Search results for "MÖSSBAUER SPECTROSCOPY"
showing 10 items of 364 documents
Synthesis, spectroscopic characterization and in vitro antimicrobial activity of diorganotin(IV) dichloride adducts with [1,2,4]triazolo-[1,5-a]pyrim…
2006
Abstract The heterocyclic ligands [1,2,4]triazolo-[1,5-a]pyrimidine (tp) and 5,7-dimethyl-[1,2,4]triazolo-[1,5-a]pyrimidine (dmtp), react with diorganotin dichlorides giving the addition compounds Me2SnCl2(tp)2, Et2SnCl2(tp)2, Me2SnCl2(dmtp)2, Et2SnCl2(dmtp)2, Bu2SnCl2(dmtp), Ph2SnCl2(dmtp). The organotin:ligand stoichiometry goes from 1:2 to 1:1 by increasing the steric hindrance of the organic groups bound to tin. The compounds have been characterized by means of infrared, 119Sn Mossbauer and 1H AND 13C NMR spectroscopy. The ligands presumably coordinate to tin classically through the nitrogen atom at the position 3. The 1:1 complexes adopt trigonal bipyramidal structures, with the organi…
The 5/2,3/2 Spin Admixture in the Chloroiron(III) Derivative of the Sterically Crowded 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetraphenylporphyrin
1999
Despite similar ring deformations in solution and in the solid state, the chloroiron(III) derivative of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin ([FeCl(oetpp)], shown schematically) prepared in this study exhibits only a very weak quantum-mechanical admixture of spin S=3/2 (only 4-10 %) with spin S=5/2. In contrast, for the variety of [FeCl(oetpp)] studied earlier by other researchers a 40 % contribution of the S=3/2 state was found.
Magnetic ordering in Fe-doped Gd2 BaCuO5
1994
The structural and magnetic properties of iron-doped Gd2BaCuO5 have been studied by X-ray diffractometry, Mossbauer spectroscopy and susceptibility measurements. Mossbauer data on Gd2BaCu0.8Fe0.2O5 show that at room temperature Fe is not magnetically ordered, displaying hyperfine parameters similar to those generally assigned to Fe at Cu(2) sites in the GdBa2(Cu1−x; Fe; x; )3O7 superconductor. Susceptibility measurements demonstrate that Gd2BaCu1−x; Fe; x; O5 behaves like a three-dimensional antiferromagnet withT; N=11.9±0.1 K, independent ofx. The effective magnetic moment calculated within a mean field approximation is consistent with an ordering of the Gd sublattice.
Hierachical Ni@Fe2O3superparticles through epitaxial growth of γ-Fe2O3nanorods on: In situ formed Ni nanoplates
2016
One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mossbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 …
Synthesis, UV/vis, FT-IR and Mössbauer spectroscopic characterization and molecular structure of the Bis[4-(2-aminoethyl)morpholine](tetrakis(4-metox…
2016
International audience; The synthesis, the UV-visible, FT-IR and Mossbauer spectroscopy and the crystal structure characterizations of the bis[4-(2-Aminoethyl)morpholine]tetrakis(4-metoxyphenyl)porphy-rinato)iron(II) complex are described. The title compound crystallizes in the triclinic, space group P-1, with a = 11.1253(4) angstrom, b = 11.2379(4) angstrom, c = 11.5488(4) angstrom, alpha = 72.304(2)degrees, beta = 86.002(2)degrees gamma = 72.066(2)degrees, V = 1308.28(8) angstrom(3), Z = 1. The Mossbauer data are consistent with an iron(II) low-spin (S = 0) porphyin species. The spin-state is confirmed by the value of the average equatorial iron-nitrogen pyrrole distance (Fe-Np = 1.988(2)…
61Ni Mössbauer study of the surface hyperfine magnetic field in nickel
1988
61Ni Mossbauer measurements have been performed at 4.2 K on spherical Ni particles with an average diameter of 100 and 30 A, covered with a protective layer of SiO. Their spectra contain a surface component with a significantly reduced hyperfine magnetic field as compared with the field in the bulk. This result confirms recent theoretical predictions.
Organotin(IV) azido and mixed azidothiocyanato complex anions; A Mössbauer and vibrational spectroscopic study
1975
Abstract Tetraphenylarsonium and tetramethylammonium salts of the complex anions Ph 3 Sn(N 3 ) − 2 , Ph 3 Sn(N 3 )(NCS) − , Me 2 Sn(N 3 ) 2− 4 and Ph 2 Sn(N 3 ) 2 (NCS) 2− 2 have been synthesized, and the solid state configuration of the complex anions has been studied by Mossbauer and vibrational spectroscopies. Trigonal bipyramidal structures are advanced for the Ph 3 Sn IV derivatives, with equatorial SnC 3 and apical pseudohalide ligands, while the R 2 Sn IV compounds are assumed to be trans -octahedral species. The NCS − ligands are observed to be N-bonded to Sn IV . Conductance and PMR (for the Me 2 Sn IV compound) data suggest the presence of the complex anions also in solution phase…
The Two‐Step Spin Conversion in a Supramolecular Triple Helicate Dinuclear Iron(II) Complex Studied by Mössbauer Spectroscopy
2006
The triple helicate dinuclear iron(II) complex, [Fe-2(L)(3)](ClO4)(4)center dot 2H(2)O (1), previously reported by Tuna et al. (Chem. Eur. J. 2004, 10, 5737), was prepared and characterised by detailed SQUID and Fe-57 Mbssbauer measurements. Compound 1 exhibits a thermochromic two-step spin conversion at T-SC((1)) ca. 240 K and T-SC((2)) ca. 120 K, but does not switch its spin state further below 20 K as proven by Mossbauer spectroscopy. The sharp variation of the susceptibility below 20 K is due to zero-field splitting of the remaining iron(II) high-spin species. Applied field Fe-57 Mossbauer spectroscopy experiments at 4.2 K indicate that the gradual thermal spin conversion from [HS-HS] p…
Synthesis, infrared and121Sb M�ssbauer spectra of some Antimony(III) Thiocyanate Complexes
1989
The first isolation of an antimony(III) thiocyanate complex salt, [(CH3)4N][Sb(CNS)4] (I), and of two adducts of the Sb(CNS)3 formal unit with potentially tridentate nitrogen donors, Sb(CNS)3tpta (II) and [Sb(CNS)3]3(dqp)2 (III), is described. In these derivatives, infrared and Mossbauer spectral data are essentially indicating the predominant presence of N-bonded thiocyanate. For complex I, the occurrence also of groups bridging through the nitrogen atom is advanced. Synthese, IR- und 121Sb-Mosbauer-Spektren von Antimon (III)-thiocyanat-Komplexen Die erstmalige Darstellung eines Antimon(III)-thiocyanat-Komplexes, [(CH3)4N][Sb(CNS)4] (I) und von zwei Addukten der formalen Sb(CNS)3-Einheit m…
Thermal and Light-Induced Spin Transition in [Fe(bpen)X2] (bpen = 1,6-Bis(2-pyridyl)-2,5-diazahexane, X = NCS-, NCSe-)
1996
The thermal and light-induced spin transitions in [Fe(bpen)(NCS)2] and [Fe(bpen)(NCSe)2] have been investigated by means of magnetic susceptibility and Mossbauer measurements. The HS → LS transition in [Fe(bpen)(NCS)2] is detected at temperatures below 120 K (T1/2 [when the fraction of high-spin species γHS = 0.5] = 68 K) with a residual HS fraction of 8% at 20 K. The transition is fairly abrupt and no hysteresis is observed, in contrast to earlier studies (ref. [8]). The generation of metastable HS states in [Fe(bpen)(NCS)2] is achieved by rapid cooling of the sample and by irradiating the compound at low temperatures with light of appropriate wavelengths (LIESST). The HS → LS relaxation o…