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Erik Wächtler, Sven Wahlicht, Steven H Privér, Martin A Bennett, Birgit Gerke, Rainer Pöttgen, Erica Brendler, Robert Gericke, Jörg Wagler, Suresh K Bhargava
The tin(IV) compounds MexSn(2-C6F4PPh2)4-x (1, x = 1; 2, x = 2) and ClSn(2-C6F4PPh2)3 (3) were obtained from the reactions of 2-LiC6F4PPh2 with MeSnCl3 (3:1), Me2SnCl2 (2:1), or SnCl4 (3:1), respectively. The reactions of 2-LiC6F4PPh2 with SnCl4 in different stoichiometric ratios (4:1-1:1) gave 3 as the main product. Compound Cl2Sn(2-C6F4PPh2)2 (4) was formed in the transmetalation reaction of 3 and [AuCl(tht)] but could not be isolated. 1 and 2 react with palladium(0) sources {[Pd(PPh3)4] and [Pd(allyl)Cp]} by the oxidative addition of one of their Sn-CAryl bonds to palladium(0) with formation of the heterobimetallic complexes [MeSn(μ-2-C6F4PPh2)2Pd(κC-2-C6F4PPh2)] (5) and [Me2Sn(μ-2-C6F4PPh2)Pd(κ(2)-2-C6F4PPh2)] (6) featuring Sn-Pd bonds...
April 13, 2017: Inorganic Chemistry
B Pacakova, S Kubickova, G Salas, A R Mantlikova, M Marciello, M P Morales, D Niznansky, J Vejpravova
This work aims to emphasize that the magnetic response of single-domain magnetic nanoparticles (NPs) is driven by the NPs' internal structure, and the NP size dependencies of magnetic properties are overestimated. The relationship between the degree of the NPs' crystallinity and magnetic response is unambiguously demonstrated in eight samples of uniform maghemite/magnetite NPs and corroborated with the results obtained for about 20 samples of spinel ferrite NPs with different degrees of crystallinity. The NP samples were prepared by the thermal decomposition of an organic iron precursor subjected to varying reaction conditions, yielding variations in the NP size, shape and relative crystallinity...
April 20, 2017: Nanoscale
Matthew J Chalkley, Trevor J Del Castillo, Benjamin D Matson, Joseph P Roddy, Jonas C Peters
We have recently reported on several Fe catalysts for N2-to-NH3 conversion that operate at low temperature (-78 °C) and atmospheric pressure while relying on a very strong reductant (KC8) and acid ([H(OEt2)2][BAr(F)4]). Here we show that our original catalyst system, P3(B)Fe, achieves both significantly improved efficiency for NH3 formation (up to 72% for e(-) delivery) and a comparatively high turnover number for a synthetic molecular Fe catalyst (84 equiv of NH3 per Fe site), when employing a significantly weaker combination of reductant (Cp*2Co) and acid ([Ph2NH2][OTf] or [PhNH3][OTf])...
March 22, 2017: ACS Central Science
M Albino, L Clark, J Lhoste, C Payen, J-M Grenèche, P Lightfoot, V Maisonneuve, M Leblanc
A series of triazole fluoride weberites (M1-x(2+)Mx(3+))M(3+)F5(Htaz)1-x(taz)x is obtained by hydrothermal synthesis. All phases are found to be isostructural to ZnAlF5(Htaz) by powder X-ray diffraction. Weberite structures are prone to induce the magnetic frustration of antiferromagnetic interactions originating from the cationic topology of HTB layers. The (nD) magnetic properties of (0D) Co-Ga, (1D) Zn-Fe, (3D) Fe-Ga, Mn-Fe, Co-Fe and Co-V couples are thus reported. Co(2+) or Fe(2+) magnetic anisotropy induces a negative magnetisation below TN and compensation temperatures for Mn-Fe and Co-Fe couples...
April 19, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Vincenzo Iannotti, Alessio Adamiano, Giovanni Ausanio, Luciano Lanotte, Giuliana Aquilanti, John Michael David Coey, Marco Lantieri, Gabriele Spina, Maria Fittipaldi, George Margaris, Kalliopi Trohidou, Simone Sprio, Monica Montesi, Silvia Panseri, Monica Sandri, Michele Iafisco, Anna Tampieri
Doping of biocompatible nanomaterials with magnetic phases is currently one of the most promising strategies for the development of advanced magnetic biomaterials. However, especially in the case of iron-doped magnetic hydroxyapatites, it is not clear if the magnetic features come merely from the magnetic phases/ions used as dopants or from complex mechanisms involving interactions at the nanoscale. Here, we report an extensive chemical-physical and magnetic investigation of three hydroxyapatite nanocrystals doped with different iron species and containing small or no amounts of maghemite as a secondary phase...
April 5, 2017: Inorganic Chemistry
Lukas Bucinsky, Martin Breza, Wei-Tsung Lee, Anne K Hickey, Diane A Dickie, Ismael Nieto, Jordan A DeGayner, T David Harris, Karsten Meyer, J Krzystek, Andrew Ozarowski, Joscha Nehrkorn, Alexander Schnegg, Karsten Holldack, Rolfe H Herber, Joshua Telser, Jeremy M Smith
High-oxidation-state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin-state preferences of threefold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(Im(R))3}FeN], R = (t)Bu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(Im(R))3}Fe(NR')](+), R = Mes, R' = 1-adamantyl (3), (t)Bu (4), were investigated by electronic absorption and Mössbauer effect spectroscopies...
April 5, 2017: Inorganic Chemistry
Nathan R Erickson, Cole D Holstrom, Hannah M Rhoda, Gregory T Rohde, Yuriy V Zatsikha, Pierluca Galloni, Victor N Nemykin
Metal-free (1) and zinc (2) 5,10,15,20-tetra(1'-hexanoylferrocenyl)porphyrins were prepared using an acid-catalyzed tetramerization reaction between pyrrole and 1'-(1-hexanoyl)ferrocencarboxaldehyde. New organometallic compounds were characterized by combination of (1)H, (13)C, and variable-temperature NMR, UV-vis, magnetic circular dichroism, and high-resolution electrospray ionization mass spectrometry methods. The redox properties of 1 and 2 were probed by electrochemical (cyclic voltammetry and differential pulse voltammetry), spectroelectrochemical, and chemical oxidation approaches coupled with UV-vis-near-IR and Mössbauer spectroscopy...
April 4, 2017: Inorganic Chemistry
Niklas Struch, Christoph Bannwarth, Tanya K Ronson, Yvonne Lorenz, Bernd Mienert, Norbert Wagner, Marianne Engeser, Eckhard Bill, Rakesh Puttreddy, Kari Rissanen, Johannes Beck, Stefan Grimme, Jonathan R Nitschke, Arne Lützen
By employing the subcomponent self-assembly approach utilizing 5,10,15,20-tetrakis(4-aminophenyl)porphyrin or its zinc(II) complex, 1H-4-imidazolecarbaldehyde, and either zinc(II) or iron(II) salts, we were able to prepare O-symmetric cages having a confined volume of ca. 1300 Å(3) . The use of iron(II) salts yielded coordination cages in the high-spin state at room temperature, manifesting spin-crossover in solution at low temperatures, whereas corresponding zinc(II) salts led to the corresponding diamagnetic analogues...
March 30, 2017: Angewandte Chemie
Kwing To Lai, Alexander Christoph Komarek, Maria Teresa Fernández-Díaz, Pi-Shan Chang, Sungjoon Huh, Helge Rosner, Chang-Yang Kuo, Zhiwei Hu, Tun-Wen Pi, Peter Adler, Vadim Ksenofontov, Liu Hao Tjeng, Martin Valldor
From stoichiometric amounts of CaO, Fe, and Se, pure powders and single crystals of quaternary [Formula: see text] can be obtained by solid-state reaction and self-flux growth, respectively. The as-synthesized compound exhibits a polymorphic crystal structure, where the two modifications have different stacking sequences of [Formula: see text] layers. The two polymorphs have similar unit cells but different crystal symmetries (Cmc21 and Pnma), of which the former is non-centrosymmetric. Fe is divalent (d(6)) and high-spin, as proven by X-ray spectroscopy, Mössbauer spectroscopy, and powder neutron diffraction data...
March 27, 2017: Inorganic Chemistry
A E Böhmer, A Sapkota, A Kreyssig, S L Bud'ko, G Drachuck, S M Saunders, A I Goldman, P C Canfield
We study the effect of applied strain as a physical control parameter for the phase transitions of Ca(Fe_{1-x}Co_{x})_{2}As_{2} using resistivity, magnetization, x-ray diffraction, and ^{57}Fe Mössbauer spectroscopy. Biaxial strain, namely, compression of the basal plane of the tetragonal unit cell, is created through firm bonding of samples to a rigid substrate via differential thermal expansion. This strain is shown to induce a magnetostructural phase transition in originally paramagnetic samples, and superconductivity in previously nonsuperconducting ones...
March 10, 2017: Physical Review Letters
Yulong Liu, Wei Xu, Jing Zhang, William Fuller, Charles E Schulz, Jianfeng Li
The five coordinate iron porphyrin carbene complexes [Fe(TPP)(CCl<u>2</u>)] (TPP = tetraphenylporphyrin), [Fe(TTP)(CCl<u>2</u>)] (TTP = tetratolylporphyrin) and [Fe(TFPP)(CPh<u>2</u>)] (TFPP = tetra(pentafluorophenyl)porphin), utilizing two types of carbene ligands (CCl<u>2</u> and CPh<u>2</u>), have been investigated by single crystal X-ray, XANES (X-ray Absorption Near Edge Spectroscopy), Mössbauer, NMR and UV-vis spectros-copies. The XANES unambiguously suggested the iron(II) oxida-tion state of the complexes...
March 24, 2017: Journal of the American Chemical Society
Graham de Ruiter, Kurtis M Carsch, Sheraz Gul, Ruchira Chatterjee, Niklas B Thompson, Michael K Takase, Junko Yano, Theodor Agapie
We report the synthesis, characterization, and reactivity of [LFe3 (PhPz)3 OMn((s) PhIO)][OTf]x (3: x=2; 4: x=3), where 4 is one of very few examples of iodosobenzene-metal adducts characterized by X-ray crystallography. Access to these rare heterometallic clusters enabled differentiation of the metal centers involved in oxygen atom transfer (Mn) or redox modulation (Fe). Specifically, (57) Fe Mössbauer and X-ray absorption spectroscopy provided unique insights into how changes in oxidation state (Fe(III)2 Fe(II) Mn(II) vs...
March 24, 2017: Angewandte Chemie
Martin Clémancey, Thibault Cantat, Geneviève Blondin, Jean-Marc Latour, Pierre Dorlet, Guillaume Lefèvre
Mechanistic studies of the reduction of Fe(III) and Fe(II) salts by aryl Grignard reagents in toluene/tetrahydrofuran mixtures in the absence of a supporting ligand, as well as structural insights regarding the nature of the low-valent iron species obtained at the end of this reduction process, are reported. It is shown that several reduction pathways can be followed, depending on the starting iron precursor. We demonstrate, moreover, that these pathways lead to a mixture of Fe(0) and Fe(I) complexes regardless of the nature of the precursor...
April 3, 2017: Inorganic Chemistry
Airi Kawamura, Arin R Greenwood, Alexander S Filatov, Audrey T Gallagher, Giulia Galli, John S Anderson
A series of isoreticular metal-organic frameworks (MOFs) of the formula M(BDC)(L) (M = Fe(II) or Co(II), BDC = 1,4-benzenedicarboxylate, L = pyrazine (pyz) or 4,4'-bipyridine (bipy)) has been synthesized and characterized by N2 gas uptake measurements, single crystal and powder X-ray diffraction, magnetometry, X-ray absorption spectroscopy, and Mössbauer spectroscopy. These studies indicate the formation of a permanently porous solid with high-spin Fe(II) and Co(II) centers that are weakly coupled, consistent with first-principles density functional theory calculations...
March 3, 2017: Inorganic Chemistry
Zeba Haque, Gohil Singh Thakur, Rangasamy Parthasarathy, Birgit Gerke, Theresa Block, Lukas Heletta, Rainer Pöttgen, Amish G Joshi, Ganesan Kalai Selvan, Sonachalam Arumugam, Laxmi Chand Gupta, Ashok Kumar Ganguli
We have synthesized two new Eu-based compounds, EuSr2Bi2S4F4 and Eu2SrBi2S4F4, which are derivatives of Eu3Bi2S4F4, an intrinsic superconductor with Tc = 1.5 K. They belong to a tetragonal structure (SG: I4/mmm, Z = 2), similar to the parent compound Eu3Bi2S4F4. Our structural and (151)Eu Mössbauer spectroscopy studies show that, in EuSr2Bi2S4F4, Eu-atoms exclusively occupy the crystallographic 2a-sites. In Eu2SrBi2S4F4, 2a-sites are fully occupied by Eu-atoms and the other half of Eu-atoms and Sr-atoms together fully occupy 4e-sites in a statistical distribution...
February 28, 2017: Inorganic Chemistry
Brian Ginn, Christof Meile, Jared Wilmoth, Yuanzhi Tang, Aaron Thompson
Iron oxides are important structural and biogeochemical components of soils that can be strongly altered by redox-driven processes. This study examined the influence of temporal oxygen variations on Fe speciation in soils from the Luquillo Critical Zone Observatory (Puerto Rico). We incubated soils under cycles of oxic-anoxic conditions (τoxic:τanoxic = 1:6) at three frequencies with and without phosphate addition. Fe(II) production, P availability, and Fe mineral composition were monitored using batch analytical and spectroscopic techniques...
February 28, 2017: Environmental Science & Technology
Daniel L Reger, Andrea E Pascui, Elizabeth A Foley, Mark D Smith, Julia Jezierska, Agnieszka Wojciechowska, Sebastian A Stoian, Andrew Ozarowski
A series of monochloride-bridged, dinuclear metallacycles of the general formula [M2(μ-Cl)(μ-L)2](ClO4)3 have been prepared using the third-generation, ditopic bis(pyrazolyl)methane ligands L = m-bis[bis(1-pyrazolyl)methyl]benzene (Lm), M = Cu(II), Zn(II), and L = m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (Lm*), M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II). These complexes were synthesized from the direct reactions of M(ClO4)2·6H2O, MCl2, and the ligand, Lm or Lm*, in the appropriate stoichiometric amounts...
February 20, 2017: Inorganic Chemistry
Joshua D Wofford, Mrinmoy Chakrabarti, Paul A Lindahl
Cardiac function requires continuous high levels of energy, and so iron, a critical player in mitochondrial respiration, is an important component of the heart. Hearts from (57)Fe-enriched mice were evaluated by Mössbauer spectroscopy. Spectra consisted of a sextet and two quadrupole doublets. One doublet was due to residual blood, whereas the other was due to [Fe4S4](2+) clusters and low-spin Fe(II) hemes, most of which were associated with mitochondrial respiration. The sextet was due to ferritin; there was no evidence of hemosiderin, a ferritin decomposition product...
March 31, 2017: Journal of Biological Chemistry
Sebastian F M Schmidt, Changhyun Koo, Valeriu Mereacre, Jaena Park, Dieter W Heermann, Vladislav Kataev, Christopher E Anson, Denis Prodius, Ghenadie Novitchi, Rüdiger Klingeler, Annie K Powell
We present the synthesis, structure, magnetic properties, as well as the Mössbauer and electron paramagnetic resonance studies of a ring-shaped [Fe(III)4Ln(III)2(Htea)4(μ-N3)4(N3)3(piv)3] (Ln = Y 1, Gd 2, Tb 3, Dy 4, Ho 5, Er, 6) coordination cluster. The Dy, Tb, and Ho analogues show blocking of the magnetization at low temperatures without applied fields. The anisotropy of the 3d ion and the exchange interaction between 3d and 4f ions in Fe4Ln2 complexes are unambiguously determined by high-field/high-frequency electron paramagnetic resonance measurements at low temperature...
February 10, 2017: Inorganic Chemistry
R A Susilo, J M Cadogan, W D Hutchison, G A Stewart, M Avdeev, S J Campbell
We have investigated the low temperature magnetic properties of Dy2Fe2Si2C by using magnetisation, specific heat, x-ray diffraction, neutron powder diffraction and (57)Fe Mössbauer spectroscopy measurements over the temperature range 1.5 K-300 K. Dy2Fe2Si2C exhibits two magnetic transitions at low temperatures: an antiferromagnetic transition at [Formula: see text] K and a spin-reorientation transition at [Formula: see text] K. The magnetic structure above T t can be described with a propagation vector [Formula: see text] with the ordering of the Dy magnetic moments along the monoclinic b-axis whereas on cooling below T t the Dy moment tips away from the b-axis towards the ac-plane...
March 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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