A series of tris(β-diketonato)iron(III) complexes, with the β-diketonato ligand bearing different substituent groups, have been synthesized and characterized by Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis) and mass spectroscopic methods. The maximum band UV-Vis absorption wavelengths of the tris(β-diketonato)iron(III) complexes were in the range of 270–380 nm. The complexes have very good solubility in various solvents such as chloroform, dichloromethane, ethyl acetate, tetrahydrofurane, dimethylsulphoxide and dimethylformamide. After the syntheses and characterization processes, spectroscopic and electrochemical properties of these tris(β-diketonato)iron(III) complexes were investigated. A density functional theory (DFT) study related to the spectroscopic and electrochemical properties of the tris(β-diketonato)iron(III) complexes was used to investigate the possible application of these complexes as dye sensitizers or redox mediators in dye-sensitized solar cells.

The syntheses, characterization and experimental solid state X-ray structures of five low-spin paramagnetic 2-pyridyl-(1,2,3)-triazole-copper compounds, [Cu(Lⁿ)₂Cl₂], are presented in this study, for the following five Lⁿ ligands: L¹ = 2-(1-(p-tolyl)-1H-(1,2,3-triazol-4-yl)pyridine), L² = 2-(1-(4-chlorophenyl)-1H-(1,2,3-triazol-4-yl)pyridine), L³ = 4-(4-(pyridin-2-yl)-1H-(1,2,3-triazol-4-yl)benzonitril), L⁴ = 2-(1-phenyl-1H-(1,2,3-triazol-4-yl)pyridine) and L⁵ = 2-(1-(4-(trifluoromethyl)phenyl)-1H-(1,2,3-triazol-4-yl)pyridine). These five [Cu(Lⁿ)₂Cl₂] complexes each contain two bidentate 2-pyridyl-(1,2,3)-triazole (Lⁿ) and two chloride ions as ligands, with the Cu–N(pyridine) bonds, Cu–N(triazole) and Cu–Cl bonds trans to each other. All five [Cu(Lⁿ)₂Cl₂] compounds display elongation Jahn–Teller distortion, either along opposite Cu–N(triazole) bonds, or along opposite Cu–Cl bonds, as indicated by their obtained solid state crystal structures. Quantum chemistry calculations, using density functional theory, indicated however that elongation Jahn–Teller distortion is in fact possible along any two opposite bonds in these octahedral compounds with the elongation distortion along the opposite Cu–N(triazole) bonds being the most stable structure.

Electronic and free energy data of density functional theory calculated optimized geometries of the reactants, transition state of the oxidative addition reaction and different reaction products of the [Rh(RCOCHCOCF3)(CO)(PPh3)] + CH3I reactions (R = C4H3S, C4H3S-C4H2S and C4H3S-C4H2S-C4H2S) are presented to illustrate the influence of the amount of thiophene groups, the implicit solvent and dispersion correction on the calculated energies. All calculations were done with the B3LYP functional, in gas as well as in solvent phase, with and without dispersion correction. The data can save computational chemists time when choosing an appropriate method to calculate reaction energies of oxidative addition reactions. Detailed knowledge of energies involved in the oxidative addition reaction of methyl iodide to rhodium complexes have an important implication in catalysis, for example the Monsanto process where methanol is converted to acetic acid catalysed by a rhodium complex. For more insight in the reported data, see the related research article “Synthesis, characterization, electrochemistry, DFT and kinetic study of the oligothiophene-containing complex [Rh((C4H3S-C4H2S)COCHCOCF3)(CO)(PPh3)]”, published in Polyhedron [1].

In coordination chemistry, 2,2′:6′,2″-terpyridine is a versatile and extensively studied tridentate ligand. Terpyridine forms stable complexes with a variety of metal ions through coordination sites provided by the three nitrogen atoms in its pyridine rings. This paper presents an electrochemical study on various bis(terpyridine)osmium(II) complexes, addressing the absence of a systematic investigation into their redox behavior. Additionally, a computational chemistry analysis was conducted on these complexes, as well as on eight previously studied osmium(II)-bipyridine and -phenanthroline complexes, to expand both the experimental and theoretical understanding. The experimental redox potentials, Hammett constants, and DFT-calculated energies show linear correlations due to the electron-donating or electron-withdrawing nature of the substituents, as described by the Hammett constants. These substituent effects cause shifts to lower or higher redox potentials, respectively.