Theoretical and Density Functional Theory (DFT) studies for the organic compound: 2-Amino-6-chloro-N-methylbenzamide

 

Amir Lashgari, Shahriar Ghammamy, Masomeh Shahsavari*

Department of Chemistry, Faculty of Science, Imam Khomeini International University, Qazvin, Iran.

*Corresponding Author E-mail: Ikiu2014@gmail.com

In this paper, the optimized geometries and frequencies of the stationary point and the minimum-energy paths of C₈H₉ClN₂O are calculated by using the DFT (B3LYP) methods with LANL2DZ basis sets. B3LYP/ LANL2DZ calculation results indicated that some selected bond length and bond angles values for the C₈H₉ClN₂O.

 

 

 

INTRODUCTION:

In the title compound, C₈H₉ClN₂O, the dihedral angle between the benzene ring and the methylamide substituent is 68.39 (11)°. In the crystal, molecules are linked by N--- H...O hydrogen bonds, forming layers parallel to the ab plane. Anthranilamide-based derivatives exhibit interesting biological activities such as antibacterial, antifungal, antiviral, antimalarial and insecticidal activities. We report here the crystal structure of the title compound, 2-amino-6-chloro-_JV-methylbenzamide, and an important organic intermediate in the synthesis of medicines, agricultural chemicals and animal drugs. In the title compound. The dihedral angle formed by the benzene ring and the methylamide substituent (r.m.s. deviation 0.0065 A) is 68.39 (11)°. In the crystal structure molecules are connected via N---H...O hydrogen bonds (Table 1) into layers running parallel to the ab plane^{, [1-10]}. During this study we report the optimized geometries, assignments and electronic structure calculations for the compound. The structure of the compound has been optimized by using the DFT (B3LYP) method with the LANL2DZ basis sets, using the Gaussian 98 program ^[11]. The comparison between theory and experiment is made. Density functional theory methods were employed to determine the optimized structures of C₈H₉ClN₂O and Initial calculations were performed at the DFT level and split- valence plus polarization LANL2DZ basis sets were used. Local minima were obtained by full geometrical optimization have all positive frequencies ^[12].

 

METHODS:

All computational are carried out using Gaussian 98 program^[13]. The optimized structural parameters were used in the vibrational frequency calculations at DFT levels to characterize all stationary points as minima. Harmonic vibrational frequencies (i) in cm^-1 and infrared intensities (int) in Kilometer per mole of all compounds were performed at the same level on the respective fully optimized geometries. Energy minimum molecular geometries were located by minimizing energy, with respect to all geometrical coordinates without imposing any symmetrical constraints.

 

RESULTS AND DISCUSSION:

Molecular properties

The structures of compounds are shown in Figure 1. All calculations were carried out using the computer program Gaussian 98. Theoretical calculation of bond and angle for the compound was determined by optimizing the geometry (Table 1).

 

NBO Analysis in Table1 and The NBO Calculated Hybridizations are reported in Table2. We could not compare the calculation results given in bond lengths and bond angle values with the experimental data. Because the crystal structure of the title compound is not available till now. Amides are far less basic than amines because the nonbonded electron pair of nitrogen is much less available, a consequence of electron withdrawal by the carbonyl group. Amides are no more basic than water or alcohols. Amides undergo acidic or basic hydrolysis to the corresponding carboxylic acid and amine or ammonia. The basic reaction produces the carboxylate salt, whereas the acidic reaction produces the amine salt.

 

Fig. 1: The schematic structure of the C₈H₉ClN₂O.

 

NBO study on structures

Natural Bond Orbital's (NBOs) are localized few-center orbital's that describe the Lewis-like molecular bonding pattern of electron pairs in optimally compact form. More precisely, NBOs are an orthonormal set of localized "maximum occupancy" orbital's whose leading N/2 members (or N members in the open-shell case) give the most accurate possible Lewis-like description of the total N-electron density. This analysis is carried out by examining all possible interactions between "filled" (donor) Lewis-type NBOs and "empty" (acceptor) non-Lewis NBOs, and estimating their energetic importance by 2nd-order perturbation theory. Since these interactions lead to donation of occupancy from the localized NBOs of the idealized Lewis structure into the empty non-Lewis orbitals (and thus, to departures from the idealized Lewis structure description), they are referred to as "delocalization" corrections to the zeroth-order natural Lewis structure. Natural charges have been computed using natural bond orbital (NBO) module implemented in Gaussian 98.

 

 

Table 2: The NBO Calculated Hybridizations for (C₈H₉ClN₂O), B3LYP/LANL2DZ.

 

 

The NBO Calculated Hybridizations are significant parameters for our investigation. These quantities are derived from the NBO population analysis. The former provides an orbital picture that is closer to the classical Lewis structure. The NBO analysis involving hybridizations of selected bonds are calculated at B3LYP methods and LANL2DZ level of theory (Table 2).

 

These data shows the hyper conjugation of electrons between ligand atoms with central metal atom. The NBO calculated hybridization for C₈H₉ClN₂O shows that all of complexes have Sp^x hybridization and non-planar configurations. The total hybridization of these molecules are Sp^x that confirmed by structural. The amount of bond hybridization showed the in equality between central atoms angles (Table 2) Shown distortion from octahedral and VSEPR structural and confirmed deviation from VSEPR structures. Second order perturbation theory analysis of Fock matrix in NBO basis for C₉H₁₁Cl₂NO₃ show in Table 3.

 

Frontier molecular orbital

Both the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are the main orbital take part in chemical stability. The HOMO represents the ability to donate an electron, LUMO as an electron acceptor represents the ability to obtain an electron. The HOMO and LUMO energy were calculated by B3LYP/ LANL2DZ method ^[14]. This electronic absorption corresponds to the transition from the ground to the first excited state and is mainly described by one electron excitation from the highest occupied molecular or orbital (LUMO). Therefore, while the energy of the HOMO is directly related to the ionization potential, LUMO energy is directly related to the electron affinity. Energy difference between HOMO and LUMO orbital is called as energy gap that is an important stability for structures. In addition, 3D plots of highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) are shown in Figure 2. The HOMO-LUMO energies were also calculated at the LANL2DZ and the values are listed in Figure 2, respectively.

 

Fig. 2: The atomic orbital of the frontier molecular orbital for C₈H₉ClN₂O B3LYP/LANL2DZ level of theory.

 

 

Table 3: Second order perturbation theory analysis of Fock matrix in NBO basis for C₈H₉ClN₂O means energy of hyper conjugative interaction (stabilization energy); ^b Energy difference between donor and acceptor i and j NBO orbital's; ^c F(i, j) is the Fock matrix element between i and j NBO.

Donor (i)		Type	ED/e	Acceptor (j)	Type	ED/e	E(2) a(KJ/mol)	E(j) E(i) b(a.u)	F(i,j)c (a.u)
C1-C2		σ	1.96383	C11-C6	σ*	0.02847	2.37	1.25	0.049
C2-C3		σ	1.97269	CI10-C18	σ*	0.390841	1.19	0.78	0.30
	C3-C4	σ	1.97591	CI10-H18	σ*	0.390841	3.03	0.77	0.048
	C4-C5	σ	1.97873	CI10-H20	σ*	0.14216	1.98	6.65	0.106
	C6-H9	σ	1.97557	C1-N11	σ*	0.02743	0.62	0.86	0.021
	CI10-H20	σ	1.91553	N16-C18	σ*	0.04647	0.94	1.38	0.032
	N16-H17	σ	1.96357	CI10-C18	σ*	0.39084	4.57	0.75	0.058
	N16	n	1.83128	CI10-C18	σ*	0.39084	2.63	0.41	0.031
	O15	n	1.97510	N16-C18	σ*	0.04674	0.72	0.47	0.017
	N11	n	1.92751	C14-O15	σ*	0.01501	0.53	0.76	0.018
CI10		σ	1.96556	N16-C18	σ*	O.4674	3.88	0.82	0.051

 

 

CONCLUSION:

In this research we are interested in studying on two Halo Organic Compounds was chosen to theoretical studies. In this paper, the optimized geometries and frequencies of the stationary point and the minimum-energy paths are calculated by using the DFT (B3LYP) methods with LANL2DZ basis sets. B3LYP/ LANL2DZ calculation results indicated that some selected bond length and bond angles values for the C₈H₉ClN₂O.

 

ACKNOWLEDGMENTS:

The authors wish to express their warm thanks to Dr. Ghammamy for his valuable discussions and Imam Khomeini International University, for their assistance.

 

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Received on 02.05.2014          Modified on 25.05.2014

Accepted on 01.06.2014         © AJRC All right reserved