Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Stability and Conformational Flexibility Using a Macrocylic Ligand
A dinucleating macrocycle, H[subscript 2]PIM, containing phenoxylimine metal-binding units has been prepared. Reaction of H[subscript 2]PIM with [Fe[subscript 2](Mes)[subscript 4]] (Mes = 2,4,6-trimethylphenyl) and sterically hindered carboxylic acids, Ph[subscript 3]CCO[subscript 2]H or ArTolCO[sub...
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| Format: | Article |
| Language: | en_US |
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American Chemical Society (ACS)
2012
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| Online Access: | http://hdl.handle.net/1721.1/74051 https://orcid.org/0000-0002-2693-4982 |
| _version_ | 1826193913943162880 |
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| author | Do, Loi Hung Lippard, Stephen J. |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Do, Loi Hung Lippard, Stephen J. |
| author_sort | Do, Loi Hung |
| collection | MIT |
| description | A dinucleating macrocycle, H[subscript 2]PIM, containing phenoxylimine metal-binding units has been prepared. Reaction of H[subscript 2]PIM with [Fe[subscript 2](Mes)[subscript 4]] (Mes = 2,4,6-trimethylphenyl) and sterically hindered carboxylic acids, Ph[subscript 3]CCO[subscript 2]H or ArTolCO[subscript 2]H (2,6-bis(p-tolyl)benzoic acid), afforded complexes [Fe[subscript 2](PIM)(Ph[subscript 3]CCO[subscript 2])[subscript 2]] (1) and [Fe[subscript 2](PIM)(Ar[subscript Tol]CO[subscript 2])[subscript 2]] (2), respectively. X-ray diffraction studies revealed that these diiron(II) complexes closely mimic the active site structures of the hydroxylase components of bacterial multicomponent monooxygenases (BMMs), particularly the syn disposition of the nitrogen donor atoms and the bridging μ-η[superscript 1]η[superscript 2] and μ-η[superscript 1]η[superscript 1] modes of the carboxylate ligands at the diiron(II) centers. Cyclic voltammograms of 1 and 2 displayed quasi-reversible redox couples at +16 and +108 mV vs ferrocene/ferrocenium, respectively. Treatment of 2 with silver perchlorate afforded a silver(I)/iron(III) heterodimetallic complex, [Fe[subscript 2](μ-OH)[subscript 2](ClO[subscript 4])[subscript 2](PIM)(Ar[superscript Tol]CO[subscript 2])Ag] (3), which was structurally and spectroscopically characterized. Complexes 1 and 2 both react rapidly with dioxygen. Oxygenation of 1 afforded a (μ-hydroxo)diiron(III) complex [Fe[subscript 2](μ-OH)(PIM)(Ph[subscript 3]CCO[subscript 2])[subscript 3]] (4), a hexa(μ-hydroxo)tetrairon(III) complex [Fe[subscript 4](μ-OH)[subscript 6](PIM)[subscript 2](Ph[subscript 3]CCO[subscript 2])[subscript 2]] (5), and an unidentified iron(III) species. Oxygenation of 2 exclusively formed di(carboxylato)diiron(III) compounds, a testimony to the role of the macrocylic ligand in preserving the dinuclear iron center under oxidizing conditions. X-ray crystallographic and [superscript 57]Fe Mössbauer spectroscopic investigations indicated that 2 reacts with dioxygen to give a mixture of (μ-oxo)diiron(III) [Fe[subscript 2](μ-O)(PIM)(Ar[superscript Tol]CO[subscript 2])[subscript 2]] (6) and di(μ-hydroxo)diiron(III) [Fe[subscript 2](μ-OH)[subscript 2](PIM)(Ar[superscript Tol]CO[subscript 2])[subscript 2]] (7) units in the same crystal lattice. Compounds 6 and 7 spontaneously convert to a tetrairon(III) complex, [Fe[subscript 4](μ-OH)[subscript 6](PIM)[subscript 2](Ar[superscript Tol]CO[subscript 2])[subscript 2]] (8), when treated with excess H[subscript 2]O. |
| first_indexed | 2024-09-23T09:47:16Z |
| format | Article |
| id | mit-1721.1/74051 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T09:47:16Z |
| publishDate | 2012 |
| publisher | American Chemical Society (ACS) |
| record_format | dspace |
| spelling | mit-1721.1/740512022-09-30T16:50:41Z Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Stability and Conformational Flexibility Using a Macrocylic Ligand Do, Loi Hung Lippard, Stephen J. Massachusetts Institute of Technology. Department of Chemistry Lippard, Stephen J. Do, Loi Hung Lippard, Stephen J. A dinucleating macrocycle, H[subscript 2]PIM, containing phenoxylimine metal-binding units has been prepared. Reaction of H[subscript 2]PIM with [Fe[subscript 2](Mes)[subscript 4]] (Mes = 2,4,6-trimethylphenyl) and sterically hindered carboxylic acids, Ph[subscript 3]CCO[subscript 2]H or ArTolCO[subscript 2]H (2,6-bis(p-tolyl)benzoic acid), afforded complexes [Fe[subscript 2](PIM)(Ph[subscript 3]CCO[subscript 2])[subscript 2]] (1) and [Fe[subscript 2](PIM)(Ar[subscript Tol]CO[subscript 2])[subscript 2]] (2), respectively. X-ray diffraction studies revealed that these diiron(II) complexes closely mimic the active site structures of the hydroxylase components of bacterial multicomponent monooxygenases (BMMs), particularly the syn disposition of the nitrogen donor atoms and the bridging μ-η[superscript 1]η[superscript 2] and μ-η[superscript 1]η[superscript 1] modes of the carboxylate ligands at the diiron(II) centers. Cyclic voltammograms of 1 and 2 displayed quasi-reversible redox couples at +16 and +108 mV vs ferrocene/ferrocenium, respectively. Treatment of 2 with silver perchlorate afforded a silver(I)/iron(III) heterodimetallic complex, [Fe[subscript 2](μ-OH)[subscript 2](ClO[subscript 4])[subscript 2](PIM)(Ar[superscript Tol]CO[subscript 2])Ag] (3), which was structurally and spectroscopically characterized. Complexes 1 and 2 both react rapidly with dioxygen. Oxygenation of 1 afforded a (μ-hydroxo)diiron(III) complex [Fe[subscript 2](μ-OH)(PIM)(Ph[subscript 3]CCO[subscript 2])[subscript 3]] (4), a hexa(μ-hydroxo)tetrairon(III) complex [Fe[subscript 4](μ-OH)[subscript 6](PIM)[subscript 2](Ph[subscript 3]CCO[subscript 2])[subscript 2]] (5), and an unidentified iron(III) species. Oxygenation of 2 exclusively formed di(carboxylato)diiron(III) compounds, a testimony to the role of the macrocylic ligand in preserving the dinuclear iron center under oxidizing conditions. X-ray crystallographic and [superscript 57]Fe Mössbauer spectroscopic investigations indicated that 2 reacts with dioxygen to give a mixture of (μ-oxo)diiron(III) [Fe[subscript 2](μ-O)(PIM)(Ar[superscript Tol]CO[subscript 2])[subscript 2]] (6) and di(μ-hydroxo)diiron(III) [Fe[subscript 2](μ-OH)[subscript 2](PIM)(Ar[superscript Tol]CO[subscript 2])[subscript 2]] (7) units in the same crystal lattice. Compounds 6 and 7 spontaneously convert to a tetrairon(III) complex, [Fe[subscript 4](μ-OH)[subscript 6](PIM)[subscript 2](Ar[superscript Tol]CO[subscript 2])[subscript 2]] (8), when treated with excess H[subscript 2]O. National Institute of General Medical Sciences (U.S.) (Grant GM032134) 2012-10-17T18:37:11Z 2012-10-17T18:37:11Z 2011-06 2011-03 Article http://purl.org/eprint/type/JournalArticle 0002-7863 1520-5126 http://hdl.handle.net/1721.1/74051 Do, Loi H., and Stephen J. Lippard. “Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Structural Stability and Conformational Flexibility Using a Macrocylic Ligand Framework.” Journal of the American Chemical Society 133.27 (2011): 10568–10581. https://orcid.org/0000-0002-2693-4982 en_US http://dx.doi.org/ 10.1021/ja2021312 Journal of the American Chemical Society Creative Commons Attribution-Noncommercial-Share Alike 3.0 http://creativecommons.org/licenses/by-nc-sa/3.0/ application/pdf American Chemical Society (ACS) Prof. Lippard via Erja Kajosalo |
| spellingShingle | Do, Loi Hung Lippard, Stephen J. Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Stability and Conformational Flexibility Using a Macrocylic Ligand |
| title | Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Stability and Conformational Flexibility Using a Macrocylic Ligand |
| title_full | Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Stability and Conformational Flexibility Using a Macrocylic Ligand |
| title_fullStr | Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Stability and Conformational Flexibility Using a Macrocylic Ligand |
| title_full_unstemmed | Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Stability and Conformational Flexibility Using a Macrocylic Ligand |
| title_short | Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Stability and Conformational Flexibility Using a Macrocylic Ligand |
| title_sort | toward functional carboxylate bridged diiron protein mimics achieving stability and conformational flexibility using a macrocylic ligand |
| url | http://hdl.handle.net/1721.1/74051 https://orcid.org/0000-0002-2693-4982 |
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