Experimental and theoretical comparative studies on two 2-pyrazoline derivatives

Two 2-pyrazoline derivatives of 1-phenyl-3-(4-methylphenyl)-5-phenyl-2-pyrazoline (1) and 1-phenyl-3-(4-methylphenyl)-5-(2,4-dichlorophenyl)-2-pyrazoline (2) have been synthesized and characterized by elemental analysis, IR, UV–vis and fluorescence spectroscopy. The crystal structure of 2 has been determined by X-ray single crystal diffraction. For the two compounds, density functional theory (DFT) calculations of the structures and natural population atomic charge analysis have been performed at B3LYP/6-311G** level of theory. By using TD-DFT method, electron spectra of 1 and 2 have been predicted, which suggests the B3LYP/6-311G** method can approximately simulate the electron spectra for the system presented here. Comparative studies on 1 and 2 indicate that the change of substituent in 5-phenyl ring of pyrazoline ring influences the peak location and intensity in electronic and fluorescence spectra.     

Structure of hexakis(imidazole)cadmium(II) carbonate trihydrate: [Cd(Im)6]CO3 ⋅ 3H2O

The crystal and molecular structure of the title compound [Cd(Im)₆]CO₃ 3H₂O, where Im = imidazole, has been determined by X-ray crystallography. The crystal structure consists of discrete Cd(Im)₆ ²⁺ cations, CO₃ ^2– anions and three uncoordinated water molecules. It crystallizes in the hexagonal system, space group P6₃/m, with lattice parameters a = 9.0552(l) Å, c = 21.745(l) Å, and Z = 2; The Cd(II) ion assumes centrosymmetric octahedron geometry. The bond distance of Cd–N is 2.361(l) Å. A three-dimensional intermolecular hydrogen bond network is formed between the free carbonate anions, the imidazole ligands, and the free water molecules.     

Crystal structure and characterization of the dinuclear Cd(II) complex [Cd(H2O)2(o-HOC6H4COO)2]2

The structure of a new binuclear cadmium (II) complex, [Cd(H2O)2(Sal)2]2 (Sal= salicylate), has been determined by X-ray crystallography. It was also characterized by elemental analysis, its IR spectrum and thermogravimetric-differential scanning calorimetry (TG-DSC). It crystallizes in the monoclinic system, space group P2(1)/c, with lattice parameters a = 15.742(3) A, b = 12.451(3) A, c = 7.7225(15) A, beta = 96.07(3)degrees and Z = 4. Two cadmium (II) ions are bridged by two mu(2)-carboxy oxygen atoms. Each cadmium atom lies in a distorted capped octahedron coordination geometry. The thermal gravimetry (TG) data indicate that there are four discrete decomposition steps with two endothermic peaks and one exothermic peak. The final thermal decomposition product is CdO.     

Synthesis of 2,3-diaryltetrazole-5-thiones and theoretical studies on atomic charge distributions of 2,3-diphenyltetrazole-5-thione

Four 2,3-diaryltetrazole-5-thiones have been synthesized in high yields using a new synthetic method under mild reaction conditions. Theoretical calculations of the structure, vibrational frequencies, and natural population analysis (NPA) of atomic charge distributions on 2,3-diphenyltetrazole-5-thione 1 have been performed by DFT-B3LYP, HF, and MP2 methods using several basis sets. According to the NPA results a new resonance hybrid structure of 1 has been proposed with an exocyclic sulfur atom and a tetrazole ring carrying negative charges and two phenyl rings having positive charges. On the basis of this new proposed structure, the calculated results can explain experimental facts logically. In addition, a new chemical property of 1 has been predicted: the protonation should occur not only on the exocyclic S atom, but also on the N atoms having negative charges.     

Di‐μ‐chlorido‐bis({2‐[1‐(2‐pyridylethylimino)ethyl]pyrrolato‐κ3N,N′,N′′}copper(II))

The title compound, [Cu₂(C₁₃H₁₄N₃)₂Cl₂], is a neutral dimeric copper(II) complex. The two Cu^II atoms are asymmetrically bridged by two chloride ions. Each Cu^II atom is also bound to the three N atoms of a deprotonated tridentate Schiff base ligand, giving a distorted square‐pyramidal N₃Cl₂ coordination environment overall. The dinuclear complex lies across an inversion centre in the space group P. This work demonstrates the effect of ligand flexibility and steric constraints on the structures of copper(II) complexes.     

FT-Raman and FT-IR spectra, ab initio and density functional studies of 3,4-dichlorobenzyl alcohol

The Fourier transform Raman and Fourier transform infrared spectra of 3,4-dichlorobenzyl alcohol were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, depolarization ratios, reduced masses were calculated by HF and density functional B3LYP method with the 6-311 G** basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compound were also performed at HF/6-311G** and B3LYP/6-311G** levels of theory. A detailed interpretations of the infrared and Raman spectra of 3,4-dichlorobenzyl alcohol is reported. The theoretical spectrograms for FT-IR spectra of the title molecule have been constructed.     

Synthesis, characterization, crystal structure and DFT studies on 3-(1H-benzo[d][1,2,3]triazol-1-yl)-1-oxo-1-m-tolylpropan-2-yl-nicotinate

3-(1H-Benzo[d][1,2,3]triazol-1-yl)-1-oxo-1-m-tolylpropan-2-yl-nicotinate (BOTN) has been synthesized and characterized by elemental analysis, IR, UV-vis and fluorescence spectroscopy. Its crystal structure has also been determined by X-ray single crystal diffraction. For BOTN, density functional theory (DFT) calculations of the structure and vibrational frequencies have been performed at B3LYP/6-311G** level. The comparisons between the experimental vibrational frequencies and the predicted data show that B3LYP/6-311G** method can simulate the IR of BOTN on the whole. Based on the vibration analysis, thermodynamic properties of BOTN have been calculated. The correlative equations between the thermodynamic properties and the temperatures have also been listed. The experimental UV-vis spectra present two peaks and theoretical UV-vis spectra obtained by TD-DFT method exhibit three peaks. The comparison between them suggests that the B3LYP/6-311G** method can only approximately simulate the UV-vis spectra of BOTN. The fluorescence determination reveals two emission bands at 423 and 489 nm, respectively.     

Synthesis, characterization and spectra studies on Zn(II) and Cu(II) complexes with thiocarbamide ligand containing Schiff base group

The ligand of 4-phenyl-1-(1-phenylethylidene)thiosemicarbazide (HL) and its metal complexes of ZnL₂ (1) and CuL₂ (2) have been synthesized. Elemental analysis, IR and X-ray single crystal diffraction characterizations for 1 and 2 have been carried out. In the complexes 1 and 2, the central metallic ions Zn²⁺ and Cu²⁺, coordinate with two deprotonated ligands, L⁻, respectively and adopt distorted tetrahedral geometries. The thermal analyses result shows that the two complexes undergo two similar decomposition processes because of their similar geometric configurations. For the two complexes, UV–Vis spectra have been measured and DFT calculations at B3LYP/LANL2DZ level of theory prove that the electronic spectra of 1 are corresponding with intraligand electronic transitions, and the electronic spectra of 2 are attributed to intraligand electronic transitions as well as d–d electronic transitions. Fluorescence spectra measurements indicate that the complex of 1 emits stronger fluorescence than the ligand of HL, and the complex 2 does not emit fluorescence at all. Electrochemical analyses reveal that both the oxidation peak currents and the reduction peak currents of 1 and 2 are stronger than those of the ligand, respectively.