Complex Carbonates of Iron(III)

The complex carbonates of iron(III) are shown to be anionic in nature. The solutions containing these complexes show a maximum absorbance at 460 nm. The complex carbonates of iron(III), viz., (i) K₆[Fe₂(OH)₂(CO₃)₅] · H₂O, — (ii) Na₂[Fe₃O₂(OH)₃(CO₃)₂], — (iii) K[Co(NH₃)₆]₂[Fe₃(OH)₄(CO₃)₆], — (iv) K₅[Co(NH₃)₆]₃[Fe₃(OH) ₄(CO₃)₆]₂, — (v) K[Co(NH₃)₆][Fe₂(OH)₄(CO₃)₃], and (vi) NH₄[Co(NH₃)₆][Fe₂(OH)₄(CO₃)₃] are isolated and studied by thermogravimetry. The infrared spectra of these compounds are recorded and probable band assignments made. Besides, the reaction between KHCO₃ and Fe(NO₃)₃ was studied through chemical and physicochemical methods.     

新型-meso-四(4-十四氨基甲酰苯基)卟啉及其-金属（Co）配合物的合成与液晶性能

对羧基苯甲醛和吡咯经缩合反应制得meso-四(4-羧基苯基)卟啉(1); 1与氯化亚砜反应得meso-四(4-氯甲酰基苯基)卟啉(2); 2与n-十四胺反应制得meso-四(4-十四氨基甲酰苯基)卟啉(3); 3与CoC_l2经配位反应合成了meso-四(4-十四氨基甲酰苯基)卟啉钴(4)。 3和4为新化合物,其结构经U-Vis, ¹H NMR和IR表征。偏光显微镜和DSC检测结果表明： 3和4具有液晶性能。     

Oxidative Alkoxylation of Hypophosphite in Coordination Sphere of Iron(III)

The kinetics of oxidation of sodium hypophosphite with oxygen in Fe(III) alcoholic solutions is studied. At 50-90°C, hypophosphite was found to be oxidized to dialkyl phosphite (RO)₂HPO, di-, and trialkyl phosphates (RO)₂(OH)PO, (RO)₃PO. The redox potentiometry, IR, UV, EPR, Mössbauer, and ³¹P NMR spectroscopies, X-ray powder diffraction analysis, and gas-liquid chromatography were used to determine the key stages of the process: the Fe(III) reduction with hypophosphite with the formation of the phosphorus ethers and the reoxidation of Fe(II) with oxygen. The molar ratio of the products depends on the composition of the Fe(III) coordination sphere.     

Framework-Reactive Siderophore Analogs as Potential Cell-Selective Drugs. Design and Syntheses of Trimelamol-Based Iron Chelators

Currently, the role of DNA-directed alkylating agents as potential anticancer/ antimicrobial drugs is of wide interest. Most of the alkylating agents used clinically as drugs damage DNA in cells without specificity, and this can lead to undesired toxicity problems. Minimizing serum residence time by targeting the drug to select pathogens or organs might diminish the effects of nonselective reactivity. This paper describes the syntheses and preliminary studies of analogs of siderophores (microbial iron chelators) 2 and 20 that incorporate centers within the siderophore framework capable of generating potent electrophiles (iminium ions), hopefully after directed cellular recognition and uptake. Formation of N-aminals from trimelamol (3) and substituted hydroxamic acid 4 or 5was critical for the design and synthesis of the targets. In preliminary biological testing, compound 2, a trimelamol-based siderophore analog, was active against Escherichia coli X580, illustrating the therapeutic potential of this new type of siderophore-mediated drug design and delivery.     

Concomitant Carboxylate and Oxalate Formation From the Activation of CO2 by a Thorium(III) Complex

Improving our comprehension of diverse CO₂ activation pathways is of vital importance for the widespread future utilization of this abundant greenhouse gas. CO₂ activation by uranium(III) complexes is now relatively well understood, with oxo/carbonate formation predominating as CO₂ is readily reduced to CO, but isolated thorium(III) CO₂ activation is unprecedented. We show that the thorium(III) complex, [Th(Cp′′)₃] ( 1 , Cp′′={C₅H₃(SiMe₃)₂‐1,3}), reacts with CO₂ to give the mixed oxalate‐carboxylate thorium(IV) complex [{Th(Cp′′)₂[κ²‐O₂C{C₅H₃‐3,3′‐(SiMe₃)₂}]}₂(μ‐κ²:κ²‐C₂O₄)] ( 3 ). The concomitant formation of oxalate and carboxylate is unique for CO₂ activation, as in previous examples either reduction or insertion is favored to yield a single product. Therefore, thorium(III) CO₂ activation can differ from better understood uranium(III) chemistry.     

Coordination Compounds of Chromium(III), Manganese(II), and Iron(III) with Diphenyl Thiocarbazide

Complexes of chromium(III), manganese(II), iron(III) with diphenyl thiocarbazide weresynthesized.     

Characterization of a Thiolato Iron(III) Peroxy Dianion Complex

Nucleophilic oxidant: The reaction between a thiolato iron(II) complex 1 and superoxide in aprotic solvent at -90?°C yields a novel thiolato iron(III) peroxide intermediate 2, which exhibits unusually high nucleophilic reactivity. Compound 2 is an isomer of the thiolato iron(II) superoxide intermediate that is invoked in the reaction between superoxide reductase and superoxide.     

Coordination and Redox Isomerization in the Reduction of a Uranium(III) Monoarene Complex

Synthetic studies on the redox chemistry of trivalent uranium monoarene complexes were undertaken with a complex derived from the chelating tris(aryloxide)arene ligand (^Ad,MeArO)₃mes^3?. Cyclic voltammetry of [{(^Ad,MeArO)₃mes}U^III] ( 1 ) revealed a nearly reversible and chemically accessible reduction at ?2.495 V vs. Fc/Fc⁺—the first electrochemical evidence for a formally divalent uranium complex. Chemical reduction of 1 indicates that reduction induces coordination and redox isomerization to form a uranium(IV) hydride, and addition of a crown ether results in hydride insertion into the coordinated arene to afford uranium(IV) complexes. This stoichiometric reaction sequence provides structural insight into the mechanism of arene functionalization at diuranium inverted sandwich complexes.     

The (Bio)Chemistry of Non-Transferrin-Bound Iron

In healthy individuals, virtually all blood plasma iron is bound by transferrin. However, in several diseases and clinical conditions, hazardous non-transferrin-bound iron (NTBI) species occur. NTBI represents a potentially toxic iron form, being a direct cause of oxidative stress in the circulating compartment and tissue iron loading. The accumulation of these species can cause cellular damage in several organs, namely, the liver, spleen, and heart. Despite its pathophysiological relevance, the chemical nature of NTBI remains elusive. This has precluded its use as a clinical biochemical marker and the development of targeted therapies. Herein, we make a critical assessment of the current knowledge of NTBI speciation. The currently accepted hypotheses suggest that NTBI is mostly iron bound to citric acid and iron bound to serum albumin, but the chemistry of this system remains fuzzy. We explore the complex chemistry of iron complexation by citric acid and its implications towards NTBI reactivity. Further, the ability of albumin to bind iron is revised and the role of protein post-translational modifications on iron binding is discussed. The characterization of the NTBI species structure may be the starting point for the development of a standardized analytical assay, the better understanding of these species’ reactivity or the identification of NTBI uptake mechanisms by different cell types, and finally, to the development of new therapies.     

Coordination Chemistry and Analytical Methods of Metal Separation

Methods used for the separation of metals and based on the reactions of formation and distribution of neutral metal complexes in two-phase liquid systems are considered.     

Synthesis and Characterization of a Novel Phenol‐tailed Porphyrin Ligand and Its Iron(III) Complex

The phenol‐tailed porphyrin ligand, H₃L was synthesized as a model compound for catalases. H₃L and its corresponding iron complex [Fe(L)] were synthesized by using the precursor, 5‐(8‐ethoxycarbonyl‐1‐naphthyl)‐10, 15, 20‐triphenyl porphyrin (ENTPP). They were characterized by ¹H NMR spectroscopy, mass spectrometry, X‐ray crystallography, and cyclic voltammetry. All the results have confirmed that the phenol group is covalently attached to the porphyrin. In the iron complex, phenolate oxygen is coordinated to iron(III) as the fifth ligand, leading to the five‐coordinate high‐spin iron(III) species.     

Preparation and study of new Complex Halogeno Acids of Iron(III)

The preparation of three simple and mixed halogeno acids of iron(III) is reported, and some physical and chemical properties as well as their I.R.-spectra are described.     

铁-荧光镓极谱络合吸附波的研究

在 p H6.1 0的 0 .1 mol/L ( CH2 ) 6 N4-HCl底液中 ,用单扫示波极谱法可获得铁( ) -荧光镓体系灵敏的络合吸附波。在 1 .0× 1 0 - 7～ 7.0× 1 0 - 6 mol/L范围内 ,铁浓度与波高呈线性关系 ,检测限达 7.0× 1 0 - 8mol/L,已成功地应用于金属镁粉中的铁和铝的测定 ,并测得电活性络合物的组成为铁∶荧光镓 =1∶ 1 ,条件形成常数β=3 .2× 1 0 4,表面电极反应速率常数 ks为 2 .9s- 1 。