Molecular structure and vibrational spectra of lepidine and 2-chlorolepidine by density functional theory and ab initio Hartree–Fock Calculations

The molecular geometry and vibrational frequencies of lepidine and 2-chlorolepidine in the ground state have been calculated by using the Hartree–Fock and density functional methods (B3LYP) with 6-31G (d) as the basis set. The optimized geometric bond lengths obtained by using B3LYP and bond angles obtained by HF that correspond to the experimental values of 2-cl-lepidine molecule were given. Comparison of the observed fundamental vibrational frequencies of lepidine and 2-chlorolepidine, and calculated results by density functional B3LYP and Hartree–Fock methods indicates that B3LYP is superior to the scaled Hartree–Fock approach for molecular vibrational problems.     

Experimental and Theoretical Study on New Zn(II) Halide Complexes of 3,5-Diazaindole

3,5-Diazaindole — zinc(II) halide complexes (halogen: Cl, Br, I) are synthesized for the first time. Experimental mid-IR spectra of the compounds were recorded in the range 4000–550 cm^–1, and far-IR spectrum of the zinc(II) chloride complex is recorded in range 700–40 cm^–1. The structural features of the zinc(II) halide complexes of 3,5-diazaindole (ICPY) are studied by quantum chemical methods. The optimized geometry and vibrational frequencies of the ICPY — zinc(II) halide complexes are calculated using the B3LYP/DFT method with the LANL2DZ basis set in the ground state. Vibrational assignments of the most important bands are made with the help of the vibrational energy distribution analysis. The frontier molecular orbital energies, NBO charges, and dipole moments are presented. ¹H and ¹³C NMR spectra of the zinc(II) chloride complex is also given.     

On some normability conditions

Various normability conditions of locally convex spaces (including Vogt interpolation classes DN _φ and Ω_φ as well as quasi‐ and asymptotic normability) are investigated. In particular, it is shown that on the class of Schwartz spaces the property of asymptotic normability coincides with the property GS , which is a natural generalization of Gelfand–Shilov countable normability (cf. [9, 25], where the metrizable case was treated). It is observed also that there are certain natural duality relationships among some of normability conditions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

FT-IR, FT-Raman, NMR spectra and DFT simulations of 4-(4-fluoro-phenyl)-1H-imidazole

The FT-IR, FT-Raman and FT-NMR spectra of the compound 4-(4-Fluoro-phenyl)-1H-imidazole (4-FPI) were recorded and analyzed. Density functional method (B3LYP level with the 6–311G(d, p) and 6–311++G(d, p) and cc-pVQZ as basis sets) has been used to compute optimized geometry, vibrational wavenumbers of the 4-FPI. Only one tautomeric form was found most stable by using DFT/B3LYP. The detailed interpretation of the vibrational spectra was carried out with the aid of total energy distribution following the scaled quantum mechanical force field methodology. Potential Energy Surface scan studies has also been carried out by ab initio calculations with the same basis sets.     

Vibrational Spectroscopic Studies of 3,4-Lutidine Metal (II) Tetracyanonickelate Complexes

Infrared and Raman spectra of seven new metal (II) 3,4-lutidine tetracyanonickelate complexes, M(3,4 L)₂ Ni(CN)₄ [where 3,4 L = 3,4 - dimethyl-pyridine or 3,4-lutidine; M = Mn, Fe, Co, Zn, Ni, Cu or Cd] (abbreviated to M - Ni - 3,4 L) have been investigated. Spectroscopic and magnetic susceptibility measurements indicate that the compounds have the structure of Hofmann-type complexes. The copper complex has spectral features different from the other compounds.     

Collective excitations of the element <Emphasis Type="Italic">Z</Emphasis> = 120

The low-lying vibrational excitations of superheavy even-even nuclei around Z=120 and N=172, predicted to be spherical by the relativistic mean-field (RMF) model, are studied within a phenomenological collective approach. In the framework of the macroscopic model for giant resonances, we compute the transition densities of the isoscalar monopole, quadrupole, and octupole and isovector dipole modes for the superheavy nucleus ²⁹²120, whose ground-state density is determined from the RMF model. The results are also compared to those for²⁰⁸Pb.     

Experimental and theoretical studies on molecular structures and vibrational modes of novel compounds containing silver

The two novel silver containing complexes of N-(pyridin-2-yl)pyridin-2-amine (NDPA) molecule has been synthesized and characterized by elemental analysis, FT-Raman and FT-IR (at far and mid regions) spectroscopies. The optimized geometries of the compounds were obtained by using DFT/B3LYP method with LANL2DZ basis set for the (C₁₀H₉N₃) · AgNO₃ and B3LYP method with DGDZVP basis set for the (C₁₀H₉N₃) · AgClO₄. The vibrational frequencies and their IR and Raman intensities were determined by theoretical methods. In addition, the HOMO-LUMO energies, thermochemical properties and atomic charges for the complexes were obtained in same level of theory. The experimental and theoretical results show that the silver atoms are coordinated to ligands in bidentate fashion. In addition, in the structures of complexes there are intra-molecular interactions. The oxygen atoms of nitrate and perchlorate are bonded to ligand via hydrogen bonds.     

Theoretical and FT-IR, FT-Raman studies of nipecotamide and its tautomers, isomers

The structure, conformers, energies and vibrational spectra of the important nipecotamide molecule have been characterized by FT-IR (mid-IR, far-IR), FT-Raman spectroscopy and by DFT calculations. The structure is optimized by B3LYP/6-311++G(d,p) calculations. All vibrational frequencies assigned in detail with the help of total energy distribution (TED). The calculated vibrational wavenumbers were compared with IR and Ra experimental data. In the most stable tautomer (NT-1), the piperidine ring adopts the chair conformation and the amide group is in the axial orientation and is stabilized by an intramolecular N-H…O hydrogen bond of 4.37 Å.     

DFT study of solvent effects on 3-hydroxy-2-quinoxalinecarboxylic acid tautomers

By using the combination of density functional theory (DFT) B3LYP/6-311++G(d,g) within polarized continuum (PCM) model, solvent effects on 3-hydroxy-2-quinoxalinecarboxylic acid (3HQC) tautomers were investigated. Geometrical parameters, vibrational frequencies, electronic and energetic properties, and the nucleus-independent chemical shifts (NICS) were calculated in benzene, diethyl ether, and water. It has been seen that these molecular features of 3HQC are mostly solvent dependent.     

Quantum chemical studies on prototautomerism of 1H‐imidazo[4,5‐c]pyridine

The structural features of the 1H‐imidazo[4,5‐c]pyridine (ICPY) tautomers and homodimers of the most stable tautomers have been studied by quantum chemical methods. FTIR and Raman spectra of the ICPY were recorded in the range of 4000–60 cm^?1 and 3500–5 cm^?1. The predominant tautomer among four possible isomers of ICPY were determined. The optimized geometries and vibrational frequencies of possible ICPY tautomers and dimers were computed by B3LYP/DFT method with 6‐311++G(d,p) and 6‐31G(d) basis sets. All vibrational frequencies assigned in detail with the help of total energy distribution (TED) and isotopic shifts. ICPY dimeric forms were also characterized according to their hydrogen bonding interactions, and it has been found that the most stable ICPY homodimer establishes moderate strong N ? H …N type hydrogen bond. ¹H NMR, ¹³C NMR, and ¹⁵N NMR properties have been calculated for all tautomeric forms using the gauge independent atomic orbital (GIAO) method. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011