Tris(dithiocarbamato) complexes of iron(II), iron(III), and iron(IV).  Electrochemical study

Chant, R.; Hendrickson, A. R.; Martin, R. L.; Rohde, N. M.

doi:10.1021/ic50150a033

Cited by 71 publications

(17 citation statements)

References 36 publications

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“…This exceptional trend of smaller magnetic moments and more positive redox potentials has been found for the derivatives with phenyl substituent such as N, TV-diphenyl, jV-methyl-TV-phenyl, and 7V-ethyl-7V-phenyl derivatives. The withdrawal of π electrons by the aryl group was suggested as the cause of harder oxidation (or easier reduction) and lower magnetic moment of the complex [28]. In the present study, an exception to the approximate linear relationship between the logarithm of the rate constant and the redox potential was found for a N,N-dibenzyl derivative.…”

Section: Methodscontrasting

confidence: 64%

“…Electrochemical studies have demonstrated that the redox potentials for dithiocarbamates of Cr(III), Mn(III), Fe(III), and Co (III) show nearly the same effects of the substituents attached to the nitrogen atoms; N, jV-dibenzyl drivatives of these metal chelates are the most reducible, the N, jV-dicyclohexyl derivatives the least reducible, and the N, 7V-diethyl derivatives the intermediate irrespective of the kinds of the metal ions [29]. In a series of iron(III) dithiocarbamates, the magnetic moments show a trend more or less parallel to the redox potentials [28]. The least reducible TV, 7V-dicyclohexyl derivative, Fe(c-Hx 2 dtc) 3 , is predominantly low-spin ( 2 T 2 ), while the highly reducible pyrrolidinyl derivative, Fe (Pyrrdtc) 3 , is typically highspin ( 6 Aj) at room temperature.…”

Section: Methodsmentioning

confidence: 97%

“…These rate constants seem to be closely related to the redox potentials of the chelates. In order to find the correlation between the rate constant and the redox potential, we plotted the logarithms of the rate constants against the half-wave potentials of the complexes measured in acetone [28] in Fig. 2, and the numerical values of the rate constants are listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

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Ortho-positronium Quenching in Benzene Solutions of Iron(III) Dithiocarbamates

et al. 1980

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Lifetimes of the long-lived component of positronium, orthopositronium (o-Ps) were measured in benzene solutions of sixcoordinate iron(III) dithiocarbamates. The lifetime decreased with increasing solute concentration. The lifetime was strongly affected by the substituent group attached to the nitrogen atom in the ligand, and was related to the redox potential of the compound; highly reducible tris(pyrrolidinyl-N-carbodithioato) iron(III), Fe(Pyrrdtc) 3 , gave the greatest rate constant, 14.9X 10' M" 1 s" 1 , whereas the least reducible of the compounds examined, tris(N, N-dicyclohexyldithiocarbamato) iron (III), Fe(c-Hx 2 dtc) 3 , gave the smallest, 4.5 X 10' M" 1 s~l. The fivecoordinate halogenobis(diethyldithiocarbamato) iron (III) complexes, which are paramagnetic and hardly reducible, were also tested for the effect on the o-Ps quenching. Unlike the six-coordinate iron(III) dithiocarbamates, they only slightly affected the o-Ps lifetime, indicating that the spin-conversion process of o-Ps quenching is much less important than the oxidation process.Positronium, which is the bound state of a positron with an electron, has attracted increasing attention from many researchers and the positron annihilation as a nuclear probe has been widely applied to the study of the chemical [ 1 -6 ], miceller [ 7 -9 ], and biological systems [10][11][12]. The variation of the intensity of the long-lived component of positronium against the inhibitor concentration in systems of organic solutions has recently been successfully explained in terms of the spur model [13][14][15]. On the other hand, the changes of the lifetime by inorganic salts have been investigated mainly in aqueous solutions and several attempts have been made to estimate the redox potential of e + /Ps couple [2,6]. In aqueous solutions, the rate constants for the reaction of o-Ps with inorganic salts have been reported to vary over a wide range; i. e., (18.0-29.0) X 10' M' 1 s" 1 for KMnO, [4,16], and nearly zero for NaCl, ZnCl 2 , KCl, etc. [17].Although the reactions of o-Ps have been comparatively well examined for simple inorganic salts, few systematic studies have been conducted on the reactions with coordination compounds. Previously, we have examined the reactions of o-Ps with various kinds of (3-diketonates in benzene, and found that the acceleration of o-Ps decay is mainly attributable to the oxidation of o-Ps by the compounds [18][19][20][21]. As an extension of our previous work, we investigated the reactions of o-Ps with a series of substituted dithiocarbamatoiron(III) complexes in benzene. As the values of the ligand field splitting parameter, Δ, of the dithiocarbamatoiron(III) complexes are close to the spin-pairing energy, the complexes show spin crossover properties, depending on the kind of the substituents in the legating dithiocarbamate. The equilibrium between the high-spin and low-spin states ( 6 A, ^ J T 2 ) may be affected by the inductive, mesomeric, and steric effects of the substituents attached to the nitrogen atom [22][23][24]. At a ...

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Section: Methodscontrasting

confidence: 64%

Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

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Ortho-positronium Quenching in Benzene Solutions of Iron(III) Dithiocarbamates

et al. 1980

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“…The absence of any shift in redox potential with substrate suggests that the spin-state conversion for the ferric ion upon substrate binding may occur independently of redox potential. Indeed, the correlation between E mid and spin equilibrium has been predicted to be a relatively small effect (Cant et al 1975), notably less significant than inductive or substituent effects that are often observed (Sligar 1976, Fisher & Sligar 1985. Redox potentials are predominantly influenced by the binding constants to both oxidized and reduced forms of the enzyme.…”

Section: Discussionmentioning

confidence: 99%

Direct electrochemistry of human, bovine and porcine cytochrome P450c17

Johnson

Conley²,

Martin

2006

Journal of Molecular Endocrinology

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The direct electrochemistry of human, bovine and porcine cytochrome P450c17 (CYP17) has been examined on an edge-oriented pyrolytic graphite electrode. The recombinant protein was immobilized on an electrode modified with a surfactant to simulate the environment of a biological membrane, and hence physiological electron-transfer conditions. The P450 enzymes all retained 'electron-transfer' activity while immobilized at the electrode surface as assessed by the presence of catalytic signals under aerobic conditions. The redox potentials for porcine P450c17 were more positive (anodic) than both the human and bovine forms, perhaps reflecting the differences in substrate specificity for these species. In addition, these enzymes were all influenced by pH, consistent with a single proton associated with the single electron-transfer event. Ionic strength of the buffer medium also shifted the redox potentials towards positive, suggesting that electrostatic forces contribute to the protein environment required for the electron-transfer process. The effect of substrate on the redox potential for each P450c17 was measured in the presence of pregnenolone, progesterone, 17 -hydroxypregnenolone and 17 -hydroxyprogesterone. However, no influence on the redox parameters was observed.

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“…32,42 In addition, the Fe(IV)(dtc) 3 C ions may also oxidize free dtc to produce tds. 31 Bond et al 15 did not report the presence of tds ions in the spectra of their Fe(III)(dtc) 3 complexes; however, they did report low-abundance ions corresponding to [fFe R 2 dtc 3 g 2 R 4 bitt ] C2 , where (R 4 bitt C2 is the 3,5-bis(N,N-dialkyliminium)-1,2,4-trithiolane dication formed from reaction of the dtc ligands in solution with the NO C formed from NOBF 4 . In addition to the ions discussed above, Fe(III)(mepipdtc) 3 also shows an ion at m/z 177, attributed to [mepipdtc C 2H] C and Fe(III) i-pr 2 dtc 3 shows an [Fe(III) i-pr 2 dtc 3 C Li]…”

Section: 39mentioning

confidence: 99%