UV-Vis Spectroscopy, Electrochemical and DFT Study of Tris(ß-diketonato)iron(III) Complexes with Application in DSSC: Role of Aromatic Thienyl Groups.

A series of tris(ß-diketonato)iron(III) complexes, with the ß-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(ß-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(ß-diketonato)iron(III) complexes were investigated. A density functional theory (DFT) study related to the spectroscopic and electrochemical properties of the tris(ß-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.

DFT data to relate calculated LUMO energy with experimental reduction potentials of Cu(II)-ß-diketonato complexes.

We present data on the computed lowest unoccupied molecular orbital energy (ELUMO ) of two series of Cu(II)-ß-diketonato complexes, calculated via density functional theory (DFT). These are correlated to experimental reduction potential data (E pc), obtained by cyclic voltammetry under different experimental conditions (solvent, working and reference electrodes). All calculations were done with the B3LYP functional in the gas phase. Knowledge of the influence of different ligands on the redox potential of copper complexes, as measured by DFT calculated energy data, are very useful. These theoretical correlations are vital in the further design of similar compounds, to be customized for specific applications. The correlations can be used to predict and fine-tune redox potentials prior to synthesis, saving experimental chemists time and laboratory expenses. Redox potentials influence the catalytic property of bis(ß-diketonato)copper(II) compounds. New catalysts can therefore be customized with a specific reduction potential and catalytic activity. Further, the Cu(II/I) redox couple is a potential alternative as electrolyte for dye-sensitized solar cells [1], [2], [3]. The redox potential of the electrolyte can drastically affect the photovoltage output and should therefore be optimized for efficiency and durability. By adjusting the reduction potential via different ligands on the complex, the properties of copper dyes can be fine-tuned at molecular level. For more insight into the reported data, see the related research article "Synthesis, Characterization, DFT and Biological Activity of Oligothiophene ß-diketone and Cu-complexes" published in Polyhedron [4].

Density functional theory calculated data of the iodomethane oxidative addition to oligothiophene-containing rhodium complexes - Importance of dispersion correction.

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].

Data of the rhodium(triphenylphosphine)carbonyl-2,4-dioxo-3-pentyl-4-hydroxybenzoate plus iodomethane oxidative addition and follow-up reactions.

Density functional theory (DFT) free energy data and the reaction mechanism of the rhodium(triphenylphosphine)carbonyl-2,4-dioxo-3-pentyl-4-hydroxybenzoate plus iodomethane reaction are presented. The rhodium(I) reactant is a simplified model of the rhodium(I) of the rhodium(triphenylphosphine)carbonyl-2,4-dioxo-3-pentyl-4-decanyloxybenzoate plus iodomethane reaction (full model), presented in the related research article "Rhodium(triphenylphosphine)carbonyl-2,4-dioxo-3-pentyl-4-decanyloxybenzoate: A DFT study of Oxidative Addition and Methyl Migration" [1]. The goal is to illustrate that DFT calculations of a simplified model give the same information regarding the reaction scheme and free energy data as for the full model, while it requires much less computational resources to obtain the data. Furthermore the reaction scheme of the simplified model are in agreement with experimental observation of the full model [2].

Cyclic voltammetry data of polypyridine ligands and Co(II)-polypyridine complexes.

The data presented in this article is related to the research article entitled "Electrochemical and electronic properties of a series of substituted polypyridine ligands and their Co(II) complexes" (Ferreira et al., 2019). This data article presents electrochemical data of five polypyridine ligands, as well as of the three redox couples of each of their corresponding five polypyridine-containing Co(II) complexes. All complexes exhibit two Co-based redox couples (CoIII/II and CoII/I), as well as a ligand-based reduction of the Co(I) complex.

Electrochemical data of Co(II) complexes containing phenanthroline functionalized ligands.

The data presented in this paper are related to the research article entitled "Electrochemical properties of a series of Co(II) complexes, containing substituted phenanthrolines" (Ferreira et al., 2018) [1]. This paper presents detailed electrochemical data of eight octahedral Co(II) complexes containing functionalized phenanthrolines-ligands. The data illustrate the shift in the CoIII/II and CoII/I redox couples due to different substituents on the phenanthrolines. Polypyridine Co(II) and Co(III) complexes exhibit properties as potential mediators in dye-sensitized solar cells (DSSCs) (Gajardo and Loeb, 2011; Yu et al., 2011) [2], [3]. The ability of a compound to act as a redox mediator to be used in DSSC, depends on the redox potential of the compound (Grätzel, 2005) [4]. Accurate data of the CoIII/II redox couple is presented here.

Methyl iodide oxidative addition to [Rh(acac)(CO)(PPh3)]: an experimental and theoretical study of the stereochemistry of the products and the reaction mechanism.

Density functional theory was used to investigate the oxidative addition and subsequent carbonyl insertion and deinsertion steps of the reaction of methyl iodide to a rhodium(I) acetylacetonato complex of the formula [Rh(acac)(CO)(PPh(3))] (Hacac = acetylacetone). This process has been studied experimentally for many rhodium ß-diketonato complexes, but, to the best of our knowledge, this is the first systematic computational study of the complete reaction sequence. Experimental (1)H techniques complement the theoretical results on the stereochemistry of the reaction intermediates and products. (1)H NMR also revealed the existence of a second rhodium(III)-acyl product, which has not been previously observed in this reaction. The calculated Gibbs free energy of activation of the oxidative addition reaction is 71 kJ mol(-1), which is in agreement with the experimental value of 82(1) kJ mol(-1). The DFT-calculated oxidative addition corresponds to an associative S(N)2 nucleophilic attack by the rhodium metal centre on the methyl iodide, which is in agreement with calculated and experimental (in brackets) activation parameters of the reaction, 27 (38.8) kJ mol(-1) for ΔH((≠)) and -147 (-146) J K(-1) mol(-1) for ΔS((≠)).

Capturing the spin state diversity of iron(III)-aryl porphyrins: OLYP is better than TPSSh.

DFT calculations with a variety of exchange-correlation functionals, including PW91, OLYP, TPSSh, B3LYP and B3LYP*, have been carried out on the low-energy spin states of chloroiron(III) porphyrin and four aryliron(III) porphyrins, viz. Fe(III)(P)Ph (S=1/2), Fe(III)(P)C(6)F(5) (S=5/2), Fe(III)(P)(3,4,5-C(6)F(3)H(2)) (S=1/2), Fe(III)(P)(2,4,6-C(6)F(3)H(2)) (S=5/2), where the expected spin states have been indicated within parentheses. Qualitatively, OLYP reproduces all the expected ground spin states. B3LYP appears to have some difficulty yielding the observed sextet ground states. B3LYP*, TPSSh and PW91 all fail to reproduce the sextet ground states, the latter two by rather large margins of energy. As far as this study is concerned, the overall performance of the functionals appears to be OLYP/OPBE>B3LYP>B3LYP*>>TPSSh>PW91/BLYP/BP86/TPSS.