Reversible Proton-Coupled Reduction of an Iron Nitrosyl Porphyrin within [DBU-H]-Based Protic Ionic Liquid Nanodomains.

The reduction of [Fe(OEP)(NO)] has been studied in the presence of aprotic room-temperature ionic liquids (RTIL) and protic (PIL) ionic liquids dissolved within a molecular solvent (MS). The cyclic voltammetric results showed the formation of RTIL nanodomains at low concentrations of the RTIL/PIL solutions. The p values of the two PILs studied (i.

Ion Pairing versus Solvation of Dinitrobenzene Anions in Room-Temperature Ionic Liquids (RTILs): Vibrational Signatures of RTIL-Substrate Interactions.

The mechanism of solvation of ions by ionic liquids is more complex than solvation in most molecular solvents as the ionic liquid itself provides the counter ion. Solvation and ion pairing of anionic substrates in room-temperature ionic liquids (RTILs) were investigated using resonance Raman spectroscopy and DFT calculations. The purpose of this study was to differentiate between the formation of discrete cation/anion structures and a double-layer cloud of counter ions without specific atomic interactions between the ionic species.

Infrared Spectroelectrochemistry of Iron-Nitrosyl Triarylcorroles. Implications for Ligand Noninnocence.

Recent DFT calculations have suggested that iron nitrosyl triarylcorrole complexes have substantial {FeNO}-corrole character. With this formulation, reduction of Fe(C)(NO) complexes, where C = triarylcorrole, should be centered on the corrole macrocycle rather than on the {FeNO} moiety. To verify this proposition, visible and infrared spectroelectrochemical studies of Fe(C)(NO) were carried out and the results were interpreted using DFT (B3LYP/STO-TZP) calculations.

Voltammetry and Spectroelectrochemistry of TCNQ in Acetonitrile/RTIL Mixtures.

Understanding the solvation and ion-pairing interactions of anionic substrates in room-temperature ionic liquids (RTIL) is key for the electrochemical applications of these new classes of solvents. In this work, cyclic voltammetry and visible and infrared spectroelectrochemistry of tetracyanoquinodimethane (TCNQ) was examined in molecular (acetonitrile) and RTIL solvents, as well as mixtures of these solvents. The overall results were consistent with the formation of RTIL/acetonitrile nanodomains.

Proton Transfer versus Hydrogen Bonding in a Reduced Iron Porphyrin Nitrosyl Complex.

The H NMR spectra of Fe(OEP)(HNO), which was formed from Fe(OEP)(NO) in the presence of 3,5-dichlorophenol, were studied as a function of temperature. The chemical shift of the HNO proton showed a unique behavior which could be explained based on the equilibrium between the protonated complex, Fe(OEP)(HNO), and the hydrogen-bonded complex, Fe(OEP)(NO)···HOPh. This equilibrium was consistent with UV/visible spectroscopy and the voltammetric data.

Altering the Coordination of Iron Porphyrins by Ionic Liquid Nanodomains in Mixed Solvent Systems.

The solvent environment around iron porphyrin complexes was examined using mixed molecular/RTIL (room temperature ionic liquid) solutions. The formation of nanodomains in these solutions provides different solvation environments for substrates that could have significant impact on their chemical reactivity. Iron porphyrins (Fe(P)), whose properties are sensitive to solvent and ligation changes, were used to probe the molecular/RTIL environment.

Redox and Spectroscopic Properties of Iron Porphyrin Nitroxyl in the Presence of Weak Acids.

The spectroelectrochemistry and voltammetry of Fe(OEP) (NO) in the presence of substituted phenols was studied. Cyclic voltammetry showed that two closely spaced waves were observed for the reduction of Fe(OEP) (NO) in the presence of substituted phenols. The first wave was a single electron reduction under voltammetric conditions.

X-ray Structure and Properties of the Ferrous Octaethylporphyrin Nitroxyl Complex.

The preparation and characterization of the iron octaethylporphyrin nitroxyl ion, [Fe(OEP)(NO)(-)], is reported. The complex was synthesized by the one-electron reduction of Fe(OEP)(NO) using anthracenide as the reducing agent. The compound was isolated as the potassium (2.

Spectroscopic Evidence of Nanodomains in THF/RTIL Mixtures: Spectroelectrochemical and Voltammetric Study of Nickel Porphyrins.

The presence and effect of RTIL nanodomains in molecular solvent/RTIL mixture were investigated by studying the spectroelectrochemistry and voltammetry of nickel octaethylporphyrin (Ni(OEP)) and nickel octaethylporphinone (Ni(OEPone)). Two oxidation and 2-3 reduction redox couples were observed, and the UV-visible spectra of all stable products in THF and RTIL mixtures were obtained. The E° values for the reduction couples that were studied were linearly correlated with the Gutmann acceptor number, as well as the difference in the E° values between the first two waves (ΔE12° = |E1° - E2°|).

Electrochemistry and spectroelectrochemistry of 1,4-dinitrobenzene in acetonitrile and room-temperature ionic liquids: ion-pairing effects in mixed solvents.

Room-temperature ionic liquids (RTILs) have been shown to have a significant effect on the redox potentials of compounds such as 1,4-dinitrobenzene (DNB), which can be reduced in two one-electron steps. The most noticeable effect is that the two one-electron waves in acetonitrile collapsed to a single two-electron wave in a RTIL such as butylmethyl imidazolium-BF4 (BMImBF4). In order to probe this effect over a wider range of mixed-molecular-solvent/RTIL solutions, the reduction process was studied using UV-vis spectroelectrochemistry.

In situ study of the photodegradation of carbofuran deposited on TiO2 film under UV light, using ATR-FTIR coupled to HS-MCR-ALS.

The in situ study of the photodegradation of carbofuran deposited on a TiO2 catalyst film under UV light was carried out using the ATR-FTIR technique. The data were analyzed using a Hard-Soft Multivariate Curve Resolution-Alternating Least Squares (HS-MCR-ALS) methodology. Using S-MCR-ALS, four factors were deduced from the evolving factor analysis of the data, and their concentrations and spectra were determined.

Infrared spectroelectrochemical reduction of iron porphyrin complexes.

The spectroelectrochemistry of iron porphinones and their nitrosyl complexes were examined by infrared spectroscopy, as well as ferrous octaethylporphyrin nitrosyl. With the use of d(8)-THF, the solvent was transparent down to 1200 cm(-1). For the porphinones, the reduction of the macrocycle ring could be observed by the changes in the nu(CO) band and, for the nitrosyl complex, the changes in the nitrosyl ligand were directly observable from the nu(NO) band.

Chemical and Electrochemical Studies of Cl(2)FeS(2)MS(2)FeCl(2)(n)()(-) Clusters [M = Mo (n = 2), W (n = 2), V (n = 3)].

The electrochemistry and spectroelectrochemistry of [Cl(2)FeS(2)MS(2)FeCl(2)](n)()(-) clusters (where n = 2 for M = Mo and W and n = 3 for M = V; Ia,Ib, and Ic, respectively) and the dimetal complex [Cl(2)FeS(2)MoS(2)](2)(-) (IIIa) were examined in order to characterize the structures and properties of the one-electron-reduced complexes. A stable reduction product for Ia was observed spectroelectrochemically at -1.05 V, which could be oxidized back to the starting complex.

Reactions of Hydroxylamine with Metal Porphyrins.

The reaction of hydroxylamine with a series of metal porphyrins was examined in methanol/chloroform media. The reductive nitrosylation reaction was observed for the manganese and iron porphyrins, leading to a nitrosyl complex that precipitated out of the solution in good isolatable yield (80-90%). This reaction could be used synthetically for the generation of iron and manganese porphyrin nitrosyl complexes and was particularly useful for making isotopically labeled nitrosyl complexes.