Structural Properties, Natural Bond Orbital, Theory Functional Calculations (DFT), and Energies for the C₁₃H₁₀N₄O₂S Compounds

 

Shahriar Ghammamy, Nastaran Sohrabi*

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

*Corresponding Author E-mail: shghamami2012@yahoo.com

Two new compounds formed from with C₁₃H₁₀N₄O₂S 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 6-311 basis sets. The geometries and normal modes of vibrations obtained from B3LYP/6-311 calculations are in good agreement with the experimentally observed data. B3LYP/6-311 calculation results indicated that some selected bond length and bond angles values for the C₁₃H₁₀N₄O₂S. The group point of compound is Cs respectively.

 

 

INTRODUCTION:

Organic compounds have many used in theoretical and industrial [1, 2]. Many different data have been found about the structural properties of compounds, but they are insufficient and opposing in somewhere new primitive synthesized compounds is C₁₃H₁₀N₄O₂S, which used for structural chemistry studies and organic synthesis [3, 4].

The investigation of the structures and properties of the compound and similarities are interested. The structure has been confirmed by neutron diffraction studies and is justified by VSEPR theory [5-8]. 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 6-311 basis sets, using the Gaussian 98 program [9]. The comparison between theory and experiment is made. Density functional theory methods were employed to determine the optimized structures of C₁₃H₁₀N₄O₂S Initial calculations were performed at the DFT level and split- valence plus polarization 3-21G basis sets were used. Local minima were obtained by full geometrical optimization have all positive frequencies [10].

                      

EXPERIMENTAL:

Chemicals and reagents

All computational are carried out using Gaussian 98 program [11].

 

 

The optimized structural parameters were used in the vibrational frequency calculations at the HF and DFT levels to characterize all stationary points as minima. Harmonic vibrational frequencies (ν) 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. Geometry optimization shows that symmetry for compounds C₁₃H₁₀N₄O₂S is Cs respectively.

 

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. B3LYP/6-311 calculation results showed that the (N₂₅-S₃₀) and (C₁-O₃₀) bond length values for the C₁₃H₁₀N₄O₂S in compounds is 2.77Å and 2.44Å respectively. The group point of compounds 1-2 are Cs respectively.

 

Figure 1. Optimized geometries of C₁₃H₁₀N₄O₂S   at B3LYP/6-311 level of theory.

 

Table 1. Geometrical parameters optimized for C13H10N4O2S some selected bond lengths (Å) and angles (◦).

 

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 (table-3). 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 Gaussian98. 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 6-311 level of theory (Table 2).

 

Table 2-The NBO Calculated Hybridizations for C₁₃H₁₀N₄O₂S at the B3LYP/6-311..

Bond	Atom	B3LYP
C-N	C7-N8	S1P2.23
C-S	C29-S30	S1P99.99
O-H	O22-H24	S1P99.99
N-H	N26-H28	S1P3.27
C-O	C20-O22	S1P3.90

 

These data shows the hyper conjugation of electrons between ligand atoms with central metal atom. These conjugations stand on the base of p-d π-bonding.

 

The NBO calculated hybridization for C₁₃H₁₀N₄O₂S 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.

 

Table 3 Second order perturbation theory analysis of Fock matrix in NBO basis for C₁₃H₁₀N₄O₂S 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

Donor (i)	Type	ED/e	Acceptor (j)	Type	E(j)‐E(i) b(a.u)	F(i,j)c (a.u)
C13H10N4O2S  N2C3 N25C29 C4H14 C29-S30	σ σ σ σ	1.98264 1.98007 1.97772 1.98749	C1N2 C1C16 C5H15 N26H28	σ* σ* σ* σ*	1.32 1.11 1.06 0.79	0.024 0.074 0.021 0.036

 

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/6-311 method [12]. 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 3-21G and the values are listed in Figure 2, respectively.

 

Figure 2. The atomic orbital of the frontier molecular orbital for C₁₃H₁₀N₄O₂S at B3LYP/6-311 level of theory

 

CONCLUSION:

In this research we are interested in studying on two new aluminate 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 6-311 basis sets. B3LYP/6-311 calculation results indicated that some selected bond length and bond angles values for th. C₁₃H₁₀N₄O₂S The group point of compounds is Cs respectively.

 

ACKNOWLEDGEMENT:

We gratefully acknowledge the financial support from the Research Council of Imam Khoemieni International University and many technical supports that provided by Tarbiat Modaress University, Iran.

 

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Received on 23.01.2013         Modified on 31.01.2013

Accepted on 08.02.2013         © AJRC All right reserved