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Members of the monothiol glutaredoxin family and members of the BolA-like protein family have recently emerged as specific interacting partners involved in iron-sulfur protein maturation and redox regulation pathways. It is known that human mitochondrial BOLA1 and BOLA3 form [2Fe-2S] cluster-bridged dimeric heterocomplexes with the monothiol glutaredoxin GRX5. The structure and cluster coordination of the two [2Fe-2S] heterocomplexes as well as their molecular function are, however, not defined yet. Experimentally-driven structural models of the two [2Fe-2S] cluster-bridged dimeric heterocomplexes, the relative stability of the two complexes and the redox properties of the [2Fe-2S] cluster bound to these complexes are here presented on the basis of UV/vis, CD, EPR and NMR spectroscopies and computational protein-protein docking. While the BOLA1-GRX5 complex coordinates a reduced, Rieske-type [2Fe-2S] 1+ cluster, an oxidized, ferredoxin-like [2Fe-2S] 2+ cluster is present in the BOLA3-GRX5 complex. The [2Fe-2S] BOLA1-GRX5 complex is preferentially formed over the [2Fe-2S] BOLA3-GRX5 complex, as a result of a higher cluster binding affinity. All these observed differences provide the first indications discriminating the molecular function of the two [2Fe-2S] heterocomplexes. [ABSTRACT FROM AUTHOR]

The geometrical, electronic, and optical properties of superhard structures tP10-FeB and I4 /acd-FeB have been investigated using different density functional theory (DFT) approaches. The geometrical and electronic properties were calculated using DFT with projector augmented wave pseudopotentials. To obtain reasonable fundamental bandgaps and optical properties, we performed post-DFT calculations by solving the Bethe-Salpeter equation (BSE) based on Green's function calculations. The absorption, reflectivity, refractivity, and photoconductivity were calculated, analyzed, and compared with results available in literature. The results of the BSE method show that the optical properties of both the tP10-FeB and I4 /acd-FeB structures demonstrate several novel characteristics, implying they are potential optical materials with various applications. [ABSTRACT FROM AUTHOR]

An investigation of the active site cofactors of the molybdenum and vanadium nitrogenases (FeMoco and FeVco) was performed using high-resolution X-ray spectroscopy. Synthetic heterometallic iron–sulfur cluster models and density functional theory calculations complement the study of the MoFe and VFe holoproteins using both non-resonant and resonant X-ray emission spectroscopy. Spectroscopic data show the presence of direct iron–heterometal bonds, which are found to be weaker in FeVco. Furthermore, the interstitial carbide is found to perturb the electronic structures of the cofactors through highly covalent Fe–C bonding. The implications of these conclusions are discussed in light of the differential reactivity of the molybdenum and vanadium nitrogenases towards various substrates. Possible functional roles for both the heterometal and the interstitial carbide are detailed. [ABSTRACT FROM AUTHOR]

We have investigated the propagation of {332}<113> twins in a multilayered Ti-10Mo-xFe (x = 1–3) alloy fabricated by multi-pass hot rolling. The material contains a macroscopic Fe-graded structure (about 130 μm width) between 1 and 3 wt% Fe in the direction perpendicular to rolling. We observe strong influence of the Fe-graded structure in the twin propagation behavior. The propagation of {332}<113> twins that are nucleated in Fe-lean regions (~1 wt% Fe) is interrupted in the grain interiors at a specific Fe content, namely, about 2 wt% Fe. We ascribe this effect to the role of Fe content in solid solution on the stress for twin propagation. The interruption of twins in the grain interiors results in the development of characteristic dislocation configurations such as highly dense dislocation walls (HDDWs) associated to strain localization phenomena. The nucleation and propagation of these dislocation configurations is ascribed to the underlying plastic accommodation mechanisms of the stress field at the twin tips. We find that the crystallographic alignment of HDDWs is determined by the stress field at the twin tips and the deformation texture. The excellent plastic accommodation at the interrupted twin tips allows attaining the good ductility of the present material (total elongation of 28%). [ABSTRACT FROM PUBLISHER]

Three routes are explored to the title halide/cyanide complexes trans-Fe(CO)(NO)(X)(P((CH2)14)3P) (9c-X; X = Cl/Br/I/CN), the Fe(CO)(NO)(X) moieties of which can rotate within the diphosphine cages (ΔH‡/ΔS‡ (kcal mol−1/eu−1) 5.9/−20.4 and 7.4/−23.9 for 9c-Cl and 9c-I from variable temperature 13C NMR spectra). First, reactions of the known cationic complex trans-[Fe(CO)2(NO)(P((CH2)14)3P)]+ BF4− and Bu4N+ X− give 9c-Cl/-Br/-I/-CN (75–83%). Second, reactions of the acyclic complexes trans-Fe(CO)(NO)(X)(P((CH2)mCH=CH2)3)2 and Grubbs’ catalyst afford the tris(cycloalkenes) trans-Fe(CO)(NO)(X)(P((CH2)mCH=CH(CH2)m)3P) (m/X = 6/Cl,Br,I,CN, 7/Cl,Br, 8/Cl,Br) as mixtures of Z/E isomers (24–41%). Third, similar reactions of trans-[Fe(CO)2(NO)(P((CH2)mCH=CH2)3)2]+ BF4− and Grubbs’ catalyst afford crude trans-[Fe(CO)2(NO)P((CH2)mCH=CH(CH2)m)3P)]+ BF4− (m = 6, 8). However, the C=C hydrogenations required to consummate routes 2 and 3 are problematic. Crystal structures of 9c-Cl/-Br/-CN are determined. Although the CO/NO/X ligands are disordered, the void space within the diphosphine cages is analyzed in terms of horizontal and vertical constraints upon Fe(CO)(NO)(X) rotation and the NMR data. The molecules pack in identical motifs with parallel P–Fe–P axes, and without intermolecular impediments to rotation in the solid state. [ABSTRACT FROM AUTHOR]

A new iron(iii) complex [Fe(H2Vi)3]·py·4H2O (1) {H3Vi = violuric acid, py = pyridine} was self-assembled and characterized. In the crystal structure, adjacent [Fe(H2Vi)3] blocks are H-bonded into a complex 3D network, which was topologically classified as a pcu [alpha-Po primitive cubic] network. Importance of π-stacking interactions was also highlighted and analyzed computationally. Magnetic studies confirmed antiferromagnetic exchange coupling, while ZFCM/FCM experiments indicated an ordering temperature Tc = 50 K. Finally, magnetic hysteresis at 5 K possesses the coercive field of Bc = 69 mT. [ABSTRACT FROM AUTHOR]

Monodispersed γ-Fe2O3@SiO2 ellipsoids are prepared by the three-step approach of hydrothermal synthesis, reduction–oxidation and SiO2 coating. The magnetic field induced self-assembly processes are designed and carried out in different conditions. Influences of magnetic field strength, solvent, temperature, concentration and substrate are carefully investigated and evaluated by SEM and reflective spectra. The optimal self-assembly conditions of γ-Fe2O3@SiO2 ellipsoid ordered structures are confirmed to be dispersed in ethanol at 0.06 mol L−1 followed by evaporation on a glass substrate in a magnetic field of strength 5000 Oe at 35 °C. Finally, an air–liquid interfacial mechanism is suggested to understand the self-assembly processes. [ABSTRACT FROM AUTHOR]

Phosphate glasses are very promising materials from the application and fundamental point of view. Properties of the glasses are strongly related to the structure which may be modified by various glass constituents. In the paper density functional theory calculations of simple phosphate structural units, chains build of them and iron-phosphate clusters are presented. Influence of a position of the unit in the chain is described. Structural changes of the units due to formation of bonds between non-bridging oxygens and iron atoms in different coordinations are shown. The optimized clusters are used then to calculate theoretical Raman and Fourier transform infrared spectra. The calculated spectra are then compared to the experimental results for an iron-phosphate glass from the pyrophosphate stoichiometry region. Finally the structural features of the glass are described. [ABSTRACT FROM AUTHOR]

The present study is devoted to developing high Fe-content Fe-B-Si-Zr bulk metallic glasses (BMGs) with good soft magnetic properties and exploring their structure-property correlations. Using the atomic-cluster-plus-glue-atom model, a series of high Fe-content Fe-B-Si-Zr quaternary alloys, namely [Si-B 2 Fe 7.6 Zr 0.4 ]Fe + Fe x (x = 0, 0.5, 1, 1.5, 2, 2.5 and 3), have been derived from a basic BMG composition formula of [Si-B 2 Fe 7.6 Zr 0.4 ]Fe (Fe 71.7 B 16.7 Si 8.3 Zr 3.3 ). Our experimental results show that the critical glass formation size gradually decreases from 2.5 mm to 1 mm with increasing Fe-content. [Si–B 2 Fe 7.6 Zr 0.4 ]Fe + Fe 2.5 (Fe 76.5 B 13.8 Si 6.9 Zr 2.8 ) glassy alloys exhibit high saturation magnetization of B s ~ 1.54 T and a very low coercive force of H c ~ 0.5 A/m. The deceasing tendencies of the glass transition temperature, thermal stability, glass-forming ability and Curie temperature with increasing Fe-content in the series of alloys are discussed in view of the occurrence of micro-segregation of Fe clusters in the model structure. [ABSTRACT FROM AUTHOR]

We performed laser-heated diamond anvil cell experiments combined with state-of-the-art electron microanalysis (focused ion beam and aberration-corrected transmission electron microscopy) to study the distribution and valence of iron in Earth's lower mantle as a function of depth and composition. Our data reconcile the apparently discrepant existing dataset, by clarifying the effects of spin (high/low) and valence (ferrous/ferric) states on iron partitioning in the deep mantle. In aluminum-bearing compositions relevant to Earth's mantle, iron concentration in silicates drops above 70 GPa before increasing up to 110 GPa with a minimum at 85 GPa; it then dramatically drops in the postperovskite stability field above 116 GPa. This compositional variation should strengthen the lowermost mantle between 1,800 km depth and 2,000 km depth, and weaken it between 2,000 km depth and the D" layer. The succession of layers could dynamically decouple the mantle above 2,000 km from the lowermost mantle, and provide a rheological basis for the stabilization and nonentrainment of large low-shearvelocity provinces below that depth. [ABSTRACT FROM AUTHOR]

In this study, we investigated the correlation between the crystal planes of L 1 0 FePt and the structure disordering caused by ion irradiation. As part of the experiment, Ar ions were irradiated onto ordered L 1 0 FePt films at several angles, corresponding to different crystal planes. The efficiency of the L 1 0 FePt structure disordering depended on the areal atomic density of the crystal planes facing the ion irradiation direction. Thus, the efficiency of disordering on the (101) crystal plane, which has a lower areal atomic density, was higher than that of the (111) crystal plane, which has a higher areal atomic density. Based on the results of the dose dependence of the L 1 0 structure disordering, the disordered regions seemed to propagate from the surfaces to the bottoms of the films. [ABSTRACT FROM AUTHOR]

To understand the effect of an iron precursor on the structure and oxygen reduction activity of an Iron–Nitrogen–Carbon (Fe–N–C) catalyst, several iron precursors, FeCl 3 , FeCl 2 , Fe(C 2 H 3 O 2 ) 2 , and FeSO 4 , were mixed with polyaniline (PANI) and carbon black and then pyrolyzed at 700 °C under a nitrogen atmosphere; the obtained nonprecious metal catalysts were denoted as FeCl 3 –PANI/C, FeCl 2 –PANI/C, Fe(C 2 H 3 O 2 ) 2 –PANI/C, and Fe 2 SO 4 –PANI/C, which were compared for the activity of oxygen reduction reaction (ORR) in acidic media and characterized through X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption near-edge spectroscopy, and extended X-ray absorption fine structure. The ORR activity of the catalysts was ranked in the following order: FeCl 3 –PANI/C, FeCl 2 –PANI/C, Fe(C 2 H 3 O 2 ) 2 –PANI/C, and Fe 2 SO 4 –PANI/C, where the electron-transfer numbers were 3.99, 3.98, 3.94, and 3.83, respectively. FeCl 3 –PANI/C and FeCl 2 –PANI/C exhibited Fe–N 4 structures and Fe 3+ chelates, in which a large amount of quaternary-type nitrogen and pyrrolic-type nitrogen but a small amount of cyanide were formed in the catalysts. Fe(C 2 H 3 O 2 ) 2 –PANI/C showed that Fe–N 4 structures and Fe 2+ chelates were formed mostly in the catalyst, but showed the lowest nitrogen content among all catalysts. Fe 2 SO 4 –PANI/C was composed of FeS and Fe 2 O 3 compounds. These results indicated that iron precursors affected the carbon–nitrogen composition, iron oxidation state of iron chelate, and chelate structure of Fe–N–C catalysts, resulting in the change of the ORR activity. [ABSTRACT FROM AUTHOR]

Structural conversion of [Fe4S4] clusters into [Fe2S2] clusters has been suggested to be a fundamental process for some O2-sensing proteins. While the formation of [Fe2S2] clusters from synthetic [Fe4S4] clusters has been unprecedented, an all-ferric [Fe4S4]4+ cluster Fe4S4{N(SiMe3)2}4 (1) was found to split in the presence of pyridines, giving [Fe2S2] clusters Fe2S2{N(SiMe3)2}2(L)2 (2, L = pyridines). The structural conversion between [Fe4S4] and [Fe2S2] clusters appeared to be reversible, and the thermodynamic parameters for the equilibrium reactions between 1 + L and 2 were determined. Assembly of two [Fe2S2] clusters was also induced by chemical reductions of Fe2S2{N(SiMe3)2}2(Py)2 (Py = pyridine), and the resultant [Fe4S4] clusters [1]− and [1]2- were found to split into two [Fe2S2] clusters by oxidation with [Cp2Fe]+ in the presence of pyridine. [ABSTRACT FROM AUTHOR]

Quantum chemical calculations at the BP86 level with various basis sets (SVP, TZVPP, and TZ2P+) were carried out for the Fe(CO)4 of group-13 half-sandwich ECp* [Fe(CO)4- ECp*] ( Fe4- E) ( E = B to Tl). The chemical bonding of the Fe(CO)4- ECp* bond was analyzed with charge- and energy decomposition methods. The calculated equilibrium structures of complexes Fe4- E show that the ligands ECp* are bonded in an end-on way to the fragment Fe(CO)4 in Fe4- E with E = B to Ga. The compound Fe4-In has a distorted end-on ligand InCp*. In contrast, Fe4-Tl has a side-on bonded ligand TlCp*. The calculated bond dissociation energies (BDEs) suggest that the bond in the iron group-13 half-sandwich complexes Fe4- E decreases from Fe4-B to Fe4-Tl. Natural bond orbital (NBO) analysis of the bonding situation reveals that the Fe(CO)4← ECp* donation in Fe4- E comes from the σ lone-pair orbital of ECp*. Bonding analysis indicates that the ligand ECp* in complexes are strong σ donors and the NOCV pairs of the bonding show small π-back donation from the Fe(CO)4 to the ECp* ligands. [ABSTRACT FROM AUTHOR]

Iron(iii) meso-tartrate, a metal–organic complex, is a new anticaking agent for sodium chloride. A molecular structure in solution is proposed, based on a combination of experimental and molecular modelling results. We show that the active complex is a binuclear iron(iii) complex with two bridging meso-tartrate ligands. The iron atoms are antiferromagnetically coupled, resulting in a reduced paramagnetic nature of the solution. In solution, a water molecule coordinates to each iron atom as a sixth ligand, resulting in an octahedral symmetry around each iron atom. When the water molecule is removed, a flat and charged site is exposed, matching the charge distribution of the {100} sodium chloride crystal surface. This charge distribution is also found in the iron(iii) citrate complex, another anticaking agent. This gives a possible adsorption geometry on the crystal surface, which in turn explains the anticaking activity of the iron(iii) meso-tartrate complex. [ABSTRACT FROM AUTHOR]

Gallium(III) tetraphenylporphyrinates (TPP) containing anionic sulfur ligands have been prepared and characterized in the solid state and solution. The complexes serve as structural models for iron(III) heme sites containing sulfur coordination that otherwise prove challenging to synthesize due to the propensity for reduction to iron(II). The compounds prepared include the first well-characterized example of a trivalent metalloporphyrinate containing a terminal hydrosulfide ligand, [Ga(SH)(TPP)], as well as [Ga(SEt)(TPP)], [Ga(SPh)(TPP)], and [Ga(SSiiPr3)(TPP)]. The stability of these compounds toward reduction has permitted an investigation of their solid-state structures and electrochemistry. The structural features and reaction chemistry of the complexes in relation to their iron(III) analogs is discussed. [ABSTRACT FROM AUTHOR]

We have recently reported that the superconducting transition temperature of FeTe0.5Se0.5 flakes attached onto commercial Scotch tape can be enhanced by about 1-2 K due to a thermal-mismatch induced compressive strain. In this work, we further investigated the Scotch tape effect on structural variation of FeTe0.5Se0.5 and Fe1.05Te flakes by X-ray diffraction measurements. We show that for FeTe0.5Se0.5, the lattice constant c of taped flakes is elongated by about 0.5% at 15 K as compared with bulk crystal. Upon warming from 15 K, the lattice constant c of the taped flakes first levels off then displays negative thermal expansion followed by monotonic increase at temperatures above 100 K. For antiferromagnetic Fe1.05Te, the structural transition around 70 K is remarkably broadened by about 2 K. The present results demonstrate that the Scotch tape is a simple and effective tool to probe structure sensitive physical properties of layered materials. [ABSTRACT FROM AUTHOR]

The title complex was obtained by the reaction of (μ-SCH2CH2CH2S-μ)Fe2(CO)6with tris(p-tolyl)phosphine in the presence of the decarbonylating agent Me3NO·2H2O in CH2Cl2/MeCN solutions. The molecular structure was determined by X-ray diffraction analysis. The title complex contains a butterfly diiron dithiolate cluster with five terminal carbonyls and a tris(p-tolyl)phosphine. The phosphorus atom of tris(p-tolyl)phosphine occupies an apical position of the square-pyramidal coordination sphere of the Fe2 atom. The van der Waals’ interactions stabilize the solid state in the crystal packing. [ABSTRACT FROM PUBLISHER]

Tetraaqua bismaleato iron(II) [Fe(CHO)(HO)], (1) is a new synthetic antimicrobial agent. Thermal analysis shows that the dehydration of the compound occurs in agreement with the structure. The single crystal salt crystallizes in the triclinic space group P-1 with a = 5.171(2) Å, b = 7.309(3) Å, c = 9.731(3) Å, α = 109.15(2)°, β = 115.02(2)°, γ = 92.42(1)°, V = 313.6(3) Å and Z = 1. Three dimensional network is formed by strong intermolecular O - H ...O hydrogen bonds. Magnetic susceptibility measurements of 1 in the range 2-300 K exhibited paramagnetic behavior at high temperature. However, at low temperature, the susceptibility data showed weak antiferromagnetic interactions between the local spins. Antimicrobial activity of 1 was tested. It showed high response against gram-positive and gram-negative bacteria as well as fungi and the MIC and IC50 values ranged from 8 to 256 μg.mL and from 1.38 to 22.19 μg.mL, respectively. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We demonstrate, using first-principles calculations, that the electronic structure of FeSe1-xTex (x = 0.5) is topologically nontrivial and characterized by an odd Z2 invariant and Dirac cone type surface states, in sharp contrast to the end member FeSe (x = 0). This topological state is induced by the enhanced three-dimensionality and spin-orbit coupling due to Te substitution (compared to FeSe), and characterized by a band inversion at the Z point of the Brillouin zone, which is confirmed by our ARPES measurements. The results suggest that the surface of FeSe0.5Te0.5 may support a nontrivial superconducting channel in proximity to the bulk. [ABSTRACT FROM AUTHOR]

Three iron(III) complexes, [Fe III (Him) 2 (n-MeOhapen)]PF 6 ( 1 : n = 4, 2 : n = 5, 3 : n = 6), where Him = imidazole and n-MeOhapen = N,N ′-bis(n-methoxy-2-oxyacetophenylidene)ethylenediamine, were synthesized. Each Fe III ion was coordinated by N 4 O 2 donor atoms of equatorial n-MeOhapen and two axial Him. The saturated FeC 2 N 2 chelate ring involving the ethylenediamine moiety adopted a gauche conformation and the two phenylidene planes of [Fe III (Him) 2 (n-MeOhapen)] + were oriented opposite to the FeO 2 N 2 coordination plane. Two adjacent [Fe III (Him) 2 (4-MeOhapen)] + cations in 1 were connected via PF 6 − ions by hydrogen bonds between the imidazole group and PF 6 − to give a one-dimensional chain. Two adjacent cations in 2 were connected via hydrogen bonds between the phenylidene oxygen and imidazole atoms to form a cyclic dimer structure. Two EtOH molecules were involved in a hydrogen-bonded cyclic dimer structure in 3 . Compounds 1 and 2 showed spin crossover behavior, but 3 showed incomplete spin crossover. [ABSTRACT FROM AUTHOR]

Iron (III) phthalocyanine complexes were employed for the first time as a mild and efficient Lewis acid catalyst in the selective oxidation of cyclohexene to cyclohexane-1,2-diol. It was found that the catalyst FePcOTf shown excellent conversion and moderate selectivity relative to other iron (III) phthalocyanine complexes. The optimum conditions of the oxidation reaction catalyzed by FePcOTf/H2O2 have been researched in this paper. Iron (III) phthalocyanine triflate (1 mol %) as catalyst, hydrogen peroxide as oxidant, methanol as solvent, and a mole ratio of substrate and oxidant (H2O2) of 1:1 were used for achieving moderate yields of 1,2-diols under reflux conditions after eight hours. [ABSTRACT FROM AUTHOR]

An iron(II) complex with a cyclic tetradentate ligand containing four N-heterocyclic carbenes was synthesized and characterized by means of NMR and IR spectroscopies, as well as by single-crystal X-ray structure analysis. The iron center exhibits an octahedral coordination geometry with two acetonitrile ligands in axial positions, showing structural analogies with porphyrine-ligated iron complexes. The acetonitrile ligands can readily be substituted by other ligands, for instance, dimethyl sulfoxide, carbon monoxide, and nitric oxide. Cyclic voltammetry was used to examine the electronic properties of the synthesized compounds. [ABSTRACT FROM AUTHOR]

P/M high density pure iron with excellent magnetic properties was prepared by the combination of high density forming technology and heat treatment. The effects of sintering parameters on microstructural evolution and magnetic properties of sintered pure iron were investigated. The results showed that the grain sizes of the samples increased with increasing sintering temperature and time, facilitating the enhancement of permeability and the decrease of coercive force. When the specimens were sintered at 1450 °C for 4 h, the maximum permeability reached 10,746, and saturation induction of 1.85 T and coercive force of 50.12 A/m were achieved. [ABSTRACT FROM AUTHOR]

Effect of Fe doping on structural, optical and magnetic properties of the (In 1 − x Fe x ) 2 O 3 films (0 ⩽ x ⩽ 0.31) are investigated systematically by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), UV–Vis, Hall effect and magnetic measurements. Combining XRD, XPS and EXAFS measurements, it reveals that Fe dopant ions substitute for In 3+ sites of In 2 O 3 lattice with a mixed-valence (Fe 2+ /Fe 3+ ) in the (In 1 − x Fe x ) 2 O 3 films with low Fe concentration ( x ⩽ 0.16), while a part of Fe atoms form the precipitate of Fe metal clusters in the (In 1 − x Fe x ) 2 O 3 films with high Fe concentration ( x ⩾ 0.22). The decreased transmittance and optical band gap of films with Fe doping is ascribed to sp - d exchange interaction associated with the Fe dopants. Magnetic characterizations show that all the films display a clear room-temperature (RT) ferromagnetic behavior. The saturated magnetization ( M S ) increases monotonically with the increase of Fe concentration and reaches 85.5 emu/cm 3 for the (In 0.69 Fe 0.31 ) 2 O 3 film. However, the Hall measurements show that the carrier concentration n c decreases monotonically with Fe doping, implying that the ferromagnetism is not mediated by carriers in the (In 1 − x Fe x ) 2 O 3 films ( x ⩽ 0.16). It can be concluded that oxygen vacancies play an important role in activating the observed intrinsic RT ferromagnetism in the (In 1 − x Fe x ) 2 O 3 films ( x ⩽ 0.16). However, the larger M S in the (In 1 − x Fe x ) 2 O 3 films ( x ⩾ 0.22) should be partially due to precipitated Fe metal clusters. [ABSTRACT FROM AUTHOR]

Dinuclear iron(III) complexes, [(phenO)Fe(SO 4 )] 2 ·2CH 3 OH ( 1 ) and [(bpmapO)Fe(NO 3 )] 2 (NO 3 ) 2 ·3CH 3 OH ( 2 ) have been prepared by the reaction of phenOH/bpmapOH and FeSO 4 ·7H 2 O/Fe(NO 3 ) 3 ·9H 2 O in methanol, respectively (phenOH = N -(2-pyridylmethyl)- N ′-(2-hydroxyethyl)ethylenediamine, bpmapOH = N -(bis(2-pyridylmethyl)amino)-2-methylpropan-2-ol). Both complexes are ethoxy-bridged dinuclear species and the iron(III) ions in 1 and 2 have distorted octahedral geometries. Both complexes show strong antiferromagnetic interactions through the bridged ethoxy groups within the dimeric units. [ABSTRACT FROM AUTHOR]

Crystal structures are reported for four (2,2′-bipyridyl)(ferrocenyl)boronium derivatives, namely (2,2′-bipyridyl)(ethenyl)(ferrocenyl)boronium hexafluoridophosphate, [Fe(C5H5)(C17H15BN2)]PF6, (I b), (2,2′-bipyridyl)( tert-butylamino)(ferrocenyl)boronium bromide, [Fe(C5H5)(C19H22BN3)]Br, (II a), (2,2′-bipyridyl)(ferrocenyl)(4-methoxyphenylamino)boronium hexafluoridophosphate acetonitrile hemisolvate, [Fe(C5H5)(C22H20BN3O)]PF6·0.5CH3CN, (III b), and 1,1′-bis[(2,2′-bipyridyl)(cyanomethyl)boronium]ferrocene bis(hexafluoridophosphate), [Fe(C17H14BN3)2](PF6)2, (IV b). The asymmetric unit of (III b) contains two independent cations with very similar conformations. The B atom has a distorted tetrahedral coordination in all four structures. The cyclopentadienyl rings of (I b), (II a) and (III b) are approximately eclipsed, while a bisecting conformation is found for (IV b). The N-H groups of (II a) and (III b) are shielded by the ferrocenyl and tert-butyl or phenyl groups and are therefore not involved in hydrogen bonding. The B-N(amine) bond lengths are shortened by delocalization of π-electrons. In the cations with an amine substituent at boron, the B-N(bipyridyl) bonds are 0.035 (3) Å longer than in the cations with a methylene C atom bonded to boron. A similar lengthening of the B-N(bipyridyl) bonds is found in a survey of related cations with an oxy group attached to the B atom. [ABSTRACT FROM AUTHOR]

An attempt to control the three structural features linkage, structural dimensionality and coordination mode is presented for the combination of FeII and FeIII chlorides together with the ditopic ligand piperazine (pipz). Thermal conversion of small units like complexes into highly aggregated structures such as coordination polymers is demonstrated for the framework formation of ³∞[FeIICl2(pipz)] starting from both FeCl2 and FeCl3. Depending on the oxidation state of iron, different reaction paths and metastable products are observed. Iron(II)chloride reacts with piperazine to form the previously unknown 2-dimensional network, ²∞[Fe2IICl4(pipz)3]·pipz, which can be thermally converted into the 3-dimensional framework at elevated temperatures by release of piperazine. The use of iron(III)chloride starts with an internal redox reaction giving the divalent complex [FeIICl3(Hpipz)(pipz)] in the first step, followed by thermal conversion yielding the framework ³∞[FeIICl2(pipz)] and the salt [FeIICl3(Hpipz)(pipz)](Hpipz)Cl2. Both thermal conversion mechanisms were further investigated by in situ IR-spectroscopy, differential thermal analysis and thermogravimetry. [ABSTRACT FROM AUTHOR]

A discrete octanuclear high-spin FeII cage [Fe8 L12](BF4)16 x n(solvent) was synthesised via metal ion-directed self-assembly. The cage formation is facilitated by incorporating a relatively flexible ditopic ligand with chelating pyrazolyl-pyridine functional units. The synthesis, structure, and magnetic properties of this metallo-cage are presented. The structure and magnetic properties of an octanuclear iron(ii)-containing cage material of the type [FeII8 L12](BF4)16 is reported. [ABSTRACT FROM AUTHOR]

Knölker's iron complex is a "green" catalyst that exhibits low toxicity and is abundant in nature. Density functional theory (DFT) was used to explore the highly chemoselective nature of the catalytic hydrogenation of CH2=CHCH2CHO. An outer-sphere concerted hydrogen transfer was found to be the most reasonable kinetic route for the hydrogenation of the olefin. However, the C=C hydrogenation reaction has a high free energy barrier of 28.1 kcal/mol, requiring a high temperature to overcome. By comparison, the CH=O bond concerted hydrogen-transfer reaction catalyzed using Knölker's iron catalyst has an energy barrier of only 14.0 kcal/mol. Therefore, only the CH=O of CH2=CHCH2CHO can be hydrogenated in the presence of Knölker's catalyst at room temperature, due to kinetic domination. All computational results were in good agreement with experimental results. [ABSTRACT FROM AUTHOR]

Three new tetranuclear complexes [MnIII2CoIII2O2(L)2][ClO4]2 ( 1), [MnIII2FeIII2O2(L)2][ClO4]2 ( 2), and [MnIII2MnIII2O2(L)2][MnII(NCS)4] ( 3) have been synthesized through reactions of the mononuclear [MnIIIL] precursor with the corresponding metal perchlorate under aerobic conditions [H3L = tris(2-salicylaldimine)amine, a condensation product between tris(2-aminoethyl)amine and salicylaldehyde in a 1:3 molar ratio]. These compounds have been characterized by spectroscopic and analytical techniques including single-crystal X-ray structure analysis, electron paramagnetic resonance (EPR) spectroscopy, Mössbauer spectroscopy, and magnetic measurements. The structure of 1 consists of oxo-/phenoxo-bridged CoIII and MnIII centers in a defective double-cubane topology. The molecules of 2 and 3 have similar structures with the CoIII centers changed to FeIII centers in 2 and to MnIII centers in 3. These isostructural complexes have been scrutinized with regard to changes in distortions (distances and angles) of the metal coordination spheres. Magnetic studies indicate that 1, 2, and 3 show predominant antiferromagnetic interactions. Changes in the electronic properties concomitant with changes in the distortions in 1, 2, and 3 are analyzed in terms of magnetostructural correlations. [ABSTRACT FROM AUTHOR]

The reaction of FeCl3 with a pincer ligand, 2,6-di(1H-pyrazol-3-yl)pyridine (bppyH2), produced a mononuclear Fe(III) complex [Fe(bppyH2)Cl3] (1), which could be reduced to the corresponding Fe(II) dichloride complex [Fe(bppyH2)Cl2] (2) by suitable reducing agents such as Cp2Co or Fe powder. 1 and 2 exhibited a reversible transformation from each other with appropriate redox reagents. 1 could be utilized as a precatalyst to initiate the ring-opening polymerization of ε-caprolactone in the presence of alcohol but 2 did not work. The 1/alcohol system displayed characteristics of a well-controlled polymerization with the resulting poly(ε-caprolactone) having low molecular weight distributions, a linear tendency of molecular weight evolution with conversion, and polymer growth observed for the sequential additions of e-caprolactone monomer to the polymerization reaction. The polymerization was completely turned off by the in situ reduction of the catalytic Fe center via Cp2Co and then turned back upon the addition of [Cp2Fe]-PF6. The rate of polymerization was modified by switching in situ between the Fe(III) and Fe(II) species. [ABSTRACT FROM AUTHOR]

A study was made of the structural and magnetic properties of the FeNb alloy using X-ray diffraction, Mössbauer spectrometry at different temperatures, and ac susceptibility techniques. The alloy was obtained after 30 hours of milling in a high energy planetary mill and subsequently sintered at 700 K for 72 hours. The alloy is paramagnetic and presents the bcc-Fe and hcp-FeNb structural phases, with a mean crystallite size of 75 and 91 nm, respectively. From the magnetic measurements, it was found that the FeNb hexagonal structure exhibits: reentrant spin-glass behavior with a freezing temperature of 67 K, ferromagnetic and paramagnetic phases which coexist between 67 and 265 K, and paramagnetic behavior above 265 K. [ABSTRACT FROM AUTHOR]

The iron hydride complexes bearinga Si–H or a Ge–H functional group in a ligand [2,5-SiPh3-3,4-butylene-(η5-C4COEEt2H)]Fe(CO)2H (E = Si (4), Ge (5)) and [2,5-SiPh3-3,4-butylene-(η5-C4COSiMe2OSiMe2H)]Fe(CO)2H (6), were synthesized in the reaction of the ironacetonitrile complex [2,5-SiPh3-3,4-butylene-(η4-C4CO)]Fe(CO)2(NCCH3) (3) with Et2EH2or HSiMe2OSiMe2H. These complexes did not hydrogenate a polar unsaturatedbond in either ketones or aldehydes but did hydrogenate a nonpolarunsaturated bond in alkynes and alkenes to give alkenes and alkanesselectively. These complexes also catalyzed a transfer hydrogenationreaction from isopropyl alcohol (IPA) to alkynes and alkenes. [ABSTRACT FROM AUTHOR]

The six-coordinate FeIII-aqua complex [FeIII(dpaq)(H20)]2+ (1, dpaq is 2-[bis(pyridine-2-ylmethyl)]amino-N-quinolin-8-yl-acetamido) is an electro-catalyst for water oxidation in propylene carbonate-water mixtures. An electrochemical kinetics study has revealed that water oxidation occurs by oxidation to Fev(0)2+ followed by a reaction first order in catalyst and added water, respectively, with Ko = 0.035(4) M-1 s-1 by the single-site mechanism found previously for Ru and Ir water oxidation catalysts. Sustained water oxidation catalysis occurs at a high surface area electrode to give 02 through at least 29 turnovers over an 15 h electrolysis period with a 45% Faradaic yield and no observable decomposition of the catalyst. [ABSTRACT FROM AUTHOR]

Rotated geometry: The first example of a dinuclear iron(I)–iron(I) complex featuring a fully rotated geometry related to the active site of [Fe–Fe] hydrogenase is reported (see figure). [ABSTRACT FROM AUTHOR]

The reactions of FeCl3 with benzotriazole (btaH), 1-methylbenzotriazole (Mebta), 5,6-dimethylbenzotriazole (5,6Me2btaH) and 5-chlorobenzotriazole (5ClbtaH) were studied in non-polar solvents. The new solid complexes [FeCl3(btaH)2] (1), [FeCl3(Mebta)2] (2), [FeCl3(5,6Me2btaH)2] (3) and [FeCl3(5ClbtaH)2]·2(5ClbtaH) (4) have been isolated. The structures of the complexes have been determined by single-crystal, X-ray crystallography. The structures of 1–4 consist of mononuclear, high-spin 5-coordinate molecules; in addition, the crystal structure of 4 contains two lattice 5ClbtaH molecules per [FeCl3(5ClbtaH)2] unit. The coordinated benzotriazole molecules behave as monodentate ligands with their ligated atom being the nitrogen of the position 3 of the azole ring. The geometry at iron(III) is trigonal bipyramidal with the chlorido ligands occupying the equatorial sites. The crystal structures of the complexes are stabilized by stacking interactions and H bonds (for 1, 3 and 4 only). The new complexes were characterized by elemental analyses, magnetic susceptibilities at room temperature and spectroscopic (IR, far-IR, solid-state electronic UV/VIS/near-IR, 57Fe-Mössbauer, EPR only for complex 4) methods. All data are discussed in terms of the nature of bonding and the known structures. Complexes 1, 2 and 4 have been tested as homogeneous (MeCN) oxidation catalysts in the presence of the “green” H2O2 oxidant; they display moderate to high catalytic activity in the oxidation of several alkenes, cyclohexane and n-hexane, which is described in detail. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis, structure and magnetic properties of an octametallic iron(III) ring is reported. Alternate edges of the ring are bridged by a hydroxide and two pivalates, or by one pivalate and two phenoxides. By addition of biphenol to the reaction a hexadecametallic iron(III) cage can be made where the 16 metals are arranged in two linked {Fe8} rings. The rings are staggered with respect to one another, and lie on the vertices of an octagonal anti-prism. Magnetic studies on the octametallic ring allows exchange parameters to be obtained. Similar studies on the {Fe16} barrel shows the exchange interactions within the rings to be similar, with a significant paramagnetic impurity present. [Copyright &y& Elsevier]

The mononuclear ferric compound Fe(H-5-Cl-thsa-Me)(5-Cl-thsa-Me)·H2O (1) was synthesized and characterized using powder/single-crystal X-ray diffraction, Mössbauer spectroscopy, differential scanning calorimetry (DSC), and magnetic susceptibility measurements. This photo-responsive compound shows reversible, two-step spin-crossover behaviour. Moreover, dielectric anomalies were observed during the spin transitions, demonstrating the multifunctional properties of compound 1. [ABSTRACT FROM AUTHOR]

The magnetic properties of Mn, Co, and Ni substituted Fe4N are calculated from first principles theory. It is found that the generalized gradient approximation reproduces with good accuracy the magnetic moment and equilibrium volume for the parent Fe4N structure, with the atomic moment largest for the Fe atom furthest away from the N atom (Fe I site), approaching a value of 3 μB/atom, whereas the Fe atom closer to the N atom (Fe II site) has a moment closer to that of bcc Fe. The substitution of Fe for Mn, Co, or Ni, shows an intricate behavior in which the Mn substitution clearly favors the Fe II site, Ni favors substitution on the Fe I site, and Co shows no strong preference for either lattice site. The Ni and Co substitution results in a ferromagnetic coupling to the Fe atoms, whereas Mn couples antiferromagnetically on the Fe II site and ferromagnetically on the Fe I site. For all types of doping, the total magnetic moment is enhanced compared to Fe4N only in the energetically very unfavorable case of Mn doping at the Fe I site. [ABSTRACT FROM AUTHOR]

While a general model of H2 activation has been proposed for [FeFe]-hydrogenases, the structural and biophysical properties of the intermediates of the H-cluster catalytic site have not yet been discretely defined. Electron paramagnetic resonance (EPR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to characterize the H-cluster catalytic site, a [4Fe-4S]H subcluster linked by a cysteine thiolate to an organometallic diiron subsite with CO, CN, and dithiolate ligands, in [FeFe]-hydrogenase HydA1 from Chlamydomonas reinhardtii (CrHydA1). Oxidized CrHydA1 displayed a rhombic 2.1 EPR signal (g = 2.100, 2.039, 1.997) and an FTIR spectrum previously assigned to the oxidized H-cluster (Hox). Reduction of the Hox sample with 100% H2 or sodium dithionite (NaDT) nearly eliminated the 2.1 signal, which coincided with appearance of a broad 2.3-2.07 signal (g = 2.3-2.07, 1.863) and/or a rhombic 2.08 signal (g = 2.077, 1.935, 1.880). Both signals displayed relaxation properties similar to those of [4Fe-4S] clusters and are consistent with an S = 1/2 H-cluster containing a [4Fe-4S]H+ subcluster. These EPR signals were correlated with differences in the CO and CN ligand modes in the FTIR spectra of H2- and NaDT-reduced samples compared with Hox. The results indicate that reduction of [4Fe-4S]H from the 2+ state to the 1+ state occurs during both catalytic H2 activation and proton reduction and is accompanied by structural rearrangements of the diiron subsite CO/CN ligand field. Changes in the [4Fe-4S]H oxidation state occur in electron exchange with the diiron subsite during catalysis and mediate electron transfer with either external carriers or accessory FeS clusters. [ABSTRACT FROM AUTHOR]

Five compounds displaying an unprecedented binding modeof chloroquine to ferrocene through the bridging of the cyclopentadienylrings were studied alongside their monosubstituted ferrocene analoguesand organic fragments. The antiplasmodial activity was evaluated againststrains of the malaria parasite (Plasmodium falciparum). While the chloroquine-bridged ferrocenyl derivatives were lessactive than their five monosubstituted ferrocenyl analogues, theyretained activity in the drug-resistant strains. The biological andphysical properties were correlated to antiplasmodial activity. Intramolecularhydrogen bonding was associated with increased antiplasmodial action,but it is not the determining factor. Instead, balance between lipophilicityand hydrophilicity had a greater influence. It was found that calculatedpartition coefficient (log P) values of 4.5–5.0and topological polar surfaces area (tPSA) values of ∼26.0Å2give the best balance. The particular conformation,compact size, and lipophilicity/hydrophilicity balance observed inthe bridged compounds provide them with the structural characteristicsneeded to escape the mechanisms responsible for resistance. [ABSTRACT FROM AUTHOR]

Abstract: To better understand the effects of Co-doping on the crystal and electronic structures of FeF3, the theoretical studies of three types of doped models (CoFe5F18, Co2Fe4F18, and Co3Fe3F18) have been carried out by means of first principles method based on density functional theory. It is found that the stability of Co-doped FeF3 decreases with the increase of Co-doping concentration. And Co doping does not impair the crystal structure of FeF3, but it can make G-type anti-magnetic structure of FeF3 convert into metamagnetism structure. Besides, the band gap of FeF3 decreases via Co doping, and the conductivity of the Co doping FeF3 compounds can be improved, thus indicating a high discharge specific capacity when the Co doping FeF3 compounds are used as cathode material of lithium ion batteries. [Copyright &y& Elsevier]

A mononuclear Fe(ii) complex bearing 1-aminocyclopropane-1-carboxylic acid (ACCH) was synthesized and characterized. X-ray crystallography demonstrated that ACC binds to the Fe(ii) ion in a bidentate mode constituting the first structural mimic of the expected binding of ACC to the Fe(ii) center of the ethylene forming enzyme ACC-oxidase (ACCO). [Fe(BPMEN)ACC]SbF6 also constitutes a functional biomimetic complex of ACCO, as it reacts with hydrogen peroxide producing ethylene. [ABSTRACT FROM AUTHOR]

Two novel dinitrosyl iron complexes with thiolate bridging ligands [Fe(μ-SCHCHNHR)(NO)] (R = Ac, Boc), derived from the cysteamine complex [Fe(μ-SCHCHNH)(NO)] are described. The complex with acylated cysteamine is characterized by X-ray diffraction analysis. The cysteamine complex is a convenient precursor for modification of the bridging ligand. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structure of a diiron(ii) complex containing a bridging semiquinonate radical are presented. The unique electronic structure of this S = 7/2 complex is examined with spectroscopic (absorption, EPR, resonance Raman) and computational methods. [ABSTRACT FROM AUTHOR]

The basic properties of defects (self-interstitial and vacancy) in BCC iron under uniaxial tensile strain are investigated with atomic simulation methods. The formation and migration energies of them show different dependences on the directions of uniaxial tensile strain in two different computation boxes. In box-1, the uniaxial tensile strain along thedirection influences the formation and migration energies of thedumbbell but slightly affects the migration energy of a single vacancy. In box-2, the uniaxial tensile strain along thedirection influences the formation and migration energies of both vacancy and interstitials. Especially, adumbbell has a lower migration energy when its migration direction is the same or close to the strain direction, while along these directions, a vacancy has a higher migration energy. All these results indicate that the uniaxial tensile strain can result in the anisotropic formation and migration energies of simple defects in materials. [ABSTRACT FROM AUTHOR]

The cover picture shows the circular blocks of Fe(CO)4 complexes of Group‐13 half‐sandwich ligand ECp* with occupied orbitals of the molecules, the first circle consisting of Fe(CO)4←ECp* σ‐type donor orbitals. The shape of the highest‐lying occupied orbitals, which have π‐ and σ‐symmetry of the ligands {ECp*}, are shown in the following circle. The outer circle shows the plots of the pairs of orbitals that yield the shape of NOCVs pairs, with the blue/red color indicating the sign of the orbitals and the yellow/white color in the deformation density designating charge depletion (the charge flow occurs in the direction from yellow to white). More details are discussed in the article by Thi Ai Nhung Nguyen et al. on pp. 609ff. [ABSTRACT FROM AUTHOR]

Metal complexes with thiosemicarbazonato ligands have been investigated due to their possible antitumor, antifugal and antiviral properties. Thiosemicarbazone ligand has several potential donor sites that allows it to bind to the metal through sulfur atom, hydrazine nitrogen atom and phenolic oxygen atom. The iron(III) complex with salicylaldehyde thiosemicarbazone (STSC) ligand of general formula Na[Fe(STSC)2] was prepared and characterized using UV/Vis spectrophotometry, infrared spectroscopy and ESI ToF mass spectrometry. Infra-red spectrum of the ligand and complex indicate the existence of dianionic tridentate nature of ligand which undergo coordination to metal ion with ONS donor atom sets. Band due to ν (C=N) vibration was shifted towards lower frequencies in a complex (1603 cm-1) when compared with a ligand (1616 cm-1) confirming coordination of a given ligand via azomethine nitrogen. Shift in (C-O) group frequency towards a higher values in IR spectra of the complex (1304 cm-1) when compared to the ligand (1263 cm-1), confirms coordination of a ligand via phenol oxygen. Due to their great importance, the structural aspects of newly synthesized complexes have been investigated using density functional theory (DFT) methods at B3LYP level with a 6-311++G (d,p) basis set to explore the geometries and electronic features of proposed compounds. Good correlation between experimental IR and calculated spectra was found. The lowest energy transition from the UV-Vis spectrum related to metal-to-ligand charge transfer (MLCT) was correlated to the HOMO-LUMO calculated energies. [ABSTRACT FROM AUTHOR]

Fe2CoGa Heusler nanoparticles are synthesized by a chemical method. The structure and magnetic properties of Fe2CoGa Heusler nanoparticles are investigated by x-ray diffraction, extended x-ray absorption fine structure and Mössbauer spectroscopy. The crystal structure of Fe2CoGa nanoparticles is described by the X-type structure (prototype: Li2AgSb). Magnetic measurements reveal the presence of small Fe2CoGa nanoparticles and lower magnetic moments compared with the theoretically predicted values. [ABSTRACT FROM AUTHOR]