52325-39-0

Upstream product

• 3193-72-4 tetraethylammonium phenylthiolate 
• 108-98-5 thiophenol 
• 19229-76-6 iron(III) 
• 13133-62-5 thiophenolate 
• 52627-89-1 tetrakis[benzenethiolato-μ3-sulphido-iron](3-) 
• 146070-05-5 1,5,9-tris-(4-mercaptobenzoyl)-1,5,9-triazacyclododecane 
• 146070-04-4 1,4,7-tris-(4-mercaptobenzoyl)-1,4,7-triazacyclononane 

Downstream Products

• 52627-89-1 tetrakis[benzenethiolato-μ3-sulphido-iron](3-) 

Relevant academic research and scientific papers

The role of Mo atoms in nitrogen fixation: Balancing substrate reduction and dihydrogen production

The core issue: Cofactors in nitrogenases transform dinitrogen into ammonia, and protons into dihydrogen (see scheme). Studies on cuboidal {Fe4S4}2+ and {MoFe3S4}3+ clusters show that Mo clusters are protonated more slowly, but have a higher affinity for binding substrates, than Mo-free clusters. These reactivities explain why the Mo-based nitrogenase is the most efficient at fixing dinitrogen rather than producing dihydrogen.

Structure and Properties of [Fe4S4{2,6-bis(acylamino)benzenethiolato-S} 4]2- and [Fe2S2{2,6-bis(acylamino)benzenethiolato-S} 4]2-: Protection of the Fe-S Bond by Double NH?S Hydrogen Bonds

Iron-sulfur clusters containing a singly or doubly NH?S hydrogen-bonded arenethiolate ligand, [Fe4S4(S-2-RCONHC6H4) 4]2- (R = CH3) t-Bu, CF3), [Fe4S4{S-2,6-(RCONH)2C6H 3}4]2-, [Fe2S2(S-2-RCONHC6H4) 4]2- (R = CH3, t-Bu, CF3), and [Fe2S2{S-2,6-(RCONH)2C6H 3}4]2-, were synthesized as models of bacterial [4Fe-4S] and plant-type [2Fe-2S] ferredoxins. The X-ray structures and IR spectra of (PPh4)2[Fe4S4{S-2,6-(CH 3-CONH)2C6H3} 4]·2CH3CN and (NEt4)2[Fe2S2{S-2,6-(t-BuCONH) 2C6H3}4] indicate that the two amide NH groups at the o,o'-positions are directed to the thiolate sulfur atom and form double NH?S hydrogen bonds. The NH?S hydrogen bond contributes to the positive shift of the redox potential of not only (Fe4S4)+/(Fe4S4) 2+ but also (Fe4S4)2+/(Fe4S4) 3+ in the [4Fe-4S] clusters as well as (Fe2S2)2+/(Fe2S2) 3+ in the [2Fe-2S] clusters. The doubly NH?S hydrogen-bonded thiolate ligand effectively prevents the ligand exchange reaction by benzenethiol because the two amide NH groups stabilize the thiolate by protection from dissociation.

Proton affinity of [Fe4S4{SCH2CH(OH)Me}4] 2- in methanol: Relevance to hydrogen bonding of Fe-S clusters in proteins

The reaction between PhS- and [Fe4S4{SCH2CH(OH)Me}4] 2- to form [Fe4S4(SPH)4]2- has been studied in methanol, and in the presence of the weak acid, [NHEt3]+. The kinetics are similar to those observed earlier for a variety of Fe-S-based clusters studied in MeCN. A major difference between the studies in the two solvents concerns the identity of the solution species. In MeCN, [NHEt3]+ is a sufficiently strong acid to convert all PhS- to PhSH. However, in MeOH, PhSH is a comparatively stronger acid and consequently PhS- is little protonated by [NHEt3]+. The rate law for the reaction in MeOH is consistent with a mechanism in which initial protonation of a thiolate ligand is followed by protonation of the cluster core (presumably a μ3-S) which labilises the terminal thiol ligand. Subsequent attack of PhS- at the vacant site thus created on one of the Fe atoms completes the first act of substitution. Analysis of the data yields pKa = 8.5 for [Fe4S3(μ-SH){SCH2CH(OH)Me}4] -. The relevance of this result to hydrogen bonding interactions of Fe-S-based clusters in proteins is discussed. The X-ray crystal structure of [NMe4]2[Fe4S4{SCH 2CH(OH)Me}4] is also reported, and the arrangement of the ligands is consistent with an extensive hydrogen bonding network between some of the hydroxyl groups.

Enhanced electrocatalytic reduction of CO2 with ternary Ni-Fe4S4 and Co-Fe4S4-based biomimetic chalcogels

Enzymes that catalytically transform small molecules such as CO, formate, or protons are naturally composed of transition metal cluster units bound into a larger superstructure. Artificial biomimetic catalysts are often modeled after the active sites but are typically molecular in nature. We present here a series of fully integrated porous materials containing Fe4S4 clusters, dubbed "biomimetic chalcogels". We examine the effect of third metal cations on the electrochemical and electrocatalytic properties of the chalcogels. We find that ternary biomimetic chalcogels containing Ni or Co show increased effectiveness in transformations of carbon dioxide and can be thought of as solid-state analogues of NiFe or NiFeS reaction centers in enzymes.

Protonation of the Iron-Sulfur Core in 2- (X = Cl or Br): Chemical Precedent for the Elementary Reaction of the Hydrogenases and Nitrogenases

Kinetic studies on 2- (X = Cl or Br) show that the substitution of the first halide for thiolate is catalysed by protonation of the Fe4S4 cubane core, this is the first demonstration that these cores will bind protons.

Subsite-specific reactions of a cyclotriveratrylene [4Fe-4S] cluster complex

Ligand exchange reactions are carried out exclusively at the unique iron site of a subsite-differentiated cyclotriveratrylene [4Fe-4S] cluster complex. The effect of a variety of thiolate, phenolate, bidentate, and bridging ligands on the redox potential of the subsite-differentiated [4Fe-4S] cluster complex is studied and compared with the effects of such ligands on an [Fe4S4Cl4]2- cluster. The redox potential can be modulated within the range of -1.60 to -1.80 V (vs. Fc0/+) by varying the ligand. The introduction of an electron releasing substituent shifts the redox potential to more negative values, whereas an electron withdrawing substituent has the opposite effect. A linear relationship exists between the number of substituted sites and the reduction potential of the cluster. VCH Verlagsgescllschaft mbH.

Formation, spectroscopic characterization, and solution stability of an [Fe4S4]2+ cluster derived from β-cyclodextrin dithiolate

The formation and solution properties, including stability in mixed aqueous-Me2SO media, have been investigated for an [Fe 4S4]2+ cluster derived from β-cyclodextrin (CD) dithiolate. Clusters of the type [Fe4S4(SAr) 4]2- (Ar = Ph, C6H4-3-F) are generated in Me2SO by redox reactions of [Fe4S 4(SEt)4]2- with 2 equiv of ArSSAr. An analogous reaction with the intramolecular disulfide of 6A,6 D-(3-NHCOC6H4-1-SH)2-6 A,6D-dideoxy-β-cyclodextrin (14), whose synthesis is described, affords a completely substituted cluster formulated as [Fe 4S4{β-CD-(1,3-NHCOC6H4S) 2}2]2- (15). Ligand binding is indicated by a circular dichroism spectrum and also by UV-visible and isotropically shifted 1H NMR spectra and redox behavior convincingly similar to [Fe 4S4(SPh)4]2-. One formulation of 15 is a single cluster to which two dithiolates are bound, each in bidentate coordination. With there being no proven precedent for this binding mode, we show that the cluster [Fe4S4(S2-m-xyl) 2]2- is a single cubane whose m-xylyldithiolate ligands are bound in a bidentate arrangement. This same structure type was proposed for a cluster formulated as [Fe4S4{β-CD-(1,3-SC 6H4S)2}2]2- (16; Kuroda et al. J. Am. Chem. Soc.1988, 110, 4049-4050) and reported to be water-stable. Clusters 15 and 16 are derived from similar ligands differing only in the spacer group between the thiolate binding site and the CD platform. In our search for clusters stable in aqueous or organic-aqueous mixed solvents that are potential candidates for the reconstitution of scaffold proteins implicated in cluster biogenesis, 15 is the most stable cluster that we have thus far encountered under anaerobic conditions in the absence of added ligand.

Triazacyclane-based Trithiols and Their Use in the Preparation of Site-differentiated Iron-Sulfur Clusters

The new tripodal thiol ligands 1,4,7-tris(4-mercaptobenzoyl)-1,4,7-triazacyclononane (H3L1) and 1,5,9-tris(4-mercaptobenzoyl)-1,5,9-triazacyclododecane (H3L2) have been synthesised and characterised.On reaction with iron-sulfur clust

Synthetic nickel-containing heterometal cubane-type clusters with NiFe3Q4 cores (Q = S, Se)

Reaction of the linear trinuclear Fe(III) clusters [Fe3Q4(SEt)4]3- with Ni(PPh3)4 in acetonitrile solution affords the products [NiFe3Q4(PPh3)(SEt)3]2- (Q = S (9). Se (10)) and [NiFe3Q4(SEt)4]3- (Q = S (11) Se (12)) in ca. 30% yield. The reactions involve reductive rearrangement of the initial cluster to a cuboidal fragment and capture of the nickel atom. The compounds (Tt4 N)2 [9/10) are isomorphous and contain cluster anions with the cubane-type [NiFe3Q4]1+ core units and Ni-PPh3 and Fe-SEt terminal ligation. The compound (Et4N)3[12] is isomorphous with (Et4N)3[Fe4Se4(SEt)4] and contains the same cubane unit but with all-thiolate terminal ligation and disordered Ni and Fe subsites. The dimensions of the [NiFe3Q4]1+ cores are closely similar to those of the more familiar [Fe4Q4]2+,1+ cluster cores, rendering separation of the salts of the same cation and cluster charge difficult, Collective structural, magnetic, and spectroscopic results are consistent with the simplified charge distribution [Fe3Q4]1- (S = 5/2) + Ni2+ (S = 1) and an S = 3/2 ground state that arises from antiparallel coupling of the two fragment spins. This mode of spin coupling causes oppositely signed isotropic shifts of the identical ligands at Ni and Fe subsites. Subsite-diffcrentiated cluster 9 undergoes regiospecific substitution reactions to afford products with phosphines, cyanide, and isonitrile at the Ni subsite. These reactions are often accompanied by formation of (Fe4S4(SEt)4]2-,3- minority products. Comparison of properties of the synthetic clusters and of a reconstituted NiFe3S4 species formed with Pyrococcus furiosus ferredoxin (Conover, R. C.; Park, J.-B.; Adams, M. W.; Johnson, M. K. J. Am. Chem. Soc. 1990, 112, 4562) reveals that they are isoelectronic with the same ground state. Consequently, the protein-bound species almost certainly has the cubane-type structure of the synthetic cluster, Some seven types of heterometal cubane clusters MFe3S4 (M = V, Nb, Mo, W, Re, Co. Ni) have now been prepared. Reductive rearrangement reactions are likely to provide routes to additional members of the set. several of which are good structural models fur the immediate hetcrometal coordination environment in enzymes (M = V, Mo), but none of which has as yet been shown to occur naturally.

On the molecular/solid-state boundary. A cyclic iron-sulfur cluster of nuclearity eighteen: synthesis, structure, and properties

The reaction system FeCl3:3.15Na[PhNC(O)Me]:1.78Li2S in ethanol/methanol (2:1 (v/v)) affords, after the addition of Pr4NBr and a 5-day period of reaction and crystallization, the black compound (Pr4N)6Na4Fe18S30 in 60-75% yield. When this material is very slowly crystallized from acetonitrile/ether, the solvated compound (Pr4N)6Na4Fe18S 30·14MeCN is obtained. This compound crystallizes in triclinic space group P1? with a = 16.286 (8) A?, b = 16.718 (8) A?, c = 17.902 (9) A?, α = 115.28 (3)°, β = 91.07 (4)°, xγ = 101.64 (4)°, and Z = 1. The structure was refined to R = 6.5%. The crystal structure consists of discrete Pr4N+ ions and two Na+ ions weakly associated with the cluster [Na2Fe18S30]8-, which has a remarkable and unprecedented structure. It is constructed by the fusion of 24 nonplanar Fe2S2 rhombs in edge- and corner-sharing modes such that there are 20 μ2-S, 8 μ3-S, and 2 μ4-S, every FeS4 unit is tetrahedral, and the 18 Fe atoms are essentially planar. The result is a cyclic or toroidal structure, of lateral dimensions 13.3 × 16.0 A? and a maximum thickness of ca. 3.3 A?, in which there are no terminal ligands. Two Na+ ions are bound to interior sulfur atoms of the cluster, whose framework can be considered to arise from the sequential connection of known Fe3S4 and Fe6S9 cluster cores. Alternative conceptions of cluster buildup in terms of shared Fe2S2 rhombs and FeS4 tetrahedra are presented and illustrated. The cyclic cluster is isolated from reaction solutions whose absorption spectra indicate the presence of the green linear chain polymer {[FeS2]-}n (λmax 435, 530, 618 nm). [Na2Fe18S30]8- forms brown solutions (λmax 396, 520 (sh), 600 (sh)). The cluster is mixed valence (14Fe(III) + 4Fe(II)), is antiferromagnetic with a singlet ground state, and from its Mo?ssbauer spectrum does not contain localized Fe(II) sites and thus is substantially electronically delocalized. The integrity of the cyclic structure in solution is indicated by its absorption and 23Na NMR spectra and the retention of the Mo?ssbauer spectrum of the solid compound. In Me2SO solution the cluster is unreactive to NaSPh, forms [Fe4S4(S-p-tol)4]2- with excess p-toluenethiol, and affords a mixture of [Fe4S4(SPh)4]2- (major product) and [Fe2S2(SPh)4]2- with [Fe(SPh)4]2-. From calculations at the extended-Hu?ckel level, the cluster has a quasi-band structure in which orbitals divide into at least four well-separated blocks. Certain aspects of the electronic structure are briefly considered. Cluster size and structural relationships to binary and ternary Fe-S phases place [Na2Fe18S30]8- on the boundary of molecular and solid-state compounds.