An Example of O2 Binding in a Cobalt(II) Corrole System and High-Valent Cobalt−Cyano and Cobalt−Alkynyl Complexes
- 6 February 2004
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 126 (8) , 2515-2525
- https://doi.org/10.1021/ja036983s
Abstract
The novel cobalt corrolazine (Cz) complexes (TBP)8CzCoCN (1) and (TBP)8CzCo(CCSiPh3) (2) have been synthesized and examined in light of the recent intense interest regarding the role of corrole ligands in stabilizing high oxidation states. In the case of 2, the molecular structure has been determined by X-ray crystallography, revealing a short Co−C distance of 1.831(4) Å and an intermolecular π-stacking interaction between Cz ring planes, and this structure has been analyzed in regards to the electronic configuration. By a combination of spectroscopic techniques it has been shown that 1 is best described as a cobalt(III)−π-cation-radical complex, whereas 2 is likely best represented as the resonance hybrid (Cz)CoIV(CCSiPh3) ↔ (Cz+•)CoIII(CCSiPh3). The reduced cobalt(II) complex, [(TBP)8CzCoII(py)]-, has been generated in situ and shown to bind dioxygen at low temperature to give [(TBP)8CzCoIII(py)(O2)]-. For the reduced complex [(TBP)8CzCoII(py)]-, the EPR spectrum in frozen solution is indicative of a low-spin cobalt(II) complex with a dz2 ground state. Exposure of [(TBP)8CzCoII(py)]- to O2 leads to the reversible formation of the cobalt(III)−superoxo complex [(TBP)8CzCoIII(py)(O2)]-, which has been characterized by EPR spectroscopy. VT-EPR measurements show that the dioxygen adduct is stable up to T ≈ 240 K. This work is the first observation, to our knowledge, of O2 binding to a cobalt(II) corrole.Keywords
This publication has 60 references indexed in Scilit:
- Synthesis and Functionalization of meso-Aryl-Substituted CorrolesThe Journal of Organic Chemistry, 2000
- Epoxidation Catalysis by a Manganese Corrole and Isolation of an Oxomanganese(V) CorrolePublished by Wiley ,2000
- Electrochemical and Spectral Characterization of Iron Corroles in High and Low Oxidation States: First Structural Characterization of an Iron(IV) Tetrapyrrole π Cation RadicalInorganic Chemistry, 1996
- Synthesis and Electrochemistry of Iron(III) Corroles Containing a Nitrosyl Axial Ligand. Spectral Characterization of [(OEC)FeIII(NO)]n where n = 0, 1, 2, or -1 and OEC is the Trianion of 2,3,7,8,12,13,17,18-OctaethylcorroleJournal of the American Chemical Society, 1994
- Metallocorroles with Formally Tetravalent IronAngewandte Chemie International Edition in English, 1994
- First Direct Synthesis of a Corrole Ring From a Monopyrrolic Precursor. Crystal and Molecular Structure of (Triphenylphosphine)(5,10,15-triphenyl-2,3,7,8,12,13,17,18-octamethylcorrolato)cobalt(III)-DichloromethaneInorganic Chemistry, 1994
- Theory of the Spin Hamiltonian Parameters for Low Spin Cobalt(II) ComplexesCanadian Journal of Chemistry, 1975
- In vitro dechlorination of a 4,6-dichloro-Δ4,6-keto steroidBiochemistry, 1971
- Chelate Chemistry. III. Chelates of High Coordination NumberJournal of the American Chemical Society, 1965
- Electron Spin Resonance of α- and β-Cobalt Phthalocyanine1aJournal of the American Chemical Society, 1965