Copper(II), nickel(II) and cobalt(II) complexes of 4-cyanobenzonic acid: syntheses, crystal structures and spectral properties

Vibrational spectroscopic, molecular structure, first hyperpolarizability and NBO studies of 4'-methylbiphenyl-2-carbonitrile

The FT-IR, FT-Raman spectra and XRD of 4'-methylbiphenyl-2-carbonitrile were recorded and analyzed. The frequencies were computed at various density functional theoretical levels using Gaussian09 software package. The data obtained from theoretical calculations were used to assign vibrational bands obtained in infrared and Raman spectra of the studied molecule. Potential energy distribution of the normal modes of vibrations were done using GAR2PED program. The geometrical parameters of the title compound are in agreement with XRD crystal structure data. The first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non linear optics. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. According to XRD data, the dihedral angles between the mean planes of the two benzene rings is 44.7° and the crystal packing is stabilized by weak intermolecular π-π stacking interactions.

Crystal Structures and Magnetic and Luminescent Properties of a Series of Homodinuclear Lanthanide Complexes with 4-Cyanobenzoic Ligand

A series of homodinuclear lanthanide(III) complexes with the 4-cba ligand, [La2(4-cba)6(phen)2(H2O)6] (1) and [Ln2(4-cba)6(phen)2(H2O)2] (Ln = Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), and Dy (7); 4-Hcba = 4-cyanobenzoic acid; phen = 1,10-phenanthroline), have been synthesized and structurally characterized by single-crystal X-ray diffraction. In 1, two water molecules bridge two nine-coordinated La ions, and six 4-cba ligands coordinate to the two La ions in terminal mode. In the isostructural complexes 2-7, two eight-coordinated Ln ions are connected by four bidentate 4-cba ligands, and another two 4-cba ligands terminate the two Ln ions. The variable-temperature magnetic properties of 2-7 have been investigated. Complex 7 shows a significant ferromagnetic interaction between Dy(III), while no magnetic interaction exists between Gd(III) ions in 6. In 2-5, the value of chi(M)T decreases with decreasing temperature, but the magnetic interactions between the Ln(III) ions cannot definitely be concluded. Notably, the spin-orbit coupling parameters, lambda, for Sm(III) (216(2) cm(-1)) and Eu(III) (404(2) cm(-1)) have been obtained in 4 and 5, respectively. The strong fluorescent emissions of 4, 5, and 7 demonstrate that ligand-to-Ln(III) energy transfer is efficient and that the coordinated water molecules do not quench their luminescence by the nonradiative dissipation of energy.