organic compounds
N—H⋯N hydrogen bonding in 4,6-diphenyl-2-pyrimidinylamine isolated from the plant Justicia secunda (Acanthaceae)
aSchool of Chemical Sciences, Dublin City University, Dublin 9, Ireland, bDepartment of Chemistry, B.E. College (Deemed University), Botanic Garden, Howrah 711 103, West Bengal, India, and cDepartment of Chemistry, IIT, Kharagpur, West Bengal, India
*Correspondence e-mail: john.gallagher@dcu.ie
The title compound, C16H13N3, isolated from Justicia secunda (Acanthaceae), comprises two molecules (which differ slightly in conformation) in the of P. Intermolecular Namino—H⋯Npyrm interactions (Npyrm is a pyrimidine ring N atom) involve only one of the two donor amino H atoms and pyrimidine N atoms per molecule, forming dimeric units via (8) rings, with N⋯N distances of 3.058 (2) and 3.106 (3) Å, and N—H⋯N angles of 172.7 (18) and 175.8 (17)°. The dimers are linked by C—H⋯π(arene) contacts, with an H⋯centroid distance of 2.77 Å and a C—H⋯centroid angle of 141°.
Comment
The title compound, 4,6-diphenyl-2-pyrimidinylamine, (I), was isolated as a natural product from the plant Justicia secunda (Acanthaceae) collected in Trinidad, West Indies. The parent structure, viz. 4,6-diphenyl-1,2-dihydropyrimidine, has been reported (Weis & Vishkautsan, 1985), but the coordinates are not in the Cambridge Structural Database (CSD; Allen, 2002) for comparison with (I) (CSD refcode DEZMEA for parent compound).
Compound (I) crystallizes in P (No. 2) with two independent molecules, A and B, in the which differ slightly in conformation (Fig. 1). Bond lengths and angles are largely unexceptional and in accord with anticipated values (Orpen et al., 1994); selected dimensions are given in Table 1. The central C—N bond lengths range from 1.340 (2) to 1.346 (2) Å, while the aromatic C—C distances are in the range 1.381 (3)–1.387 (3) Å. Torsion-angle differences are evident from analysis of the N1—C4—C21—C26 angles, which are −29.8 (3) and 36.5 (3)° in molecules A and B, respectively (Table 1). Even more dramatic is the difference in dihedral angles between the C11–C16 and C21–C26 planes, which are 52.15 (7) and 31.79 (7)° in molecules A and B, respectively. The weighted (unit weight) r.m.s. fit for the superposition of the non-H atoms in both molecules is 0.65 Å (0.55 Å) (Spek, 2003).
Molecules A and B associate in pairs through Namino—H⋯Npyrm intermolecular interactions (Npyrm is a pyrimidine ring N atom), which only involve two of the four amino donor H atoms and N pyrimidine acceptors per A/B pair. The N⋯N distances are 3.058 (2) and 3.106 (3) Å, and the N—H⋯N angles are 172.7 (18) and 175.8 (17)° (Table 2), thus forming a hydrogen-bonded ring with an (8) graph set similar to that observed in centrosymmetric carboxylic acid pairs. A C—H⋯π(arene) contact from C12A—H12A to the C21A–C26A ring links the dimeric units into a dimer of dimers, which is further augmented via a contact from C26A—H26A group to the N1A/N2A/C1A–C4A ring into a one-dimensional stack (Fig. 2 and Table 2). These are the only contacts of note in the structure of (I), apart from the N—H⋯N hydrogen bonding.
Examination of the structure of (I) for interactions involving N2A/N2B reveals that, along the b direction, atom H24A (a potential donor) is 2.99 Å from N2Ai, with a C24A—H24A⋯N2Ai angle of 163° [symmetry code: (i) x, 1 + y, z]. Likewise, the closest N⋯H intermolecular distance involving atom N2B is N2B⋯H24Bi of 3.08 Å, with an N2B⋯H24Bi—C24Bi angle of 155°. Neither of these interactions constitutes a hydrogen bond.
Inspection of Fig. 2 shows the dimeric units in a two-dimensional through the parallel to the [101] plane. In the a more efficient packing could involve dimer formation about inversion centres, which would necessitate rotation of the phenyl rings to align and fulfil symmetry requirements, e.g. the phenyl rings have interplanar angles of 52.12 (7) and 31.79 (7)° in molecules A and B, respectively. The reason why this does not arise is due to the initial hydrogen-bonded dimer formation. Utilization of only half of the N—H⋯N donor/acceptors per A/B hydrogen-bonded dimer prevents the N2A/N2B pair from forming hydrogen bonds, as potential (C)N—H⋯N donor/acceptor pairs cannot approach one another and because of the concurrent formation of unfavourable H⋯H contacts. Interactions in (I) are therefore limited to the two N—H⋯N interactions per A/B pair.
Ab initio calculations on (I) gave results similar to those observed in molecules A and B. Calculations were undertaken at the 6-31+G(d) level in the search for a local minimum for comparison with molecules A and B, using GAUSSIAN03 (Frisch et al., 2003). The N—C—C—C torsion angles are 27.55°, similar to the value of −29.8 (3)° found in molecule A. The H2N—C distance is 1.362 Å and the N—C—N angle is 116.79° [range 116.15 (17)–117.05 (17)° in molecule A]. Overall, the calculated results resemble those of molecule A. However, no attempt was made to find the global minimum in the system.
Crystal structures with more than one molecule present in the ; Gallagher et al., 1998). Recently, Görbitz (2002, 2003) has reported on dipeptide derivatives, e.g. two forms of L-valyl-L-phenylalanine trihydrate (P21, Z = 16, Z′ = 8; P212121, Z = 4, Z′ = 1) and L-methionyl-L-alanine (P61, Z = 42, Z′ = 7), which provide rare examples of systems with Z′ = 8 and 7 molecules in their respective asymmetric units, in contrast with Z′ = 2, which is not uncommon. Analysis of the CSD (February 2004, version 5.25; Allen, 2002) reveals a total of 65 935 crystal structures in P (No. 2) (and equivalents with no restrictions), 7625 with Z′ > 1, some 11.6% of the total, and 6775 with Z′ = 2. No attempt was made to examine incorrect space groups.
are not uncommon (Steiner, 2000Experimental
The plant Justicia secunda (Acanthaceae) was collected in Trinidad, West Indies, and dried at 308–313 K. A large quantity (1 kg) of this dried powdered plant (except root and flower/fruit) was placed in a large separating funnel and soaked in acetone overnight. The acetone layer was collected and the process repeated until the acetone layer became faintly green in colour. The combined acetone extracts were evaporated and the dry mass extracted with benzene. The benzene-soluble fraction was dried, dissolved in the minimum amount of dry warm CHCl3 and spread over activated silica gel in a sintered glass Buchner funnel. It was then eluted with 50 ml portions of benzene and then a CHCl3–benzene mixture (1:4) under a slight vacuum. The fraction obtained from CHCl3–benzene (1:4) was collected and the solvent removed. It was then subjected to with light petroleum (b.p. 313–333 K) and benzene. After concentration, the benzene fraction yielded gummy crystals upon refrigeration. These crystals were further purified by preparative to afford the pure title compound, (I), as well shaped crystals from CHCl3.
Crystal data
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Data collection
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Refinement
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Compound (I) crystallized in the triclinic system, the permitting P1 or P; P was assumed and confirmed by the analysis. All H atoms bonded to C atoms were treated as riding atoms, with C—H distances of 0.93 Å, while the four amino H atoms were refined with isotropic displacement parameters, giving N—H distances in the range 0.89 (2)–0.91 (2) Å.
Data collection: XSCANS (Siemens, 1996); cell XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and PLATON (Spek, 2003); software used to prepare material for publication: NRCVAX96 (Gabe et al., 1989), SHELXL97 and PREP8 (Ferguson, 1998).
Supporting information
10.1107/S0108270104002902/gd1292sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S0108270104002902/gd1292Isup2.hkl
The plant Justicia Secunda (Acanthaceae) was collected from Trinidad, West Indies, and dried at 308–313 K. A large quantity (1 kg) of this dried powdered plant (except root and flower/fruit) was placed in a large separating funnel and soaked in acetone overnight. The acetone layer was collected and the process was repeated until the acetone layer became faint green in colour. The combined acetone extracts were evaporated and the dry mass was extracted with benzene. The benzene-soluble fraction was dried, dissolved in the minimum amount of dry warm CHCl3 and spread over activated silica gel in a sintered glass Buchner funnel. It was then eluted with 50 ml portions of benzene and then a CHCl3:benzene mixture (1:4) under a slight vacuum. The fraction obtained from CHCl3:benzene (1:4) was collected and the solvent removed. It was then subjected to
with light petroleum (b.p. 313–333 K) and benzene. After concentration, the benzene fraction yielded gummy crystals upon refrigeration. These crystals were further purified by preparative to afford the pure compound, (I), as well shaped crystals from CHCl3.Compound (I) crystallized in the triclinic system, 1; P1 was assumed, and confirmed by the analysis. All H atoms bonded to C were treated as riding atoms, with a C—H distance of 0.93 Å, while the four amino H atoms were refined with isotropic displacement parameters, giving N—H distances in the range 0.89 (2)–0.91 (2) Å.
P1 or PData collection: XSCANS (Siemens, 1996); cell
XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and PLATON (Spek, 2003); software used to prepare material for publication: NRCVAX96 (Gabe et al., 1989), SHELXL97 and PREP8 (Ferguson, 1998).Fig. 1. A view of molecules in (I) as a hydrogen-bonded dimer, with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. | |
Fig. 2. A view of the dimeric units in (I) linked by C—H···π(arene) interactions. Atoms are depicted as small spheres of an arbitrary size. The ten phenyl-ring H atoms in molecule B have been omitted for clarity. The centroid labels are as defined in Table 2. Atoms labelled with an asterisk (*) or a prime (') are at symmetry positions (i) and (ii), respectively, as given in Table 2. |
C16H13N3 | Z = 4 |
Mr = 247.29 | F(000) = 520 |
Triclinic, P1 | Dx = 1.279 Mg m−3 |
Hall symbol: -P 1 | Melting point: 408 K |
a = 7.8263 (9) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 10.8009 (9) Å | Cell parameters from 74 reflections |
c = 15.7878 (12) Å | θ = 5.4–17.9° |
α = 83.457 (5)° | µ = 0.08 mm−1 |
β = 77.039 (7)° | T = 294 K |
γ = 82.326 (7)° | Plate, colourless |
V = 1284.0 (2) Å3 | 0.50 × 0.30 × 0.08 × not measured (radius) mm |
Siemens P4 diffractometer | Rint = 0.019 |
Radiation source: X-ray tube | θmax = 25.0°, θmin = 1.9° |
Graphite monochromator | h = −9→1 |
ω/2θ scans | k = −12→12 |
5607 measured reflections | l = −18→18 |
4529 independent reflections | 4 standard reflections every 296 reflections |
2987 reflections with I > 2σ(I) | intensity decay: 1% |
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)] = 0.047 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.119 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | w = 1/[σ2(Fo2) + (0.055P)2 + 0.13P] where P = (Fo2 + 2Fc2)/3 |
4529 reflections | (Δ/σ)max = 0.001 |
359 parameters | Δρmax = 0.18 e Å−3 |
0 restraints | Δρmin = −0.17 e Å−3 |
C16H13N3 | γ = 82.326 (7)° |
Mr = 247.29 | V = 1284.0 (2) Å3 |
Triclinic, P1 | Z = 4 |
a = 7.8263 (9) Å | Mo Kα radiation |
b = 10.8009 (9) Å | µ = 0.08 mm−1 |
c = 15.7878 (12) Å | T = 294 K |
α = 83.457 (5)° | 0.50 × 0.30 × 0.08 × not measured (radius) mm |
β = 77.039 (7)° |
Siemens P4 diffractometer | Rint = 0.019 |
5607 measured reflections | 4 standard reflections every 296 reflections |
4529 independent reflections | intensity decay: 1% |
2987 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.047 | 0 restraints |
wR(F2) = 0.119 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | Δρmax = 0.18 e Å−3 |
4529 reflections | Δρmin = −0.17 e Å−3 |
359 parameters |
Geometry. Gaussian '03 reference ====================== M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, J. A. Montgomery, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morokuma, G. A. Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W. Wong, C. Gonzalez, and J. A. Pople, Gaussian, Inc., Pittsburgh PA, 2003. Torsional angles #=============== Dihedral angle NCCC −29.81 (26) N1A–C4A–C21A–C26A −36.46 (27) N1B–C4B–C21B–C26B 154.15 (18) N2A–C2A–C11A–C16A −152.50 (19) N2B–C2B–C11B–C16B Dihedral angle CCCC 106.98 (22) C12A–C11A–C21A–C22A −170.55 (24) C12B–C11B–C21B–C22B 1.34 (32) C14A–C2A–C4A–C24A −1.40 (34) C14B–C2B–C4B–C24B Mean plane data ex-SHELXL97 for molecule (I) ############################################ Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) -5.8182(0.0047)x + 6.0658(0.0079)y − 2.5280(0.0137)z = 2.8570(0.0128) * 0.0067 (0.0013) C11A * −0.0072 (0.0014) C12A * 0.0012 (0.0015) C13A * 0.0053 (0.0016) C14A * −0.0057 (0.0016) C15A * −0.0003 (0.0015) C16A Rms deviation of fitted atoms = 0.0051 7.2778(0.0022)x − 1.3368(0.0077)y + 7.0895(0.0113)z = 4.0232(0.0104) Angle to previous plane (with approximate e.s.d.) = 29.31 (8) * 0.0120 (0.0013) C1A * −0.0045 (0.0013) C2A * 0.0136 (0.0013) C3A * −0.0108 (0.0013) C4A * −0.0020 (0.0012) N1A * −0.0082 (0.0012) N2A 0.0009 (0.0029) N4A Rms deviation of fitted atoms = 0.0095 5.4509(0.0048)x + 0.0533(0.0089)y + 13.2611(0.0074)z = 8.3696(0.0127) Angle to previous plane (with approximate e.s.d.) = 30.48 (8) * −0.0048 (0.0013) C21A * 0.0072 (0.0014) C22A * −0.0026 (0.0016) C23A * −0.0045 (0.0015) C24A * 0.0068 (0.0015) C25A * −0.0021 (0.0014) C26A Rms deviation of fitted atoms = 0.0050 −5.8182(0.0047)x + 6.0658(0.0079)y − 2.5280(0.0137)z = 2.8570(0.0128) Angle to previous plane (with approximate e.s.d.) = 52.15 (7) * 0.0067 (0.0013) C11A * −0.0072 (0.0014) C12A * 0.0012 (0.0015) C13A * 0.0053 (0.0016) C14A * −0.0057 (0.0016) C15A * −0.0003 (0.0015) C16A Rms deviation of fitted atoms = 0.0051 −6.9426(0.0035)x + 3.6543(0.0097)y − 2.9128(0.0142)z = 2.8663(0.0190) Angle to previous plane (with approximate e.s.d.) = 14.50 (11) * −0.0005 (0.0014) C11B * 0.0078 (0.0015) C12B * −0.0089 (0.0017) C13B * 0.0028 (0.0017) C14B * 0.0045 (0.0016) C15B * −0.0056 (0.0015) C16B Rms deviation of fitted atoms = 0.0058 7.5633(0.0019)x + 0.8967(0.0086)y + 7.2350(0.0118)z = 6.2720(0.0176) Angle to previous plane (with approximate e.s.d.) = 27.74 (6) * −0.0114 (0.0014) C1B * 0.0099 (0.0014) C2B * −0.0051 (0.0014) C3B * −0.0071 (0.0013) C4B * 0.0153 (0.0013) N1B * −0.0015 (0.0013) N2B −0.0378 (0.0033) N4B Rms deviation of fitted atoms = 0.0095 −7.1932(0.0030)x − 0.2947(0.0097)y + 2.7303(0.0144)z = 5.5969(0.0173) Angle to previous plane (with approximate e.s.d.) = 37.24 (5) * −0.0060 (0.0014) C21B * −0.0018 (0.0016) C22B * 0.0059 (0.0017) C23B * −0.0022 (0.0017) C24B * −0.0056 (0.0016) C25B * 0.0097 (0.0015) C26B Rms deviation of fitted atoms = 0.0058 −6.9426(0.0035)x + 3.6543(0.0097)y − 2.9128(0.0142)z = 2.8663(0.0190) Angle to previous plane (with approximate e.s.d.) = 31.79 (7) * −0.0005 (0.0014) C11B * 0.0078 (0.0015) C12B * −0.0089 (0.0017) C13B * 0.0028 (0.0017) C14B * 0.0045 (0.0016) C15B * −0.0056 (0.0015) C16B Rms deviation of fitted atoms = 0.0058 |
x | y | z | Uiso*/Ueq | ||
N1A | 0.2906 (2) | 0.98395 (14) | 0.45438 (9) | 0.0400 (4) | |
N2A | 0.1831 (2) | 0.79337 (13) | 0.52793 (10) | 0.0414 (4) | |
N4A | 0.3263 (3) | 0.80359 (18) | 0.38421 (12) | 0.0534 (5) | |
C1A | 0.2662 (2) | 0.86235 (17) | 0.45848 (12) | 0.0398 (5) | |
C2A | 0.1229 (2) | 0.85133 (16) | 0.60125 (11) | 0.0379 (4) | |
C3A | 0.1455 (3) | 0.97573 (17) | 0.60400 (12) | 0.0431 (5) | |
C4A | 0.2277 (2) | 1.04082 (16) | 0.52846 (12) | 0.0380 (4) | |
C11A | 0.0241 (2) | 0.77766 (16) | 0.67766 (12) | 0.0409 (5) | |
C12A | −0.0673 (3) | 0.68216 (17) | 0.66437 (13) | 0.0457 (5) | |
C13A | −0.1672 (3) | 0.61669 (19) | 0.73382 (14) | 0.0562 (6) | |
C14A | −0.1751 (3) | 0.6447 (2) | 0.81763 (15) | 0.0627 (6) | |
C15A | −0.0830 (3) | 0.7372 (2) | 0.83208 (14) | 0.0619 (6) | |
C16A | 0.0159 (3) | 0.80401 (19) | 0.76258 (13) | 0.0534 (5) | |
C21A | 0.2457 (2) | 1.17614 (16) | 0.52505 (11) | 0.0377 (4) | |
C22A | 0.1199 (3) | 1.25391 (17) | 0.57738 (12) | 0.0468 (5) | |
C23A | 0.1299 (3) | 1.38105 (19) | 0.57199 (14) | 0.0562 (6) | |
C24A | 0.2672 (3) | 1.4328 (2) | 0.51521 (15) | 0.0595 (6) | |
C25A | 0.3950 (3) | 1.3568 (2) | 0.46384 (14) | 0.0569 (6) | |
C26A | 0.3841 (3) | 1.22946 (18) | 0.46815 (12) | 0.0464 (5) | |
N4B | 0.4727 (3) | 1.10820 (19) | 0.27553 (13) | 0.0658 (6) | |
N1B | 0.5567 (2) | 0.91786 (14) | 0.21871 (10) | 0.0446 (4) | |
N2B | 0.6145 (2) | 1.11152 (14) | 0.13196 (10) | 0.0487 (4) | |
C1B | 0.5502 (3) | 1.04366 (18) | 0.20622 (12) | 0.0458 (5) | |
C2B | 0.6895 (3) | 1.04656 (17) | 0.06315 (12) | 0.0426 (5) | |
C3B | 0.6976 (3) | 0.91746 (17) | 0.06856 (12) | 0.0464 (5) | |
C4B | 0.6286 (2) | 0.85520 (17) | 0.14819 (12) | 0.0422 (5) | |
C11B | 0.7655 (3) | 1.12079 (17) | −0.01874 (12) | 0.0443 (5) | |
C12B | 0.8234 (3) | 1.23583 (19) | −0.01535 (14) | 0.0543 (6) | |
C13B | 0.8942 (3) | 1.3053 (2) | −0.09111 (16) | 0.0643 (6) | |
C14B | 0.9032 (3) | 1.2623 (2) | −0.17068 (16) | 0.0689 (7) | |
C15B | 0.8456 (3) | 1.1497 (2) | −0.17527 (14) | 0.0641 (6) | |
C16B | 0.7778 (3) | 1.0784 (2) | −0.09973 (13) | 0.0533 (5) | |
C21B | 0.6333 (3) | 0.71662 (17) | 0.15886 (12) | 0.0444 (5) | |
C22B | 0.6101 (3) | 0.65153 (19) | 0.09227 (14) | 0.0573 (6) | |
C23B | 0.6179 (3) | 0.5226 (2) | 0.10172 (17) | 0.0677 (7) | |
C24B | 0.6505 (3) | 0.4568 (2) | 0.17753 (17) | 0.0679 (7) | |
C25B | 0.6736 (3) | 0.5198 (2) | 0.24393 (15) | 0.0617 (6) | |
C26B | 0.6631 (3) | 0.64968 (18) | 0.23587 (13) | 0.0517 (5) | |
H1A | 0.397 (3) | 0.8411 (18) | 0.3389 (13) | 0.052 (6)* | |
H2A | 0.326 (3) | 0.721 (2) | 0.3912 (15) | 0.076 (8)* | |
H1B | 0.448 (3) | 1.190 (2) | 0.2646 (14) | 0.067 (7)* | |
H2B | 0.418 (3) | 1.0687 (18) | 0.3265 (14) | 0.054 (6)* | |
H3A | 0.1063 | 1.0147 | 0.6555 | 0.052* | |
H12A | −0.0610 | 0.6622 | 0.6079 | 0.055* | |
H13A | −0.2290 | 0.5538 | 0.7241 | 0.067* | |
H14A | −0.2429 | 0.6009 | 0.8646 | 0.075* | |
H15A | −0.0873 | 0.7550 | 0.8888 | 0.074* | |
H16A | 0.0772 | 0.8669 | 0.7728 | 0.064* | |
H22A | 0.0273 | 1.2196 | 0.6167 | 0.056* | |
H23A | 0.0436 | 1.4319 | 0.6069 | 0.067* | |
H24A | 0.2739 | 1.5186 | 0.5114 | 0.071* | |
H25A | 0.4891 | 1.3915 | 0.4260 | 0.068* | |
H26A | 0.4702 | 1.1792 | 0.4326 | 0.056* | |
H3B | 0.7481 | 0.8734 | 0.0201 | 0.056* | |
H12B | 0.8145 | 1.2664 | 0.0384 | 0.065* | |
H13B | 0.9356 | 1.3812 | −0.0882 | 0.077* | |
H14B | 0.9487 | 1.3100 | −0.2216 | 0.083* | |
H15B | 0.8520 | 1.1209 | −0.2294 | 0.077* | |
H16B | 0.7403 | 1.0014 | −0.1033 | 0.064* | |
H22B | 0.5890 | 0.6953 | 0.0407 | 0.069* | |
H23B | 0.6011 | 0.4799 | 0.0568 | 0.081* | |
H24B | 0.6568 | 0.3698 | 0.1836 | 0.081* | |
H25B | 0.6965 | 0.4752 | 0.2949 | 0.074* | |
H26B | 0.6759 | 0.6919 | 0.2818 | 0.062* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1A | 0.0424 (9) | 0.0397 (9) | 0.0362 (9) | −0.0074 (7) | −0.0027 (7) | −0.0043 (7) |
N2A | 0.0437 (9) | 0.0400 (9) | 0.0388 (9) | −0.0081 (7) | −0.0023 (8) | −0.0052 (7) |
N4A | 0.0684 (13) | 0.0465 (11) | 0.0400 (11) | −0.0141 (10) | 0.0076 (9) | −0.0107 (9) |
C1A | 0.0409 (11) | 0.0408 (11) | 0.0364 (10) | −0.0054 (9) | −0.0042 (9) | −0.0057 (9) |
C2A | 0.0378 (11) | 0.0381 (10) | 0.0368 (10) | −0.0038 (8) | −0.0057 (9) | −0.0046 (8) |
C3A | 0.0526 (12) | 0.0400 (11) | 0.0341 (10) | −0.0068 (9) | −0.0016 (9) | −0.0058 (8) |
C4A | 0.0380 (11) | 0.0379 (10) | 0.0382 (10) | −0.0045 (8) | −0.0076 (9) | −0.0042 (8) |
C11A | 0.0430 (11) | 0.0360 (10) | 0.0397 (11) | −0.0026 (9) | −0.0034 (9) | 0.0002 (8) |
C12A | 0.0505 (12) | 0.0379 (11) | 0.0462 (11) | −0.0046 (9) | −0.0062 (10) | −0.0021 (9) |
C13A | 0.0618 (14) | 0.0419 (11) | 0.0608 (14) | −0.0119 (10) | −0.0033 (11) | 0.0009 (10) |
C14A | 0.0702 (16) | 0.0513 (13) | 0.0532 (14) | −0.0074 (12) | 0.0075 (12) | 0.0109 (11) |
C15A | 0.0799 (17) | 0.0623 (14) | 0.0371 (12) | −0.0054 (13) | −0.0026 (11) | −0.0003 (10) |
C16A | 0.0687 (15) | 0.0500 (12) | 0.0408 (12) | −0.0103 (11) | −0.0090 (11) | −0.0028 (9) |
C21A | 0.0432 (11) | 0.0381 (10) | 0.0335 (10) | −0.0091 (9) | −0.0102 (9) | −0.0011 (8) |
C22A | 0.0551 (13) | 0.0404 (11) | 0.0428 (11) | −0.0079 (10) | −0.0047 (10) | −0.0038 (9) |
C23A | 0.0710 (15) | 0.0426 (12) | 0.0547 (13) | −0.0037 (11) | −0.0115 (12) | −0.0094 (10) |
C24A | 0.0851 (18) | 0.0393 (12) | 0.0617 (14) | −0.0187 (12) | −0.0265 (13) | −0.0001 (11) |
C25A | 0.0640 (15) | 0.0577 (14) | 0.0533 (13) | −0.0290 (12) | −0.0132 (11) | 0.0041 (11) |
C26A | 0.0482 (12) | 0.0492 (12) | 0.0439 (11) | −0.0135 (10) | −0.0095 (10) | −0.0033 (9) |
N1B | 0.0515 (10) | 0.0420 (9) | 0.0372 (9) | −0.0037 (8) | −0.0034 (8) | −0.0043 (7) |
N2B | 0.0606 (11) | 0.0427 (9) | 0.0376 (9) | −0.0063 (8) | 0.0011 (8) | −0.0038 (8) |
N4B | 0.1016 (17) | 0.0440 (12) | 0.0395 (11) | −0.0028 (11) | 0.0087 (11) | −0.0059 (9) |
C1B | 0.0541 (13) | 0.0433 (11) | 0.0361 (11) | −0.0027 (10) | −0.0017 (10) | −0.0065 (9) |
C2B | 0.0419 (11) | 0.0448 (11) | 0.0385 (11) | −0.0033 (9) | −0.0046 (9) | −0.0022 (9) |
C3B | 0.0543 (13) | 0.0429 (11) | 0.0362 (11) | 0.0000 (10) | 0.0007 (9) | −0.0063 (9) |
C4B | 0.0408 (11) | 0.0445 (11) | 0.0396 (11) | −0.0029 (9) | −0.0061 (9) | −0.0040 (9) |
C11B | 0.0437 (12) | 0.0442 (11) | 0.0393 (11) | −0.0006 (9) | −0.0007 (9) | −0.0005 (9) |
C12B | 0.0607 (14) | 0.0488 (12) | 0.0497 (13) | −0.0059 (11) | −0.0057 (11) | −0.0005 (10) |
C13B | 0.0643 (15) | 0.0529 (13) | 0.0692 (16) | −0.0151 (12) | −0.0027 (13) | 0.0082 (12) |
C14B | 0.0619 (16) | 0.0781 (17) | 0.0542 (15) | −0.0091 (13) | 0.0020 (12) | 0.0199 (13) |
C15B | 0.0683 (16) | 0.0774 (16) | 0.0403 (12) | −0.0095 (13) | −0.0007 (11) | 0.0014 (11) |
C16B | 0.0566 (13) | 0.0573 (13) | 0.0427 (12) | −0.0087 (11) | −0.0035 (10) | −0.0019 (10) |
C21B | 0.0434 (12) | 0.0394 (11) | 0.0456 (12) | −0.0026 (9) | −0.0008 (9) | −0.0035 (9) |
C22B | 0.0690 (15) | 0.0501 (13) | 0.0531 (13) | −0.0037 (11) | −0.0132 (12) | −0.0085 (10) |
C23B | 0.0787 (17) | 0.0479 (13) | 0.0796 (17) | −0.0068 (12) | −0.0177 (14) | −0.0172 (12) |
C24B | 0.0706 (17) | 0.0415 (12) | 0.0856 (18) | −0.0064 (12) | −0.0057 (14) | −0.0020 (13) |
C25B | 0.0654 (15) | 0.0502 (13) | 0.0601 (14) | −0.0036 (11) | −0.0021 (12) | 0.0094 (11) |
C26B | 0.0546 (13) | 0.0482 (12) | 0.0464 (12) | −0.0045 (10) | −0.0005 (10) | −0.0017 (10) |
N1A—C1A | 1.345 (2) | N1B—C1B | 1.346 (2) |
N1A—C4A | 1.346 (2) | N1B—C4B | 1.343 (2) |
N2A—C1A | 1.343 (2) | N2B—C1B | 1.343 (2) |
N2A—C2A | 1.340 (2) | N2B—C2B | 1.340 (2) |
N4A—C1A | 1.357 (2) | N4B—C1B | 1.347 (2) |
C2A—C3A | 1.385 (2) | C2B—C3B | 1.381 (3) |
C2A—C11A | 1.488 (2) | C2B—C11B | 1.488 (3) |
C3A—C4A | 1.384 (2) | C3B—C4B | 1.387 (3) |
C4A—C21A | 1.481 (2) | C4B—C21B | 1.484 (3) |
C11A—C16A | 1.388 (3) | C11B—C16B | 1.386 (3) |
C11A—C12A | 1.390 (3) | C11B—C12B | 1.389 (3) |
C12A—C13A | 1.378 (3) | C12B—C13B | 1.382 (3) |
C13A—C14A | 1.377 (3) | C13B—C14B | 1.372 (3) |
C14A—C15A | 1.374 (3) | C14B—C15B | 1.368 (3) |
C15A—C16A | 1.382 (3) | C15B—C16B | 1.383 (3) |
C21A—C26A | 1.387 (3) | C21B—C22B | 1.386 (3) |
C21A—C22A | 1.389 (2) | C21B—C26B | 1.392 (3) |
C22A—C23A | 1.378 (3) | C22B—C23B | 1.378 (3) |
C23A—C24A | 1.373 (3) | C23B—C24B | 1.377 (3) |
C24A—C25A | 1.378 (3) | C24B—C25B | 1.369 (3) |
C25A—C26A | 1.383 (3) | C25B—C26B | 1.387 (3) |
N4A—H1A | 0.89 (2) | N4B—H1B | 0.89 (2) |
N4A—H2A | 0.89 (2) | N4B—H2B | 0.91 (2) |
C3A—H3A | 0.9300 | C3B—H3B | 0.9300 |
C12A—H12A | 0.9300 | C12B—H12B | 0.9300 |
C13A—H13A | 0.9300 | C13B—H13B | 0.9300 |
C14A—H14A | 0.9300 | C14B—H14B | 0.9300 |
C15A—H15A | 0.9300 | C15B—H15B | 0.9300 |
C16A—H16A | 0.9300 | C16B—H16B | 0.9300 |
C22A—H22A | 0.9300 | C22B—H22B | 0.9300 |
C23A—H23A | 0.9300 | C23B—H23B | 0.9300 |
C24A—H24A | 0.9300 | C24B—H24B | 0.9300 |
C25A—H25A | 0.9300 | C25B—H25B | 0.9300 |
C26A—H26A | 0.9300 | C26B—H26B | 0.9300 |
C1A—N1A—C4A | 116.02 (15) | C1B—N1B—C4B | 115.96 (16) |
C1A—N2A—C2A | 116.30 (15) | C1B—N2B—C2B | 116.09 (16) |
N1A—C1A—N2A | 126.76 (17) | N1B—C1B—N2B | 126.72 (17) |
N1A—C1A—N4A | 117.05 (17) | N1B—C1B—N4B | 116.73 (18) |
N2A—C1A—N4A | 116.15 (17) | N2B—C1B—N4B | 116.55 (18) |
N2A—C2A—C3A | 121.13 (17) | N2B—C2B—C3B | 121.59 (17) |
N2A—C2A—C11A | 116.88 (16) | N2B—C2B—C11B | 116.43 (17) |
C3A—C2A—C11A | 121.94 (17) | C3B—C2B—C11B | 121.98 (18) |
C2A—C3A—C4A | 118.63 (17) | C2B—C3B—C4B | 118.26 (18) |
N1A—C4A—C3A | 121.11 (16) | N1B—C4B—C3B | 121.32 (17) |
N1A—C4A—C21A | 117.32 (16) | N1B—C4B—C21B | 117.49 (16) |
C3A—C4A—C21A | 121.56 (17) | C3B—C4B—C21B | 121.19 (17) |
C12A—C11A—C2A | 119.64 (17) | C12B—C11B—C2B | 120.26 (18) |
C16A—C11A—C2A | 121.73 (18) | C16B—C11B—C2B | 121.24 (18) |
C12A—C11A—C16A | 118.59 (18) | C16B—C11B—C12B | 118.49 (18) |
C11A—C12A—C13A | 120.85 (19) | C11B—C12B—C13B | 120.6 (2) |
C12A—C13A—C14A | 119.8 (2) | C12B—C13B—C14B | 119.9 (2) |
C13A—C14A—C15A | 120.1 (2) | C13B—C14B—C15B | 120.2 (2) |
C14A—C15A—C16A | 120.3 (2) | C14B—C15B—C16B | 120.2 (2) |
C15A—C16A—C11A | 120.3 (2) | C15B—C16B—C11B | 120.5 (2) |
C22A—C21A—C4A | 120.32 (17) | C22B—C21B—C4B | 120.76 (18) |
C26A—C21A—C4A | 121.40 (17) | C26B—C21B—C4B | 120.34 (18) |
C22A—C21A—C26A | 118.25 (17) | C22B—C21B—C26B | 118.89 (18) |
C21A—C22A—C23A | 121.08 (19) | C21B—C22B—C23B | 120.6 (2) |
C22A—C23A—C24A | 120.1 (2) | C22B—C23B—C24B | 120.1 (2) |
C23A—C24A—C25A | 119.64 (19) | C23B—C24B—C25B | 119.9 (2) |
C24A—C25A—C26A | 120.4 (2) | C24B—C25B—C26B | 120.6 (2) |
C25A—C26A—C21A | 120.4 (2) | C25B—C26B—C21B | 119.8 (2) |
C2A—C3A—H3A | 120.7 | C2B—C3B—H3B | 120.9 |
C4A—C3A—H3A | 120.7 | C4B—C3B—H3B | 120.9 |
C13A—C12A—H12A | 119.6 | C13B—C12B—H12B | 119.7 |
C11A—C12A—H12A | 119.6 | C11B—C12B—H12B | 119.7 |
C14A—C13A—H13A | 120.1 | C14B—C13B—H13B | 120.0 |
C12A—C13A—H13A | 120.1 | C12B—C13B—H13B | 120.0 |
C15A—C14A—H14A | 119.9 | C15B—C14B—H14B | 119.9 |
C13A—C14A—H14A | 119.9 | C13B—C14B—H14B | 119.9 |
C14A—C15A—H15A | 119.9 | C14B—C15B—H15B | 119.9 |
C16A—C15A—H15A | 119.9 | C16B—C15B—H15B | 119.9 |
C15A—C16A—H16A | 119.8 | C15B—C16B—H16B | 119.7 |
C11A—C16A—H16A | 119.8 | C11B—C16B—H16B | 119.7 |
C23A—C22A—H22A | 119.5 | C23B—C22B—H22B | 119.7 |
C21A—C22A—H22A | 119.5 | C21B—C22B—H22B | 119.7 |
C24A—C23A—H23A | 119.9 | C24B—C23B—H23B | 119.9 |
C22A—C23A—H23A | 119.9 | C22B—C23B—H23B | 119.9 |
C23A—C24A—H24A | 120.2 | C23B—C24B—H24B | 120.1 |
C25A—C24A—H24A | 120.2 | C25B—C24B—H24B | 120.1 |
C24A—C25A—H25A | 119.8 | C24B—C25B—H25B | 119.7 |
C26A—C25A—H25A | 119.8 | C26B—C25B—H25B | 119.7 |
C25A—C26A—H26A | 119.8 | C25B—C26B—H26B | 120.1 |
C21A—C26A—H26A | 119.8 | C21B—C26B—H26B | 120.1 |
C1A—N4A—H1A | 119.5 (13) | C1B—N4B—H1B | 116.3 (14) |
C1A—N4A—H2A | 114.8 (15) | C1B—N4B—H2B | 121.1 (12) |
H1A—N4A—H2A | 122 (2) | H1B—N4B—H2B | 119.8 (19) |
N1A—C4A—C21A—C26A | −29.8 (3) | N1B—C4B—C21B—C26B | −36.5 (3) |
C3A—C4A—C21A—C26A | 151.83 (19) | C3B—C4B—C21B—C26B | 142.9 (2) |
C3A—C2A—C11A—C12A | 149.4 (2) | C3B—C2B—C11B—C12B | −152.6 (2) |
C2A—N2A—C1A—N1A | −2.0 (3) | C2B—N2B—C1B—N1B | 1.4 (3) |
C2A—N2A—C1A—N4A | −179.66 (17) | C2B—N2B—C1B—N4B | −179.29 (19) |
C4A—N1A—C1A—N2A | 1.4 (3) | C4B—N1B—C1B—N2B | −3.0 (3) |
C4A—N1A—C1A—N4A | 179.04 (17) | C4B—N1B—C1B—N4B | 177.69 (19) |
C1A—N2A—C2A—C3A | 0.3 (3) | C1B—N2B—C2B—C3B | 0.8 (3) |
C1A—N2A—C2A—C11A | 177.57 (17) | C1B—N2B—C2B—C11B | −178.38 (18) |
N2A—C2A—C3A—C4A | 1.8 (3) | N2B—C2B—C3B—C4B | −1.2 (3) |
C11A—C2A—C3A—C4A | −175.34 (17) | C11B—C2B—C3B—C4B | 177.94 (18) |
C1A—N1A—C4A—C3A | 0.9 (3) | C1B—N1B—C4B—C3B | 2.4 (3) |
C1A—N1A—C4A—C21A | −177.45 (16) | C1B—N1B—C4B—C21B | −178.26 (17) |
C2A—C3A—C4A—N1A | −2.5 (3) | C2B—C3B—C4B—N1B | −0.5 (3) |
C2A—C3A—C4A—C21A | 175.85 (17) | C2B—C3B—C4B—C21B | −179.81 (18) |
N2A—C2A—C11A—C16A | 154.15 (18) | N2B—C2B—C11B—C16B | −152.50 (19) |
C3A—C2A—C11A—C16A | −28.6 (3) | C3B—C2B—C11B—C16B | 28.3 (3) |
N2A—C2A—C11A—C12A | −27.9 (3) | N2B—C2B—C11B—C12B | 26.5 (3) |
C16A—C11A—C12A—C13A | 1.4 (3) | C16B—C11B—C12B—C13B | −1.0 (3) |
C2A—C11A—C12A—C13A | −176.68 (18) | C2B—C11B—C12B—C13B | 180.0 (2) |
C11A—C12A—C13A—C14A | −0.9 (3) | C11B—C12B—C13B—C14B | 1.8 (3) |
C12A—C13A—C14A—C15A | −0.3 (3) | C12B—C13B—C14B—C15B | −1.3 (4) |
C13A—C14A—C15A—C16A | 1.0 (3) | C13B—C14B—C15B—C16B | 0.0 (4) |
C14A—C15A—C16A—C11A | −0.5 (3) | C14B—C15B—C16B—C11B | 0.8 (3) |
C12A—C11A—C16A—C15A | −0.7 (3) | C12B—C11B—C16B—C15B | −0.3 (3) |
C2A—C11A—C16A—C15A | 177.30 (19) | C2B—C11B—C16B—C15B | 178.7 (2) |
N1A—C4A—C21A—C22A | 148.11 (18) | N1B—C4B—C21B—C22B | 144.24 (19) |
C3A—C4A—C21A—C22A | −30.3 (3) | C3B—C4B—C21B—C22B | −36.4 (3) |
C26A—C21A—C22A—C23A | 1.2 (3) | C26B—C21B—C22B—C23B | −0.6 (3) |
C4A—C21A—C22A—C23A | −176.82 (19) | C4B—C21B—C22B—C23B | 178.7 (2) |
C21A—C22A—C23A—C24A | −1.0 (3) | C21B—C22B—C23B—C24B | −0.6 (4) |
C22A—C23A—C24A—C25A | −0.2 (3) | C22B—C23B—C24B—C25B | 0.6 (4) |
C23A—C24A—C25A—C26A | 1.1 (3) | C23B—C24B—C25B—C26B | 0.5 (4) |
C24A—C25A—C26A—C21A | −0.9 (3) | C24B—C25B—C26B—C21B | −1.6 (3) |
C22A—C21A—C26A—C25A | −0.3 (3) | C22B—C21B—C26B—C25B | 1.7 (3) |
C4A—C21A—C26A—C25A | 177.71 (18) | C4B—C21B—C26B—C25B | −177.7 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N4A—H1A···N1B | 0.89 (2) | 2.17 (2) | 3.058 (2) | 172.7 (18) |
N4B—H2B···N1A | 0.91 (2) | 2.20 (2) | 3.106 (3) | 175.8 (17) |
C12A—H12A···Cg1i | 0.93 | 2.77 | 3.538 (2) | 141 |
C26A—H26A···Cg2ii | 0.93 | 2.78 | 3.393 (2) | 124 |
Symmetry codes: (i) −x, −y+2, −z+1; (ii) −x+1, −y+2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C16H13N3 |
Mr | 247.29 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 294 |
a, b, c (Å) | 7.8263 (9), 10.8009 (9), 15.7878 (12) |
α, β, γ (°) | 83.457 (5), 77.039 (7), 82.326 (7) |
V (Å3) | 1284.0 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.50 × 0.30 × 0.08 × not measured (radius) |
Data collection | |
Diffractometer | Siemens P4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5607, 4529, 2987 |
Rint | 0.019 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.047, 0.119, 1.01 |
No. of reflections | 4529 |
No. of parameters | 359 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.18, −0.17 |
Computer programs: XSCANS (Siemens, 1996), XSCANS, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPIII (Burnett & Johnson, 1996) and PLATON (Spek, 2003), NRCVAX96 (Gabe et al., 1989), SHELXL97 and PREP8 (Ferguson, 1998).
N1A—C1A | 1.345 (2) | N1B—C1B | 1.346 (2) |
N1A—C4A | 1.346 (2) | N1B—C4B | 1.343 (2) |
N2A—C1A | 1.343 (2) | N2B—C1B | 1.343 (2) |
N2A—C2A | 1.340 (2) | N2B—C2B | 1.340 (2) |
N4A—C1A | 1.357 (2) | N4B—C1B | 1.347 (2) |
C2A—C3A | 1.385 (2) | C2B—C3B | 1.381 (3) |
C2A—C11A | 1.488 (2) | C2B—C11B | 1.488 (3) |
C3A—C4A | 1.384 (2) | C3B—C4B | 1.387 (3) |
C4A—C21A | 1.481 (2) | C4B—C21B | 1.484 (3) |
N1A—C1A—N2A | 126.76 (17) | N1B—C1B—N2B | 126.72 (17) |
N1A—C1A—N4A | 117.05 (17) | N1B—C1B—N4B | 116.73 (18) |
N2A—C1A—N4A | 116.15 (17) | N2B—C1B—N4B | 116.55 (18) |
N1A—C4A—C21A—C26A | −29.8 (3) | N1B—C4B—C21B—C26B | −36.5 (3) |
C3A—C4A—C21A—C26A | 151.83 (19) | C3B—C4B—C21B—C26B | 142.9 (2) |
C3A—C2A—C11A—C12A | 149.4 (2) | C3B—C2B—C11B—C12B | −152.6 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N4A—H1A···N1B | 0.89 (2) | 2.17 (2) | 3.058 (2) | 172.7 (18) |
N4B—H2B···N1A | 0.91 (2) | 2.20 (2) | 3.106 (3) | 175.8 (17) |
C12A—H12A···Cg1i | 0.93 | 2.77 | 3.538 (2) | 141 |
C26A—H26A···Cg2ii | 0.93 | 2.78 | 3.393 (2) | 124 |
Symmetry codes: (i) −x, −y+2, −z+1; (ii) −x+1, −y+2, −z+1. |
Acknowledgements
JFG thanks Dublin City University for the purchase of a diffractometer and computer system. The authors thank the Department of Chemistry, University of West Indies, St Augustine, Trinidad, West Indies, for the plant material. SPG thanks CSIR, Government of India, for a fellowship to SJ.
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The title compound, 4,6-diphenyl-2-pyrimidinylamine, (I), was isolated as a natural product from the plant Justicia Secunda (Acanthaceae) in Trinidad, West Indies. The parent structure, 4,6-diphenyl-1,2-dihydropyrimidine, has been reported (Weis & Vishkautsan, 1985), but the coordinates are not in the Cambridge Structural Database (CSD; Allen, 2002) for comparison with (I) (CSD refcode DEZMEA). \sch
Compound (I) crystallizes in space group P1 (No. 2) with two independent molecules, A and B, in the asymmetric unit, which differ slightly in conformation (Fig. 1). Bond lengths and angles are largely unexceptional and are in accord with anticipated values (Orpen et al., 1994); selected dimensions are given in Table 1. The central C—N bond lengths are from 1.340 (2) to 1.346 (2) Å, while the aromatic C—C distances are in the range 1.381 (3)–1.387 (3) Å. Torsion-angle differences are evident from analysis of the N1—C4—C21—C26 angles, which are −29.8 (3) and 36.5 (3)° in molecules A and B, respectively (Table 1). Even more dramatic is the difference in dihedral angles between the C11—C16 and C21—C26 planes, at 52.15 (7) and 31.79 (7)° in A and B, respectively. The weighted (unit weight) r.m.s. fit for the superposition of the non-H atoms in both molecules is 0.65(0.55) Å (Spek, 2003).
Molecules A and B associate in pairs through Namino—H···Npyrm intermolecular interactions, which only involve two of the four amino donor H atoms and N pyrimidine acceptors per A/B pair. The N···N distances are 3.058 (2) and 3.106 (3) Å and the N—H···N angles 172.7 (18) and 175.8 (17)° (Table 2), thus forming a hydrogen-bonded ring with an R22(8) graph set similar to that observed in centrosymmetric carboxylic acid pairs. A C—H···π(arene) contact from C12A—H12A to the C21A—C26A ring links the dimeric units into a dimer of dimers, which is further augmented, by a contact from C26A—H26A to the N1A/N2A/C1A—C4A ring, into a one-dimensional stack (Fig. 2, Table 2). These are the only contacts of note in the structure of (I), apart from the N—H···N hydrogen bonding.
Examination of the structure of (I) for interactions involving N2A/N2B reveals that, along the b direction, atom H24A (a potential donor) is 2.99 Å from N2Ai, with C24A—H24A···N2Ai 163° [symmetry code: (i) x, 1 + y, z]. Likewise, the closest N···H intermolecular distance involving atom N2B is N2B···H24Bi of 3.08 Å, with N2B···H24Bi—C24Bi 155°. Neither of these constitutes a hydrogen bond.
Inspection of Fig. 2 shows the dimeric units in a two-dimensional cross section through the crystal structure parallel to the [101] plane. In the crystal structure packing, a more efficient packing could involve dimeric formation about inversion centres, which would necessitate rotation of the phenyl rings to align and fulfil symmetry requirements, e.g. the phenyl rings have interplanar angles of 52.12 (7) and 31.79 (7)° in A and B, respectively. The reason why this does not arise is due to the initial hydrogen-bonded dimer formation. Utilization of only half of the N—H/N donor/acceptors per A/B hydrogen-bonded dimer prevents the N2A/N2B pair from forming hydrogen bonds, as potential (C)N—H/N donor/acceptor pairs cannot approach one another, and largely due to the concurrent formation of H···H contacts Please clarify to what this last clause refers. Interactions in (I) are therefore limited to the two N—H···N per A/B pair.
Ab initio calculations on the 4,6-diphenyl-2-pyrimidinylamine system, (I), gave results similar to that observed in the A/B molecules. Calculations were undertaken at the 6–31+G(d) level in the search for a local minimum for comparison with the A/B molecules, using GAUSSIAN03 (Frisch et al., 2003). The N—C—C—C torsion angles are 27.55°, similar to the value of −29.8 (3)° in A. The H2N—C distance is 1.362 Å and the N—C—N angle is 116.79° [range 116.15 (17)–117.05 (17)° in molecule A]. Overall, the calculation result resembles molecule A. However, no attempt was made to find the global minimum in the system.
Crystal structures with more than one molecule present in the asymmetric unit are not uncommon (Steiner, 2000; Gallagher et al., 1998). Recently, Görbitz (2002, 2003) has reported on dipeptide derivatives, e.g. the two forms of L-valyl-L-phenylalanine trihydrate (P21, Z = 16, Z' = 8, and P212121, Z = 4, Z' = 1) and L-methionyl-L-alanine (P61, Z = 42, Z' = 7), which provide rare examples of systems with Z' = 8 and 7 molecules in their respective asymmetric units, in contrast with Z' = 2 which is not uncommon. Analysis of the CSD (February 2004, version 5.25; Allen, 2002) reveals a total of 65935 crystal structures in space group P1 (No. 2) (and equivalents with no restrictions), 7625 with Z' > 1, some 11.6% of the total, and 6775 with Z'= 2. No attempt was made to examine incorrect space groups.
Table 2. Hydrogen-bond and contact data (Å, °) for compound (I). Cg1 and Cg2 represent the centroids of the rings C21A—C26A and N1A/N2A/C1A—C4A, respectively.