Delocalization Of Unpaired Electron Research Articles

Boosting peroxymonosulfate activation by porous single-atom catalysts with FeN4O1 configuration for efficient organic pollutants degradation

The construction of single Fe atoms with favorable electron structures is highly desired to boost peroxymonosulfate (PMS) activation for organics degradation. Herein, this study embedded isolated Fe atoms on N, O co-doped porous carbon substrate (FeSA-N/OC), and first found the constructed FeN4O1 configuration can realize efficient PMS activation via electron transfer by inner-sphere complexation, instead of the usual reactive oxygen species (ROS) as a major role. Structural investigation showed that the FeN4O1 moieties possess high content of high spin (HS) Fe(II), resulting in the delocalization of unpaired electrons around Fe centers, which is benefit to transfer electrons when reacted with PMS. EIS and LSV curves further certified the electron transfer process. Density functional theory (DFT) calculations unveiled that the FeN4O1 configuration can directly adsorb OO bond of PMS, leading to electron accumulation around Fe-O2 bond, and then ulteriorly trigger the electron shuttling in organics degradation. Consequently, the optimized FeSA-N/OC/PMS system exhibited superior oxidation ability for various organic pollutants, and was not affected by initial pH variation (3.19 ∼ 10.89), inorganic anions (ClO4−, Cl− and H2PO4−) and natural organic matter (NOM) interference. Importantly, the developed system presented certain applicability in the treatment of actual water from Taihu Lake basin, China. Hence, this study not only elucidates the inner-sphere complexation-oriented electron transfer mechanism between unique FeN4O1 configuration and PMS, but provides new insights into engineered single atom catalysts for wastewater purification.

Retaining Hückel Aromaticity in the Triplet Excited State of Azobenzene.

The implication of the potential concept of aromaticity in the relaxed lowest triplet state of azobenzene, an efficient molecular switch, using elementary aromaticity indices based on magnetic, electronic, and geometric criteria has been discussed. Azobenzene exhibits a major Hückel aromatic character retained in the diradical lowest relaxed triplet state (T1 ) by virtue of a twisted geometry with partial delocalization of unpaired electrons in the perpendicular p-orbitals of two nitrogen atoms to the corresponding phenyl rings. The computational analysis has been expanded further to stilbene and N-diphenylmethanimine for an extensive understanding of the effect of closed-shell Hückel aromaticity in double-bond-linked phenyl rings. Our analysis concluded that stilbene has Hückel aromatic character in the relaxed T1 state and N-diphenylmethanimine has a considerable Hückel aromaticity in the phenyl ring near the carbon atom while a paramount Baird aromaticity in the phenyl ring near the nitrogen atom of the C=N double bond. The results reveal the application of excited-state aromaticity as a general tool for the design of molecular switches.

Carbazole Isomerism in Helical Radical Cations: Spin Delocalization and SOMO-HOMO Level Inversion in the Diradical State.

We report a new molecular design to afford persistent chiral organic open-shell systems with configurational stability and an inversion in energy of the singly occupied molecular orbital (SOMO) and the highest doubly occupied molecular orbital (HOMO) for both mono- and diradical states. The unpaired electron delocalization within the designed extended helical π-conjugated systems is a crucial factor to reach chemical stabilities, which is not obtained using the classical steric protection approach. The unique features of the obtained helical monoradicals allow an exploration of the chiral intramolecular electron transfer (IET) process in solvents of different polarity by means of optical and chiroptical spectroscopies, resulting in an unprecedented electronic circular dichroism (ECD) sign inversion for the radical transitions. We also characterized the corresponding helical diradicals, which show near-infrared electronic circular dichroism at wavelengths up to 1100 nm and an antiferromagnetic coupling between the spins, with an estimated singlet-triplet gap (ΔEST) of about -1.2 kcal mol-1. The study also revealed an intriguing double SOMO-HOMO inversion (SHI) electronic configuration for these diradicals, providing new insight regarding the peculiar energetic ordering of radical orbitals and the impact on the corresponding (chiral) optoelectronic properties.

Presence and absence of intrinsic magnetism in graphitic carbon nitrides designed through C\u2013N\u2013H building blocks

We use the first principle calculation to investigate the intrinsic magnetism of graphitic carbon nitrides (GCNs). By preserving three-fold symmetry, the GCN building blocks have been built out of different combinations between 6 components which are C atom, N atom, s-triazine, heptazine, heptazine with C atom at the center, and benzimidazole-like component. That results in 20 phases where 11 phases have been previously reported, and 9 phases are newly derived. The partial density of states and charge density have been analyzed through 20 phases to understand the origin of the presence and absence of intrinsic magnetism in GCNs. The intrinsic magnetism will be present not only because the GCNs comprising of radical components but also the pi-conjugated states are not the valence maximum to break the delocalization of unpaired electrons. The building blocks are also employed to study alloys between g-hbox {C}_3hbox {N}_4 and g-hbox {C}_4hbox {N}_3. The magnetization of the alloys has been found to be linearly dependent on a number of C atoms in the unit cell and some magnetic alloys are energetically favorable. Moreover, the intrinsic magnetism in GCNs can be promoted or demoted by passivating with a H atom depending on the passivated positions.

Improvement of antioxidative activity of resveratrol by calix[4]arene-like tetramer: A theoretical study

Resveratrol is a natural antioxidant in a wide variety of plant species, developing an effective strategy to further improve its antioxidative activity has attracted enormous research attention in recent years. In this work, tetra-(3,5-dihydroxy)styryl-calix[4]arene (TSC, a calix[4]arene-like tetramer of resveratrol) has been theoretically studied at the DFT-BP86/6-311+G(d,p) level of theory. The results demonstrates that TSC has highly symmetrical molecular geometry with four equivalent resveratrol units, the 4′-OH and 4′-CO bonds were elongated and distinct deviation from planarity was observed in four resveratrol units in TSC. More interestingly, TSC has remarkably lower 4′-OH BDE, IP, and PA of 4′-phenolate than those of resveratrol, indicating that TSC exhibits much more excellent antioxidative activities than resveratrol. Spin density in 4′-phenoxyl radical and cation radical are delocalized over whole molecular skeleton of TSC, thus leading to more stable radical species than that of resveratrol. The topologies analysis of unpaired electron occupying orbitals reveals that calix[4]arene skeleton plays very important role in delocalization of unpaired electron. Molecular simplification studies proved that the synergistic effect of calix[4]arene skeleton, the A benzene ring and CC double bonds on the upper rim were responsible for the higher activity of TSC, and calix[4]arene skeleton amongst played the most important role.

Hydrogen motional disorder in crystalline iron group chloride dihydrates.

The principal components and the relative orientation of the 2H paramagnetic shift and quadrupolar coupling tensors have been measured for the MCl2·2D2O family of compounds, M = Mn, Fe, Co, Ni, and Cu, using the two-dimensional shifting-d echo nuclear magnetic resonance experiment in order to determine (1) the degree of unpaired electron delocalization and (2) the number and location of crystallographically distinct hydrogen sites around oxygen and their fractional occupancies. Expressions for the molecular susceptibility of 3d ion systems, where the spin-orbit coupling is a weak perturbation onto the crystal field, are derived using the generalized Van Vleck equation and used to predict molecular susceptibilities. These predicted molecular susceptibilities are combined with various point dipole source configurations modeling unpaired electron delocalization to predict 2H paramagnetic shift tensors at potential deuterium sites. The instantaneous deuterium quadrupolar coupling and shift tensors are then combined with parameterized motional models, developed for trigonally (M = Mn, Fe, Co, and Cu) and pyramidally (M = Ni) coordinated D2O ligands, to obtain the best fit of the experimental 2D spectra. Dipole sources placed onto metal nuclei with a small degree of delocalization onto the chlorine ligands yield good agreement with the experiment for M = Mn, Fe, Co, and Ni, while good agreement for CuCl2·2D2O is obtained with additional delocalization onto the oxygen. Our analysis of the salts with trigonally coordinated water ligands (M = Mn, Fe, Co, and Cu) confirms the presence of bisector flipping and the conclusions from neutron scattering measurements that hydrogen bonding to chlorine on two adjacent chains leads to the water molecule in the [M(D2O)2Cl4] cluster being nearly coplanar with O-M-Cl involving the shortest metal-chlorine bonds of the cluster. In the case of NiCl2·2D2O, the experimental parameters were found to be consistent with a motional model where the D2O ligands are pyramidally coordinated to the metal and undergo bisector flipping while the water ligand additionally hops between two orientations related by a 120° rotation about the Ni-O bond axis. The position of the three crystallographically distinct hydrogen sites in the unit cell was determined along with fractional occupancies. This restricted water ligand motion is likely due to van der Waals interactions and is concerted with the motion of neighboring ligands.

Stable Expanded Porphycene-Based Diradicaloid and Tetraradicaloid.

The synthesis of a bithiophene-bridged 34π conjugated aromatic expanded porphycene 1 and a cyclopentabithiophene bridged 32π conjugated anti-aromatic expanded porphycene 2 by a McMurry coupling strategy is presented. Magnetic measurements and theoretical calculations reveal that both 1 and 2 exhibit an open-shell singlet ground state with significant radical character (y0 =0.63 for 1; y0 =0.68, y1 =0.18 for 2; y0 : diradical character, y1 : tetraradical character) and a small singlet-triplet energy gap (ΔES-T =-3.25 kcal mol-1 for 1 and ΔES-T =-0.92 kcal mol-1 for 2). Despite the open-shell radical character, both compounds display exceptional stability under ambient air and light conditions owing to effective delocalization of unpaired electrons in the extended cyclic π-conjugation pathway.

Stable Expanded Porphycene‐Based Diradicaloid and Tetraradicaloid

AbstractThe synthesis of a bithiophene‐bridged 34π conjugated aromatic expanded porphycene 1 and a cyclopentabithiophene bridged 32π conjugated anti‐aromatic expanded porphycene 2 by a McMurry coupling strategy is presented. Magnetic measurements and theoretical calculations reveal that both 1 and 2 exhibit an open‐shell singlet ground state with significant radical character (y0=0.63 for 1; y0=0.68, y1=0.18 for 2; y0: diradical character, y1: tetraradical character) and a small singlet–triplet energy gap (ΔES‐T=−3.25 kcal mol−1 for 1 and ΔES‐T=−0.92 kcal mol−1 for 2). Despite the open‐shell radical character, both compounds display exceptional stability under ambient air and light conditions owing to effective delocalization of unpaired electrons in the extended cyclic π‐conjugation pathway.

A DFT and QSAR study of the role of hydroxyl group, charge and unpaired-electron distribution in anthocyanidin radical stabilization and antioxidant activity

Density function theory study was conducted to examine the structure, planarity, and charge and unpaired electron delocalization of some anthocyanidins and monohydroxy flavylium ions as well as all their possible phenoxyl radicals. Bond dissociation energy of O–H bond was in the order of 3-<5-<4′-<7-OH bond except for in malvidin where 4′-OH has less bond dissociation energy than 5-OH bond because of the extra stability provided by the two o-OMe groups. Stabilization by both charge and unpaired electron resonances were suggested for each radical. The present work revealed that the 3-anthocyanidin radicals were stabilized by three types of resonance through 5-, 7- or 4′-oxygen atoms while 5-, 7- or 4′-radicals were stabilized only by resonance through pyrylium or 3-oxygen atom. Positive charge was found delocalized on carbons 2, 5, 7, 9, and 4′ by resonance and moves towards the radical oxygen upon radical formation. In all radicals, radical oxygen carries the highest spin density and least negative charge therefore, its charge, spin density and the least bond dissociation energy (O–H) in each anthocyanidin were well quantitatively correlated with the experimental radical scavenging activity.

Potent 1,2,4‐Triazole‐3‐thione Radical Scavengers Derived from Phenolic Acids: Synthesis, Electrochemistry, and Theoretical Study

AbstractNine 1,2,4‐triazole‐3‐thiones containing phenolic acid moiety have been synthesized and examined by scavenging of stable DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) radical, measurement of reducing capacity, cyclic voltammetry experiments and density functional theory (DFT). The differences in DPPH‐radical scavenging activity of the compounds 4 a‐i are affected by the stability of the corresponding radicals or radical cations and possibility of delocalization of unpaired electron through benzene and triazole ring. Significantly, lower proton affinity (PA) values than bond dissociation enthalpy (BDE) indicate SPLET (sequential proton loss electron transfer) mechanism under these experimental conditions.

Molecular structure, vibrational spectra, MEP, HOMO-LUMO and NBO analysis of Hf(SeO3)(SeO4)(H2O)4

Hf(SeO3)(SeO4)(H2O)4 was obtained with the hydrothermal synthesis. The geometry optimization of this molecule was done by Density Functional Theory (DFT/B3LYP) method with 6-31G(d) basis set and LANL2DZ for Hf. The experimental infrared spectrum was compared with calculated and complete vibrational assignment was provided. The bond orders and the electronic properties of the molecule were calculated. The natural bond orbital analysis (NBO) was performed in order to study the intramolecular bonding interactions among bonds and delocalization of unpaired electrons. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) with frontier orbital gap were presented. The electrostatic potential was calculated in order to investigate the reaction properties of the molecule. The thermodynamic properties of the studied compound at different temperatures were calculated.

Vibrational spectra analysis, NBO, HOMO–LUMO, and nonlinear optical behavior studies on 3-(3,4-dimethoxyphenyl)-1-(pyridin-2-yl)prop-2-en-1-one

A combined experimental and theoretical study on molecular structure, vibrational spectra, HOMO–LUMO analysis, and hyperpolarizability of organic nonlinear optical crystal 3-(3,4-dimethoxyphenyl)-1-(pyridin-2-yl)prop-2-en-1-one is reported. Vibrational wavenumbers with Raman intensities and infrared absor ption intensities have been calculated in the ground state by the density functional theory method using 6-31G(d,p) basis set and Becke’s three-parameter hybrid functional (B3LYP). Finally, the calculation results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with the observed spectra. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis. The natural bond orbital analysis was performed to study the intramolecular bonding, interactions among bonds, and delocalization of unpaired electrons. Electrostatic potential surface and HOMO–LUMO are reported along with global reactivity descriptors. First, hyperpolarizability of the molecule was also calculated and nonlinear behavior of the molecule analyzed using computed data.

Design, Synthesis and Vibrational Spectroscopic Studies of the Nonlinear Optical Crystal l-histidine Potassium Chloride

L-Histidine Potassium Chloride (LHPC) crystals were grown by slow evaporation technique. The grown crystals were characterized by powder X-ray diffraction and analyzed by FT-IR and FT-Raman techniques. The geometry optimization, harmonic vibrational wavenumbers, natural bond orbital and thermodynamical analysis have been carried out using density functional theory (DFT) method at B3LYP/6-311++G(d,p) basis set. Optimized geometry values show a small deviation between the experimental and theoretical values, which reveals the inter- and intra-molecular hydrogen bonding in the crystal. Normal coordinate analysis has been performed on the basis of potential energy distribution analysis using MOLVIB program. The potential energy distribution analysis is useful to predict the vibrational modes, unambiguously. The natural bond orbital analysis has been performed in order to study the intramolecular bonding interactions among bonds and delocalization of unpaired electrons. HOMO and LUMO energies, molecular electrostatic potential and the first-order hyperpolarizability have been also studied. The scaled wavenumbers are in good agreement with the experimental wavenumbers. The first-order hyperpolarizability (β) of the title compound is found to be 9.50x10-30 e.s.u. The large hyperpolarizability and lowering of HOMO-LUMO energy gap supported the nonlinearility of the LHPC crystal. On the basis of vibrational analysis the thermodynamic properties of LHPC at different temperatures have been calculated, revealing the correlations between heat capacity, enthalpy and entropy.

A theoretical antioxidant pharmacophore for natural hydroxycinnamic acids

Abstract The structure-activity relationship analysis has been performed for trans- and cis-hydroxycinnamic acids, to determine their theoretical antioxidant pharmacophore. Based on the detailed conformational studies, the most stable rotamers have been selected. We have analyzed the descriptors of four antioxidant mechanisms important in free radical scavenging: hydrogen atom transfer, sequential proton loss electron transfer, single electron transfer - proton transfer and transition metal chelation, based on the B3LYP/6-311++G(2d,2p) calculations in vacuum and polar media. The results explain the activity difference between cinnamic acid and its derivatives. The descending order of antioxidant potential is as follows: caffeic &gt; sinapinic ~ ferulic &gt; p-coumaric &gt; o-coumaric &gt; m-coumaric ~ phenol. The results have shown that transisomers indicate higher reactivity than cis- and may be considered as good antioxidants. It has been determined that the highest antioxidant ability is related to the hydroxyl group in para position, supported by planar structure and stability of radical forms. π-Type delocalization of unpaired electron on aromatic ring, double bond and para O-atom is the key to radical stabilization. The ortho-dihydroxy substitution in benzene ring positively influences the ability to neutralize free radicals and makes caffeic acid the antioxidant pharmacophore of hydroxycinnamic acids.

EPR and ESE of CuS4 complex in Cu(dmit)2: g-Factor and hyperfine splitting correlation in tetrahedral Cu–sulfur complexes

Pseudotetrahedral CuS4 complexes of Cu(dmit)2 compound in DMF solution were studied by EPR, UV–Vis and electron spin echo methods. After rapid freezing at 77K a good glassy state is formed and the CuS4 complex has a D2d symmetry of a compressed tetrahedron with xy ground state and spin-Hamiltonian parameters g||=2.089, g⊥=2.026, A||=146×10−4cm−1 and A⊥=30×10−4cm−1. The complex is not deformed in the glassy state and is very rigid as indicated by the echo detected spectrum and by electron spin relaxation which is governed by reorientations of methyl groups of surrounding DMF molecules as shown by electron spin echo envelope modulation (ESEEM) spectrum. The g|| and A|| of Cu(dmit)2 and other CuS4 complexes collected in Peisach–Blumberg correlation diagram were analyzed using extended Molecular Orbital theory. We explain why the correlation line for copper–sulfur complexes has larger slope compared to the CuO4 and CuN4 tetrahedra. Along the correlation line the delocalization of unpaired electron density onto ligand is constant and varies from β=0.78–0.83 for g|| in the range 2.06–2.10 of correlation diagram. The slope of the line is determined by the product of MO-coefficients αc1, where α is a parameter characterizing delocalization of unpaired electron in x2–y2 and c1<1 is a mixing parameter decreasing when 4p contribution grows. We found, unexpectedly, that αc1≈0.7 for all CuS4 complexes suggesting a correlation between degree of tetrahedral deformation and MO-parameters. MO-coefficients for Cu(dmit)2 are α=0.753, β=0.752 and c1=0.930 confirming a strong delocalization of unpaired electron in xy and x2–y2 orbitals.

Charged states in diphenylamino endcapped thiophenes with a 1,4-phenylene core: In situ electron spin resonance/ultraviolet–visible–near infrared and nuclear magnetic resonance spectroelectrochemistry and quantum chemical study

The three diphenylamino-endcapped thiophene compounds 1,4-bis-(2-diphenylamino-thiophen-5-yl)-benzene (A), 1,4-bis-[2-(phenothiazin-10-yl)-thiophen-5-yl]-benzene (B), and 1,4-bis-(5-diphenylamino-[2,2′]bithiophen-5′-yl)-benzene (C) with a central phenylene core were investigated by in situ ESR/UV–vis–NIR and in situ NMR spectroelectrochemistry and quantum chemical studies. The computed vertical ionization potentials are 4.85eV for A, 5.39eV for B and 4.80eV for C while the adiabatic ionization potentials are slightly lower 4.45eV (for A), 4.96eV (for B) and 4.47eV (for C). The minimal difference between computed ionization potentials of A and C and the lower oxidation ability of B are in good agreement with the experimental electrochemical findings with the first half-wave anodic potentials 0.69V (for A), 0.81V (for B) and 0.67V (for C), all vs. decamethylferrocene (DmFc+/DmFc). For the radical monocations A+ and C+ the spin delocalisation on the central phenylene moiety was confirmed both experimentally and by theoretical calculations. For the radical cation B+, the presence of a phenothiazinyl moiety is responsible for the delocalization of unpaired electron in the lateral part of this molecule. The stability of the charged states was increased substantially by the incorporation of two further 2,5-thienylene moieties between the central moiety and the side groups in C. Detailed spectroelectrochemical studies of the cation radical, dication, trication and tetracation of C are in good agreement with the calculated electronic transitions and experimental values for all redox states. In situ NMR spectroelectrochemical studies at different temperatures indicate dimerisation reactions of charged 1,4-bis-(5-diphenylamino-[2,2′]bithiophen-5′-yl)-benzenes.

Synthesis, characterization, and solid state electrical conductivity of coordination polymers with copper and zinc

Heterobimetallic complexes [Cu x Zn1− x (dadb) · yH2O] n {where dadb = 2,5-diamino-3,6-dichloro-1,4-benzoquinone (1); x = 1 (2), 0.5 (4), 0.25 (5), 0.125 (6), 0.0625 (7), and 0 (3); y = 2; n = degree of polymerization} were synthesized and characterized. All metal complexes are stable at room temperature but weakly absorb moisture on exposure to air. Monometallic 2 exhibits subnormal magnetic moment whereas 3 exhibits diamagnetism. Heterobimetallic complexes exhibit normal magnetic moments. Heterobimetallic complexes are characterized from powder X-ray diffraction, thermal analysis, and electron spin resonance (ESR) spectral studies. Delocalization of unpaired electron from metal to ligand has been inferred from ESR and natural bond orbital (NBO) analysis. Greater delocalization of unpaired electron of Cu(II) on ligand of 4 as compared to that of 2 is reflected from NBO analysis. Heterobimetallic complexes show higher conductivity than monometallic complexes; all the complexes exhibit semiconductor behavior.

Vibrational spectroscopy and density functional theory analysis of 3-O-caffeoylquinic acid

Density functional theory (DFT) calculations are being performed to investigate the geometric, vibrational, and electronic properties of the chlorogenic acid isomer 3-CQA (1R,3R,4S,5R)-3-{[(2E)-3-(3,4-dihydroxyphenyl)prop-2-enoyl]oxy}-1,4,5-trihydroxycyclohexanecarboxylic acid), a major phenolic compound in coffee. DFT calculations with the 6-311G(d,p) basis set produce very good results. The electrostatic potential mapped onto an isodensity surface has been obtained. A natural bond orbital analysis (NBO) has been performed in order to study intramolecular bonding, interactions among bonds, and delocalization of unpaired electrons. HOMO–LUMO studies give insights into the interaction of the molecule with other species. The calculated HOMO and LUMO energies indicate that a charge transfer occurs within the molecule.

Intramolecular cyclization reaction mechanism and regioselectivities of unsubstituted and benzene-substituted 4-penteniminyl radicals: A DFT investigation

The cyclization mechanisms and regioselectivities of 4-penteniminyl and benzene-substituted 4-penteniminyl radicals were investigated systematically by density functional theory method and Marcus theory. For the 4-penteniminyl radical, the 5-exo-trig cyclization via a boat-like transition state was found to be the dominant pathway, whereas for the benzene-substituted 4-penteniminyl ring closure processes the 6-endo-trig is the favorable reaction mode. The preferred 5-exo-trig over 6-endo-trig in 4-penteniminyl radical cyclization is believed to come from a stereoelectronic effect and can be elucidated by orbital interactions between HOMO of iminyl radical and FMO of unsaturated CC double bond in the transition state models. The Marcus theory analysis demonstrated that the surprising regiochemistry of benzene-substituted 4-penteniminyl radical cyclization can be attributed to a thermodynamic effect. The extremely high thermodynamic stability of 6-endo-trig product radical resulting from strong p–π delocalization of unpaired electron in benzene ring leads to a significant decrease in reaction activation energy, and further makes the reaction regioselectivity reverse dramatically relative to the unsubstituted system. Therefore, the kinetic and thermodynamic effects dominate the regioselectivities of 4-penteniminyl and benzene-substituted 4-penteniminyl radical cyclization reactions, respectively.

Molecular structure and vibrational spectroscopic investigation of 4-chloro-4′dimethylamino-benzylidene aniline using density functional theory

The Fourier Transform Raman and infrared spectra of the crystallized 4-chloro-4′dimethylamino-benzylidine aniline (CDMABA) have been recorded in the region 3500–200 cm −1 and 4000–400 cm −1, respectively. The geometry optimization, electrostatic potential surface and vibrational wavenumbers with Raman scattering activities and infrared absorption intensities have been investigated by density functional theory (DFT) method using 6-311++G(d,p) basis set and Becke’s three-parameters hybrid functional (B3LYP). The calculated molecular geometry has been compared with the experimental data obtained from XRD. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis (NCA). The natural bond orbital analysis (NBO) has been performed in order to study the intramolecular bonding, interactions among bonds and delocalization of unpaired electrons. The electrostatic potential surface mapped with isodensity surface has been obtained.