The chemistry and behaviour of antimony in the soil environment with comparisons to arsenic: A critical review

Multimetallic catalysis based on heterometallic complexes and clusters.

Antimony as a global dilemma: Geochemistry, mobility, fate and transport ☆

Environmental context. Antimony first attracted public attention in the mid-1990s amid claims that it was involved in Sudden Infant Death Syndrome. A substantial number of papers have now been published on the element and its behaviour in the natural environment. However, many key aspects of the environmental chemistry of antimony remain poorly understood. These include critical areas such as its ecotoxicology, its global cycling through different environmental compartments, and what chemical form it takes in different environments. More focussed research would help the situation. The present review highlights several areas of environmental antimony chemistry that urgently need to be addressed. Abstract. The objective of the present article is to present a critical overview of issues related to the current state of knowledge on the behaviour of antimony in the environment. It makes no attempt to systematically review all published data. However, it does provide a list of the main published reviews on antimony and identifies subjects where systematic reviews are needed. Areas where our knowledge is strong – and the corresponding gaps – in subjects ranging from total concentrations and speciation in the various environmental compartments, to ecotoxicity, to cycling between compartments, are discussed, along with the underlying research. Determining total antimony no longer poses a problem for most environmental samples but speciation measurements remain challenging throughout the process, from sampling to analysis. This means that the analytical tools still need to be improved but experience shows that, to be useful in practice, this should be directly driven by the requirements of laboratory and field measurements. Many different issues can be identified where further research is required, both in the laboratory and in the field, the most urgently needed studies probably being: (i) long-term spatial and temporal studies in the different environmental compartments in order to collect the data needed to establish a global biogeochemical cycle; (ii) laboratory studies of antimony interactions with potential natural binders; (iii) reliable ecotoxicological studies.

/pdf/antimony-in-the-environment-knowns-and-unknowns-4jbx9vp47h.pdf

Antimony in the environment: knowns and unknowns

Adsorption of antimony onto iron oxyhydroxides: adsorption behavior and surface structure.

Bimetallic promotion of alcohol production in CO hydrogenation and olefin hydroformylation on RhFe, PtFe, PdFe, and IrFe cluster-derived catalysts

Multiple iron atoms bridged by hydrides is a common structural feature of the active species that have been postulated in the biological and industrial reduction of N2. In this study, the reactions of an Fe(II) amide complex with pinacolborane in the presence/absence of phosphines afforded a series of hydride-supported [Fe4] and [Fe6] clusters Fe4(μ-H)4(μ3-H)2{N(SiMe3)2}2(PR3)4 (PR3 = PMe3 (2a), PMe2Ph (2b), PEt3 (2c)), Fe6(μ-H)10(μ3-H)2(PMe3)10 (3), and (η6-C7H8)Fe4(μ-H)2{μ-N(SiMe3)2}2{N(SiMe3)2}2 (4), which were characterized crystallographically and spectroscopically. Under ambient conditions, these clusters catalyzed the silylation of N2 to furnish up to 160 ± 13 equiv of N(SiMe3)3 per 2c (40 equiv per Fe atom) and 183 ± 18 equiv per 3 (31 equiv per Fe atom). With regard to the generation of the reactive species, dissociation of phosphine and hydride ligands from the [Fe4] and [Fe6] clusters was indicated, based on the results of the mass spectrometric analysis on the [Fe6] cluster, as well as the for...

[Fe4] and [Fe6] Hydride Clusters Supported by Phosphines: Synthesis, Characterization, and Application in N2 Reduction

Several types of calcium ferrite base catalysts (Ca/Fe = 0.33–3) for propylene (C3H6) combustion were prepared. Calcium ferrite catalyst with brownmillerite crystal structure provided catalytic activity for C3H6 combustion in the temperature range of 250–450 °C. The brownmillerite phase (Ca2Fe2O5) was responsible for the formation of oxygen adspecies (O2−) in the surface layer below 450 °C.

Formation of brownmillerite type calcium ferrite (Ca2Fe2O5) and catalytic properties in propylene combustion

Abiotic reduction of antimony(V) by green rust (Fe4(II)Fe2(III)(OH)12SO4 · 3H2O)

Green rusts (GRs), which are mixed ferrous/ferric hydroxides, occur in many suboxic soils and sediments and are thought to play an important role in the fate and transport of many inorganic contaminants. In this study, the interaction of Sb with sulfate GR (GRSO4) was investigated using multitechnique approaches such as X-ray absorption fine structure (XAFS), XRD, and BET analyses. XANES analyses show that the oxidation states of Sb(V) sorbed on GRSO4 is dominantly Sb(V), suggesting that GRSO4 does not work as a strong reductant in the system of the present study. The sorption experiment EXAFS, and XRD results suggested that there are two bonding modes for Sb(V) sorption on GRSO4, (i) the sorption to edge sites with inner-sphere complex and (ii) to interlayer surface with outer-sphere complex. In addition, it was found that fraction (i) is dominant for Sb(V) sorption on GRSO4. The transformation of "metastable" GRSO4 was inhibited by the presence of Sb(V). The transformed products of GRSO4, such as magnetite and Fe(OH)2, have larger surface areas and higher capacities as adsorbent for Sb(V) than GRSO4, and the fraction of the transformed product largely affectsthe distribution of Sb between water and solid, a mixture of GRSO4, magnetite, and Fe(OH)2.

Yoichi Sakai

Papers

Bimetallic promotion of alcohol production in CO hydrogenation and olefin hydroformylation on RhFe, PtFe, PdFe, and IrFe cluster-derived catalysts

[Fe4] and [Fe6] Hydride Clusters Supported by Phosphines: Synthesis, Characterization, and Application in N2 Reduction

Formation of brownmillerite type calcium ferrite (Ca2Fe2O5) and catalytic properties in propylene combustion

Abiotic reduction of antimony(V) by green rust (Fe4(II)Fe2(III)(OH)12SO4 · 3H2O)

Interaction of synthetic sulfate green rust with antimony(V).