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Structural properties, theory functional calculations (DFT), natural bond orbital Acetamide and Sulfonamide.

INTRODUCTION

Acetamide is an amide of acetic acid having a formula C2H5NO, commercially known as lipamide and schercomide [1]. It is a neutral molecule , is acidic and basic properties being so weak that they are not manifested in water solution [2]. Owing to its polarity and high dielectric constant it acts as solvent for organic and inorganic compounds and forms many stable solvates [3-4]. Its neutral and amphoteric characteristics make it valuable as a anti-acid in the lacquer , explosives and in cosmetic industries [5]. It has been widely used as a soldering flux ingredient, as a dye solvent and in urea molding compounds [6]. Its hygroscopic properties are the reason for its use as a plasticizer in leather, cloth and various other films and coatings and as a humectant for paper [7]. Other uses involve activator in bleaching liquors , as a wetting agent and penetration accelerator in dyeing, as a special food for promoting mold growth and as a raw material in organic synthesis. It is used in synthesis of many important drugs; ampicillin , cephaclor, cephalexin, cephradine, sulphacetamide acetamidine hydrochloride and methyl le amine [8]. Acetamide was prepared by various ways Cheronis in 1957 prepared it from ester and ammonia, followed by the heating of ammonium acetate at 100-200c [9].

Experimental:

Chemicals and reagents:

All computations are carried out using Gaussian 09 program. The optimized structural parameters were used in the vibrational frequency calculations at the DFT level to characterize all stationary points as minima. Harmonic vibrational frequencies (v) in [cm.sup.-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.

NBO study on structures:

The structure of the compound has been optimized by using the DFT (B3LYP) method with the LanL2DZ basis sets, using the Gaussian 09 program. Density functional theory methods were employed to determine the optimized structures of [C.sub.12][H.sub.11]NSO and [C.sub.8][H.sub.9]NO (Table 1, Figure 1) 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 (Table 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 Gaussian09w. 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, 3). These data shows the hyper conjugation of electrons between ligand atoms with central metal atom. These conjugations stand on the base of p-d [pi]-bonding. The NBO calculated hybridization for [C.sub.12][H.sub.11]NSO and [C.sub.8][H.sub.9]NO shows that all compounds have [sp.sup.X] hybridization and non planar configurations. The total hybridization of these molecules are [sp.sup.X] that confirmed by structural propertise. The amount of bond hybridization showed the in equality between central atoms angles (Table 2) show distortion from normal VSEPR structures and confirmed deviation from VSEPR structures. (Figure 2). Some thermodynamic parameters Frequencies for (1) [C.sub.12][H.sub.11]NSO and (2) [C.sub.8][H.sub.9]NO Zero-point Energy, correction Energy, Enthalpy lengths, Gibbs free Energy are calculated and confirmed with other blished theoretical data. (Table 4).

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. 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.

Conclusion:

In this research we studied on Sulfonamide and Acetamide compounds theoretical studies. 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 [C.sub.12][H.sub.11]NSO and [C.sub.8][H.sub.9]NO.

ARTICLE INFO

Article history:

Received 28 February 2014

Received in revised form 19 April 2014

Accepted 23 April 2014

Available online 25 May 2014

ACKNOWLEDGEMENTS

We gratefully acknowledge the financial support from the Research Council of Takestan Islamic Azad University.

REFERENCES

[1] Michael and Irene, 1986. The thesaurus of Chemical Products, Generic to Trade, 1(1).

[2] Kirk and Othemer, 2002. Encyopedia of Chemical technology, 1: 45-49.

[3] Jander, G. and G. Winkler, 1985. J. Inorg. Nucl. Chem., 2: 24-33.

[4] Kimiko, U. and O. Kenichi, 1980. Acctamide in polar soivents: hindered internal rotationnd intermolecular interactions. Org, Mag. Reson., 15: 13-17.

[5] Isaac, I.Y. and D.H. Kerridge, 1988. Effect of acetamide on solubility of metals, J. Chm. Soc., 21: 2201-2208.

[6] Eweka, E.I. and D.H. Kerridge, 1999. Chemistry of molten amide-nitrte eutectics. Chem Papers, 53: 11-15.

[7] Dagang, L. and L. Zhang, 2006. Structure and properties of soy protein plasticized with acetamide. Macromol. Mater. Eng., 291: 820-828.

[8] Maryadele, J.O., N. Patricia, C.B. Koch, K.J. Roma, 2006. Marck Index. Published by Merck Research Laboratories, White House Station USA, 9-10.

[9] Chronis, N.D. and J.B. Entrikin, 1963. Identification of organic compounds, Interscience, Inc, New York, pp: 534.

(1) Ali Rahmani, (2) Mohamad Mirzaie, (3) Meisam Rahmani

(1,3) Young Researchers and Elite Club, Takestan Branch, Islamic Azad University, Takestan, Iran

(2) Department of Chemistry, Takestan branch, Islamic Azad University, Takestan, Iran

Corresponding Author: Ali Rahmani, Young Researchers and Elite Club, Takestan Branch, Islamic Azad University, Takestan, Iran

Table 1: Optimized Geometrical parameters of for (1)
[C.sub.12][H.sub.11]NSO and (2) [C.sub.8][H.sub.9]NO some
selected bond lengths ([Angstrom]) and angles ([degrees]).

B3LYP/LanL2DZ
                                    (1) [C.sub.12][H.sub.11]NSO
Bond lengths ([Angstrom])
[C.sub.1]-[C.sub.7]                            1.0873
[C.sub.3]-[N.sub.12]                           1.4272
[N.sub.12]-[S.sub.13]                          1.7833
[O.sub.25]-[C.sub.19]                          1.3888
[C.sub.6]-[H.sub.11]                           1.0869
[C.sub.17]-[H.sub.23]                          1.0875
Bond angles ([degrees])                  angles ([degrees])
[C.sub.2]-[C.sub.1]-[C.sub.6]                 120.8507
[C.sub.4]-[C.sub.3]-[N.sub.12]                119.0854
[C.sub.3]-[N.sub.12]-[S.sub.13]               125.0095
[S.sub.13]-[C.sub.19]-[C.sub.14]              104.5189
[C.sub.14]-[C.sub.19]-[O.sub.25]              118.952
[S.sub.13] [N.sub.12]-[H.sub.27]              116.3572

Method
                                      (2) [C.sub.8][H.sub.9]NO
Bond lengths ([Angstrom])
[C.sub.1]-[C.sub.2]                            1.4069
[C.sub.3]-[N.sub.12]                           1.4259
[N.sub.12]-[H.sub.19]                          1.0136
[C.sub.5]-[H.sub.10]                           1.0874
[C.sub.13]-[O.sub.15]                          1.256
[C.sub.14]-[H.sub.17]                          1.957
Bond angles ([degrees])                  angles ([degrees])
[C.sub.2]-[C.sub.1]-[C.sub.6]                 121.2973
[C.sub.4]-[C.sub.3]-[N.sub.12]                117.1079
[C.sub.14]-[C.sub.12]-[O.sub.15]              121.3515
[C.sub.13]-[N.sub.12]-[H.sub.19]              116.1316
[C.sub.13]-[C.sub.14]-[H.sub.17]              108.8771
[C.sub.5]-[C.sub.6]-[H.sub.11]                120.3218

Table 2: The NBO Calculated Hybridizations for (1)
[C.sub.12][H.sub.11]NSO and (2) [C.sub.8][H.sub.9]NO
at the B3LYP/LanL2DZ.

           (1) [C.sub.12]
            [H.sub.11]NSO

Bond            Atom                    B3LYP           Bond

C-C     [C.sub.14]-[C.sub.19]    [S.sup.1][P.sup.1]      C-C
C-H     [C.sub.14]-[H.sub.20]   [S.sup.1][p.sup.2.38]    C-H
O C-    [C.sub.19]-[O.sub.25]   [S.sup.1][P.sup.2.97]    N-H
C-H     [C.sub.15]-[H.sub.21]   [S.sup.1][p.sup.2.44]    C-O

            (2) [C.sub.8]
             [H.sub.9]NO

Bond            Atom                    B3LYP

C-C      [C.sub.1]-[C.sub.2]    [S.sup.1][P.sup.1.18]
C-H      [C.sub.1]-[H.sub.7]    [S.sup.1][P.sup.2.47]
O C-    [N.sub.12]-[H.sub.19]   [S.sup.1][P.sup.2.78]
C-H     [C.sub.13]-[O.sub.15]    [S.sup.1][P.sup.1]

Table 3: Second order perturbation theory analysis of Fock matrix
in NBO basis for (1) [C.sub.12][H.sub.11]NSO and (2)
[C.sub.8][H.sub.9]NO E(2) (a) 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 orbital's.

Donor (i)                   Type       ED/e         Acceptor(j)

[C.sub.12][H.sub.11]
  NSO(1)
[C.sub.1][C.sub.2]        [sigma]    1.977769    [C.sub.1][C.sub.6]
[C.sub.1][H.sub.7]        [sigma]    1.97667     [C.sub.2][C.sub.3]
[C.sub.3][N.sub.12]       [sigma]    1.98874     [C.sub.1][C.sub.2]
[N.sub.12][S.sub.13]      [sigma]    1.97140     [C.sub.3][C.sub.4]

[C.sub.8][H.sub.9]NO(2)
[C.sub.3][C.sub.2]        [sigma]    1.97731     [C.sub.1][C.sub.6]
[C.sub.1][C.sub.6]        [sigma]    1.98155     [C.sub.1][C.sub.2]
[C.sub.3][N.sub.12]       [sigma]    1.98479     [C.sub.1][C.sub.2]
[C.sub.13][O.sub.15]      [sigma]    1.99073    [N.sub.12][H.sub.19]

                                                         E(2) (a)
Donor (i)                    Type             ED/e      (KJ/mol)

[C.sub.12][H.sub.11]
  NSO(1)
[C.sub.1][C.sub.2]        [[sigma].sup.*]    1.977769      1.62
[C.sub.1][H.sub.7]        [[sigma].sup.*]     1.97667      5.43
[C.sub.3][N.sub.12]       [[sigma].sup.*]     1.98874      2.34
[N.sub.12][S.sub.13]      [[sigma].sup.*]     1.97140      1.83

[C.sub.8][H.sub.9]NO(2)
[C.sub.3][C.sub.2]        [[sigma].sup.*]     1.97731      1.65
[C.sub.1][C.sub.6]        [[sigma].sup.*]     1.98155      1.53
[C.sub.3][N.sub.12]       [[sigma].sup.*]     1.98479      2.16
[C.sub.13][O.sub.15]      [[sigma].sup.*]     1.99073      2.09

                          E(j)-E(i)      F(i,j)
Donor (i)                  (b)(a.u)    (c) (a.u)

[C.sub.12][H.sub.11]
  NSO(1)
[C.sub.1][C.sub.2]           1.23        0.040
[C.sub.1][H.sub.7]           1.04         0.06
[C.sub.3][N.sub.12]          1.36        0.050
[N.sub.12][S.sub.13]         1.19        0.042

[C.sub.8][H.sub.9]NO(2)
[C.sub.3][C.sub.2]           1.23        0.040
[C.sub.1][C.sub.6]           1.24        0.039
[C.sub.3][N.sub.12]          1.35        0.048
[C.sub.13][O.sub.15]         1.43        0.049

Table 4: Some thermodynamic parameters Frequencies for (1)
[C.sub.12][H.sub.11]NSO and (2) [C.sub.8][H.sub.9]NO Zero-point
Energy, correction Energy, Enthalpy lengths, Gibbs free Energy.

                                             (1)
                                   [C.sub.12][H.sub.11]NS

Zero - point correlation         0.205936(Hartree/particle)
Thermal correction to Energy              0.165459
Thermal correction to Enthalpy            0.221329
Thermal correction to                     0.160624
  Gibbs free Energy

                                             (1)
                                    [C.sub.8][H.sub.9]NO

Zero - point correlation         0.156480 (Hartree/particle)
Thermal correction to Energy              0.220385
Thermal correction to Enthalpy            0.166403
Thermal correction to                     0.121301
  Gibbs free Energy
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Author:Rahmani, Ali; Mirzaie, Mohamad; Rahmani, Meisam
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:7IRAN
Date:Apr 15, 2014
Words:2204
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