2001
DOI: 10.1021/ic001412b
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Factors Affecting the Electronic Ground State of Low-Spin Iron(III) Porphyrin Complexes

Abstract: To determine the factors affecting the ground-state electron configuration of low-spin Fe(III) porphyrin complexes, we have examined the (1)H NMR, (13)C NMR, and EPR spectra of a series of low-spin bis-ligated Fe(III) porphyrin complexes [Fe(Por)L(2)](+/-), in which the positions of porphyrin substituents and the coordination ability of axial ligands are different. The seven porphyrins used in this study are meso-tetraalkylporphyrins (TRP: R is propyl, cyclopropyl, or isopropyl), meso-tetraphenylporphyrin (TPP… Show more

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Cited by 73 publications
(180 citation statements)
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“…[7,[81][82][83] This unique spectroscopic feature can be related to the extensive ruffling of the macrocycle, [82,[84][85][86] equatorial C-coordination, and/or axial pyridine coordination. [7] A conformational rearrangement process was detected which involves two structures differentiated by macrocyclic ruffling.…”
Section: Low-spin Organoiron(iii) N-confused Pyriporphyrinmentioning
confidence: 99%
“…[7,[81][82][83] This unique spectroscopic feature can be related to the extensive ruffling of the macrocycle, [82,[84][85][86] equatorial C-coordination, and/or axial pyridine coordination. [7] A conformational rearrangement process was detected which involves two structures differentiated by macrocyclic ruffling.…”
Section: Low-spin Organoiron(iii) N-confused Pyriporphyrinmentioning
confidence: 99%
“…[26] It should be emphasized that the meso 13 C chemical shift is also particularly useful to determine the electronic configuration. [27,28] Thus, the meso carbon signal in complexes with the (d xy ) 2 (d xz ,d yz ) 3 configuration appears more upfield than the corresponding signal in diamagnetic complexes because the 3e g orbital, which interacts with the half-occupied d π orbital has a node at the meso carbon atom. By contrast, the complexes with a (d xz ,d yz ) 4 (d xy ) 1 ground state have large spin density at the meso carbon as a result of the a 2 u -d xy interaction, exhibiting a meso carbon signal at a downfield position.…”
Section: Electronic Ground State Of Low-spin Complexesmentioning
confidence: 98%
“…Devese, igualmente, fazer alusão ao fato de que a distorção não é única, podendo se apresentar de formas variadas e, por consequência, com propriedades peculiares correspondentes a cada uma delas. 184 Em complexos modelos, uma configuração distorcida ocorre se uma das condições seguintes é satisfeita: os ligantes axiais serem, ao mesmo tempo, fracos s-doadores e fortes p-receptores, tais como tert-butil isocianeto (BuNC) e 4-cianopiridina (4-CNPy); 163,185 os anéis porfirínicos serem fortemente S 4 -distorcidos, tais como meso-tetraisopropilporfirina, meso-tetrametilquiroporfirina e mesotetraciclo-hexilporfirina. 163 Considerando-se que o bolsão do heme e a significativa influência mecânica das cadeias polipeptídicas podem funcionar nas hemoproteínas como os impedimentos estéricos nos complexos metálicos, as mudanças conformacionais das cadeias polipeptídicas, ocasionadas pela alteração de pH, poderiam ser um fator desencadeador da mudança conformacional do anel porfirínico.…”
Section: A Configuração Eletrônica Dos Grupos Heme Férricos Para Os Sunclassified