Search results for "Mössbauer Spectroscopy"
showing 10 items of 364 documents
Organotin(IV)n+ complexes formed with biologically active ligands: equilibrium and structural studies, and some biological aspects
2002
Abstract The organotin(IV) cations form complexes with ligands containing {O}, {N}, {S}, or {phosphorus(O)} donor atoms with various composition and stability. The emergence of new experimental techniques (EXAFS, multinuclear 1 H-, 13 C-, 119 Sn-NMR, 119 Sn Mossbauer, etc., spectroscopic techniques) provided useful information about the structure and stabilities of the complexes formed. We reviewed the literature on these type of complexes taking into account the biological aspects of the complexes discussed.
Infrared and Mössbauer studies on adducts R3SnOH · R3MX (M = Sn, Pb; X = Pseudohalide)
1975
Abstract The synthesis of the solid adducts Me3SnOH · Me3 SnNCO, Me3SnOH · Me3SnNCS, Me3SnOH · Me3PbN3, Ph3SnOH · Ph3SnN3 is reported. The compounds have been investigated by infrared and Mossbauer spectroscopy. Their structure probably consists of polymeric OH-R3Sn-X-R3Sn(Pb) chains in which hydroxyl and pseudohalide (X) groups are bridging pentacoordinate tin atoms. In contrast to the triphenyl compound, the trimethyl derivatives show evidence of hydrogen bonding between adjacent chains.
Unprecedented multistability in dodecanuclear complex compound observed by Mössbauer spectroscopy
2007
Abstract The precursors [Fe(III)( 5X L)Cl] ( 5X LH 2 = N , N ′-bis(1-hydroxy-2-benzyliden)-1,6-diamino-3-X-hexane, X = N,S) are high-spin ( S = 5/2) complexes. This precursors are combined with the bridging unit [(NC) 5 Fe(II)-CN-Co(III)(CN) 5 ] 6− to yield star-shaped dodecanuclear clusters, [( 5X LFe(III)-NC) 5 Fe(II)-CN-Co(III)(CN-Fe(III) 5X L) 5 ]Cl 4 . The star-shaped compounds are high-spin systems at room temperature. On cooling to 20 K some of the iron(III) centers in the N-star switch to the low-spin state as proven by Mossbauer spectroscopy, i.e. multiple electronic transitions, while the S-star remains in the high-spin state.
In situ— High Temperature Mössbauer Spectroscopy of Iron Nitrides and Nitridoferrates
2003
The stoichiometric iron nitrides γ′-Fe4N, e-Fe3N and ζ-Fe2N were characterized by Mossbauer spectroscopy. The thermal decomposition of e-Fe3N was studied in-situ by means of a specially developed Mossbauer furnace. We found e-Fe3N to γ′-Fe4N and e-Fe3Nx (x ≥ 1.3) as decomposition products and determined the border of γ′/e transformation at T ≅ 930 K. Mossbauer spectroscopy was applied to study in-situ the thermal decomposition of the nitridometalate Li3[FeIIIN2] and the formation of Li2[(Li1-xFeIx)N], the compound with the largest local magnetic field ever observed in an iron containing material. The kinetics of formation and the stability of Li2[(Li1-xFeIx)N] was of particular interest in …
A Novel Dinuclear Fe II Spin‐Crossover Complex Based on a 2,2‐Bipyrimidine Bridge Ligand: [Fe(CH 3 bipy)(NCS) 2 ] 2 bpym
2004
The dinuclear iron(II) complex {[Fe(CH3bipy)(NCS)2]2bpym} has been synthesised and its crystal structure determined at 293 K. The magnetic properties display intramolecular antiferromagnetic coupling at 1 bar (J = −4.2 cm−1), and the onset of a pressure-induced spin conversion is observed at 11 kbar. Magnetic field Mossbauer measurements have been carried out at 4.2 K, and indicate that the HS species correspond to [HS-HS] pairs. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Towards Molecular Conductors with a Spin‐Crossover Phenomenon:Crystal Structures, Magnetic Properties and Mössbauer Spectra of[Fe(salten)Mepepy][M(dm…
2005
Three new iron(III) compounds of formula [Fe(salten)Mepepy][M(dmit)2]·CH3CN (M = Ni, Pd, Pt; H2salten = 4-azaheptamethylene-1,7-bis(salicylideneiminate); Mepepy = 1-(pyridin-4-yl)-2-(N-methylpyrrol-2-yl) ethane; dmit2– = 1,3-dithiole-2-thione-4,5-dithiolato) have been synthesised and the crystal structure of each compound has been solved at different temperatures. The structures consist of alternating layers of [M(dmit)2]– units and [Fe(salten)Mepepy] cations. In the Ni compound photo-isomerisation of the Mepepy ligand can be observed in dichloromethane solution. The temperature dependence of the magnetic susceptibility of the compounds reveals a gradual S = 5/2 blabla S = 1/2 spin crossove…
Crystal structure, magnetic properties and Mössbauer studies of [Fe(qsal)2][Ni(dmit)2]
2007
Abstract A new compound of formula [Fe(qsal)2][Ni(dmit)2] (1) has been synthesised, structurally and magnetically characterised (qsalH = N-(8-quinolyl)salicylaldimine, dmit2− = 1,3-dithiol-2-thione-4,5-dithiolato). Its structural features and its magnetic behaviour were compared with those of [Fe(qsal)2]-based complexes, and more particularly [Fe(qsal)2][Ni(dmit)2] · 2CH3CN.
Thermal and Light-Induced Spin Transition in the High- and Low-Temperature Structure of [Fe0.35Ni0.65(mtz)6](ClO4)2
1996
The thermal and light induced spin transition in [Fe(0.35)Ni(0.65)(mtz)(6)](ClO(4))(2) (mtz = 1-methyl-1H-tetrazole) was studied by (57)Fe Mössbauer spectroscopy and magnetic susceptibility measurements. In addition to the spin transition of the iron(II) complexes the compound undergoes a structural phase transition. The high-temperature structure could be determined by X-ray crystallography of the isomorphous [Fe(0.25)Ni(0.75)(mtz)(6)](ClO(4))(2) complex at room temperature. The X-ray structural analysis shows this complex to be rhombohedric, space group Rthremacr;, with a = 10.865(2) Å and c = 23.65(1) Å with three molecules in the unit cell. The transition to the low-temperature structur…
Synthesis, crystal structure, magnetic properties and 57Fe Mossbauer spectroscopy of the new trinuclear [Fe3(4-(2'-hydroxyethyl)-1,2,4- triazole)6(H2…
2000
Hyetrz = 4-(2prime-hydroxyethyl)-1,2,4-triazole represents the first structurally characterized iron(II) spin crossover compound for which the structure has been solved above and below room temperature in both spin states. The compound crystallizes in the trigonal system, space group R3, a = 12.763(1) b= 67.144(1), V = 1684.3(1) 3, Z = 6 at 120K. At 330K the space group is retained and a = 13.0183(3) b=67.376(3), V = 1805.8(1) 3. The molecular structure consists of trinuclear FeII entities linked together by an unprecedented three-dimensional network of hydrogen bonds. This compound shows a gradual spin crossover behavior centered around room temperature, which has been followed by temperat…
Mononuclear Complexes of Iron(II) Based on Symmetrical Tripodand Ligands: Novel Parent Systems for the Development of New Spin Crossover Metallomesog…
2011
The synthesis and characterization of a series of mononuclear tripodand-based FeII complexes by means of Mossbauer andUV/Vis spectroscopic as well as magnetic methods is reported. The complexes were obtained from the reactions of FeII salt with heterocyclic aldehydes (imd = imidazole-4(5)-carboxaldehyde, py = picolinaldehyde, or 6-Mepy = 6-methylpicolinaldehyde) and a symmetric triamine [tren = tris(2-aminoethyl)amine, tame = 2,2,2-tris(aminomethyl)ethane, or tach = 1,3,5-cis,cis-cyclohexanetriamin]. Because of extreme rigidity of the capping triamine tach, the molecular structure of {Fe[tach(imd)3](BF4)2} (1) features an unprecedented tapered trigonal prismatic FeN6 polyhedron. The molecul…