Synthesis and solid-state molecular structures of nitrosoalkane complexes of iron porphyrins containing methanol, pyridine, and 1-methylimidazole ligands

Sohl, Christal D.; Lee, Jonghyuk; Alguindigue, Susan S.; Khan, Masood A.; Richter‐Addo, George B.

doi:10.1016/j.jinorgbio.2004.04.008

Cited by 18 publications

(11 citation statements)

References 32 publications

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“…The C-N-O plane of the PhNO ligand bisects adjacent porphyrin N atoms, and the axial ligands are essentially mutually perpendicular. Similar axial ligand orientations have been observed previously for (OEP)Fe(i-PrNO)(py), 53 (por)Fe(i-PrNO)-(1-MeIm) (por = TPP, TTP), 53 and (TPP)Fe(PhNO) 2 , 54 although parallel (or near-parallel) orientations are present in the crystal structures of (OEP)Fe(i-PrNO)(1-MeIm), 53 and related complexes. 16 Based on the products formed from the reactions of the NONOate compounds with 1-MeIm (top of Scheme 1; path A), we propose the initial binding of 1-MeIm trans to the NONOate group would likely need to be coincident with a bidentate-to-monodentate binding shift of the NONOate group, analogous to the products of eqn (4).…”

Section: Reactivitysupporting

confidence: 87%

Six-coordinate ferric porphyrins containing bidentate N-t-butyl-N-nitrosohydroxylaminato ligands: structure, magnetism, IR spectroelectrochemisty, and reactivity

Christian

Dalal

et al. 2015

Dalton Trans.

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NONOates (diazeniumdiolates) containing the [X{N2O2}](-) functional group are frequently employed as nitric oxide (NO) donors in biology, and some NONOates have been shown to bind to metalloenzymes. We report the preparation, crystal structures, detailed magnetic behavior, redox properties, and reactivities of the first isolable alkyl C-NONOate complexes of heme models, namely (OEP)Fe(η(2)-ON(t-Bu)NO) (1) and (TPP)Fe(η(2)-ON(t-Bu)NO) (2) (OEP = octaethylporphyrinato dianion, TPP = tetraphenylporphyrinato dianion). The compounds display the unusual NONOate O,O-bidentate binding mode for porphyrins, resulting in significant apical Fe displacements (+0.60 Å for 1, and +0.69 Å for 2) towards the axial ligands. Magnetic susceptibility and magnetization measurements made from 1.8-300 K at magnetic fields from 0.02 to 5 T, yielded magnetic moments of 5.976 and 5.974 Bohr magnetons for 1 and 2, respectively, clearly identifying them as high-spin (S = 5/2) ferric compounds. Variable-frequency (9.4 GHz and 34.5 GHz) EPR measurements, coupled with computer simulations, confirmed the magnetization results and yielded more precise values for the spin Hamiltonian parameters: g(avg) = 2.00 ± 0.03, |D| = 3.89 ± 0.09 cm(-1), and E/D = 0.07 ± 0.01 for both compounds, where D and E are the axial and rhombic zero-field splittings. IR spectroelectrochemistry studies reveal that the first oxidations of these compounds occur at the porphyrin macrocycles and not at the Fe-NONOate moieties. Reactions of 1 and 2 with a histidine mimic (1-methylimidazole) generate RNO and NO, both of which may bind to the metal center if sterics allow, as shown by a comparative study with the Cupferron complex (T(p-OMe)PP)Fe(η(2)-ON(Ph)NO). Protonation of 1 and 2 yields N2O as a gaseous product, presumably from the initial generation of HNO that dimerizes to the observed N2O product.

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Section: Reactivitysupporting

confidence: 87%

Six-coordinate ferric porphyrins containing bidentate N-t-butyl-N-nitrosohydroxylaminato ligands: structure, magnetism, IR spectroelectrochemisty, and reactivity

Christian

Dalal

et al. 2015

Dalton Trans.

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“…They subsequently reported the first crystallographical characterization of an RNO model heme complex, (TTP)Fe( i PrNO)( i PrNH 2 ) [120]. More recently, the group of Richter-Addo has published a series of papers concerning Fe- [121,122] Ru- [123,124], and Os-porphyrin adducts [125,126] of alkylnitroso compounds.…”

Section: Rno and Hno Complexes Of Heme Proteins And Metalloporphyrinsmentioning

confidence: 99%

Coordination chemistry of the HNO ligand with hemes and synthetic coordination complexes

Farmer

Sulc

2005

Journal of Inorganic Biochemistry

138

179

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“…The hydrolysis of M7 to M6 would be expected to yield the released nitrogen as hydroxylamine; however, this has not been demonstrated. M7 has not been observed in the ex vivo experiments, but oximes and their tautomeric nitrosoalkanes are isoelectronic with O 2 and bind strongly to heme iron (Sohl et al, 2004), so they might be difficult to extract and detect.…”

Section: Discussionmentioning

confidence: 95%

Preclinical Evaluation of the Metabolism and Disposition of RRx-001, a Novel Investigative Anticancer Agent

et al. 2012

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Synthesis and solid-state molecular structures of nitrosoalkane complexes of iron porphyrins containing methanol, pyridine, and 1-methylimidazole ligands

Cited by 18 publications

References 32 publications

Six-coordinate ferric porphyrins containing bidentate N-t-butyl-N-nitrosohydroxylaminato ligands: structure, magnetism, IR spectroelectrochemisty, and reactivity

Six-coordinate ferric porphyrins containing bidentate N-t-butyl-N-nitrosohydroxylaminato ligands: structure, magnetism, IR spectroelectrochemisty, and reactivity

Coordination chemistry of the HNO ligand with hemes and synthetic coordination complexes

Preclinical Evaluation of the Metabolism and Disposition of RRx-001, a Novel Investigative Anticancer Agent

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