http://www.cnr.it/ontology/cnr/individuo/prodotto/ID33328
Probing the Compound I-Like Reactivity of a Bare High-Valent Oxo Iron Porphyrin Complex: The Oxidation of Tertiary Amines (Articolo in rivista)
- Type
- Label
- Probing the Compound I-Like Reactivity of a Bare High-Valent Oxo Iron Porphyrin Complex: The Oxidation of Tertiary Amines (Articolo in rivista) (literal)
- Anno
- 2008-01-01T00:00:00+01:00 (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
- 10.1021/ja077286t (literal)
- Alternative label
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- Chiavarino B.; Cipollini R.; Crestoni M.E.; Fornarini S.; Lanucara F.; Lapi A. (literal)
- Pagina inizio
- Pagina fine
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
- Rivista
- Note
- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- Dipartimento di Chimica e Tecnologia delle Sostanze Biologicamente Attive, Universita` di Roma
\"La Sapienza\"
Dipartimento di Chimica Universita` di Roma \"La Sapienza\"
IstitutoCNR di Metodologie Chimiche-IMC, Sezione Meccanismi di Reazione (literal)
- Titolo
- Probing the Compound I-Like Reactivity of a Bare High-Valent Oxo Iron Porphyrin Complex: The Oxidation of Tertiary Amines (literal)
- Abstract
- The mechanisms of oxidative N-dealkylation of amines by heme enzymes including peroxidases
and cytochromes P450 and by functional models for the active Compound I species have long been studied. A debated issue has concerned in particular the character of the primary step initiating the oxidation sequence, either a hydrogen atom transfer (HAT) or an electron transfer (ET) event, facing problems such as the possible contribution of multiple oxidants and complex environmental effects. In the present study, an oxo iron(IV) porphyrin radical cation intermediate 1, [(TPFPP)¥+FeIVdO]+ (TPFPP ) meso-tetrakis (pentafluorophenyl)porphinato dianion), functional model of Compound I, has been produced as a bare species. The gas-phase reaction with amines (A) studied by ESI-FT-ICR mass spectrometry has revealed for the first time the elementary steps and the ionic intermediates involved in the oxidative activation. Ionic
products are formed involving ET (A¥+, the amine radical cation), formal hydride transfer (HT) from the amine ([A(sH)]+, an iminium ion), and oxygen atom transfer (OAT) to the amine (A(O), likely a carbinolamine product), whereas an ionic product involving a net initial HAT event is never observed. The reaction appears to be initiated by an ET event for the majority of the tested amines which included tertiary aliphatic and aromatic amines as well as a cyclic and a secondary amine. For a series of N,N-dimethylanilines the reaction efficiency for the ET activated pathways was found to correlate with the ionization energy of the amine. A stepwise pathway accounts for the CsH bond activation resulting in the formal HT product, namely a primary ET process forming A¥+, which is deprotonated at the R-CsH bond forming an N-methyl-N-arylaminomethyl radical, A(sH)¥, readily oxidized to the iminium ion, [A(sH)]+. The kinetic isotope effect (KIE) for proton transfer (PT) increases as the acidity of the amine radical cation increases and the PT reaction to the base, the ferryl group of (TPFPP)FeIV=O, approaches thermoneutrality. The ET reaction displayed by 1 with gaseousN,N-dimethylaniline finds a counterpart in the ET reactivity of FeO+, reportedly a potent oxidant in the gas phase, and with the barrierless ET process for a model (P)+FeIV=O species (where P is the porphine dianion) as found by theoretical calculations. Finally, the remarkable OAT reactivity of 1 with C6F5N(CH3)2 may hint to a mechanism along a route of diverse spin multiplicity. (literal)
- Prodotto di
- Autore CNR
Incoming links:
- Prodotto
- Autore CNR di
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#rivistaDi
