Şenay Yurdakul

Molecular structure and vibrational spectra of 1,2-bis(4-pyridyl) ethane by density functional theory and ab initio Hartree-Fock calculations

The molecular geometry and vibrational frequencies of 1,2-bis(4-pyridyl) ethane (bpa) in the ground state have been calculated using the Hartree-Fock and density functional methods (B3LYP and BLYP) with 6-31G (d) basis set. The optimized geometric bond lengths obtained by using HF and bond angles obtained by DFT (BLYP) show the best agreement with the experimental values. Comparison of the observed fundamental vibrational frequencies of bpa and calculated results by density functional B3LYP, BLYP and Hartree-Fock methods indicates B3LYP is superior to the scaled Hartree-Fock and BLYP approach for molecular vibrational problems.

Coordination behaviour of nicotinamide: an infrared spectroscopic study

Abstract A series of Hofmann-type complexes containing two nicotinamide(nia) molecules attached to transition metal (II) (M) tetracyanonickelate frame with the formula: M(nia) 2 Ni(CN) 4 (where M=Mn, Co, Ni, Cu or Cd) have been synthesised for the first time. Metal (II) halide complexes of nicotinamide complexes of the type [M(nia) 2 X 2 (M=Cd, Ni, Cu, Hg; X=Cl, Br) and Ni(nia) 4 Br 2 nia=nicotinamide] have also synthesised. The FTIR spectra are reported in the 4000–400 cm −1 region. Vibrational assignments are given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure–spectra correlations. A pronounced change was observed in the N–H stretching frequencies of the NH 2 group. It is proposed that the amide NH 2 group influence by the intramolecular hydrogen bond in the complexes. The coordination effect on the nicotinamide modes is analysed.

Fourier transform infrared and Raman spectroscopic studies on 8-hydroxyquinoline metal(II) tetracyanonickelate complexes

Abstract The results of an infrared and Raman spectroscopic study are reported for seven new metal(II) 8-hydroxyquinoline tetracyanonickelate complexes, M(8-HQ) 2 Ni(CN) 4 [where (8-HQ) = 8-hydroxyquinoline; M = Mn, Fe, Co, Zn, Ni, Cu or Cd]. 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 six compounds.

Infrared spectroscopic studies of some piperidine metal(II) clathrates: M(C5H11N)2Ni(CN)4·G (M = Co, Ni; G = m-xylene, p-xylene or o-xylene; M = Ni; G = dioxane)

Abstract IR spectra of M(C 5 H 11 N) 2 Ni(CN) 4 ·G (M=Co, Ni; G= o -, m - or p -xylene; M=Ni; G=dioxane) are reported. These clathrates are analogues to the previously reported classical Hofmann-type clathrates.

An infrared and Raman spectroscopic study of the Hofmann-type complexes and clathrates: M(piperidine)2Ni(CN)4; M(piperidine)2Ni(CN)4·1.5G (M=Cd, Co, Ni or Cu; G=benzene)

Abstract New Hofmann-type complexes and clathrates of the forms M(piperidine) 2 Ni(CN) 4 and M(piperidine) 2 Ni(CN) 4 ·1.5G (M=Cd, Co, Ni or Cu; G=benzene) were prepared in powder form and their infrared and Raman spectra are reported. The spectral features suggest that these compounds are similar in structure to the Hofmann-type clathrates except for the copper compounds. The complex and clathrate of Cu have different spectral features in comparison with its analogues due to the Jahn-Teller effect.

FTIR, Raman and NMR spectroscopic and DFT theoretical studies on poly(N-vinylimidazole).

In this study where the FTIR, Raman, (1)H NMR and (13)C NMR spectra of poly(N-vinylimidazole) which can be abbreviated as poly(NVIM) are first reported, a comparison of the experimental and theoretical vibrational spectral data of monomer NVIM and water-soluble poly(NVIM) has been given; such a comparison over the vibrational modes and associated spectral data calculated at B3LYP/6-31+G(d) level of theory for NVIM and its stable dimer forms provided significant contributions for getting a reliable interpretation of the observed vibrational spectra of poly(NVIM). The obtained results revealed that the change from NVIM to poly(NVIM) should be characterized by the disappearance of the CH₂CH bonds of the vinyl group and the appearance of the aliphatic CH and CH₂ bonds. Besides this, the thermal properties of poly(NVIM) were elucidated by thermogravimetric analyses such as TGA, DTA and DSC, while some electronic structure parameters of the most stable dimers of NVIM were investigated through the structure calculations performed by using B3LYP method and 6-31+G(d) basis set within the density functional theory (DFT) methodology.

Synthesis, spectroscopy, and characterization of some bis-nicotinamide metal(II) dihalide complexes

We report synthesis of six new bis-nicotinamide metal(II) dihalide complexes [M(nia)(2)Cl(2); M = Mn, Co; nia:nicotinamide, M(nia)(2)Br(2); M = Mn, Hg; M(nia)(2)I(2); M = Cd, Cu], and their characterization by combining infrared spectroscopy with density functional theory (DFT) calculations. Infrared spectra indicate that ring-nitrogen is the active donor cite, and the atomic structure of the complexes is determined to be polymeric octahedral or distorted polymeric octahedral. Spin polarized electronic ground state is obtained for Mn, Co, and Cu halide complexes. The colors of the complexes also support the conclusion of octahedral coordination around the metal atoms, in agreement with DFT results.

Vibrational spectroscopic study on pyrimidine metal(II) tetracyanometalate complexes

The results of an infrared and Raman spectroscopic study are reported for seven new metal(II) pyrimidine tetracyanonickelate complexes, M(pyr)2Ni(CN)4 [where (pyr) = pyrimidine; M = Mn, Fe, Co, Zn, Ni, Cu or Cd] and an IR spectroscopic study is presented for new cadmium pyrimidine tetracyanometalate complex, Cd(pyr)2Cd(CN)4. The spectral data suggest that the first seven compounds belong to the Hofmann-type and the last compound belongs to the Hofmann-Td-type of complexes.

Fourier Transform‐Infrared Spectroscopic Study of Isonicotinamide Metal(II) Tetracyanonickelate and Halide Complexes

Abstract In this study, fourier transform-infrared FT‐IR spectra of M(iso)2Ni(CN)4 (where M = Cd, Zn, Ni, or Cu; iso = isonicotinamide; abbreviated to M–Ni‐iso) and Cd(iso)2X2 (where X = Cl, Br, or I) complexes are reported in the 4000–400 cm−1 range. Vibrational assignments are given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure–spectra correlations. The proposed structure of tetracyanonickelate complexes consists of polymeric layers of |M–Ni(CN)4|∞ with the isonicotinamide molecules bound directly to the metal (M).

Quantum chemical and spectroscopic (FT-IR and FT-Raman) investigations of 3-methyl-3h-imidazole-4-carbaldehyde.

FT-IR and FT-Raman spectra of 3-methyl-3h-imidazole-4-carbaldehyde (3M3HI4C) were recorded in the region 4000-400cm(-1) and 3500-50cm(-1), respectively. Optimized geometric parameters, conformational equilibria, normal mode frequencies, and corresponding vibrational assignments of 3M3HI4C were theoretically examined by quantum chemical methods for the first time. All vibrational frequencies were assigned in detail with the help of total energy distribution (TEDs). The experimental wavenumbers were compared with the scaled vibrational frequencies determined by DFT/B3LYP method. The results showed that the B3LYP/6-311++G(d,p) method predicts vibrational frequencies and the structural parameters effectively. The most stable conformer of the title compound was determined. The total electron density and molecular electrostatic potential surfaces of the molecule were constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron+nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. The lower energy band was assigned to the HOMO→LUMO transition. Natural bond orbital analysis of title molecule has been performed to indicate the presence of intramolecular charge transfer. Energies, relative stabilities, and dipole moments of title molecule were also compared and analyzed in the gas phase and in solvents. Furthermore, solvent effects on the geometry and vibrational frequency of 3M3HI4C were studied theoretically at the DFT/B3LYP level in combination with the conductor polarizable continuum model (C-PCM).