (1995); Chen & He (2006); Elotmani et al. (2002); Jottier et al. (1992); Koval'chukova et al. (2004); Peeters et al. (1993); Ravikumar & Sridhar, (2006); Yu et al. (2007). For general background to heterofused pyrimidines, see: Baraldi et al. (2002); Bookser et al. (2005); Chen et al. (2004); La Motta et al. (2007); Gabbert & Giannini (1997); Goodacre et al. (2006); Hossain et al. (1997); Joseph & Burke (1993); Nikitin & Smirnov (1994); Sabnis & Rangnekar (1990); Wang et al. (2004); White et al. (2004). For the synthesis, see: Toche et al. (2008). For GAUSSIAN03 theoretical calculations, see: Becke (1988, 1993); Frisch et al. (2004); Hehre et al. (1986); Lee et al. (1988); Schmidt & Polik (2007).
Experimental
Crystal data
|
Data collection: CrysAlisPro (Oxford Diffraction, 2007); cell CrysAlisPro; data reduction: CrysAlisPro; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536809027548/ci2827sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536809027548/ci2827Isup2.hkl
The title compound was synthesized following the reported procedure (Toche et al. 2008). Pale yellow crystals of compound (I) were obtained by slow evaporation from ethyl acetate solution (m.p. 405–408 K). Analytical data: Found (calculated): C %: 59.28 (59.33); H%: 4.97 (4.98); N%: 12.54 (12.58).
All of the H atoms were placed in their calculated positions and then refined using the riding model with C—H = 0.95–0.99 Å, and with Uiso(H) = 1.18–1.50Ueq(C).
Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell
CrysAlis PRO (Oxford Diffraction, 2007); data reduction: CrysAlis PRO (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C11H11ClN2O | F(000) = 464 |
Mr = 222.67 | Dx = 1.451 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 2755 reflections |
a = 4.2546 (4) Å | θ = 4.8–32.6° |
b = 11.6274 (10) Å | µ = 0.35 mm−1 |
c = 20.604 (2) Å | T = 110 K |
V = 1019.27 (17) Å3 | Plate, colorless |
Z = 4 | 0.51 × 0.35 × 0.12 mm |
Oxford Diffraction Gemini R CCD diffractometer | 3089 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 2607 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.054 |
Detector resolution: 10.5081 pixels mm-1 | θmax = 32.6°, θmin = 4.9° |
ϕ and ω scans | h = −3→6 |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | k = −17→16 |
Tmin = 0.835, Tmax = 0.959 | l = −30→27 |
4613 measured reflections |
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)] = 0.065 | H-atom parameters constrained |
wR(F2) = 0.181 | w = 1/[σ2(Fo2) + (0.1108P)2 + 0.2652P] where P = (Fo2 + 2Fc2)/3 |
S = 1.11 | (Δ/σ)max = 0.001 |
3089 reflections | Δρmax = 0.99 e Å−3 |
138 parameters | Δρmin = −0.52 e Å−3 |
0 restraints | Absolute structure: Flack (1983), 1103 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.32 (12) |
C11H11ClN2O | V = 1019.27 (17) Å3 |
Mr = 222.67 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 4.2546 (4) Å | µ = 0.35 mm−1 |
b = 11.6274 (10) Å | T = 110 K |
c = 20.604 (2) Å | 0.51 × 0.35 × 0.12 mm |
Oxford Diffraction Gemini R CCD diffractometer | 3089 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | 2607 reflections with I > 2σ(I) |
Tmin = 0.835, Tmax = 0.959 | Rint = 0.054 |
4613 measured reflections |
R[F2 > 2σ(F2)] = 0.065 | H-atom parameters constrained |
wR(F2) = 0.181 | Δρmax = 0.99 e Å−3 |
S = 1.11 | Δρmin = −0.52 e Å−3 |
3089 reflections | Absolute structure: Flack (1983), 1103 Friedel pairs |
138 parameters | Absolute structure parameter: 0.32 (12) |
0 restraints |
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. |
x | y | z | Uiso*/Ueq | ||
Cl | 0.49448 (19) | 0.87358 (6) | 0.12093 (3) | 0.02056 (18) | |
O | 0.1937 (6) | 1.09071 (18) | 0.30555 (10) | 0.0240 (5) | |
N1 | −0.0403 (6) | 0.9961 (2) | 0.39118 (10) | 0.0150 (4) | |
N2 | 0.0097 (7) | 0.79306 (19) | 0.40322 (11) | 0.0172 (4) | |
C1 | 0.1541 (7) | 0.9982 (2) | 0.33357 (13) | 0.0151 (5) | |
C2 | −0.1616 (9) | 1.0994 (2) | 0.41318 (14) | 0.0207 (6) | |
H2A | −0.1116 | 1.1685 | 0.3909 | 0.025* | |
C3 | −0.3506 (8) | 1.1032 (3) | 0.46596 (15) | 0.0231 (6) | |
H3A | −0.4354 | 1.1744 | 0.4803 | 0.028* | |
C4 | −0.4212 (7) | 0.9999 (3) | 0.49970 (14) | 0.0211 (6) | |
H4A | −0.5530 | 1.0019 | 0.5369 | 0.025* | |
C5 | −0.3006 (8) | 0.8986 (2) | 0.47886 (13) | 0.0191 (5) | |
H5A | −0.3477 | 0.8299 | 0.5019 | 0.023* | |
C6 | −0.1033 (7) | 0.8935 (2) | 0.42262 (13) | 0.0147 (5) | |
C7 | 0.1973 (8) | 0.7917 (2) | 0.34977 (13) | 0.0155 (5) | |
C8 | 0.3087 (9) | 0.6735 (2) | 0.33069 (16) | 0.0239 (6) | |
H8A | 0.2581 | 0.6188 | 0.3653 | 0.036* | |
H8B | 0.5366 | 0.6750 | 0.3238 | 0.036* | |
H8C | 0.2038 | 0.6499 | 0.2905 | 0.036* | |
C9 | 0.2748 (7) | 0.8891 (2) | 0.31499 (12) | 0.0146 (5) | |
C10 | 0.4766 (9) | 0.8869 (2) | 0.25437 (12) | 0.0182 (5) | |
H10A | 0.6268 | 0.8220 | 0.2567 | 0.022* | |
H10B | 0.5983 | 0.9592 | 0.2511 | 0.022* | |
C11 | 0.2671 (7) | 0.8733 (3) | 0.19491 (13) | 0.0201 (5) | |
H11A | 0.1130 | 0.9371 | 0.1936 | 0.024* | |
H11B | 0.1489 | 0.8002 | 0.1982 | 0.024* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl | 0.0233 (3) | 0.0253 (3) | 0.0132 (3) | −0.0031 (3) | 0.0030 (3) | −0.0001 (2) |
O | 0.0323 (13) | 0.0185 (9) | 0.0214 (10) | −0.0029 (9) | 0.0024 (10) | 0.0048 (8) |
N1 | 0.0188 (11) | 0.0144 (8) | 0.0118 (9) | 0.0013 (9) | −0.0009 (9) | 0.0005 (7) |
N2 | 0.0200 (10) | 0.0157 (8) | 0.0160 (10) | −0.0002 (12) | −0.0001 (11) | 0.0019 (7) |
C1 | 0.0168 (12) | 0.0163 (11) | 0.0122 (11) | −0.0028 (11) | −0.0005 (10) | 0.0002 (9) |
C2 | 0.0286 (15) | 0.0163 (11) | 0.0173 (13) | 0.0039 (12) | 0.0000 (12) | −0.0001 (9) |
C3 | 0.0259 (15) | 0.0235 (13) | 0.0198 (14) | 0.0058 (13) | −0.0013 (12) | −0.0054 (10) |
C4 | 0.0198 (14) | 0.0300 (14) | 0.0135 (12) | 0.0026 (12) | 0.0017 (10) | −0.0019 (10) |
C5 | 0.0196 (13) | 0.0234 (12) | 0.0142 (12) | −0.0029 (12) | 0.0018 (11) | 0.0028 (10) |
C6 | 0.0178 (11) | 0.0146 (11) | 0.0118 (11) | −0.0013 (9) | −0.0029 (9) | 0.0017 (8) |
C7 | 0.0194 (13) | 0.0125 (10) | 0.0146 (11) | 0.0001 (11) | −0.0022 (11) | −0.0001 (9) |
C8 | 0.0282 (16) | 0.0167 (11) | 0.0267 (15) | 0.0015 (13) | 0.0028 (14) | −0.0022 (10) |
C9 | 0.0133 (11) | 0.0183 (11) | 0.0124 (12) | −0.0020 (10) | −0.0004 (9) | 0.0005 (9) |
C10 | 0.0164 (12) | 0.0245 (12) | 0.0138 (11) | −0.0008 (13) | 0.0011 (10) | 0.0003 (9) |
C11 | 0.0178 (12) | 0.0305 (13) | 0.0119 (11) | −0.0035 (12) | 0.0019 (10) | −0.0012 (11) |
Cl—C11 | 1.805 (3) | C5—C6 | 1.432 (4) |
O—C1 | 1.232 (3) | C5—H5A | 0.95 |
N1—C2 | 1.383 (4) | C7—C9 | 1.381 (4) |
N1—C6 | 1.384 (3) | C7—C8 | 1.505 (4) |
N1—C1 | 1.447 (3) | C8—H8A | 0.98 |
N2—C6 | 1.325 (3) | C8—H8B | 0.98 |
N2—C7 | 1.360 (4) | C8—H8C | 0.98 |
C1—C9 | 1.421 (4) | C9—C10 | 1.516 (4) |
C2—C3 | 1.353 (5) | C10—C11 | 1.523 (4) |
C2—H2A | 0.95 | C10—H10A | 0.99 |
C3—C4 | 1.420 (5) | C10—H10B | 0.99 |
C3—H3A | 0.95 | C11—H11A | 0.99 |
C4—C5 | 1.355 (4) | C11—H11B | 0.99 |
C4—H4A | 0.95 | ||
C2—N1—C6 | 121.5 (2) | N2—C7—C8 | 114.0 (2) |
C2—N1—C1 | 117.9 (2) | C9—C7—C8 | 122.6 (3) |
C6—N1—C1 | 120.6 (2) | C7—C8—H8A | 109.5 |
C6—N2—C7 | 117.9 (2) | C7—C8—H8B | 109.5 |
O—C1—C9 | 127.1 (3) | H8A—C8—H8B | 109.5 |
O—C1—N1 | 118.5 (3) | C7—C8—H8C | 109.5 |
C9—C1—N1 | 114.4 (2) | H8A—C8—H8C | 109.5 |
C3—C2—N1 | 120.9 (3) | H8B—C8—H8C | 109.5 |
C3—C2—H2A | 119.5 | C7—C9—C1 | 120.4 (2) |
N1—C2—H2A | 119.5 | C7—C9—C10 | 123.3 (2) |
C2—C3—C4 | 119.4 (3) | C1—C9—C10 | 116.3 (2) |
C2—C3—H3A | 120.3 | C9—C10—C11 | 109.5 (3) |
C4—C3—H3A | 120.3 | C9—C10—H10A | 109.8 |
C5—C4—C3 | 120.0 (3) | C11—C10—H10A | 109.8 |
C5—C4—H4A | 120.0 | C9—C10—H10B | 109.8 |
C3—C4—H4A | 120.0 | C11—C10—H10B | 109.8 |
C4—C5—C6 | 120.9 (3) | H10A—C10—H10B | 108.2 |
C4—C5—H5A | 119.5 | C10—C11—Cl | 111.4 (2) |
C6—C5—H5A | 119.5 | C10—C11—H11A | 109.3 |
N2—C6—N1 | 123.3 (2) | Cl—C11—H11A | 109.3 |
N2—C6—C5 | 119.6 (2) | C10—C11—H11B | 109.3 |
N1—C6—C5 | 117.2 (2) | Cl—C11—H11B | 109.3 |
N2—C7—C9 | 123.4 (2) | H11A—C11—H11B | 108.0 |
C2—N1—C1—O | −2.5 (4) | C4—C5—C6—N2 | −179.6 (3) |
C6—N1—C1—O | 177.1 (3) | C4—C5—C6—N1 | 0.5 (4) |
C2—N1—C1—C9 | 178.7 (3) | C6—N2—C7—C9 | −0.1 (4) |
C6—N1—C1—C9 | −1.8 (4) | C6—N2—C7—C8 | −178.8 (3) |
C6—N1—C2—C3 | −0.9 (5) | N2—C7—C9—C1 | −1.0 (4) |
C1—N1—C2—C3 | 178.6 (3) | C8—C7—C9—C1 | 177.6 (3) |
N1—C2—C3—C4 | 1.0 (5) | N2—C7—C9—C10 | −178.2 (3) |
C2—C3—C4—C5 | −0.3 (5) | C8—C7—C9—C10 | 0.4 (5) |
C3—C4—C5—C6 | −0.5 (5) | O—C1—C9—C7 | −176.9 (3) |
C7—N2—C6—N1 | 0.2 (4) | N1—C1—C9—C7 | 1.8 (4) |
C7—N2—C6—C5 | −179.7 (3) | O—C1—C9—C10 | 0.6 (4) |
C2—N1—C6—N2 | −179.7 (3) | N1—C1—C9—C10 | 179.3 (2) |
C1—N1—C6—N2 | 0.8 (4) | C7—C9—C10—C11 | 90.7 (3) |
C2—N1—C6—C5 | 0.2 (4) | C1—C9—C10—C11 | −86.6 (3) |
C1—N1—C6—C5 | −179.3 (3) | C9—C10—C11—Cl | 178.6 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5A···N2i | 0.95 | 2.50 | 3.394 (3) | 157 |
C2—H2A···Clii | 0.95 | 2.90 | 3.559 (3) | 128 |
Symmetry codes: (i) x−1/2, −y+3/2, −z+1; (ii) −x, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C11H11ClN2O |
Mr | 222.67 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 110 |
a, b, c (Å) | 4.2546 (4), 11.6274 (10), 20.604 (2) |
V (Å3) | 1019.27 (17) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.35 |
Crystal size (mm) | 0.51 × 0.35 × 0.12 |
Data collection | |
Diffractometer | Oxford Diffraction Gemini R CCD diffractometer |
Absorption correction | Multi-scan (CrysAlis RED; Oxford Diffraction, 2007) |
Tmin, Tmax | 0.835, 0.959 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4613, 3089, 2607 |
Rint | 0.054 |
(sin θ/λ)max (Å−1) | 0.759 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.065, 0.181, 1.11 |
No. of reflections | 3089 |
No. of parameters | 138 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.99, −0.52 |
Absolute structure | Flack (1983), 1103 Friedel pairs |
Absolute structure parameter | 0.32 (12) |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5A···N2i | 0.95 | 2.50 | 3.394 (3) | 157 |
C2—H2A···Clii | 0.95 | 2.90 | 3.559 (3) | 128 |
Symmetry codes: (i) x−1/2, −y+3/2, −z+1; (ii) −x, y+1/2, −z+1/2. |
Acknowledgements
QNMHA thanks the University of Mysore for use of its research facilities. RJB acknowledges the NSF MRI program (grant No. CHE-0619278) for funds to purchase an X-ray diffractometer.
References
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Heterofused pyrimidines exhibit promising antiviral (Hossain et al. 1997), antibacterial (Sabnis & Rangnekar, 1990), anti-AIDS (Joseph & Burke, 1993), and antinociceptive (Bookser et al. 2005) activities. Fused pyrimidines are extensively used in neurology, particularly in the treatment of neurodegenerative disorders such as Parkinson's disease (Baraldi et al. 2002), antianxiety disorders (Goodacre et al. 2006) and depression (Chen et al. 2004). Fused pyrimidines are selective inhibitors for multidrug resistance (MDR) (Wang et al. 2004). A review on the synthesis, chemical and biological properties of pyrido[1,2-a]pyrimidines is described (Nikitin & Smirnov, 1994). Pyrido[1,2-a]pyrimidin-4-one derivatives as a novel class of selective aldose reductase inhibitors exhibiting antioxidant activity has been reported (La Motta et al. 2007). The synthesis and anticonvulsant evaluation of some new 2-substituted-3-arylpyrido[2,3-d]pyrimidinones have also been reported (White et al. 2004). The crystal structures of 3-{2-[4-(6-fluoro-1,2-benzisoxazol-3-yl)piperidino]ethyl}-6,7,8,9- tetrahydro-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (risperidone) (Peeters et al. 1993), 3-{2-[4-(4-fluorobenzoyl)piperidino]ethyl}-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (Pirenperone) (Blaton et al. 1995), 5-methyl-2-morpholino-3-p-tolyl-8,9,10,11-tetrahydro-2-benzothieno[2', 3':6,5]pyrido[4,3-d]pyrimidin-4(3H)-one (Chen & He, 2006), 3-{2-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]ethyl}-2,9- dimethyl-4H-pyrido[1,2-a]pyrimidin-4-one (Ocaperidone) (Jottier et al. 1992), 2-methyl-3-(3-methyl-1H-pyrazol-5-yl)pyrido[1,2-a]pyrimidin-4-one (Elotmani et al. 2002), 2-methyl-3-chloro-9-hydroxypyrido[1,2-a]pyrimidin-4-one and bis(2-methyl-3-chloro-9-hydroxypyrido[1,2-a]pyrimidin-4-onium) perchlorate (Koval'chukova et al. 2004), 3-(2-chloroethyl)-2-methyl-4-oxo-6,7,8,9-tetrahydro-4H-pyrido[1,2-a] pyrimidin-1-ium chloride (Ravikumar & Sridhar, 2006) and 9-(4-methoxybenzoyl)-1,2,3,4-tetrahydro-6H-pyrido[1,2-a]pyrimidin-6-one (Yu et al. 2007) have also been reported.
The title compound, (I), is an intermediate in the synthesis of risperidone, which is a potent antipsychotic agent, especially useful for treating schizophrenia (Gabbert & Giannini, 1997). In view of the importance of (I), the present paper describes its crystal structure.
The overall molecular geometry of (I), including bond distances and angles, is in good agreement with related structures (Blaton et al. 1995; Jottier et al. 1992; Peeters et al. 1993; Ravikumar & Sridhar, 2006). It consists of a pyridine ring fused to a substituted pyrimidine ring creating a planar ring system (maximum deviation, C1, = -0.0148Å) with the methyl C and carbonyl O atoms nearly coplanar to the pyrimidine ring (Torsion angles C1-C9-C7-C8 = 177.6 (3)° ; C2-N1-C1-O = -2.5 (4)° (Fig. 1). The sum of the angles aroumd N1 is 360.0 (5)° indicating sp2 hybridization. The chloroethyl side chain is in a synclinal (-sc) conformation (C1—C9—C10—C11 torsion angle = -86.6 (3)°), nearly orthogonal to the pyrimidine ring, with a dihedral angle separation between the C10/C11/Cl group and the pyrimidine ring of 88.5 (1)°.
While no classic hydrogen bonds are observed, a weak intermolecular hydrogen bond interaction exists between atom C5 from the pyridine ring and N2 from a nearby pyrimidine ring (Table 1 and Fig. 2). In addition, a weak intermolecular interaction between atom C2 from the pyrimidine ring and Cl from the substituted pyrimidine group also occurs, each influencing crystal packing and, therefore, resulting in a three-dimensional network (Fig. 2). In addition, π-π interactions between N1/C1/C9/C7/N2/C6 (centroid Cg1) and N1/C2-C6 (centroid Cg2) rings of molecules at (x, y, z) and (1+x, y, z), with a Cg1···Cg2 distance of 3.538 (2) Å, provide additional stability to the crystal packing. The crystal is a racemic twin with domains of 0.68 (12) and 0.32 (12).
In support of these observations, a MOPAC AM1 (Schmidt & Polik, 2007) and density functional theory (DFT) geometry optimized theoretical calculation (Schmidt & Polik, 2007) with the GAUSSIAN03 program package (Frisch et al. 2004) employing the B3-LYP (Becke 3 parameter Lee-Yang-Parr) exchange correlation functional, which combines the hybrid exchange functional of Becke (Becke, 1988, 1993) with the gradient-correlation functional of Lee, Yang and Parr (Lee et al. 1988) and the 6–311+G(d,p) basis set (Hehre et al. 1986), was performed on (I) utilizing starting geometries taken from the X-ray refinement data. In both calculations the resulting bond distances and angles remained relatively constant. However, the C9—C10—C11—Cl torsion angle decreased by 3.2 (1)° to 175.4 (3)° (MOPAC) and 0.07° to 178.5 (7)° (DFT) and the dihedral angle between the C10/C11/Cl group and the pyrimidine ring decreased by 2.3 (8)° to 86.1 (3)° (MOPAC) and by 8.3 (6)° to 80.1 (5)° (DFT), respectively.
In summary, it is clear that the collection of weak intermolecular hydrogen bond interactions and π-π intermolecular interactions do play a role in stabilizing crystal packing of (I).