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X-ray Structure and Density Functional Theory Investigations of 4-((2R)-2-(3, 4-dibromophenyl)-1-fluoro cyclopropyl)-N-(o-tolyl)benzamide Compound

Yamina BENELHADJ-DJELLOUL ,  Nourdine BOUKABCHA ,  Nadia BENHALIMA ,  Salem YAHIAOUI ,  Abdelkader CHOUAIH ,  Abdelouahab ZANOUN

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Citation:  Yamina BENELHADJ-DJELLOUL, Nourdine BOUKABCHA, Nadia BENHALIMA, Salem YAHIAOUI, Abdelkader CHOUAIH, Abdelouahab ZANOUN. X-ray Structure and Density Functional Theory Investigations of 4-((2R)-2-(3, 4-dibromophenyl)-1-fluoro cyclopropyl)-N-(o-tolyl)benzamide Compound[J]. Chinese Journal of Structural Chemistry, 2020, 39(9): 1601-1614. doi: 10.14102/j.cnki.0254-5861.2011-2657 shu

X-ray Structure and Density Functional Theory Investigations of 4-((2R)-2-(3, 4-dibromophenyl)-1-fluoro cyclopropyl)-N-(o-tolyl)benzamide Compound

English

  • 1. INTRODUCTION

    In the past few decades, pyrethroids have a large spectrum of insecticidal activity. However, synthetic ones exhibit higher photostability and are more effective for practical use. They have a higher insecticidal capacity and especially a low toxicity for the mammals. The pyrethroids structures obtained by X-ray diffraction data and their structural requirements for insecticidal activity have been investigated by several authors[1-4]. Among them, carboxylic esters containing cyclopropane ring in their structure have powerful insecticidal activity[5-8]. In addition, the cyclopropane ring is a main structural part in many synthetic and natural compounds that exhibit a wide range of biological activities from enzyme inhibition to antibiotic, herbicidal, antitumor, and HIV antiviral activities as non-nucleoside reverse transcriptase inhibitors[9-11]. It is also known that the cyclopropane ring can be a crucial feature for the presence of asymmetric carbons as is found in the structures of several pyrethroids[12]. The study of the conformational behavior of pyrethriods is extremely important. The structural, conformational and physicochemical properties of these compounds may give information about the mechanism of their biological activity[13, 14]. This activity is related to molecular structure and strongly depends on the stereochemistry at the asymmetric centers. On the other hand, theoretical calculations were used to further study the structure-activity relationship of several heterocyclic compounds[15-17].

    In this paper, we propose a comparative study between the experimental X-ray diffraction structure and the optimized geometry predicted from ab initio molecular orbital calculations using the Becke-Lee-Yang-Part's three-parameter hybrid functional (B3LYP) and HF methods at 6-31G(d, p) basis set performed on DBFB molecule. The investigated compound, 4-((2R)-2-(3, 4-dibromophenyl)-1-fluorocyclopropyl)-N-(o-tolyl)benzamide (DBFB), appears as a useful intermediate in the synthesis of some pyrethroid insecticides. This compound was kindly supplied by the French company RUSSEL UCLAF. With the goal of understanding the nature and reactivity of the molecule, some reactivity descriptors such as ionization energy, electron affinity, HOMO-LUMO energy gap, chemical potential, molecular softness, hardness and electrophilicity index have been calculated using the DFT/ B3LYP/6-31G(d, p) level of theory.

    2. EXPERIMENTAL AND QUANTUM CHEMICAL METHODS

    2.1 X-ray diffraction measurements

    A single crystal of the title compound in appropriate dimensions was selected for X-ray diffraction measurements performed on a Philips Enraf Nonius (four-circle diffractometer) with CCD area detector using graphite-monochromated MoKα radiation (λ = 0.71073 Å). The data were corrected for Lorentz and Polarization effects. The X-ray data were collected at 298 K. A total of 3053 reflections were collected in the range of 2 < θ < 29.6° by using an ω scan mode, of which 1464 observed reflections with I > 2σ(I) were used. The structure was solved by direct methods implemented in SHELXS2013[18]. A Fourier synthesis revealed the complete structure, which was refined by full-matrix least-squares. All non-H atoms were refined anisotropically. The H atoms were located from a difference Fourier map and included in the refinement with the isotropic temperature factor of the carrier atom. The final least-squares cycle using SHELXL gave R = 0.0639 for all reflections with I > 2σ(I), wR = 0.222, S = 1.51, (Δρ)min = −0.94 and (Δρ)max = 1.45 e/Å3.

    2.2 Quantum chemical calculation

    In order to explain the biological activity of the compound, we used theoretical methods from quantum chemistry. Ab initio geometry optimization on C23H18Br2FNO was performed starting from the experimental data refinement (X-ray data). Geometry optimizations and harmonic wavenumbers for the normal modes of vibration were calculated using the Density Functional Theory, Becke's three parameter hybrid functional using the LYP correlation Functional (B3LYP) and HF theory with the 6-31G (d, p) basis set[19-21]. The compute vibrational frequencies were attributed by means of the potential energy distribution (PED) investigation of all fundamental vibration modes using VEDA 4 program[22]. Such combination is being used with good results for organic molecules[23] and hydrogen-bonded systems[24, 25] and represents a good compromise between economy of computational resources, accuracy and applicability to manyatoms molecules. All calculations were performed with the GAUSSIAN 09 program[26]. Other molecular properties of DBFB were evaluated using the same level of theory.

    3. RESULTS AND DISCUSSION

    3.1 Conformational analysis

    3.1.1   Tautomeric forms

    To determine the tautomeric forms of DBFB molecule as the initial point for further calculations, the molecule was submitted to a rigorous conformation analysis. The tautomerism of organic compounds has been studied by theoretical calculations through several quantum mechanics approaches[27, 28]. In this study, the Gaussian 09 software was used to perform the conformational analysis. The two possible conformations of DBFB are shown in Fig. 1. The stability analysis as obtained from energy minimization shows that the keto conformer (−6260.5385 Hartree) is the most stable compared to the enol conformer (−6260.5247 Hartree). The keto form predominates at equilibrium for most ketones. Therefore, our study has focused on this particular form of DBFB.

    Figure 1

    Figure 1.  Possible optimized structural conformers of DBFB
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    3.1.2   Potential energy scan (PES)

    The most stable geometry and other possible conformations of the compound have been determined from the potential energy surface (PES) using B3LYP/6-31G** method. During the analysis all geometrical parameters are simultaneously relaxed while the N(1)−C(16)−C(13)−C(14) dihedral angle varies in a step of 10o from 0o to 360o[29]. The potential energy profile which reflects the stability of the possible conformers of the molecule is shown in Fig. 2.

    Figure 2

    Figure 2.  Potential energy profile of DBFB
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    Two different conformers I and II have been determined for DBFB by PES analysis and are shown in Fig. 3. The rotation about C(13)−C(16) single bond produces two conformers: conformer I = trans and conformer II = cis. In the most stable geometry, the CH3 group is on the side of oxygen atom. In order to provide the accurate structural parameters of the compound, the most stable conformer is optimized with the B3LYP/6-31G** method.

    Figure 3

    Figure 3.  Possible conformers of DBFB
    DownLoad: Full-Size Img PowerPoint

    3.2 Structural determination

    The X-ray structure of the molecule with atomic labeling and optimized geometry is shown in Fig. 4. The experimental geometrical parameters of DBFB (bonds lengths, bond angles and dihedral angles) are listed in Table 1, in which the corresponding optimized geometrical parameters obtained by Hartree-Fock and DFT (B3LYP) levels of theory using 6-31G (d, p) basis set are also given.

    Figure 4

    Figure 4.  Geometry of DBFB (a) X-ray structure with atomic numbering scheme and (b) optimized molecular structure
    DownLoad: Full-Size Img PowerPoint

    Table 1

    Table 1.  Geometrical Parameters of DBFB
    DownLoad: CSV
    Bond Dist. (Å) Bond Dist. (Å)
    HF B3LYP X-ray HF B3LYP X-ray
    Br(1)–C(1) 1.897 1.900 1.854(12) C(17)–C(22) 1.386 1.400 1.40(3)
    Br(2)–C(2) 1.898 1.903 1.858(15) C(17)–C(18) 1.395 1.409 1.36(2)
    N(1)–C(16) 1.354 1.383 1.315(13) F(1)–C(8) 1.360 1.381 1.36(2)
    N(1)–C(17) 1.427 1.426 1.410(13) C(13)–C(14) 1.390 1.400 1.336(17)
    N(1)–H(1) 0.994 1.010 0.8600 C(7)–C(9) 1.508 1.520 1.48(2)
    C(16)–O(1) 1.202 1.224 1.224(13) C(7)–C(8) 1.508 1.531 1.501(19)
    C(16)–C(13) 1.501 1.503 1.467(13) C(14)–C(15) 1.382 1.391 1.373(16)
    C(4)–C(3) 1.387 1.401 1.371(19) C(1)–C(6) 1.385 1.395 1.30(3)
    C(4)–C(5) 1.390 1.402 1.38(2) C(1)–C(2) 1.385 1.398 1.41(2)
    C(4)–C(7) 1.496 1.490 1.483(13) C(2)–C(3) 1.385 1.394 1.365(17)
    C(12)–C(11) 1.389 1.392 1.382(16) C(10)–C(15) 1.391 1.402 1.382(19)
    C(12)–C(13) 1.387 1.402 1.41(2) C(10)–C(11) 1.390 1.402 1.37(2)
    C(19)–C(20) 1.386 1.394 1.40(3) C(10)–C(8) 1.498 1.490 1.468(15)
    C(19)–C(18) 1.390 1.401 1.414(18) C(8)–C(9) 1.485 1.496 1.48(2)
    C(21)–C(22) 1.385 1.393 1.37(2) C(18)–C(23) 1.509 1.506 1.48(3)
    C(21)–C(20) 1.389 1.394 1.37(3) C(6)–C(5) 1.380 1.391 1.39(2)
    Bond angle (°) HF B3LYP X-ray Bond angle (°) HF B3LYP X-ray
    C(16)–N(1)–C(17) 123.32 124.67 125.2(9) C(3)–C(2)–C(1) 120.26 120.34 118.0(14)
    C(17)–N(1)–H(1) 116.41 115.34 117.4(10) C(3)–C(2)–Br(2) 117.25 117.49 118.5(12)
    O(1)–C(16)–N(1) 122.83 122.85 122.5(9) C(1)–C(2)–Br(2) 122.42 122.15 123.5(11)
    O(1)–C(16)–C(13) 121.05 121.53 121.2(9) C(4)–C(3)–C(2) 118.21 120.90 123.6(14)
    N(1)–C(16)–C(13) 116.10 115.60 116.3(9) C(15)–C(10)–C(11) 118.21 118.71 118.9(11)
    C(3)–C(4)–C(5) 120.35 118.13 116.6(12) C(15)–C(10)–C(8) 119.99 120.00 120.8(13)
    C(3)–C(4)–C(7) 123.30 123.12 126.0(12) C(11)–C(10)–C(8) 121.18 121.11 120.3(12)
    C(5)–C(4)–C(7) 118.48 118.73 117.4(13) C(14)–C(15)–C(10) 120.42 120.51 119.7(13)
    C(11)–C(12)–C(13) 120.54 120.63 119.5(13) C(14)–C(15)–H(15) 119.51 120.18 120.1
    C(20)–C(19)–C(18) 121.65 121.99 121.2(18) C(10)–C(11)–C(12) 120.62 120.65 120.6(13)
    C(22)–C(21)–C(20) 119.34 119.44 116.9(18) F(1)–C(8)–C(10) 111.73 112.09 112.7(12)
    C(22)–C(17)–N(1) 118.58 117.94 118.8(15) F(1)–C(8)–C(9) 113.89 114.28 112.3(13)
    C(22)–C(17)–C(18) 121.73 120.81 120.2(14) C(10)–C(8)–C(9) 124.81 124.60 124.4(13)
    N(1)–C(17)–C(18) 120.60 121.63 120.9(14) F(1)–C(8)–C(7) 114.44 114.51 114.3(9)
    C(14)–C(13)–C(12) 118.78 118.60 118.5(10) C(10)–C(8)–C(7) 122.57 121.72 123.8(12)
    C(14)–C(13)–C(16) 118.01 117.62 121.0(11) C(9)–C(8)–C(7) 58.97 58.66 59.5(12)
    C(12)–C(13)–C(16) 123.08 123.68 120.4(11) C(19)–C(20)–C(21) 119.86 119.71 121.1(14)
    C(9)–C(7)–C(4) 124.54 123.33 120.1(12) C(17)–C(18)–C(19) 117.75 117.52 117.0(17)
    C(9)–C(7)–C(8) 58.97 58.66 59.6(12) C(17)–C(18)–C(23) 121.73 122.19 124.3(13)
    C(4)–C(7)–C(8) 121.98 122.97 121.8(11) C(19)–C(18)–C(23) 120.52 120.40 118.7(16)
    C(13)–C(14)–C(15) 120.78 120.89 122.3(12) C(1)–C(6)–C(5) 120.97 120.30 123.8(17)
    C(6)–C(1)–C(2) 119.13 119.15 118.3(13) C(21)–C(22)–C(17) 120.59 120.75 123.4(19)
    C(6)–C(1)–Br(1) 117.87 118.75 122.5(13) C(4)–C(5)–C(6) 121.06 121.15 119.3(17)
    C(2)–C(1)–Br(1) 122.99 122.08 119.2(14) C(7)–C(9)–C(8) 60.48 61.11 60.8(8)
    Dihedral angle (°) HF B3LYP X-ray Dihedral angle (°) HF B3LYP X-ray
    C(17)–N(1)–C(16)–C(13) 176.80 175.64 –176.6(15) C(15)–C(10)–C(8)–F(1) 8.47 7.94 –13.1(17)
    C(17)–N(1)–C(16)–O(1) –3.37 –4.14 2(2) C(11)–C(10)–C(8)–F(1) –172.55 –173.02 166.1(12)
    C(16)–N(1)–C(17)–C(22) –111.92 –121.09 118.5(17) C(15)–C(10)–C(8)–C(9) 152.26 152.54 −154.7(18)
    C(16)–N(1)–C(17)–C(18) 70.73 62.16 –66(2) C(11)–C(10)–C(8)–C(9) –28.68 –28.22 25(2)
    C(11)–C(12)–C(13)–C(14) –1.08 1.06 –6(2) C(15)–C(10)–C(8)–C(7) –133.32 –133.87 131.6(15)
    C(11)–C(12)–C(13)–C(16) –179.64 179.06 178.6(12) C(11)–C(10)–C(8)–C(7) 45.90 45.17 –49.1(16)
    O(1)–C(16)–C(13)–C(14) 24.93 22.47 –34.4(18) C(9)–C(7)–C(8)–F(1) –105.64 106.26 –102.5(14)
    N(1)–C(16)–C(13)–C(14) –154.85 –157.60 144.3(13) C(4)–C(7)–C(8)–F(1) –7.59 –6.60 6.2(16)
    O(1)–C(16)–C(13)–C(12) –153.17 –156.24 140.9(13) C(9)–C(7)–C(8)–C(10) 111.11 –113.93 113.2(17)
    N(1)–C(16)–C(13)–C(12) 26.22 23.70 –40.4(17) C(4)–C(7)–C(8)–C(10) 131.48 134.20 –138.0(13)
    C(3)–C(4)–C(7)–C(9) –13.27 –30.20 16(2) C(4)–C(7)–C(8)–C(9) –112.49 –111.87 108.7(15)
    C(5)–C(4)–C(7)–C(9) 166.77 149.42 –161.5(17) N(1)–C(17)–C(18)–C(19) 178.88 178.30 179.2(12)
    C(3)–C(4)–C(7)–C(8) 58.80 41.50 –55.2(16) C(22)–C(17)–C(18)–C(23) –179.01 –178.38 174.3(19)
    C(5)–C(4)–C(7)–C(8) –121.15 –138.83 127.7(15) C(20)–C(19)–C(18)–C(23) 178.85 177.54 –176.3(17)
    C(12)–C(13)–C(14)–C(15) –1.08 –1.42 7(2) C(2)–C(1)–C(6)–C(5) 0.09 –0.11 8(3)
    C(16)–C(13)–C(14)–C(15) –179.64 179.79 –177.2(13) Br(1)–C(1)–C(6)–C(5) 179.95 179.88 –174.7(16)
    Br(1)–C(1)–C(2)–C(3) –179.82 –179.85 175.2(10) C(20)–C(21)–C(22)–C(17) –0.58 –0.57 –3(3)
    C(6)–C(1)–C(2)–Br(2) 179.80 –179.87 174.0(15) N(1)–C(17)–C(22)–C(21) –178.20 –177.61 –179.0(18)
    Br(1)–C(1)–C(2)–Br(2) 0.08 0.16 –3.5(17) C(18)–C(17)–C(22)–C(21) –0.15 –0.77 5(3)
    C(7)–C(4)–C(3)–C(2) –179.77 179.27 –176.2(12) C(3)–C(4)–C(5)–C(6) –0.06 0.39 –1(2)
    C(1)–C(2)–C(3)–C(4) –0.17 0.12 3(2) C(7)–C(4)–C(5)–C(6) 179.90 –179.25 176.6(16)
    Br(2)–C(2)–C(3)–C(4) 179.97 –179.80 –178.2(11) C(4)–C(7)–C(9)–C(8) 109.66 –111.86 –111.4(13)
    C(8)–C(10)–C(15)–C(14) 179.08 0.984 –179.1(13) F(1)–C(8)–C(9)–C(7) –105.64 –105.88 106.0(12)
    C(15)–C(10)–C(11)–C(12) –0.44 –1.289 0(2) C(10)–C(8)–C(9)–C(7) 111.11 110.15 –112.3(15)
    C(8)–C(10)–C(11)–C(12) –179.67 0.68 –179.6(13)

    When the X-ray structure of the title compound is compared with its optimal counterparts, there are slight differences in compatibility between them, because experimental results are reported to solid phase while the theoretical calculations are related to the gaseous phase. In solid state, there is a crystalline field along with molecular interactions, leading to differences in the correlation parameters between calculated and experimental values. Globally, from Table 1, it can be observed that the computed geometrical parameters agreed very well with the single-crystal X-ray data. The average bond distance and bond angle in the three benzene rings for both experiment and calculation are in good agreement with literature values. The average C−F bond length in the cyclopropane ring is 1.36(2) Å and the C−C distances in this ring vary from 1.48(2) to 1.50(19) Å, which are in the expected range as found in earlier studies[30, 31]. The bond length C(16)=O(1) (1.22 Å) is ideal for tautomeric form Keto[32]. However, this distance is only shorter than C−OH (1.28 Å) of the enol form. The keto form is stabilized by intermolecular hydrogen bonds, which is not possible for the enol form. The mean values of the bond angles in the three benzene rings C(1)~C(6), C(10)~C(15) and C(17)~C(22) are 119.96°, 119.98° and 119.99°, respectively. For the cyclopropane ring, the mean bond angle is about 59.97°. The perspective view of the crystal packing in the unit cell is shown in Fig. 5.

    Figure 5

    Figure 5.  Crystal packing in the unit cell of DBFB
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    3.3 Hydrogen bonding analysis

    The compound involves intra- and intermolecular hydrogen bonding of C–H···O, N–H···O and C–H···F types in which C atoms (C(5) and C(12)) and N(1) act as donors and (O(1) and F(1)) atoms as acceptors. Fig. 6 shows N–H⋅⋅⋅O hydrogen bond in the crystal. This bond is formed due to the attraction between the oxygen atom (O(1)) of carbonyl (C(16)) and the hydrogen atom connected with nitrogen atom (N(1)). The details of H-bonds are shown in Table 2. These intermolecular interactions contribute to the stabilization of the crystal structure packing.

    Figure 6

    Figure 6.  Hydrogen bonds in the crystal packing
    DownLoad: Full-Size Img PowerPoint

    Table 2

    Table 2.  Hydrogen Bond Lengths (Å) and Bond Angles (°)
    DownLoad: CSV
    D–H···A d(D–H) d(H···A) d(D···A) ∠DHA
    N(1)−H(1)···O(1)(i) 0.86 2.20 2.939(11) 144
    C(12)−H(12)···F(1)(ii) 0.93 2.64 3.549(19) 167
    C(5)−H(5)···O(1)(iii) 0.93 2.59 3.406(19) 147
    Symmetry codes: (i) x, y, z + 1, (ii) –x, y + 1/2, –z + 2, (iii) x, y, z–1

    3.4 Vibrational analysis

    For molecule containing N atoms, the number of normal modes of vibrations is 3N-6[33] in our case N=46. This number is 132. The scaled theoretical frequencies and IR intensity with the PED contributions at B3LYP/6-31G(d, p) are summarized in Table 3. The theoretical vibrational spectra IR and Raman with B3LYP/6-31G(d, p) and B3LYP/6-311++G(d, p) basis set are shown in Fig. 7.

    Table 3

    Table 3.  Theoretical Vibrational Wavenumbers (cm–1) for DBFB
    DownLoad: CSV
    Mode Unscaled Scaled IR intensity Vibration assignments (PED ≥ 10%)
    132 3605 3482 14.0979 νNH (100%)
    131 3240 3121 0.1211 νCH ring 1 (98%)
    130 3230 3112 1.847 νCH ring 2 (97)
    129 3226 3111 4.988 νCH ring 2 (98)
    128 3216 3098 2.26 νCH ring 1 (93)
    127 3213 3094 0.0592 νCH ring 2 (97)
    126 3201 3085 27.359 νCH ring 3 (99)
    125 3193 3077 10.848 νCH ring 2 (96)
    124 3187 3071 24.59 νCH ring 3 (94)
    123 3186 3069 8.93 νCH ring 1 (93)
    122 3176 3061 20.19 νCH ring 2 (97)
    121 3173 3058 2.477 νCH ring 3 (91)
    120 3168 3053 12.127 νCH ring 3 (86)
    119 3156 3041 5.799 νCH (99)
    118 3137 3024 5.004 νCH2 (99)
    117 3122 3013 16.532 νCH3 (98)
    116 3103 2993 13.553 νCH3 (99)
    115 3039 2932 21.794 νCH3 (97)
    114 1768 1700 165.79 νOC (83)
    113 1666 1603 59.925 νCC ring 2 (64) + δHCC ring 2 (16)
    112 1661 1598 18.41 νCC ring 3 (51) + δHCC ring 3 (13) + δCCC ring 3 (12)
    111 1639 1576 5.804 νCC ring 1 (55) + δHCC ring 1 (10)
    110 1638 1576 12.774 νCC ring 3 (49)
    109 1616 1554 12.774 νCC ring 2 (60) + δHCC ring 2 (13) + δCCC ring 2 (10)
    108 1600 1540 14.876 νCC ring 1 (61)
    107 1556 1496 13.851 δHCC ring 2 (37)
    106 1544 1484 16.376 δHNC (11) + δCC R3 (30) + δCCC R3 (13)
    105 1528 1469 277.64 δHNC (11) + δHCC ring 3 (16) + δCH3 (21)
    104 1511 1453 22.498 δHCC ring 1 (31)
    103 1508 1450 43.15 δHNC (12) + δCH3 (36)
    102 1493 1435 26.571 δCH2 (56)
    101 1489 1430 27.778 δCH3 (68) + τCCCH3 (12)
    100 1473 1417 113.77 νCC ring 3 (14) + δHNC (12) + δHCC ring 3 (19)
    99 1446 1391 4.83 νCC ring 2 (36) + δHCC ring 2 (15) + δCH2 (14)
    98 1443 1388 12.076 νCC ring 2 (19) + δHCC Δ (17) + δHCC ring 2 (11)
    97 1428 1370 3.72 δCH3 (90)
    96 1407 1353 9.88 νCC ring 1 (13) + δHCC ring 1 (11)
    95 1357 1306 11 νCC ring 2 (68)
    94 1350 1298 64 νCC ring 3 (61)
    93 1341 1290 2.184 δHCC ring 2 (65)
    92 1335 1284 0.268 νCC ring 1 (44) + δHCC ring 2 (11)
    91 1315 1265 33.925 νCC ring 1 (18) + νCC (19)
    90 1315 1264 61.155 νCC ring 3 (11) + δHCC ring 3 (46)
    89 1290 1241 8.991 νCC Δ (17) + δHCC Δ (12) + δHCC ring 1 (27)
    88 1285 1236 14.092 νCC Δ (17) + δHCC ring 1 (28)
    87 1270 1222 119.66 νCC ring 2 (37) + νNC (10)
    86 1264 1215 117.24 νCC ring 3 (51) + δHNC (18) + δHCC ring R3 (10)
    85 1229 1182 6.642 νCC (15) + δHCC Δ (13) + δCCC ring 1 (15)
    84 1222 1176 12.894 νCC ring 3 (43) + δHCC ring 3 (19)
    83 1216 1169 17.488 νCC ring 2 (16) + δHCC ring 2 (62)
    82 1190 1143 0.337 νCC ring 3 (10) + δHCC ring 3 (79)
    81 1176 1130 2.746 νCC ring 1 (11) + δHCC ring 1 (51)
    80 1151 1106 27.913 δHCC ring 3 (12) + δHCC ring 2 (12) + δHCC ring 3 (13)
    79 1148 1104 6.561 νCC ring 2 (12) + δHCC ring 2 (34)
    78 1143 1099 38.136 δHCC ring 2 (14) + τHCCC Δ (12) + τHCCC Δ (16)
    77 1135 1091 14.121 νCC ring 1 (46) + δHCC ring 1 (23)
    76 1118 1075 18.110 νNC (26) + δCCC R3 (12)
    75 1092 1048 5.129 τH CCC Δ (49)
    74 1077 1036 1.458 νCC ring 3 (50) + δHCC ring 3 (12)
    73 1071 1027 3.629 δCH3 (16) + τCCCH3 (52)
    72 1066 1022 38.567 τHCCC Δ (53) + τHCCC Δ (12)
    71 1033 993 30.526 δCCC ring 2 (66)
    70 1025 986 32.326 νCC ring 1 (11) + δCCC ring 1 (73)
    69 1022 982 13.09 νCC Δ (12) + δCCC Δ (24) + τHCCC Δ (25)
    68 1017 976 2.782 δCH3 (11) + δCCC ring 3 (12) + τCCCH3 (48)
    67 1001 962 1.985 τHCCC ring 2 (78)
    66 984 944 0.064 τHCCC ring 3 (77)
    65 982 942 1.188 τHCCC (61) + τCCCC (13)
    64 969 931 1.460 δHCC (14) + τHCCC ring 2 (13) + τHCCC ring 1 (10)
    63 967 928 0.318 τHCCC ring 2 (60) + τCCCC (13)
    62 947 909 2.779 τHCCC ring 3 (68) τCCCN (10)
    61 919 883 3.003 δOCN (12) + δCNC (10) τ+ HCCC ring 3 (15)
    60 917 882 21.721 νCC Δ (21) + δHCC Δ (11) + τHCCC (31)
    59 914 880 2.327 νCC ring 2 (14) + δHCC ring 2 (12) + τHCCC (39)
    58 888 853 2.751 δHCC Δ (13) + τHCCC ring 2 (24)
    57 871 835 2.681 τHCCC ring 3 (78)
    56 865 832 11.09 νCC Δ (10) + δCCC ring 3 (19) + τHCCC ring 2 (10)
    55 860 826 5.697 τHCCC ring 2 (32) + τHCCC ring 3 (29)
    54 850 815 9.570 τHCCC ring 1 (79)
    53 840 807 32.519 τHCCC ring 2 (42)
    52 814 782 20.861 νCC Δ (10) + δCCC ring 1 (17)
    51 780 750 28.59 νCC (15) + τHCCC ring 3 (22)
    50 769 739 21.182 τCCCC ring 2 (13) + ωONCC (29)
    49 763 732 25.49 τHCCC ring 3 (60)
    48 746 717 7.065 τHCCC ring 1 (10) + ωCCCC (42)
    47 735 707 2.38 δCCC ring 2 + (15) τCCCC ring 3 (–13)
    46 721 693 2.41 ωCCCC ring 2 (11) + τCCCC ring 3 (34)
    45 707 680 16.799 τCCCC ring 2 (30) + ωONCC (26)
    44 679 653 14.69 δCCC ring 1 (50)
    43 676 649 13.30 δCCC ring 1 (14) + ωFCCC (15)
    42 649 624 0.44 νCC (10) + δCCC ring 2 (78)
    41 624 599 10.24 δCCC ring 3 (44)
    40 614 590 4.469 δCCC ring 3 (12)
    39 582 558 10.24 ωCCCC ring 2 (22) + ωCCCC ring 1 (10)
    38 569 546 18.887 τCCCC (–12) + τHNCC (–13)
    37 556 533 2.953 δCCC (13) + τCCCC ring 3 (25)
    36 544 517 49.335 νCC (12) + δCCC ring 3 (–26) + τHNCC (46)
    35 535 511 4.433 τHNCC (59) + τCCCC ring 3 (25)
    34 493 473 6.076 δFCC (23)
    33 473 455 5.459 ωCCCC ring 2 (12)
    32 464 445 1.617 τCCCC (49)
    31 458 440 8.098 τCCCC ring 1 (27) + τCCCC ring 2 (19)
    30 445 428 1.711 δCCC (12) + δCCN (18)
    29 441 423 3.507 τCCCC ring 1 (17)
    28 420 404 1.652 τHCCC ring 2 (11) + τHCCC ring 2 (13) + τCCCC ring 2 (64)
    27 406 389 0.321 δCCC (13)
    26 403 387 4.697 δCCBr (50)
    25 365 351 3.906 δFCC (16)
    24 350 336 11.990 νCC (39)
    23 330 316 0.5234 δCCC (37)
    22 311 299 0.974 νCC (11) + ωBrCCC (17)
    21 296 284 8.921 δOCN (12) + δCCC (11) + τCCCN (25)
    20 277 265 3.050 τCCCN (25)
    19 256 245 1.391 ωCCCC (11) + ωCCCC (21)
    18 231 219 4.296 δCCC (11)
    16 194 183 0.349 νBrC (14) δCCC (19)
    15 186 168 1.42 νBrC (14) + δCCC (19)
    14 172 163 1.027 δNCC (14) + δCCC (10) + τHCCC (21)
    13 154 147 0.453 τHCCC (10) + ωCCCC (13) + ωBrCCC (12)
    12 133 127 0.344 ωCCCC (22) + ωBrCCC (12)
    11 119 112 1.968 δBrCC (76)
    10 108 102 1.626 ωCCCC (10) + τCNCC (40)
    9 104.6 100 1.851 δCCC (13) + τCCCC (12) + τCNCC (20)
    8 83 79 0.237 τCCCC (34)
    7 60.82 56 0.044 δCCC (38)
    6 52.01 49 0.113 τCNCC (53)
    5 48. 46 0.118 δCCC (11) + δCCC (17) + δCNC (12) + ωCCCC (15)
    4 34 30 0.144 δCCC (12) + δCNC (33)
    3 20.93 20 0.090 τCNCC (46)
    2 19.35 13 0.638 δCNC (12) + τCCCC (55)
    1 14.54 11 0.0595 τCNCC (30) + τCNCC (12)
    ν: stretching, δ: bending, τ: twisting, γ: out of plane bending, s: symmetric, as: asymmetric

    Figure 7

    Figure 7.  Theoretical vibrational spectra (a) IR and (b) Raman
    DownLoad: Full-Size Img PowerPoint

    C−H aromatic stretching vibrations are varying 3100~3000 cm-1 that is the characteristic region for the ready identification of C−H stretching vibrations[34]. The peak of C−H stretching vibration is calculated in the region of 3041~3121 cm-1 by method B3LYP/6-31G (d, p) basis set. The maximum PED corresponding to this vibration contributes to 99%.

    N−H stretching frequency band at 3605 cm-1 in FT-IR. The contribution of broad bands of PED is 100%.

    The C−N stretching vibration is present in a composite region of the vibrational spectrum, that is to say, mixing of different bands is possible in this region[33]. The theoretical scaled frequency is calculated at 1075 and 1222 cm-1. The PED contribution is 26 and 12%, respectively.

    C=O stretching is recorded at 1768 cm-1 in FT-IR, scaled frequencies at 1700 cm-1 with PED ≈ 83%. The carbonyl group of C=O stretching vibration (strong band) has characteristic band in the 1850~1550 cm-1 region[35].

    We can see the aromatic benzene ring C−C bands at around 1650~1400 cm-1[35]. An aromatic ring replaces most of the ring modes. By referring the above notes, theoretical values of the title molecule were identified in the range of 1660~350 cm-1 via B3LYP/6-31G (d, p) method. The different frequencies in FI-IR were presented at 1603, 1598, 1576, 1554, 1540, 1306 and 1298 cm-1. The maximum contribution of PED of CC band is 68%.

    Br−C stretching vibration gives generally strong band in the region of 650~485 cm-1[36-38]. In this compound, bands observed at 168 and 183 cm-1 for C−Br stretching as a mode (mode No. 16 and 15) have been assigned to C−Br in-plane and twisting vibration of CCCBr is observed at 147 cm-1 (mode No. 13). All these tasks are well aligned with calculated values and more justified with PED values.

    3.5 Frontier molecular orbitals and structure-activity descriptors

    The frontier molecular orbitals are sketched in Fig. 8. The frontier orbital energy gap (ELUMO − EHOMO) of DBFB is found to be 4.9325 eV by B3LYP using 6-31G(d, p) basis set. This energy gap is a relatively high value, indicating significant stability of compounds that have biological activity. A lower HOMO-LUMO energy gap explains the fact that eventual charge transfer interaction is taking place within the molecule[39].

    Figure 8

    Figure 8.  Frontier molecular orbitals of DBFB
    DownLoad: Full-Size Img PowerPoint

    Both the global hardness and softness are concepts that have been used to explain chemical reactivity. According to Koopman theorem the chemical potential, hardness and softness can be written in terms of the frontier orbital energies (EHOMO and ELUMO). These two negative values define the ionization potential and electronic affinity, respectively. The calculated values of the global reactivity descriptors are listed in Table 4.

    Table 4

    Table 4.  Calculated Energy Values for (DBFB) Using B3LYP/6-31G(d, p)
    DownLoad: CSV
    Parameters Values (eV)
    EHOMO −6.226
    ELUMO −1.395
    Gap (ΔE) 4.832
    Electronegativity (χ) 3.811
    Chemical potential (μ) −3.811
    Chemical hardness (η) 4.831
    Chemical softness (S) 0.207
    Electrophilicity index (ω) 1.503
    Additional electronic charge (ΔNmax) 0.163

    According to Parr an Pearson[40], electrophilicity index (ω) is as a global reactivity index similar to the chemical hardness and chemical potential. This reactivity index measures the stabilization in energy when the system acquires an additional electronic charge (ΔNmax) from the environment. The electrophilicity index (ω) is positive, definite quantity and the direction of the charge transfer is completely determined by the electronic chemical potential (μ) of the molecule because an electrophile is a chemical species capable of accepting electrons from the environment and its energy must decrease upon accepting electronic charge. Therefore, its electronic chemical potential must be negative. The structure stability of the title compound is confirmed by the negative value of the chemical potential (μ = −3.811 eV). The calculated value of chemical hardness (η = 4.831 eV) indicates that the charge transfer occurs within the molecule.

    3.6 Atomic charge distribution analysis

    Computed Mulliken atomic charges play an important role in the application of quantum chemical computation to molecular polarizability, electronic structure and other properties of molecular systems[41]. Our calculated Mulliken charge values using HF and B3LYP with 6-31G (d, p) basis sets are gathered in Table 5. The results of Table 5 reveal the effect of DFT method and HF in the value of Mulliken charge distribution but the same behavior is observed. In fact, the Mulliken atomic charge analysis of DBFB shows that the fluorine atom has a maximum negative charge value of –0.3015 at DFT/6-31G(d, p). With the same level of theory, the maximum positive atomic charge of 0.795130 is obtained for C(16) which was imposed by O(1). However, atoms C(3), C(5), C(6), C(7), C(9), C(11), C(12) and C(14) possess small negative charges, whereas C(1) and C(2) exhibit a positive charge due to negative charge of Br(1) and Br(2). Moreover, all the hydrogen atoms have a net positive charge (for all the considered theoretical approaches).

    Table 5

    Table 5.  Mulliken Atomic Charges for DBFB
    DownLoad: CSV
    Atoms Mulliken atomic charges Atoms Mulliken atomic charges
    DFT HF DFT HF
    Br(1) –0.094459 –0.075057 C(16) 0.553734 0.795130
    Br(2) –0.093303 –0.073689 C(21) –0.098879 –0.159134
    N(1) –0.639660 –0.808507 C(22) –0.10338 –0.142897
    F(1) –0.301539 –0.400608 C(23) –0.385374 –0.346166
    O(1) –0.503772 –0.594833 C(19) –0.139060 –0.166692
    C(1) 0.039286 –0.027181 C(20) –0.074642 –0.140331
    C(2) 0.036221 –0.021984 H(4) 0.261137 0.309928
    C(3) –0.139351 –0.122195 H(3) 0.116343 0.189077
    C(4) 0.196518 0.059095 H(5) 0.094871 0.164301
    C(5) –0.131284 –0.157487 H(6) 0.116593 0.185202
    C(6) –0.088779 –0.111020 H(7) 0.111783 0.157378
    C(7) –0.203012 –0.214280 H(9B) 0.141130 0.165981
    C(8) 0.297273 0.445493 H(9A) 0.126005 0.149713
    C(9) –0.248240 –0.283870 H(15) 0.112567 0.189030
    C(10) 0.116477 –0.032461 H(14) 0.124193 0.201208
    C(15) –0.128951 –0.154107 H(11) 0.086824 0.15351
    C(14) –0.100554 –0.111773 H(20) 0.084919 0.151090
    C(13) 0.038415 –0.151646 H(21) 0.086260 0.151493
    C(12) –0.132461 –0.142267 H(22) 0.079983 0.151043
    C(11) –0.146731 –0.176673 H(23) 0.109964 0.12170
    H(19) 0.082299 0.148166 H(23B) 0.162564 0.171392
    C(17) 0.232932 0.247133 H(23A) 0.100062 0.115260
    C(18) 0.151961 0.026484 H(12) 0.093125 0.166038

    3.7 Analysis of molecular electrostatic potential (MEP)

    The chemical reactivity of the molecules can be predicted by using the MEP details[42]. Both experimental X-ray diffraction and theoretical methods are used to obtain MEP values[43, 44]. Total B3LYP/6-31G(d, p) electron density surface mapped with MEP of the DBFB molecule is shown in Fig. 9. The MEP displays molecular shape, size and electrostatic potential values. The extreme limits of the total electron density lay in the range of –5.495~5.495 e–2. The electron density varies significantly around the DBFB of electron withdrawing and donating groups. The color scheme for the MEP surface is blue-electron deficient or partially positive charge; red-electron rich or partially negative charge; light blue-slightly electron deficient region; yellow-slightly electron rich region, respectively. The title compound has several possible sites for electrophilic at O, N, F and Br atoms. The MEP map shows that the negative potential sites are on electronegative atoms and the positive potential sites are around the hydrogen atoms. These active sites are found to be clear evidence of biological activity in DBFB and give information about the region from which the compound can have intermolecular interactions.

    Figure 9

    Figure 9.  Total electron density surface mapped with molecular electrostatic potential of DBFB
    DownLoad: Full-Size Img PowerPoint

    5. CONCLUSION

    In the present study, X-ray structure of a pyrethroid derivative has been determined. This compound belongs to the monoclinic system with P21 space group. Intramolecular C–H⋅⋅⋅O, N–H⋅⋅⋅O and C–H⋅⋅⋅F hydrogen bonds are present in the crystal structure. These hydrogen bonds contribute to the stability of the crystal packing. The stability of the compound has been confirmed by conformational analysis, indicating that our molecule exhibits trans isomer. Furthermore, theoretical calculations were carried out on the most stable conformer of the title molecule. The bond lengths and angles computed at the B3LYP/6-31G (d, p) level of theory were compared with the experimental ones, which are consistent with each other. Vibrational wavenumbers of the molecule have been calculated and assigned using the same level of theory with two different bases sets. Results show a good correlation with the structurally similar compounds. The HOMO-LUMO energy gap explains the charge transfer interactions and the eventual electronic transition taking place within the molecule. The calculated HOMO and LUMO energies were used to estimate the ionization potential, electron affinity, electronegativity, electrophilicity index, hardness and chemical potential. Moreover, Mulliken charges and molecular electrostatic potential were calculated to know about the potential and charge distribution within the molecule.


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      Boubegra, N.; Chouaih, A.; Drissi, M.; Hamzaoui, F. Structural and electron charge density studies of a nonlinear optical compound 4, 4 di-methyl amino cyano biphenyl. Chin. Phys. B 2014, 23, 016103–6. doi: 10.1088/1674-1056/23/1/016103

  • Figure 1  Possible optimized structural conformers of DBFB

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    Figure 2  Potential energy profile of DBFB

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    Figure 3  Possible conformers of DBFB

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    Figure 4  Geometry of DBFB (a) X-ray structure with atomic numbering scheme and (b) optimized molecular structure

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    Figure 5  Crystal packing in the unit cell of DBFB

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    Figure 6  Hydrogen bonds in the crystal packing

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    Figure 7  Theoretical vibrational spectra (a) IR and (b) Raman

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    Figure 8  Frontier molecular orbitals of DBFB

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    Figure 9  Total electron density surface mapped with molecular electrostatic potential of DBFB

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    Table 1.  Geometrical Parameters of DBFB

    Bond Dist. (Å) Bond Dist. (Å)
    HF B3LYP X-ray HF B3LYP X-ray
    Br(1)–C(1) 1.897 1.900 1.854(12) C(17)–C(22) 1.386 1.400 1.40(3)
    Br(2)–C(2) 1.898 1.903 1.858(15) C(17)–C(18) 1.395 1.409 1.36(2)
    N(1)–C(16) 1.354 1.383 1.315(13) F(1)–C(8) 1.360 1.381 1.36(2)
    N(1)–C(17) 1.427 1.426 1.410(13) C(13)–C(14) 1.390 1.400 1.336(17)
    N(1)–H(1) 0.994 1.010 0.8600 C(7)–C(9) 1.508 1.520 1.48(2)
    C(16)–O(1) 1.202 1.224 1.224(13) C(7)–C(8) 1.508 1.531 1.501(19)
    C(16)–C(13) 1.501 1.503 1.467(13) C(14)–C(15) 1.382 1.391 1.373(16)
    C(4)–C(3) 1.387 1.401 1.371(19) C(1)–C(6) 1.385 1.395 1.30(3)
    C(4)–C(5) 1.390 1.402 1.38(2) C(1)–C(2) 1.385 1.398 1.41(2)
    C(4)–C(7) 1.496 1.490 1.483(13) C(2)–C(3) 1.385 1.394 1.365(17)
    C(12)–C(11) 1.389 1.392 1.382(16) C(10)–C(15) 1.391 1.402 1.382(19)
    C(12)–C(13) 1.387 1.402 1.41(2) C(10)–C(11) 1.390 1.402 1.37(2)
    C(19)–C(20) 1.386 1.394 1.40(3) C(10)–C(8) 1.498 1.490 1.468(15)
    C(19)–C(18) 1.390 1.401 1.414(18) C(8)–C(9) 1.485 1.496 1.48(2)
    C(21)–C(22) 1.385 1.393 1.37(2) C(18)–C(23) 1.509 1.506 1.48(3)
    C(21)–C(20) 1.389 1.394 1.37(3) C(6)–C(5) 1.380 1.391 1.39(2)
    Bond angle (°) HF B3LYP X-ray Bond angle (°) HF B3LYP X-ray
    C(16)–N(1)–C(17) 123.32 124.67 125.2(9) C(3)–C(2)–C(1) 120.26 120.34 118.0(14)
    C(17)–N(1)–H(1) 116.41 115.34 117.4(10) C(3)–C(2)–Br(2) 117.25 117.49 118.5(12)
    O(1)–C(16)–N(1) 122.83 122.85 122.5(9) C(1)–C(2)–Br(2) 122.42 122.15 123.5(11)
    O(1)–C(16)–C(13) 121.05 121.53 121.2(9) C(4)–C(3)–C(2) 118.21 120.90 123.6(14)
    N(1)–C(16)–C(13) 116.10 115.60 116.3(9) C(15)–C(10)–C(11) 118.21 118.71 118.9(11)
    C(3)–C(4)–C(5) 120.35 118.13 116.6(12) C(15)–C(10)–C(8) 119.99 120.00 120.8(13)
    C(3)–C(4)–C(7) 123.30 123.12 126.0(12) C(11)–C(10)–C(8) 121.18 121.11 120.3(12)
    C(5)–C(4)–C(7) 118.48 118.73 117.4(13) C(14)–C(15)–C(10) 120.42 120.51 119.7(13)
    C(11)–C(12)–C(13) 120.54 120.63 119.5(13) C(14)–C(15)–H(15) 119.51 120.18 120.1
    C(20)–C(19)–C(18) 121.65 121.99 121.2(18) C(10)–C(11)–C(12) 120.62 120.65 120.6(13)
    C(22)–C(21)–C(20) 119.34 119.44 116.9(18) F(1)–C(8)–C(10) 111.73 112.09 112.7(12)
    C(22)–C(17)–N(1) 118.58 117.94 118.8(15) F(1)–C(8)–C(9) 113.89 114.28 112.3(13)
    C(22)–C(17)–C(18) 121.73 120.81 120.2(14) C(10)–C(8)–C(9) 124.81 124.60 124.4(13)
    N(1)–C(17)–C(18) 120.60 121.63 120.9(14) F(1)–C(8)–C(7) 114.44 114.51 114.3(9)
    C(14)–C(13)–C(12) 118.78 118.60 118.5(10) C(10)–C(8)–C(7) 122.57 121.72 123.8(12)
    C(14)–C(13)–C(16) 118.01 117.62 121.0(11) C(9)–C(8)–C(7) 58.97 58.66 59.5(12)
    C(12)–C(13)–C(16) 123.08 123.68 120.4(11) C(19)–C(20)–C(21) 119.86 119.71 121.1(14)
    C(9)–C(7)–C(4) 124.54 123.33 120.1(12) C(17)–C(18)–C(19) 117.75 117.52 117.0(17)
    C(9)–C(7)–C(8) 58.97 58.66 59.6(12) C(17)–C(18)–C(23) 121.73 122.19 124.3(13)
    C(4)–C(7)–C(8) 121.98 122.97 121.8(11) C(19)–C(18)–C(23) 120.52 120.40 118.7(16)
    C(13)–C(14)–C(15) 120.78 120.89 122.3(12) C(1)–C(6)–C(5) 120.97 120.30 123.8(17)
    C(6)–C(1)–C(2) 119.13 119.15 118.3(13) C(21)–C(22)–C(17) 120.59 120.75 123.4(19)
    C(6)–C(1)–Br(1) 117.87 118.75 122.5(13) C(4)–C(5)–C(6) 121.06 121.15 119.3(17)
    C(2)–C(1)–Br(1) 122.99 122.08 119.2(14) C(7)–C(9)–C(8) 60.48 61.11 60.8(8)
    Dihedral angle (°) HF B3LYP X-ray Dihedral angle (°) HF B3LYP X-ray
    C(17)–N(1)–C(16)–C(13) 176.80 175.64 –176.6(15) C(15)–C(10)–C(8)–F(1) 8.47 7.94 –13.1(17)
    C(17)–N(1)–C(16)–O(1) –3.37 –4.14 2(2) C(11)–C(10)–C(8)–F(1) –172.55 –173.02 166.1(12)
    C(16)–N(1)–C(17)–C(22) –111.92 –121.09 118.5(17) C(15)–C(10)–C(8)–C(9) 152.26 152.54 −154.7(18)
    C(16)–N(1)–C(17)–C(18) 70.73 62.16 –66(2) C(11)–C(10)–C(8)–C(9) –28.68 –28.22 25(2)
    C(11)–C(12)–C(13)–C(14) –1.08 1.06 –6(2) C(15)–C(10)–C(8)–C(7) –133.32 –133.87 131.6(15)
    C(11)–C(12)–C(13)–C(16) –179.64 179.06 178.6(12) C(11)–C(10)–C(8)–C(7) 45.90 45.17 –49.1(16)
    O(1)–C(16)–C(13)–C(14) 24.93 22.47 –34.4(18) C(9)–C(7)–C(8)–F(1) –105.64 106.26 –102.5(14)
    N(1)–C(16)–C(13)–C(14) –154.85 –157.60 144.3(13) C(4)–C(7)–C(8)–F(1) –7.59 –6.60 6.2(16)
    O(1)–C(16)–C(13)–C(12) –153.17 –156.24 140.9(13) C(9)–C(7)–C(8)–C(10) 111.11 –113.93 113.2(17)
    N(1)–C(16)–C(13)–C(12) 26.22 23.70 –40.4(17) C(4)–C(7)–C(8)–C(10) 131.48 134.20 –138.0(13)
    C(3)–C(4)–C(7)–C(9) –13.27 –30.20 16(2) C(4)–C(7)–C(8)–C(9) –112.49 –111.87 108.7(15)
    C(5)–C(4)–C(7)–C(9) 166.77 149.42 –161.5(17) N(1)–C(17)–C(18)–C(19) 178.88 178.30 179.2(12)
    C(3)–C(4)–C(7)–C(8) 58.80 41.50 –55.2(16) C(22)–C(17)–C(18)–C(23) –179.01 –178.38 174.3(19)
    C(5)–C(4)–C(7)–C(8) –121.15 –138.83 127.7(15) C(20)–C(19)–C(18)–C(23) 178.85 177.54 –176.3(17)
    C(12)–C(13)–C(14)–C(15) –1.08 –1.42 7(2) C(2)–C(1)–C(6)–C(5) 0.09 –0.11 8(3)
    C(16)–C(13)–C(14)–C(15) –179.64 179.79 –177.2(13) Br(1)–C(1)–C(6)–C(5) 179.95 179.88 –174.7(16)
    Br(1)–C(1)–C(2)–C(3) –179.82 –179.85 175.2(10) C(20)–C(21)–C(22)–C(17) –0.58 –0.57 –3(3)
    C(6)–C(1)–C(2)–Br(2) 179.80 –179.87 174.0(15) N(1)–C(17)–C(22)–C(21) –178.20 –177.61 –179.0(18)
    Br(1)–C(1)–C(2)–Br(2) 0.08 0.16 –3.5(17) C(18)–C(17)–C(22)–C(21) –0.15 –0.77 5(3)
    C(7)–C(4)–C(3)–C(2) –179.77 179.27 –176.2(12) C(3)–C(4)–C(5)–C(6) –0.06 0.39 –1(2)
    C(1)–C(2)–C(3)–C(4) –0.17 0.12 3(2) C(7)–C(4)–C(5)–C(6) 179.90 –179.25 176.6(16)
    Br(2)–C(2)–C(3)–C(4) 179.97 –179.80 –178.2(11) C(4)–C(7)–C(9)–C(8) 109.66 –111.86 –111.4(13)
    C(8)–C(10)–C(15)–C(14) 179.08 0.984 –179.1(13) F(1)–C(8)–C(9)–C(7) –105.64 –105.88 106.0(12)
    C(15)–C(10)–C(11)–C(12) –0.44 –1.289 0(2) C(10)–C(8)–C(9)–C(7) 111.11 110.15 –112.3(15)
    C(8)–C(10)–C(11)–C(12) –179.67 0.68 –179.6(13)
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    Table 2.  Hydrogen Bond Lengths (Å) and Bond Angles (°)

    D–H···A d(D–H) d(H···A) d(D···A) ∠DHA
    N(1)−H(1)···O(1)(i) 0.86 2.20 2.939(11) 144
    C(12)−H(12)···F(1)(ii) 0.93 2.64 3.549(19) 167
    C(5)−H(5)···O(1)(iii) 0.93 2.59 3.406(19) 147
    Symmetry codes: (i) x, y, z + 1, (ii) –x, y + 1/2, –z + 2, (iii) x, y, z–1
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    Table 3.  Theoretical Vibrational Wavenumbers (cm–1) for DBFB

    Mode Unscaled Scaled IR intensity Vibration assignments (PED ≥ 10%)
    132 3605 3482 14.0979 νNH (100%)
    131 3240 3121 0.1211 νCH ring 1 (98%)
    130 3230 3112 1.847 νCH ring 2 (97)
    129 3226 3111 4.988 νCH ring 2 (98)
    128 3216 3098 2.26 νCH ring 1 (93)
    127 3213 3094 0.0592 νCH ring 2 (97)
    126 3201 3085 27.359 νCH ring 3 (99)
    125 3193 3077 10.848 νCH ring 2 (96)
    124 3187 3071 24.59 νCH ring 3 (94)
    123 3186 3069 8.93 νCH ring 1 (93)
    122 3176 3061 20.19 νCH ring 2 (97)
    121 3173 3058 2.477 νCH ring 3 (91)
    120 3168 3053 12.127 νCH ring 3 (86)
    119 3156 3041 5.799 νCH (99)
    118 3137 3024 5.004 νCH2 (99)
    117 3122 3013 16.532 νCH3 (98)
    116 3103 2993 13.553 νCH3 (99)
    115 3039 2932 21.794 νCH3 (97)
    114 1768 1700 165.79 νOC (83)
    113 1666 1603 59.925 νCC ring 2 (64) + δHCC ring 2 (16)
    112 1661 1598 18.41 νCC ring 3 (51) + δHCC ring 3 (13) + δCCC ring 3 (12)
    111 1639 1576 5.804 νCC ring 1 (55) + δHCC ring 1 (10)
    110 1638 1576 12.774 νCC ring 3 (49)
    109 1616 1554 12.774 νCC ring 2 (60) + δHCC ring 2 (13) + δCCC ring 2 (10)
    108 1600 1540 14.876 νCC ring 1 (61)
    107 1556 1496 13.851 δHCC ring 2 (37)
    106 1544 1484 16.376 δHNC (11) + δCC R3 (30) + δCCC R3 (13)
    105 1528 1469 277.64 δHNC (11) + δHCC ring 3 (16) + δCH3 (21)
    104 1511 1453 22.498 δHCC ring 1 (31)
    103 1508 1450 43.15 δHNC (12) + δCH3 (36)
    102 1493 1435 26.571 δCH2 (56)
    101 1489 1430 27.778 δCH3 (68) + τCCCH3 (12)
    100 1473 1417 113.77 νCC ring 3 (14) + δHNC (12) + δHCC ring 3 (19)
    99 1446 1391 4.83 νCC ring 2 (36) + δHCC ring 2 (15) + δCH2 (14)
    98 1443 1388 12.076 νCC ring 2 (19) + δHCC Δ (17) + δHCC ring 2 (11)
    97 1428 1370 3.72 δCH3 (90)
    96 1407 1353 9.88 νCC ring 1 (13) + δHCC ring 1 (11)
    95 1357 1306 11 νCC ring 2 (68)
    94 1350 1298 64 νCC ring 3 (61)
    93 1341 1290 2.184 δHCC ring 2 (65)
    92 1335 1284 0.268 νCC ring 1 (44) + δHCC ring 2 (11)
    91 1315 1265 33.925 νCC ring 1 (18) + νCC (19)
    90 1315 1264 61.155 νCC ring 3 (11) + δHCC ring 3 (46)
    89 1290 1241 8.991 νCC Δ (17) + δHCC Δ (12) + δHCC ring 1 (27)
    88 1285 1236 14.092 νCC Δ (17) + δHCC ring 1 (28)
    87 1270 1222 119.66 νCC ring 2 (37) + νNC (10)
    86 1264 1215 117.24 νCC ring 3 (51) + δHNC (18) + δHCC ring R3 (10)
    85 1229 1182 6.642 νCC (15) + δHCC Δ (13) + δCCC ring 1 (15)
    84 1222 1176 12.894 νCC ring 3 (43) + δHCC ring 3 (19)
    83 1216 1169 17.488 νCC ring 2 (16) + δHCC ring 2 (62)
    82 1190 1143 0.337 νCC ring 3 (10) + δHCC ring 3 (79)
    81 1176 1130 2.746 νCC ring 1 (11) + δHCC ring 1 (51)
    80 1151 1106 27.913 δHCC ring 3 (12) + δHCC ring 2 (12) + δHCC ring 3 (13)
    79 1148 1104 6.561 νCC ring 2 (12) + δHCC ring 2 (34)
    78 1143 1099 38.136 δHCC ring 2 (14) + τHCCC Δ (12) + τHCCC Δ (16)
    77 1135 1091 14.121 νCC ring 1 (46) + δHCC ring 1 (23)
    76 1118 1075 18.110 νNC (26) + δCCC R3 (12)
    75 1092 1048 5.129 τH CCC Δ (49)
    74 1077 1036 1.458 νCC ring 3 (50) + δHCC ring 3 (12)
    73 1071 1027 3.629 δCH3 (16) + τCCCH3 (52)
    72 1066 1022 38.567 τHCCC Δ (53) + τHCCC Δ (12)
    71 1033 993 30.526 δCCC ring 2 (66)
    70 1025 986 32.326 νCC ring 1 (11) + δCCC ring 1 (73)
    69 1022 982 13.09 νCC Δ (12) + δCCC Δ (24) + τHCCC Δ (25)
    68 1017 976 2.782 δCH3 (11) + δCCC ring 3 (12) + τCCCH3 (48)
    67 1001 962 1.985 τHCCC ring 2 (78)
    66 984 944 0.064 τHCCC ring 3 (77)
    65 982 942 1.188 τHCCC (61) + τCCCC (13)
    64 969 931 1.460 δHCC (14) + τHCCC ring 2 (13) + τHCCC ring 1 (10)
    63 967 928 0.318 τHCCC ring 2 (60) + τCCCC (13)
    62 947 909 2.779 τHCCC ring 3 (68) τCCCN (10)
    61 919 883 3.003 δOCN (12) + δCNC (10) τ+ HCCC ring 3 (15)
    60 917 882 21.721 νCC Δ (21) + δHCC Δ (11) + τHCCC (31)
    59 914 880 2.327 νCC ring 2 (14) + δHCC ring 2 (12) + τHCCC (39)
    58 888 853 2.751 δHCC Δ (13) + τHCCC ring 2 (24)
    57 871 835 2.681 τHCCC ring 3 (78)
    56 865 832 11.09 νCC Δ (10) + δCCC ring 3 (19) + τHCCC ring 2 (10)
    55 860 826 5.697 τHCCC ring 2 (32) + τHCCC ring 3 (29)
    54 850 815 9.570 τHCCC ring 1 (79)
    53 840 807 32.519 τHCCC ring 2 (42)
    52 814 782 20.861 νCC Δ (10) + δCCC ring 1 (17)
    51 780 750 28.59 νCC (15) + τHCCC ring 3 (22)
    50 769 739 21.182 τCCCC ring 2 (13) + ωONCC (29)
    49 763 732 25.49 τHCCC ring 3 (60)
    48 746 717 7.065 τHCCC ring 1 (10) + ωCCCC (42)
    47 735 707 2.38 δCCC ring 2 + (15) τCCCC ring 3 (–13)
    46 721 693 2.41 ωCCCC ring 2 (11) + τCCCC ring 3 (34)
    45 707 680 16.799 τCCCC ring 2 (30) + ωONCC (26)
    44 679 653 14.69 δCCC ring 1 (50)
    43 676 649 13.30 δCCC ring 1 (14) + ωFCCC (15)
    42 649 624 0.44 νCC (10) + δCCC ring 2 (78)
    41 624 599 10.24 δCCC ring 3 (44)
    40 614 590 4.469 δCCC ring 3 (12)
    39 582 558 10.24 ωCCCC ring 2 (22) + ωCCCC ring 1 (10)
    38 569 546 18.887 τCCCC (–12) + τHNCC (–13)
    37 556 533 2.953 δCCC (13) + τCCCC ring 3 (25)
    36 544 517 49.335 νCC (12) + δCCC ring 3 (–26) + τHNCC (46)
    35 535 511 4.433 τHNCC (59) + τCCCC ring 3 (25)
    34 493 473 6.076 δFCC (23)
    33 473 455 5.459 ωCCCC ring 2 (12)
    32 464 445 1.617 τCCCC (49)
    31 458 440 8.098 τCCCC ring 1 (27) + τCCCC ring 2 (19)
    30 445 428 1.711 δCCC (12) + δCCN (18)
    29 441 423 3.507 τCCCC ring 1 (17)
    28 420 404 1.652 τHCCC ring 2 (11) + τHCCC ring 2 (13) + τCCCC ring 2 (64)
    27 406 389 0.321 δCCC (13)
    26 403 387 4.697 δCCBr (50)
    25 365 351 3.906 δFCC (16)
    24 350 336 11.990 νCC (39)
    23 330 316 0.5234 δCCC (37)
    22 311 299 0.974 νCC (11) + ωBrCCC (17)
    21 296 284 8.921 δOCN (12) + δCCC (11) + τCCCN (25)
    20 277 265 3.050 τCCCN (25)
    19 256 245 1.391 ωCCCC (11) + ωCCCC (21)
    18 231 219 4.296 δCCC (11)
    16 194 183 0.349 νBrC (14) δCCC (19)
    15 186 168 1.42 νBrC (14) + δCCC (19)
    14 172 163 1.027 δNCC (14) + δCCC (10) + τHCCC (21)
    13 154 147 0.453 τHCCC (10) + ωCCCC (13) + ωBrCCC (12)
    12 133 127 0.344 ωCCCC (22) + ωBrCCC (12)
    11 119 112 1.968 δBrCC (76)
    10 108 102 1.626 ωCCCC (10) + τCNCC (40)
    9 104.6 100 1.851 δCCC (13) + τCCCC (12) + τCNCC (20)
    8 83 79 0.237 τCCCC (34)
    7 60.82 56 0.044 δCCC (38)
    6 52.01 49 0.113 τCNCC (53)
    5 48. 46 0.118 δCCC (11) + δCCC (17) + δCNC (12) + ωCCCC (15)
    4 34 30 0.144 δCCC (12) + δCNC (33)
    3 20.93 20 0.090 τCNCC (46)
    2 19.35 13 0.638 δCNC (12) + τCCCC (55)
    1 14.54 11 0.0595 τCNCC (30) + τCNCC (12)
    ν: stretching, δ: bending, τ: twisting, γ: out of plane bending, s: symmetric, as: asymmetric
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    Table 4.  Calculated Energy Values for (DBFB) Using B3LYP/6-31G(d, p)

    Parameters Values (eV)
    EHOMO −6.226
    ELUMO −1.395
    Gap (ΔE) 4.832
    Electronegativity (χ) 3.811
    Chemical potential (μ) −3.811
    Chemical hardness (η) 4.831
    Chemical softness (S) 0.207
    Electrophilicity index (ω) 1.503
    Additional electronic charge (ΔNmax) 0.163
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    Table 5.  Mulliken Atomic Charges for DBFB

    Atoms Mulliken atomic charges Atoms Mulliken atomic charges
    DFT HF DFT HF
    Br(1) –0.094459 –0.075057 C(16) 0.553734 0.795130
    Br(2) –0.093303 –0.073689 C(21) –0.098879 –0.159134
    N(1) –0.639660 –0.808507 C(22) –0.10338 –0.142897
    F(1) –0.301539 –0.400608 C(23) –0.385374 –0.346166
    O(1) –0.503772 –0.594833 C(19) –0.139060 –0.166692
    C(1) 0.039286 –0.027181 C(20) –0.074642 –0.140331
    C(2) 0.036221 –0.021984 H(4) 0.261137 0.309928
    C(3) –0.139351 –0.122195 H(3) 0.116343 0.189077
    C(4) 0.196518 0.059095 H(5) 0.094871 0.164301
    C(5) –0.131284 –0.157487 H(6) 0.116593 0.185202
    C(6) –0.088779 –0.111020 H(7) 0.111783 0.157378
    C(7) –0.203012 –0.214280 H(9B) 0.141130 0.165981
    C(8) 0.297273 0.445493 H(9A) 0.126005 0.149713
    C(9) –0.248240 –0.283870 H(15) 0.112567 0.189030
    C(10) 0.116477 –0.032461 H(14) 0.124193 0.201208
    C(15) –0.128951 –0.154107 H(11) 0.086824 0.15351
    C(14) –0.100554 –0.111773 H(20) 0.084919 0.151090
    C(13) 0.038415 –0.151646 H(21) 0.086260 0.151493
    C(12) –0.132461 –0.142267 H(22) 0.079983 0.151043
    C(11) –0.146731 –0.176673 H(23) 0.109964 0.12170
    H(19) 0.082299 0.148166 H(23B) 0.162564 0.171392
    C(17) 0.232932 0.247133 H(23A) 0.100062 0.115260
    C(18) 0.151961 0.026484 H(12) 0.093125 0.166038
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  • 发布日期:  2020-09-01
  • 收稿日期:  2019-11-09
  • 接受日期:  2020-06-03
通讯作者: 陈斌, bchen63@163.com
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