Vibrational spectra, powder X-ray diffractions and physical properties of cyanide complexes with 1-ethylimidazole.

The heteronuclear tetracyanonickelate(II) complexes of the type [M(etim)Ni(CN)4]n (hereafter, abbreviated as M-Ni-etim, M=Mn(II), Fe(II) or Co(II); etim=1-ethylimidazole, C5H8N2) were prepared in powder form and characterized by FT-IR and Raman spectroscopy, powder X-ray diffraction (PXRD), thermal (TG; DTG and DTA), and elemental analysis techniques. The structures of these complexes were elucidated using vibrational spectra and powder X-ray diffraction patterns with the peak assignment to provide a better understanding of the structures. It is shown that the spectra are consistent with a proposed crystal structure for these compounds derived from powder X-ray diffraction measurements. Vibrational spectra of the complexes were presented and discussed with respect to the internal modes of both the etim and the cyanide ligands. The C, H and N analyses were carried out for all the complexes. Thermal behaviors of these complexes were followed using TG, DTG and DTA curves in the temperature range 30-700 °C in the static air atmosphere. The FT-IR, Raman spectra, thermal and powder X-ray analyses revealed no significant differences between the single crystal and powder forms. Additionally, electrical and magnetic properties of the complexes were investigated. The FT-IR and Raman spectroscopy, PXRD, thermal and elemental analyses results propose that these complexes are similar in structure to the Hofmann-type complexes.

New cyano bridged heteropolynuclear Cu(II) and Cd(II)-tetracyanopalladate(II) polymeric complexes with 2-methylimidazole ligand.

New cyano-bridged heteronuclear polymeric complexes, [M(mim)2Pd(CN)4]n (M=Cu(II) (1) or Cd(II) (2); mim=2-methylmidazole), have been synthesized and characterized by elemental, thermal, FT-IR and Raman spectral analyses. The crystal structure of complex 1 has been determined by single crystal X-ray diffraction technique. The crystallographic analysis reveals that it crystallizes in the monoclinic system, space group P21/c. The Pd(II) atom is coordinated by four cyano ligands, while Cu(II) atom is also surrounded by the two mim and two cyano ligands. The structure of 1 is formed by infinite 2,2-TT type chains of the [-Cu(mim)2-NC-Pd(CN)2-CN-]n composition; these are interlinked by hydrogen bonds (HBs) leading to two-dimensional patterns. FT-IR and Raman spectral data indicate the presence of bridging cyano ligands in the structures of the complexes.

Two dimensional cyano-bridged hetero-metallic coordination polymers containing metal⋠⋠⋠π interactions.

Three cyano bridged hetero-metallic complexes of general formula, [Cu(NH3)2(µ-ampy)M(µ-CN)2(CN)2]n [ampy=4-aminomethylpyridine, M=Ni(II) (1), Pd(II) (2) and Pt(II) (3)] have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal analyses and elemental analyses. The complexes crystallize in triclinic system with space group P-1. In all complexes, M(II) ions are coordinated by four cyano ligands, and four N atoms in the equatorial plane around the Cu atom form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination is completed by the cyanide N atoms in the axial positions. In one-dimensional structures of all the complexes, [Cu(ampy)](2+) cations and [M(CN)4](2-) anions are linked via bridging cyano ligands. The adjacent one-dimensional structures form a 2D network to connect by the µ-ampy bridging ligands. The 2D layers are further linked by metal⋯π and hydrogen bonding interactions to generate a three dimensional network.

CH⋯Pd interactions: one dimensional heteropolynuclear complexes.

Three cyanide complexes, [Cu(hepH)2Pd(µ-CN)2(CN)2]n (1), [Zn(hepH)2Pd(µ-CN)2(CN)2]n (2) and [Cd(hepH)2Pd(µ-CN)2(CN)2]n (3) (2-pyridineethanol abbreviated to hepH), have been synthesized and characterized by various techniques (elemental analysis, FT-IR and Raman spectroscopy, thermal analysis and single crystal X-ray diffraction). FT-IR spectroscopy pointed out the existence of terminal and bridged cyanide ligands in the complexes. The crystallographic analyses reveal that complexes 1 and 2 crystallize in the triclinic system, space group P-1 and complex 3 crystallizes in the monoclinic system, space group P21/n. The palladium atom is coordinated with cyanide-carbon atoms in a square-planar arrangement and the metal(II) atoms are six-coordinated with two cyanide nitrogen, two hepH nitrogen and two hepH oxygen atoms, in a distorted octahedral arrangement. In all the complexes adjacent chains are connected by CH⋯Pd, π⋯π and OH⋯N hydrogen bonding interactions to form two- and three-dimensional networks. When it comes to thermal analysis, the complexes followed usual decomposition mechanism in which neutral ligands (hepH) are released first, and then cyanide ligands are decomposed. The final decomposition products are found to be the corresponding metal oxides.

A theoretical study on the molecular structure and vibrational (FT-IR and Raman) spectra of cyano-bridged heteronuclear polymeric complex of triethylenetetramine.

The cyano bridged complex of triethylenetetramine was characterized by FT-IR, Raman spectroscopy and X-ray single crystal diffraction analysis. The molecular geometry and vibrational frequencies of the complex in the ground state have been calculated by using B3LYP density functional method with LANL2DZ basis set. A good correlation was found via comparison of the experimental and theoretical vibrational frequencies of complex. The complex of the type [Zn(teta)Ni(µ-CN)(2)(CN)(2)](n) has been studied in the 4000-250cm(-1) region and assignment of all the observed bands were made. The analysis of the FT-IR and Raman spectra indicates that there are some structure spectra correlations.

Theoretical studies on the molecular structure and vibrational spectra of some dimethyl substituted pyridine derivatives.

The molecular geometries, normal mode frequencies, intensities and corresponding infrared assignments of monomeric and dimeric 2,3-dimethylpyridine, 2,4-dimethylpyridine, 3,4-dimethylpyridine, 3,5-dimethylpyridine and monomeric 2,6-dimethylpyridine in the ground state were investigated at the density functional theory (DFT)-B3LYP level using the 6-311+G(d, p) basis set. The vibrational frequencies and geometric parameters of C-H stretching and bending in the fundamental region were calculated and compared to the Fourier transform infrared (FT-IR) data obtained. In the studied monomeric and dimeric dimethyl substituted pyridine derivatives, the C-H stretching and bending frequency shifts that occur between the dimer and the monomer may be diagnostic of the magnitude of dimerization energy. As supported by data in the literature, the most stable dimeric form was obtained for the 3,4-dimethylpyridine molecule.