Spectroscopic and theoretical description of the electronic structure of S = 3/2 iron-nitrosyl complexes and their relation to O[sub 2] activation by non-heme iron enzyme active sites

Journal Article · Wed Jan 18 00:00:00 EST 1995 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00107a015· OSTI ID:6628801

Brown, C A; Pavlosky, M A; Westre, T E; Zhang, Y; Hedman, B; Hodgson, K O; Solomon, E I ^[1]

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1. Stanford Univ., CA (United States)

NO forms reversible complexes with non-heme ferrous enzymes and model complexes which exhibit unusual S = 3/2 ground states. These nitrosyl derivatives can serve as stable analogs of possible oxygen intermediates in the non-heme iron enzymes. Two complexes, Fe(Me[sub 3]TACN)(NO)(N[sub 3])[sub 2] and FeEDTA-NO, have been studied in detail using X-ray absorption, resonance Raman, absorption, magnetic circular dichroism. and electron paramagnetic resonance spectroscopies and SQUID magnetic susceptibility. These studies have been complemented by spin restricted and spin unrestricted SCF-X[Alpha]-SW electronic structure calculations. As these calculations have been strongly supported by experiment for the nitrosyl complexes, they have been extended to possible oxygen intermediates. In parallel with the Fe[sup 3+]-NO[sup [minus]] complexes, the description of the intermediate obtained involves superoxide antiferromagnetically coupled to a high spin ferric center with a strong [sigma] donation of charge from the superoxide to the iron. These studies allow spectral data on the nitrosyl complexes to be used to estimate bonding differences in possible oxygen intermediates of different non-heme iron proteins and provide insight into the activation of superoxide by coordination to the ferric center for reaction or further reduction. 75 refs., 17 figs., 9 tabs.

• OSTI ID: 6628801
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 117:2; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
IRON COMPLEXES
ABSORPTION SPECTROSCOPY
ELECTRON SPIN RESONANCE
ELECTRONIC STRUCTURE
MAGNETIC CIRCULAR DICHROISM
MAGNETIC SUSCEPTIBILITY
RAMAN SPECTROSCOPY
X-RAY SPECTROSCOPY
ORGANIC NITROGEN COMPOUNDS
ENZYMES
EXPERIMENTAL DATA
GROUND STATES
COMPLEXES
DATA
DICHROISM
ENERGY LEVELS
INFORMATION
LASER SPECTROSCOPY
MAGNETIC PROPERTIES
MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
PROTEINS
RESONANCE
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures
550200 - Biochemistry