Iron-oxo aggregates. Binuclear and tetranuclear complexes of N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopropane

Chen, Qiuhao; Lynch, John B.; Gómez‐Romero, Pedro; Ben‐Hussein, A.; Jameson, Geoffrey B.; O’Connor, Charles J.; Que, Lawrence

doi:10.1021/ic00288a022

Cited by 71 publications

(24 citation statements)

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“…In Scheme , we depict the products 1c − 3c as tetranuclear species, the structure of 3c having been crystallographically determined . Moreover, an X-ray study of the dinuclear ferric system [Fe 2 O(HPTB)(OBz)](NO 3 ) 2 , where HPTB is identical to Et-HPTB but lacks the N -ethyl groups, similarly revealed aggregation of two dinuclear units to form a tetranuclear species . We therefore assign the structures of 1c − 3c as indicated in the scheme, but recognize that the initial product of the decomposition may be dinuclear.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Studies of the Formation and Decay of Diiron(III) Peroxo Complexes in the Reaction of Diiron(II) Precursors with Dioxygen

et al. 1996

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Mechanistic studies of the reactions of three analogous alkoxo-bridged diiron(II) complexes with O(2) have been carried out. The compounds, which differ primarily in the steric accessibility of dioxygen to the diiron(II) center, form metastable &mgr;-peroxo intermediates when studied at low temperature. At ambient temperatures, these intermediates decay to form (&mgr;-oxo)polyiron(III) products. The effect of ligand steric constraints on the O(2) reactivity was investigated. When access to the diiron center was unimpeded, the reaction was first-order with respect to both [Fe(II)(2)] and [O(2)] and the activation parameters for O(2) addition were similar to those for O(2) reacting with the dioxygen transport protein hemerythrin. When the binding site was occluded, however, reduced order with respect to [O(2)] was observed and a two-step mechanism was required to explain the kinetic results. Decay of all three peroxide intermediates involves a bimolecular event, implying the formation of tetranuclear species in the transition state.

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Section: Resultsmentioning

confidence: 99%

Mechanistic Studies of the Formation and Decay of Diiron(III) Peroxo Complexes in the Reaction of Diiron(II) Precursors with Dioxygen

et al. 1996

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“…In non-heme high-spin ferric complexes, Fe(III)-Ophenolate bond lengths have a range of 1.87-1.95 Á (Magurany & Strouse, 1982;Davis et al, 1986;Heistand et al, 1982a;Lauffer et al, 1983), while Fe(lII)-N bond lengths for imidazole (or pyrazole) range from 2.10 to 2.24 Á for high-spin model compounds ; Davis et al, 1986; Gomez-Romero et Chen et al, 1988).…”

Section: Resultsmentioning

confidence: 99%

An EXAFS study of the interaction of substrate with the ferric active site of protocatechuate 3,4-dioxygenase

True¹,

Orville

Pearce

et al. 1990

Biochemistry

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X-ray crystallographic studies of the intradiol cleaving protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa have shown that the enzyme has a trigonal bipyramidal ferric active site with two histidines, two tyrosines, and a solvent molecule as ligands [Ohlendorf, D.H., Lipscomb, J.D., & Weber, P.C. (1988) Nature 336, 403-405]. Fe K-edge EXAFS studies of the spectroscopically similar protocatechuate 3,4-dioxygenase from Brevibacterium fuscum are consistent with a pentacoordinate geometry of the iron active site with 3 O/N ligands at 1.90 A and 2 O/N ligands at 2.08 A. The 2.08-A bonds are assigned to the two histidines, while the 1.90-A bonds are associated with the two tyrosines and the coordinated solvent. The short Fe-O distance for the solvent suggests that it coordinates as hydroxide rather than water. When the inhibitor terephthalate is bound to the enzyme, the XANES data indicate that the ferric site becomes 6-coordinate and the EXAFS data show a beat pattern which can only be simulated with an additional Fe-O/N interaction at 2.46 A. Together, the data suggest that the oxygens of the carboxylate group in terephthalate displace the hydroxide and chelate to the ferric site but in an asymmetric fashion. In contrast, protocatechuate 3,4-dioxygenase remains 5-coordinate upon the addition of the slow substrate homoprotocatechuic acid (HPCA). Previous EPR data have indicated that HPCA forms an iron chelate via the two hydroxyl functions.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Some crystal structures of Fe, Ni, Cu complexes containing ligand HL are known at present [18][19][20][21][22], but as far as we know, no crystal structures of cobalt complexes were reported. In this paper, the interaction with calf thymus DNA was investigated by UV absorption and fluorescent spectroscopy, as well as the DNA cleavage experiments induced by 1 are also demonstrated.…”

Section: Introductionmentioning

confidence: 98%

Synthesis, crystal structure, magnetic property and nuclease activity of a new binuclear cobat(II) complex

Tian

Liu

et al. 2007

Journal of Inorganic Biochemistry

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Iron-oxo aggregates. Binuclear and tetranuclear complexes of N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopropane

Cited by 71 publications

References 0 publications

Mechanistic Studies of the Formation and Decay of Diiron(III) Peroxo Complexes in the Reaction of Diiron(II) Precursors with Dioxygen

Mechanistic Studies of the Formation and Decay of Diiron(III) Peroxo Complexes in the Reaction of Diiron(II) Precursors with Dioxygen

An EXAFS study of the interaction of substrate with the ferric active site of protocatechuate 3,4-dioxygenase

Synthesis, crystal structure, magnetic property and nuclease activity of a new binuclear cobat(II) complex

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