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Models for Nonheme Iron Intermediates: Structural Basis for Tuning the Spin States of Fe(TPA) Complexes
- Source :
- Journal of the American Chemical Society. 119:4197-4205
- Publication Year :
- 1997
- Publisher :
- American Chemical Society (ACS), 1997.
-
Abstract
- Our efforts to model the oxygen activation chemistry of nonheme iron enzymes have yielded transient intermediates with novel properties. These properties can be dramatically affected by the introduction of a 6-methyl substituent on the pendant pyridines of the tetradentate ligand TPA (TPA = tris(2-pyridylmethyl)amine). A series of Fe(TPA) complexes has thus been synthesized and characterized to provide the structural basis for these dramatic effects. The following complexes have been obtained: [Fe(L)(CH3CN)2](ClO4)2 (1, L = TPA; 2, L = 6-MeTPA; 3, L = 6-Me2TPA; 4, L = 6-Me3TPA) and [Fe(L)(acac)](ClO4)2 (5, L = TPA; 6, L = 5-Me3TPA; 7, L = 6-MeTPA). As indicated by 1H NMR and/or EPR, 1, 5, and 6 with no 6-methyl substituent are low spin, while complexes 2, 3, 4, and 7 with at least one 6-methyl substituent are all high spin, with higher redox potentials than their low-spin counterparts. The ligands with 6-methyl substituents thus favor a metal center with a larger ionic radius, i.e., FeII over FeIII and h...
Details
- ISSN :
- 15205126 and 00027863
- Volume :
- 119
- Database :
- OpenAIRE
- Journal :
- Journal of the American Chemical Society
- Accession number :
- edsair.doi...........be86d9e5e8a4d908bff3a18a67c1c8bc