Synthesis, Characterization, and Electrochemistry of σ-Bonded Cobalt Corroles in High Oxidation States

Will, Stefan; Lex, Johann; Vogel, Emanuel; Adamian, Victor A.; Caemelbecke, Eric Van; Kadish, Karl M.

doi:10.1021/ic960484t

Cited by 106 publications

(97 citation statements)

References 58 publications

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“…[25] The electronic structures of Co(IsoC)Ph and Co(Cor)Ph appear to be of particular interest. [26,27] First, the electron spin-density profiles (Figure 2) are qualitatively different from those found in the Mn and Fe complexes. Thus, the corrole [27] or isocorrole ligand in the cobalt complexes carries large amounts of majority spin; indeed, the single unpaired electron spin appears to be roughly evenly distributed between the Co center and the macrocycle in these complexes as a result of a Co(d π )Ϫmacrocycle(π) orbital interaction.…”

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confidence: 82%

Electronic Structure of Transition Metal−Isocorrole Complexes: A First Quantum Chemical Study

2004

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Keywords: Calculations / Corrole / Isocorrole / Non-innocent ligands / Radicals / Transition metals DFT calculations indicate that the broad electronic-structural features of metalloisocorroles are rather similar to those of analogous metallocorroles. Thus, like their corrole analogues, many metalloisocorroles feature substantially non-innocent ligands. Another key point is that both corroles and isocorroles can exhibit at least two kinds of radical character, a 2 and b 1 . However, corrole and isocorrole derivatives also differ significantly in a few ways: for example, the S = 1/2 CoPh complexes of corrole and isocorrole exhibit ground states of different symmetries ( 2 AЈЈ and 2 AЈ, respectively, inCompared with the current explosion of research on corrole derivatives, [1] the chemistry of isocorrole derivatives has remained essentially unexplored since their initial synthesis and characterization by Vogel and co-workers in 1997.[2] In this context, we chose to map out the broad electronicstructural features of prototype isocorrole first-row transition-metal complexes, using density functional theory (PW91/TZP) calculations as the key tool.[3Ϫ7] While chiefly of interest to porphyrin chemists, we were gratified to find that the results impinge on a range of issues of broader interest. For example, we believe that the findings deepen our understanding of the electron distributions of high-valent transition-metal complexes and of the phenomenon of ligand non-innocence. Indirectly, the results also help place the electronic structures of high-valent heme protein intermediates in a broader chemical context. [8Ϫ12] Our results on Sc(IsoC), Ga(IsoC), Ni(IsoC), and Cu-(IsoC) (IsoC ϭ isocorrolato) as well as analogous results on the corresponding corrole [13] complexes provide a good starting point for our discussion. Table 1 presents selected adiabatic [14] ionization potentials and excitation energies for these complexes. The results show that the two lowest ionized states of Sc(IsoC) and Ga(IsoC) are almost degenerate, as they are for the analogous corrole derivatives, [13] which is clearly reminiscent of the behavior of porphyrin A 1u and A 2u radicals.[15] Figure 1 depicts the open-shell orbitals of [a]

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confidence: 82%

Electronic Structure of Transition Metal−Isocorrole Complexes: A First Quantum Chemical Study

2004

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“…most existing data on corroles is about the metal complexes of the electron-rich H 3 (oec), [3,5] while the complexes of 4 present the other extreme of the most electron-poor corroles up to date. Our initial anticipation was that these differences will have a larger effect on the corrole than on the metal, thus allowing a better separation of the redox processes.…”

Section: Synthesis Of the Germanium Tin And Phosphorus Corrolesmentioning

confidence: 99%

“…The most relevant examples from the first-row transition metals include complexes of electron-rich corroles with chromium(v), [3] iron(iv), [4] cobalt(iv), and even cobalt(v). [5] This phenomenon is especially surprising, since the Scheme 1. The formulae of corrin, octaethylporphyrin, octaethylcorrole, and of the metal complexes that are mentioned in the text.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Germanium, Tin, Phosphorus, Iron, and Rhodium Complexes of Tris(pentafluorophenyl)corrole, and the Utilization of the Iron and Rhodium Corroles as Cyclopropanation Catalysts

et al. 2001

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The germanium(IV), tin(IV). and phosphorus(v) complexes of tris(pentafluorophenyl)corrole were prepared and investigated by electrochemistry for elucidation of the electrochemical HOMO-LUMO gap of the corrole and the spectroscopic characteristics of the corrole pi radical cation. This information was found to be highly valuable for assigning the oxidation states in the various iron corroles that were prepared. Two iron corroles and the rhodium(I) complex of an N-substituted corrole were fully characterized by X-ray crystallography and all the transition metal corroles were examined as cyclopropanation catalysts. All iron (except the NO-ligated) and rhodium corroles are excellent catalysts for cyclopropanation of styrene, with the latter displaying superior selectivities. An investigation of the effect of the oxidation state of the metal and its ligands leads to the conclusion that for iron corroles the catalytically active form is iron(III), while all accesible oxidation states of rhodium are active.

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“…1) plays a special role, because it was one of the first examples reported in the literature [9] and, more recently, because some of its electronic and chemical properties hold particular value for researchers [10]. For example, corrole is able to coordinate a wide range of metal ions, stabilizing higher oxidation states than do the related porphyrins [11][12][13]. Furthermore, corrole is usually able to maintain a planar conformation even if fully substituted at the peripheral positions [14].…”

Section: Introductionmentioning

confidence: 99%

Photophysical Behaviour of Corrole and its Symmetrical and Unsymmetrical Dyads

Paolesse¹,

Sagone²,

Macagnano³

et al. 1999

J. Porphyrins Phthalocyanines

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The luminescence properties at room temperature and 77 K of octamethylcorrole are reported for the first time, together with the photophysical behaviour of corrole-corrole and porphyrin-corrole dyads covalently linked through the 10-position with a phenyl bridge. The photophysical properties of corrole free base are very similar to those of the porphyrin analogues, whereas the dimeric systems show luminescence bands different from those of the parent monomers, indicating an unexpectedly high degree of interaction between the chromophores. The porphyrin-corrole dyad undergoes photocatalysed ring opening of the corrole moiety to give the corresponding porphyrin-biliverdin species.

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Synthesis, Characterization, and Electrochemistry of σ-Bonded Cobalt Corroles in High Oxidation States

Cited by 106 publications

References 58 publications

Electronic Structure of Transition Metal−Isocorrole Complexes: A First Quantum Chemical Study

Electronic Structure of Transition Metal−Isocorrole Complexes: A First Quantum Chemical Study

Synthesis and Characterization of Germanium, Tin, Phosphorus, Iron, and Rhodium Complexes of Tris(pentafluorophenyl)corrole, and the Utilization of the Iron and Rhodium Corroles as Cyclopropanation Catalysts

Photophysical Behaviour of Corrole and its Symmetrical and Unsymmetrical Dyads

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