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Iron Porphyrin Carbenes as Catalytic Intermediates: Structures, Mössbauer and NMR Spectroscopic Properties, and Bonding
Author(s) -
Khade Rahul L.,
Fan Wenchao,
Ling Yan,
Yang Liu,
Oldfield Eric,
Zhang Yong
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201402472
Subject(s) - porphyrin , chemistry , ferrous , electrophile , mössbauer spectroscopy , catalysis , heme , photochemistry , computational chemistry , crystallography , organic chemistry , enzyme
Abstract Iron porphyrin carbenes (IPCs) are thought to be intermediates involved in the metabolism of various xenobiotics by cytochrome P450, as well as in chemical reactions catalyzed by metalloporphyrins and engineered P450s. While early work proposed IPCs to contain Fe II , more recent work invokes a double‐bond description of the iron–carbon bond, similar to that found in Fe IV porphyrin oxenes. Reported herein is the first quantum chemical investigation of IPC Mössbauer and NMR spectroscopic properties, as well as their electronic structures, together with comparisons to ferrous heme proteins and an Fe IV oxene model. The results provide the first accurate predictions of the experimental spectroscopic observables as well as the first theoretical explanation of their electrophilic nature, as deduced from experiment. The preferred resonance structure is Fe II ←{:C(X)Y} 0 and not Fe IV {C(X)Y} 2− , a result that will facilitate research on IPC reactivities in various chemical and biochemical systems.