Search results for "Mossbauer"
showing 10 items of 67 documents
Identification of Morphological Biosignatures in Martian Analogue Field Specimens Using In Situ Planetary Instrumentation
2008
International audience; We have investigated how morphological biosignatures (i.e., features related to life) might be identified with an array of viable instruments within the framework of robotic planetary surface operations at Mars. This is the first time such an integrated lab-based study has been conducted that incorporates space-qualified instrumentation designed for combined in situ imaging, analysis, and geotechnics ( sampling). Specimens were selected on the basis of feature morphology, scale, and analogy to Mars rocks. Two types of morphological criteria were considered: potential signatures of extinct life ( fossilized microbial filaments) and of extant life (crypto-chasmoendolit…
Synthese und Strukturen neuer Eisen-Sauerstoff-Alkoxid-Cluster
2004
Der Eisen-Sauerstoff-Alkoxy-Cluster [Fe9O3(OC2H5)21]·C2H5OH kann unter unterschiedlichen Bedingungen zu Molekulen umgesetzt werden, denen alle die allgemeine Formel [Fe5O(OR)8(OR′)5] gemeinsam ist. Erwarmt man [Fe9O3(OC2H5)21]·C2H5OH in Toluol, so entsteht [Fe5O(OC2H5)13], das durch Kristallisation abgetrennt werden kann, wohingegen ein Auflosen von [Fe9O3(OC2H5)21]·C2H5OH in tert-Butylamin zum 1 : 2-Addukt [Fe5O(OC2H5)13]·2 t-Bu-NH2 fuhrt. Mit Triethyl- oder Triphenylsilanol entsteht aus [Fe9O3(OC2H5)21]·C2H5OH wieder ein Sauerstoff-Eisencluster des gleichen Motivs: [Fe5O(OC2H5)8{OSi(C2H5)3}5] bzw. [Fe5O(OC2H5)8{OSi(C6H5)3}5]. Die Molekulstruktur [Fe5O(OC2H5)8{OSi(C2H5)3}5], die uber Rontg…
Spin crossover behavior in a series of iron(III) alkoxide complexes.
2015
The synthesis, crystal structures, magnetic behavior, and electron paramagnetic resonance studies of five new FeIII spin crossover (SCO) complexes are reported. The [FeIIIN5O] coordination core is constituted of the pentadentate ligand bztpen (N5) and a series of alkoxide anions (ethoxide, propoxide, n-butoxide, isobutoxide, and ethylene glycoxide). The methoxide derivative previously reported by us is also reinvestigated. The six complexes crystallize in the orthorhombic Pbca space group and show similar molecular structures and crystal packing. The coordination octahedron is strongly distorted in both the high- and low-temperature structures. The structural changes upon spin conversion ar…
Characterization of diorganotin(IV) complexes with captopril. The first crystallographically authenticated metal complex of this anti-hypertensive ag…
2003
Abstract Diorganotin(IV) complexes R 2 Sn(cap) (capH 2 = N -[( S )-3-mercapto-2-methylpropionyl]- l -proline; R=Me, Et, n -Bu and t -Bu) were prepared and characterised. The FTIR and Raman spectra demonstrated that the organotin(IV) moieties interact with the {S} atom of the ligand, while the other coordination sites are the carboxylate and the amide –CO groups. Mossbauer Δ data showed that the diorganotin(IV) compounds adopt slightly distorted trigonal-bipyramidal (tbp) geometry. A single-crystal X-ray study was performed on the compound Me 2 Sn(cap): the Sn atom is five-coordinated in a distorted tbp environment, with two {O} atoms in the axial positions and the {S} and two {C} atoms in t…
Synthesis, characterization, crystal structures and in vitro antistaphylococcal activity of organotin(IV) derivatives with 5,7-disubstituted-1,2,4-tr…
2011
Abstract New organotin(IV) complexes of 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine ( dbtp ) and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine ( dptp ) with 1:1 and/or 1:2 stoichiometry were synthesized and investigated by X-ray diffraction, FT-IR and 119 Sn Mossbauer in the solid state and by 1 H and 13 C NMR spectroscopy, in solution. Moreover, the crystal and molecular structures of Et 2 SnCl 2 (dbtp) 2 and Ph 2 SnCl 2 (EtOH) 2 (dptp) 2 are reported. The complexes contain hexacoordinated tin atoms: in Et 2 SnCl 2 (dbtp) 2 two 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine molecules coordinate classically the tin atom through N(3) atom and the coordination around the tin atom shows a …
Basaltic Rocks Analyzed by the Spirit Rover in Gusev Crater
2004
The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and MiniâThermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain â¤25% megacrysts. Chemical analyses of rocks by the Alpha Particle X-ray Spectrometer are consistent with picritic basalts, containing normative olivine, pyroxenes, plagioclase, and accessory FeTi oxides. MoÌssbauer, Pancam, and Mini-TES spectra confirm the presence of olivine, magnetite, and probably pyroxene. The…
Structure and physical properties of [mu-tris(1,4-bis(tetrazol-1-yl)butane-N4,N4 ')iron(II)] bis(hexafluorophosphate), a new Fe(II) spin-crossover co…
2004
[mu-Tris(1,4-bis(tetrazol-1-yl)butane-N4,N4')iron(II)] bis(hexafluorophosphate), [Fe(btzb)(3)](PF6)(2), crystallizes in a three-dimensional 3-fold interlocked structure featuring a sharp two-step spin-crossover behavior. The spin conversion takes place between 164 and 182 K showing a discontinuity at about T-1/2 = 174 K and a hysteresis of about 4 K between T-1/2 and the low-spin state. The spin transition has been independently followed by magnetic susceptibility measurements, Fe-57-Mossbauer spectroscopy, and variable temperature far and midrange FIR spectroscopy. The title compound crystallizes in the trigonal space group P (3) over bar (No. 147) with a unit cell content of one formula u…
Synthesis, characterization of diorganotin(IV) complexes of N-(2-hydroxyarylidene)aminoacetic acid and antitumour screening in vivo in ehrlich ascite…
2001
Some new diorganotin(IV) complexes have been prepared by reacting potassium N-(2-hydroxyarylidene)aminoacetate with R2SnCl2(R = Me,nBu,Ph). The complexes have been characterized by 1H,13C,119Sn NMR, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analysis. In the solid state, the complexes possess penta- and hexa-coordinated tin centres. The hexa-coordinated tin complexes were found to dissociate in solution, giving rise to penta-coordinated species as revealed by 119Sn NMR spectroscopy. Antitumour screening in vivo of the complexes L4snPh2,L4SnPh2· Ph3SnCl and L4SntBU2·t Bu2SnCl2 (L4 = N-(2-hydroxyacetophenone)aminoacetate) is also reported. Copyright © 2001 …
Organometallic complexes with biological molecules. XVIII. Alkyltin(IV) cephalexinate complexes: synthesis, solid state and solution phase investigat…
2004
Abstract Dialkyltin(IV) and trialkyltin(IV) complexes of the deacetoxycephalo-sporin-antibiotic cephalexin [7-( d -2-amino-2-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid] (Hceph) have been synthesized and investigated both in solid and solution phase. Analytical and thermogravimetric data supported the general formula Alk 2 SnOHceph · H 2 O and Alk 3 Snceph · H 2 O (Alk=Me, n -Bu), while structural information has been gained by FT-IR, 119 Sn Mossbauer and 1 H, 13 C, 119 Sn NMR data. In particular, IR results suggested polymeric structures both for Alk 2 SnOHceph · H 2 O and Alk 3 Snceph · H 2 O. Moreover, cephalexin appears to behave as monoanionic tridentate ligand coordinating th…
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)…