Heterobimetallic Complexes of Cobalt(IV) Porphyrin−Corrole Dyads. Synthesis, Physicochemical Properties, and X-ray Structural Characterization

Abstract

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)MClCoCl, is reported, M being either an iron(III) or manganese(III) ion. Each complex was characterized by electrochemistry, mass spectrometry, UV-vis, IR, and electron spin resonance spectroscopy. Unlike previously examined biscobalt porphyrin-corrole dyads, the cobalt ion of the corrole moiety is present in a high-valence +4 oxidation state, as proven by electrochemistry, spectroelectrochemistry, and an X-ray diffraction study of (PCB)FeClCoCl, which shows the presence of a bound Cl- anion on the cobalt corrole. Structural data: (PCB)FeClCoCl x 0.5(C7H16) x 0.5(CH2Cl2) x 2H2O, triclinic, space group P1, a = 13.8463(3) A, b = 16.8164(5) A, c = 17.9072(6) A, alpha = 93.780(1) degrees, beta = 111.143(1) degrees, gamma = 97.463(2) degrees, Z = 2.

Role of Proton‐Coupled Electron Transfer in O—O Bond Activation

“…These results are general and may be pertinent to other redox-active macrocycles. Kadish and co-workers have shown that the selective reduction of O 2 to water 54 can be accomplished using Co 2 (III,III) biscorrole Pacman 55 and porphyrin-cor- …”

Oxygen Activation Chemistry of Pacman and Hangman Porphyrin Architectures Based on Xanthene and Dibenzofuran Spacers

“…Since a cooperative redox activity is not required from two cofacial porphyrins, the second site may be redox inactive or completely absent. Kadish et al (135) have shown that similar selectivities for the 4e À reduction of O 2 to H 2 O can be accomplished using dicobalt(III)-biscorrole Pacman (136) and porphyrin-corrole Pacman assemblies (137). Moreover, the 4e À pathway is accessible for porphyrin-corrole Pacman systems in which the porphyrin macrocycle is unmetalated (138).…”

Cobalt(IV) corroles as catalysts for the electroreduction of O2: Reactions of heterobimetallic dyads containing a face-to-face linked Fe(III) or Mn(III) porphyrin

“…All subsequent aqueous solutions were prepared with deionized water of resistivity not less than 18 MX cm. The synthesis and characterization of the heterobimetallic porphyrin-corrole complexes (PCY)MClCoCl (Y = A, B, O, X and M = Fe III , Mn III ) used in this study were reported elsewhere [34,35].…”

“…These results suggest that the cobalt porphyrin macrocycle not present in (BCY)Co 2 or (PCY)H 2 Co plays a key role in the initial stage of O 2 reduction. We were therefore interested in examining the catalytic activity for a similar series of recently characterized [34,35] heterobinuclear face-to-face porphyrin-corrole dyads of the form (PCY)MClCoCl (where Y = A, B, X, or O, M = Fe(III) or Mn(III)), C represents a Co(III) corrole and P an Fe(III) or Mn(III) porphyrin linked by a rigid spacer Y (Chart 1). These results are reported in the present paper and provide a clear picture as to the role of the cobalt porphyrin in the electrocatalytic process.…”