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The synthesis of a novel family of heterobinuclear cofacial biphenylene (B), anthracene (A), 9,9-dimethylxanthene (X) or dibenzofuran (O) bridged porphyrin-corrole complexes, (PCY)MCICoCl, is reported, M being either an iron(III) or manganese(III) ion. Each complex is characterized by electrochemistry, mass spectrometry, UV-vis, IR, and electron spin resonance spectroscopy.

Research has been conducted on the cofacial biscorroles and linked Co(II) porphyrins and Co(III) corroles. The synthesis and characterization of these compounds with the same face to face orientation are discussed.

The first reproducible synthetic route to a UO(sub 2)(super +) coordination complex via a two-electron oxidation of U(III) and the first structurally characterized dioxouranium(V) halide that is found to form a one-dimensional (1D) coordination polymer in the presence of potassium iodide is described. The characteristic visible-NIR bands and the infrared UO(sub 2) asymmetric stretching frequency of the resultant green pyridine solution of the salophen complex have agreed with the presence of a pentavalent uranyl species confirming the versatility of the compound as a reagent for the preparation of new uranyl(V) complexes.

Three face-to-face linked porphyrin-corrole dyads are investigated as to their electrochemistry, spectroelectrochemistry, and chloride-binding properties in dichloromethane or benzonitrile. An axial binding of one or two Cl(super -) ligands to the cobalt center of the corrole is observed for singly and doubly oxidized (PCY)H2Co, with the exact stoichiometry of the reaction depending upon the spacer size and the concentration of Cl(super -) added to solution.

Three series of cobalt(III) corroles were tested as catalysts for the electroreduction of dioxygen to water. Cyclic voltammetry and rotating ring-disk electrode voltammetry were both used to examine the catalytic activity of the cobalt complexes in acid media.

The reaction of {[U[O.sub.2][Py.sub.5][[K].sub.2-][Py.suib.2]}.sub.n] polymer is investigated. The findings expand the scope for the preparation of polymetallic assemblies involving f-elements and a rich chemistry can be anticipated from the reaction of pentavalent uranyl with different metal cations.

Abstract: This paper presents the development of a model which calculates the composition of the organic phase for a system used to remove selectively americium from a PUREX raffinate. A phenomenological approach is performed to aggregate step by step the specificities of this complex extraction system. Modeling of the influence of TEDGA is complex because experiments have shown that the water-soluble ligand TEDGA is extracted by the diamide and that its extraction is enhanced in presence of lanthanides. The formation of mixed solvates lanthanides-TEDGA-DMDOHEMA is thus taken into account. [Copyright &y& Elsevier]

Abstract: A series of heterobinuclear cofacial porphyrin–corrole dyads containing a Co(IV) corrole linked by one of four different spacers in a face-to-face arrangement with an Fe(III) or Mn(III) porphyrin have been examined as catalysts for the electroreduction of O2 to H2O and/or H2O2 when adsorbed on the surface of a graphite electrode in air-saturated aqueous solutions containing 1M HClO4. The examined compounds are represented as (PCY)MIIIClCoIVCl where P is a porphyrin dianion, C is a corrole trianion and Y is a biphenylene (B), 9,9-dimethylxanthene (X), dibenzofuran (O) or anthracene (A) spacer. The catalytic behavior of the seven investigated dyads in the two heterobimetallic (PCY)MClCoCl series of catalysts is compared on one hand to what was previously reported for related dyads with a single Co(III) corrole macrocycle linked to a free-base porphyrin with the same set of linking bridges, (PCY)H2Co, and on the other hand to dicobalt porphyrin–corrole dyads of the form (PCY)Co2 which were shown to efficiently electrocatalyze the four electron reduction of O2 at a graphite electrode in acid media. Comparisons between the four series of porphyrin–corrole dyads, (PCY)Co2, (PCY)H2Co, (PCY)FeClCoCl and (PCY)MnClCoCl, show that in all cases the biscobalt dyads catalyze O2 electroreduction at potentials more positive by an average 110mV as compared to the related series of compounds containing a Co(III) or Co(IV) corrole macrocycle linked to a free-base metalloporphyrin or a metalloporphyrin with an Fe(III) or Mn(III) central metal ion. The data indicates that the E 1/2 values where electrocatalysis is initiated is related to the initial site of electron transfer, which is the Co(III)/Co(II) porphyrin reduction process in the case of (PCY)Co2 and the Co(IV)/Co(III) corrole reduction in the case of (PCY)MnClCoCl, (PCY)FeClCoCl and (PCY)H2Co. The overall data also suggests that the catalytically active form of the biscobalt dyad in (PCY)Co2 contains a Co(II) porphyrin and a Co(IV) corrole. [Copyright &y& Elsevier]

Combined electrochemical and UV-visible spectroelectrochemical methods were utilized to elucidate the prevailing mechanisms for electroreduction of previously synthesized porphyrin-corrole dyads of the form (PCY)H2Co and (PCY)MClCoCl where M = Fe(III) or Mn(III), PC = porphyrin-corrole, and Y is a bridging group, either biphenylenyl (B), 9,9-dimethylxanthenyl (X), anthracenyl (A), or dibenzofuranyl (O). These studies were carried out in pyridine, conditions under which the cobalt(IV) corrole in (PCY)MClCoCl is immediately reduced to its Co(III) form, thus enabling direct comparisons with the free-base porphyrin dyad, (PCY)H2Co(III) under the same solution conditions. The compounds are all reduced in multiple one-electron-transfer steps, the first of which involves the M(III)/M(II) process of the porphyrin in the case of (PCY)MClCoCl and the Co(III)/Co(II) process of the corrole in the case of (PCY)H2Co. Each metal-centered redox reaction may be accompanied by the gain or loss of pyridine axial ligands, with the exact stoichiometry of the exchange process depending upon the specific combination of metal ions in the dyad, their oxidation states, and the particular spacer in the complex. Before this study was started, it was expected that the porphyrin-corrole dyads with the largest spacers, namely, O and A, would readily accommodate the formation of cobalt(III) bis-pyridine adducts because of the larger size of the cavity while dyads with the smallest B spacer would seem to have insufficient room to add even a single pyridine within the cavity, as was structurally seen in the case of (PCB)H2Co(py). This is clearly not the case, as shown in the present study. A reversible Co(III)/Co(II) reaction is seen for (PCB)MnClCoCl at -0.62 V, which when combined with spectroscopic data, leads to the assignment of (PCB)Mn(III)(py)2Co(III)(py) as the species in pyridine. The reduction of (PCB)Mn(III)(py)2Co(III)(py) to (PCB)Mn(II)(py)Co(III)(py) is accompanied on the slower spectroelectrochemical time scale by the appearance of a 603 nm band in the UV-vis spectra and is consistent with the addition of a second pyridine ligand to the Co(III)(py) unit of the dyad as one ligand is lost from the electrogenerated manganese(II) porphyrin, thus maintaining one pyridine ligand within the cavity. A different change in the coordination number is observed in the case of (PCB)FeClCoCl. Here the initial Fe(III) complex can be assigned as (PCB)Fe(III)ClCo(III)(py), which has no pyridine molecule within the cavity and the singly reduced form is characterized as (PCB)Fe(II)(py)2Co(III)(py)2, which contains two pyridine ligands inside the cavity. A following one-electron reduction of the Fe(II)/Co(III) complex then gives [(PCB)Fe(II)(py)2Co(II)]-.