References of "Sougrati, Moulay T"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailSynthesis, Magnetism, and 57Fe Mössbauer Spectroscopic Study of a Family of [Ln3Fe7] Coordination Clusters (Ln = Gd, Tb, and Er),”
Abbas, Ghulam; Lan, Yanhua; Mereacre, Valeriu et al

in Inorganic Chemistry (2013), 52

The reaction of N-methydiethanolamine (mdeaH2), benzoic acid, FeCl3, and Ln(NO3)3·6H2O or LnCl3·xH2O yields a series of decanuclear coordination clusters, [Ln3Fe7(μ4-O)2(μ3OH)2(mdea)7(μ-benzoate)4(N3)6 ... [more ▼]

The reaction of N-methydiethanolamine (mdeaH2), benzoic acid, FeCl3, and Ln(NO3)3·6H2O or LnCl3·xH2O yields a series of decanuclear coordination clusters, [Ln3Fe7(μ4-O)2(μ3OH)2(mdea)7(μ-benzoate)4(N3)6]·4MeCN·H2O, where Ln = Gd III (1)orTb III (2), and [Er 3Fe7(μ4-O)2(μ3-OH)2(mdea)7(μbenzoate)4(N3)5(MeOH)]Cl·7.5H2O·11.5MeOH (3). The isostructural compounds 1−3 all crystallize isotypically in the triclinic space group P1̅ with Z = 2, as does the previously reported dysprosium analogue 4. Six of the Fe III ions are pseudooctahedrally coordinated, whereas the seventh has a trigonal-bipyramidal coordination geometry. Temperature-dependent direct-current magnetic susceptibility studies indicate that intracluster antiferromagnetic interactions are dominant in 1−3. The frequency-dependent out-of-phase (χ′′) alternating-current susceptibility reveals that 2 undergoes a slow relaxation of its magnetization, presumably resulting from anisotropy of the Tb III ions. Between 30 and 295 K, the 57Fe Mö ssbauer spectra reveal paramagnetic behavior with six partially resolved quadrupole doublets, one for the trigonal-bipyramidal Fe III site and five for the six pseudooctahedral Fe III sites. The Mö ssbauer spectra of 2 and 3 obtained between 3 and 30 K are consistent with the presence of Fe III intracluster antiferromagnetic coupling with slow magnetic relaxation relative to the Larmor precession time. Further, the observed changes in the effective magnetic field values in the spectra measured at 3 K with increasing applied field are consistent with the effect of the local spin polarization along the applied magnetic field direction, a behavior reminiscent of antiparallel spin-coupled iron molecular paramagnetic systems. [less ▲]

Detailed reference viewed: 12 (1 ULg)
Full Text
Peer Reviewed
See detailSlow Magnetic Relaxation and Electron Delocalization in an S = 9/2 Iron(II/III) Complex Featuring Two Crystallographically Inequivalent Iron Sites
Hazra, Susanta; Sasmal, Sujit; Fleck, Michel et al

in Journal of Chemical Physics (2011), 134

The magnetic, electronic and Mössbauer spectral properties of [Fe2L(μ-OAc)2]ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed ... [more ▼]

The magnetic, electronic and Mössbauer spectral properties of [Fe2L(μ-OAc)2]ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed valence iron(II/III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe2]V cationic configuration with a St = 9/2 ground state. Fits of the dc magnetic susceptibility between 2 and 300 K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of –32(2) cm–1 for an electron transfer parameter, B, of 950 cm–1, a zero-field uniaxial D9/2 parameter of –0.9(1) cm–1, and g = 1.95(5). In agreement with the presence of uniaxial magnetic anisotropy, ac susceptibility measurements reveal that 1 is a single-molecule magnet at low temperature with a single molecule magnetic effective relaxation barrier, Ueff, of 9.8 cm–1. At 5.25 K the Mössbauer spectra of 1 exhibit two spectral components, assigned to the two crystallographically inequivalent iron sites with a static effective hyperfine field; as the temperature increases from 7 to 310 K the spectra exhibit increasingly rapid relaxation of the hyperfine field on the iron-57 Larmor precession time of 5 × 10–8 s. A fit of the temperature dependence of the average effective hyperfine field yields |D9/2| = 0.9 cm–1. An Arrhenius plot of the logarithm of the relaxation frequency between 5 and 85 K yields a relaxation barrier of 17 cm–1. [less ▲]

Detailed reference viewed: 22 (5 ULg)
Full Text
Peer Reviewed
See detailA Seven-Coordinate Iron Platform and its Oxo and Nitrene Reactivity
Soo, Han Sen; Sougrati, Moulay T; Grandjean, Fernande ULg et al

in Inorganica Chimica Acta (2011), 369

We present a new structurally determined seven-coordinate iron platform supported by the tris(2picolyl)amine ligand 6,60 -(pyridin-2-ylmethylazanediyl)bis(methylene)bis(N-tert-butylpicolinamide) (TPA 2C(O ... [more ▼]

We present a new structurally determined seven-coordinate iron platform supported by the tris(2picolyl)amine ligand 6,60 -(pyridin-2-ylmethylazanediyl)bis(methylene)bis(N-tert-butylpicolinamide) (TPA 2C(O)NHtBu, 3) and its reactivity with oxo and nitrene transfer agents. Oxidation of the pentagonal bipyramidal, seven-coordinate iron(II)–triflate complex [TPA 2C(O)NHtBuFeII(OTf)][OTf] (4) with PhIO produces the corresponding diiron(III) l-oxo complex [(TPA 2C(O)NHtBuFeIII) 2(O)][OTf]4 (5). Mossbauer and magnetic measurements on 5 in the solid-state establish antiferromagnetic coupling between its two Fe(III) centers. Reactions of 4 with the nitrene transfer agents PhINTs (Ts = p-MeC6H4SO2) and PhINNs (Ns = p-NO2C6H4SO2) provide the corresponding iron(III)-amide congeners [TPA 2C(O)NHtBuFeIII(NHTs)][OTf]2 (6) and [TPA 2C(O)NHtBuFeIII(NHNs)][OTf] 2 (7), respectively, affording a rare pair of isolable Fe(III)-amide compounds formed from nitrene transfer. By characterizing well-defined products in the crystalline form, derived from atom and group transfer to seven-coordinate iron, the collective data provide a starting point for the exploration of high-valent and metal–ligand multiply bonded species supported by approximate pentagonal-type ligand fields. [less ▲]

Detailed reference viewed: 41 (1 ULg)
Full Text
Peer Reviewed
See detailLocal ordering and magnetism in Ga0.9Fe3.1N
Burghaus, Jens; Sougrati, Moulay T.; Moechel, Anne et al

in Journal of Solid State Chemistry (2011), 184(9), 2315-2321

Prior investigations of the ternary nitride series Ga1-xFe3+xN (0 <= x 1) have indicated a transition from ferromagnetic gamma'-Fe4N to antiferromagnetic ``GaFe3N''. The ternary nitride ``GaFe3N'' has ... [more ▼]

Prior investigations of the ternary nitride series Ga1-xFe3+xN (0 <= x 1) have indicated a transition from ferromagnetic gamma'-Fe4N to antiferromagnetic ``GaFe3N''. The ternary nitride ``GaFe3N'' has been magnetically and spectroscopically reinvestigated in order to explore the weakening of the ferromagnetic interactions through the gradual incorporation of gallium into gamma'-Fe4N. A hysteretic loop at RI reveals the presence of a minority phase of only 0.1-0.2 at\%, in accord with the sound two-step synthesis. The composition of the gallium-richest phase ``GaFe3N'' was clarified by Prompt Gamma-ray Activation Analysis and leads to the berthollide formula Ga0.91(1)Fe3.09(10)N1.05(7). Magnetic measurements indicate a transition around 8 K, further supported by Mossbauer spectral data. The weakening of the ferromagnetic coupling through an increasing gallium concentration is explained by a simple Stoner argument. In Ga0.9Fe3.1N the presence of iron on the gallium site affects the magnetism by the formation of 13-atom iron clusters. (C) 2011 Elsevier Inc. All rights reserved. [less ▲]

Detailed reference viewed: 9 (2 ULg)
Full Text
Peer Reviewed
See detailStructural, Electronic, and Magnetic Properties of UFeS3 and UFeSe3
Jin, G. B.; Ringe, Emilie; Long, Gary J. et al

in Inorganic Chemistry (2010), 49

Black prisms of UFeS3 and UFeSe3 have been synthesized by solid-state reactions of U, Fe, and S or Se with CsCl as a flux at 1173 K. The structure of these isostructural compounds consists of layers of ... [more ▼]

Black prisms of UFeS3 and UFeSe3 have been synthesized by solid-state reactions of U, Fe, and S or Se with CsCl as a flux at 1173 K. The structure of these isostructural compounds consists of layers of edge- and corner-sharing FeS6 or FeSe6 octahedra that are separated by layers of face- and edge-sharing US8 or USe8 bicapped trigonal prisms. The isomer shifts in the iron-57 Mössbauer spectra of both UFeS3 and UFeSe3 are consistent with the presence of high-spin iron(II) ions octahedrally coordinated to S or Se. The XANES spectra of UFeS3 and UFeSe3 are consistent with uranium(IV). Single-crystal magnetic susceptibility measurements along the three crystallographic axes of UFeSe3 reveal a substantial magnetic anisotropy with a change of easy axis from the a-axis above 40 K to the b-axis below 40 K, a change that results from competition between the iron(II) and uranium(IV) anisotropies. The temperature dependence of the magnetic susceptibility along the three axes is characteristic of two-dimensional magnetism. A small shoulder-like anomaly is observed in the magnetic susceptibilities along the a- and b-axes at 96 K and 107 K, respectively. Below 107 K, the iron-57 Mössbauer spectra of UFeS3 and UFeSe3 show that the iron nuclei experience a magnetic hyperfine field that results from long-range magnetic ordering of at least the iron(II) magnetic moments because the field exhibits Brillouin-like behavior. Below 40 K there is no significant change in the Mössbauer spectra as a result of change in magnetic anisotropy. The complexity of the iron-57 Mössbauer spectra and the temperature and field dependencies of the magnetic properties point towards a complex long-range magnetic structure of two independent iron(II) and uranium(IV) two-dimensional sublattices. The temperature dependence of the single-crystal resistivity of UFeSe3 measured along the a-axis reveals semiconducting behavior between 30 and 300 K with an energy gap of ca. 0.03 eV below the 53 K maximum in susceptibility, of ca. 0.05 eV between 50 and 107 K, and of 0.03 eV above 107 K; a negative magnetoresistance was observed below 60 K. [less ▲]

Detailed reference viewed: 101 (2 ULg)
Full Text
Peer Reviewed
See detailCrystal Growth, Transport, and the Structural and Magnetic Properties of Ln4FeGa12 with Ln = Y, Tb, Dy, Ho, and Er
Drake, B. L.; Grandjean, Fernande ULg; Okudzeto, E. K. et al

in Inorganic Chemistry (2010), 49

Ln4FeGa12, where Ln is Y, Tb, Dy, Ho, and Er, prepared by flux growth, crystallize with the cubic Y4PdGa12 structure with the space group and with a = 8.5650(4), 8.5610(4), 8.5350(3), 8.5080(3), and 8 ... [more ▼]

Ln4FeGa12, where Ln is Y, Tb, Dy, Ho, and Er, prepared by flux growth, crystallize with the cubic Y4PdGa12 structure with the space group and with a = 8.5650(4), 8.5610(4), 8.5350(3), 8.5080(3), and 8.4720(4) Å, respectively. The crystal structure consists of an iron-gallium octahedra and face sharing rare-earth cuboctahedra of the Au3Cu type. Y4FeGa12 exhibits weak itinerant ferromagnetism below 36 K. In contrast, Tb4FeGa12, Dy4FeGa12, Ho4FeGa12, and Er4FeGa12 order antiferromagnetically with maxima in the molar magnetic susceptibilities at 26, 18.5, 9, and 6 K. All the compounds exhibit metallic electric resistivity and their iron-57 Mössbauer spectra, obtained between 4.2 and 295 K, exhibit a single-line absorption with a 4.2 K isomer shift of ca. 0.50 mm/s, a shift that is characteristic of iron in an iron-gallium intermetallic compound. A small but significant broadening in the spectral absorption line width is observed for Y4FeGa12 below 40 K and results from the small hyperfine field arising from its spin-polarized itinerant electrons [less ▲]

Detailed reference viewed: 65 (0 ULg)
See detailCharacterization of modern Prussian blue pigments by Mössbauer spectroscopy and synchrotron radiation
Samain, Louise ULg; Silversmit, Geert; Sougrati, Moulay T. et al

Conference (2009, November 27)

Detailed reference viewed: 63 (10 ULg)
See detailFading of Modern Prussian Blue Pigments : Preliminary Study
Samain, Louise ULg; Sougrati, Moulay T.; Hatert, Frédéric ULg et al

Poster (2009, June)

Detailed reference viewed: 18 (3 ULg)