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Iron, thiolate complexes

Figure 6 Structural units occurring in iron-thiolate complexes... Figure 6 Structural units occurring in iron-thiolate complexes...
Lee CM, Hsieh CH, Dutta A, Lee GH, Liaw WF. 2003. Oxygen binding to sulfur in nitrosylated iron—thiolate complexes relevance to the Fe-containing nitrile hydratases. JAm Chem Soc 125(38) 11492-11493. [Pg.268]

In recent years, several model complexes have been synthesized and studied to understand the properties of these complexes, for example, the influence of S- or N-ligands or NO-releasing abilities [119]. It is not always easy to determine the electronic character of the NO-ligands in nitrosyliron complexes thus, forms of NO [120], neutral NO, or NO [121] have been postulated depending on each complex. Similarly, it is difficult to determine the oxidation state of Fe therefore, these complexes are categorized in the Enemark-Feltham notation [122], where the number of rf-electrons of Fe is indicated. In studies on the nitrosylation pathway of thiolate complexes, Liaw et al. could show that the nitrosylation of complexes [Fe(SR)4] (R = Ph, Et) led to the formation of air- and light-sensitive mono-nitrosyl complexes [Fe(NO)(SR)3] in which tetrathiolate iron(+3) complexes were reduced to Fe(+2) under formation of (SR)2. Further nitrosylation by NO yields the dinitrosyl complexes [(SR)2Fe(NO)2], while nitrosylation by NO forms the neutral complex [Fe(NO)2(SR)2] and subsequently Roussin s red ester [Fe2(p-SR)2(NO)4] under reductive elimination forming (SR)2. Thus, nitrosylation of biomimetic oxidized- and reduced-form rubredoxin was mimicked [121]. Lip-pard et al. showed that dinuclear Fe-clusters are susceptible to disassembly in the presence of NO [123]. [Pg.209]

Structural models, which are synthesized to imitate features of the proposed structure of the active site. These may be used to demonstrate the chemical conditions, which allow such structures to exist, to investigate their chemical properties and to give a better understanding of the spectroscopic characteristics of the native proteins. Examples of these include the mixed carbonyl/cyano complexes of iron, used to verify the infrared spectra to the hydrogenases (Fig 7.4) (Lai et al. 1998) and the nickel-thiolate complexes which have low redox potentials like the hydrogenases (Franolic et al. 1992). [Pg.170]

Butler, A. R., Glidewell, C., Hyde, A. R., and Walton, J. C. (1985). Formation of paramagnetic mononuclear iron nitrosyl complexes from diamagnetic di- and tetranuclear iron-sulphur nitrosyls Characterization by EPR spectroscopy and study of thiolate and nitrosyl ligand exchange reactions. Polyhedron 4, 797-809. [Pg.165]

Reaction of free-base porphyrin compounds with iron(II) salts in an appropriate solvent results in loss of the two N—H protons and insertion of iron into the tetradentate porphyrin dianion ligand. Five-coordinate iron(III) porphyrin complexes (hemins), which usually have the anion of the iron(II) salt for the fifth or axial ligand, are isolated if the reaction is carried out in the presence of air. Iron(II) porphyrin complexes (hemes) can be isolated if the reaction and workup is conducted under rigorously anaerobic conditions. Typically, however, iron(II) complexes are obtained from iron(III) porphyrin complexes by reduction with dithionite, thiolate, borohydride, chromous ion, or other reducing agents. [Pg.441]

The chemistry of carbonyls of higher-valent nickel and iron has not been extensively studied, but a model thiolate complex of Ni(II) with carbon monoxide (Scheme 7) and its Fe(II) analog has been synthesized [160], The methyl deriva-... [Pg.259]

There are at least five structural types of iron-sulfide thiolate complex. The best known are... [Pg.234]

More recently three other mononuclear [Fe(SR)4]- complexes containing monodentate thiolate have been structurally defined. In these SR = SPh-,219 SEt-219 and 2,3,5,6-tetramethylben-zenethiolate.220 Sterically hindered thiolate ligands appear to stabilize the [Fe(SR)4] coordination unit and thus provide a means for the preparation by ligand exchange of the previously elusive (non-hindered) monodentate tetrathiolato iron(III) complexes. [Pg.235]

A chemistry of cobalt-sulfide-thiolate molecular clusters comparable with that of iron systems has also begun to emerge. Treatment of [Co4( -SPh)6(SPh)4]2- with HS- in acetone affords the octanuclear cluster [Co8(ji4-S)6(SPh)8]4 isolated as its Pr4N+ salt.988 In MeCN solution the complex is red-purple with intense sulfur-core charge transfer bands which obscure the Co" d-d transitions. This behaviour contrasts with that of both mono- and poly-nuclear cobalt"-thiolate complexes, which all display LMCT bands below 440 nm and have well-developed v2 and v3 features. The [Co8(/j4-S6)]4+ core sustains reversible one-electron oxidation and reduction (E]l2 = —0.54, — 1.18 V, MeCN) and chemical reduction with sodium acenaphthylenide in THF gives [Co8(/r4-... [Pg.832]

A. Peptide Model and Simple Thiolate Complexes of High-Potential Iron-Sulfur Proteins... [Pg.39]

The chemistry of iron vinylidene complexes is dominated by the electrophilicity of the carbon atom adjacent to the iron organometallic unit. While addition of water leads to an acyl complex (i.e., the reverse of the dehydration shown in equation 10), addition of an alcohol leads to a vinyl ether complex. Similarly, other iron vinyl complexes can be prepared by the addition of thiolate, hydride, or an organocuprate (Scheme 33). " The nucleophilic addition of imines gave enaminoiron intermediates that could be further elaborated into cyclic aminocarbenes. This methodology has been used to provide access to /3-lactams and ultimately penicillin analogs, and good diastereoselectivities were observed (6 1-15 1) (Scheme 34). 04 Iso, vinylidene complexes are intermediates in cyclizations of alkynyl irons with substituted ketenes, acid chlorides, and related electrophiles an example is shown (equation 11). These cyclizations led to the formation of a series of isolable and characterizable cyclic vinyl iron complexes. [Pg.2029]


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See also in sourсe #XX -- [ Pg.429 , Pg.430 , Pg.431 ]




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