Structural Properties, Natural Bond Orbital, Theory Functional Calculations (DFT), and Energies for the Two New Halo Organic Compounds

 

Shahriar Ghammamy¹*, NoorAhmad Qaitmas^1,2,  Amir Lashgari¹  

¹Department of Chemistry, Faculty of Science, Imam Khomeini International University,

Qazvin, Iran.       

²Department of Chemistry, Faculty of Education, Faryab University, Faryab, Afghanistan

*Corresponding Author E-mail: Shghamami@yahoo.com; naqaitmas@yahoo.com

Two new compounds formed from with C₂BrF₄O and C₃ClF₄OH. the combination of these two compounds has not yet made our theoretical section did former is expected to be made in the future 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 calculation results indicated that some selected bond length and bond angles values for the C₂BrF₄O and C₃ClF₄OH. The group point of compounds 1-2 are Cs respectively.

 

 

 

INTRODUCTION:

Halo organic compounds have many used in theoretical and industrial [1, 2]. Many different data have been found about the structural properties of halo compounds, but they are insufficient and opposing in somewhere. Two new primitive synthesized halo compounds are C₂BrF₄O and C₃ClF₄OH, 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]. Density functional theory methods were employed to determine the optimized structures of C₂BrF₄O and C₃ClF₄OH. 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].

 

COMPUTATIONAL DETAILS:

All computational are carried out using Gaussian 98 program [11]. We calculated atoms  bond length (C-F, C-Br, C-C, C=O, C-F) and second molecule(C-F ,C-C , C-F , C-C ,C-Cl , C=0)  by Gaussian software in the  C₂F₂O molecule ,respectively : (1.53 A, 1.97 A, 1.53 A, 1.19 A, 1.37A) and second molecule (1.36 A , 1.52 A , 1.40 A  , 1.51 A, 1.19 A, 1.40A) and but atoms  bond length according to reference [13] is respectively: (1.379 A ,1.94 A, 1.54 A , 1.22 A ,1.379 A) . The mainly due to atoms is effect electronegativity in the molecule compound (Table 1) and (Table 2). 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.   

 

Table 1-A comparison of the bond length  atoms in (1) C₂Br₂F₂O  molecule   calculated by the Gaussian bond length molecule different atoms in the ordinary mode .

 

Table 2-A comparison of the bond length  atoms in (2) C₃ClF₄OH  molecule   calculated by the Gaussian bond length molecule different atoms in the ordinary mode.

 

RESULTS AND DISCUSSION:

Molecular properties

The structures of compounds are shown in Figure 1. Geometry optimization shows that symmetry for compounds 1 and 2 are 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 3).

 

NBO Analysis in Table3 and The NBO Calculated Hybridizations are reported in Table3. We could not compare the calculation results given in bond lengths and bond angle values. Because the crystal structure of the title compound is not available till now. B3LYP/6-311 calculation results showed that the (C₁-Br₆) and (C₁-Cl₇) bond length values for the C₂BrF₄O and C₃ClF₄OH in compounds 1-2 are 1.97 Å and 1.88 Å respectively. The group point of compounds 1-2 are Cs respectively.

 

Table 3- Geometrical parameters optimized for (1) C2Br2F2O, (2) C3ClF4OH some selected bond lengths (Å) and angles (◦).

 

(1)	(2)

Figure 1. Optimized geometries of (1) C2Br2F2O, (2) C3ClF4OH at B3LYP/6-311 level of theory.

 

 

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 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 4).

 

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 C₂BrF₄O and C₃ClF₄OH 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 3) Shown distortion from octahedral and VSEPR structural and confirmed deviation from VSEPR structures.

 

In C₂BrF₄O the lone pair located on chlorine atoms and significantly delocalized in the ϭ^*-hybrid orbital's of C-F bonds. Indeed, in the interaction energy from the charge transfers of n_C1→ ϭ^* C-F in the C₂BrF₄O complex confirms the above point and in the average for C₂BrF₄O the maximum interaction energy is predicted (Table 5).

 

 

Table 4 -The NBO Calculated Hybridizations for (1) C2Br2F2O, (2) C3ClF4OH at the B3LYP/6-311.

	C2Br2F2O			(2)  C3ClF4OH
Bond	Atom	B3LYP	Bond	Atom	B3LYP
C-C	C1-C2	S1P2.08	C-C	C1-C2	S1P1.99
C-F	C2-F6	S1P2.86	C-F	C1-F8	S1P3.57
-	F3	S1P99.99	-	F8	S1P99.99
-	O7	S1P1d	-	O5	S1P99.99
-	Br5	S1P99.99	-	Cl6	S1P99.99

 

Table 5- Second order perturbation theory analysis of Fock matrix in NBO basis for (1) C2Br2F2O, (2) C3ClF4OH. 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 an j NBO orbital's.

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)
C2Br2F2O  (1) C1C2 C1F3 F (3) O (7) Br (5)	σ σ n n n	1.98887 1.99119 1.92956 1.79180 1.94286	C1F3 C1F4 C2O7 C1C2 C1F3	σ* σ* σ* σ* σ*	1.98983 1.99117 1.99768 1.98887 1.98983	0.70 2.05 1.53 24.65 2.26	0.91 1.16 0.36 0.55 0.42	0.023 0.045 0.021 0.106 0.028
C3ClF4OH  (2) C1C2 C1F8 F (8) O (5) Cl (6)	σ σ n n n	1.97964 1.99181 1.93516 1.72110 1.99636	C2C3 C1F9 C1C2 C2C3 C3O5	σ* σ* σ* σ* σ*	1.98076 1.99092 1.97964 1.98076 1.99790	0.63 2.01 8.82 2.54 4.47	1.04 1.18 0.66 1.04 0.81	0.023 0.045 0.069 0.047 0.054

 

 

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 (1) C2Br2F2O, (2) C3ClF4OH at B3LYP/6-311 level of theory .

 

 

CONCLUSION:

In this research we are interested in studying on two new halo organic compounds was chosen to theoretical studies. The combination of these two compounds has not yet made our theoretical section did former is expected to be made in the future. 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 the C₂BrF₄O and C₃ClF₄OH. The group point of compounds 1-2 are Cs respectively.

 

ACKNOWLEDGEMENT:

We gratefully acknowledge the financial support from the Research Council of Imam Khoemieni International University.

 

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Received on 31.10.2014         Modified on 16.11.2014

Accepted on 05.12.2014         © AJRC All right reserved