Palladium and Platinum Complexes of Bis(alkylthio)alkanes

Novel bis (alkylthio )alkanes containing fluorinated substituents in either the sulphur atoms or the bridge have been prepared by metathetical or photochemical reactions e. g. CF3S- + CH3SCH2CH2Br --> CH3SCH2CH2SCF3 + Br- 2CH3SH + CF3C=CH -hv→ CH3CH(CF3)CH2SCH3 Photolytic reactions of CH3SSCH3 and CH3SH are considered to proceed via CH3S. radicals. Interaction of fluorinated bis (alkylthio )alkanes with [PdCl4]2-or [PtCl4]2- afforded 44 new complexes with the general formula (RSR'Sr'')MX2, where R and R'' - CH3, CF3, C6F5; R' = CH2CH2, CH(CH3) CH(CH3) CF2CH2,CH(CF3)CH(CF3), CH(CF3)CH2; M- Pd, Pt and X= Cl, Br, I; but not all combinations were obtained. Ligands containing both hydrocarbon and fluorocarbon sulphur substituents, e. g. CH3SC2H4SCF3, form 1:1 and 2:1 complexes acting as bidentate or monodentate ligands respectively. In the last case only the CH3S grouping is coordinated and both cis and trans isomers were obtained. No reaction was found to take place between fluorinated sulphides, e. g. CH3SCF3, and either palladium(II) or platinum(II) salts. Differences in the observed chemical reactions of hydrocarbon and fluorocarbon sulphides and dithioethers towards Pd(II) and Pt(II) are discussed in relation to the sulphur-metal bond. X-ray studies of (CF3SCH(CH3) CH2SCF3)PtCl2 have shown that sulphur-platinum bond lengths are slightly shorter than in cis ((p-C6H4Cl)2S)2PtCl2, the most directly comparable structure known. The results have also revealed strong non bonded sulphur-chlorine interactions between pairs of centrosymmetrically related molecules. In solution, all five membered chelate ring complexes exhibit isomerism due to inversion of configuration at sulphur. The total number of stereoisomers depends also on the substituents in the bridge. Thus for compound containing BSCH2CH2SR, RSCH(R)CH2SR and RSCH(R)CH(R)SR ligands, 2, 4 and 6 isomers are possible. N. m. r. spectra of the anti isomers of compounds containing bis (perfluoro-alkylthio)alkanes e. g. (CF3SC2H4SCF3)PtCl2 show fluorine-fluorine coupling between fluorine atoms in different sulphur substituents. This coupling is rationalized in terms of a 'through space' mechanism. N. m. r. spectra of (CF3SC2H4SCF3)PtClBr confirm the proposed structural assignment. The isomeric structure of most platinum compounds have also been tentatively assigned based on n. m. r. parameters. The effect of variable concentration in the bromine substitution reaction involving (CH3SCF3)PtCl2 has been monitored by n. m. r. spectroscopy. Substitution takes place, preferentially trans to the CF3S grouping. Viariable temperature n. m. r. of (CF3SC2H4SCF3)PtCl2 shows that the coalescence temperature of this compound is higher than that found for the corresponding hydrocarbon analogue, probably due to the higher electronegativity and larger mass of the fluorinated substituents. Dynamic n. m. r. studies of (CH3SCH(CF3)CH(CF3)SCH3)PtI2 found two different intramolecular processes: at 183 K the bridge carbon-carbon bond rotation is sufficiently slow to detect the individual resonances arising from two diastereoisomers of a syn isomer. At high temperature the coalescence of resonances arising from anti and syn structures is discussed in terms of sulphur inversion taking place preferentially at single sulphur atoms. Platinum chemical shifts determined for several complexes have been found to be dependent on both the ligands present and the structure of the compounds. The values of d195 Pt for different halide complexes seem to follow additive rules. Values of platinum chemical shift for different stereoisomers of a given complex are qualitatively discussed in terms of intramolecular magnetic fields. Brief studies of reduction and ligand substitution reactions e. g. bis(cyclo-octa-1,5-diene)platinum(0) + CF3SC2H4SCF3, were carried out in an attempt to obtain zerovalent platinum complexes with sulphur containing ligands

Efecto del tiempo de suplementación con vitamina E o pastoreo con alfalfa en el contenido de alpha-tocoferol en plasma y carne en la oxidación lipídica en corderos ligeros

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Influence of grazing on meat oxidation in light lamb

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Determinación de la concentración de α-tocoferol en carne de cordero a partir de la concentración de α-tocoferol en plasma

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Effect of grazing alfalfa on α-tocopherol content and FA composition in Longissimus and Semitendinosus muscles of light lambs

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Undertaken activities to recover and preserve the churra tensina sheep breed

En el caso de la raza Churra Tensina, en peligro de extinción y originaria del Pirineo Oscense, se realizó una prospección de individuos y una caracterización del sistema productivo a través de encuestas a ganaderos, definiéndose explotaciones de mediano tamaño que tienen su continuidad garantizada. Se estudió la morfología racial a partir de medidas zoométricas y caracteres fanerópticos de los animales inscritos en la Asociación (ATURA), lo que permitió clasificar la raza como mediolínea, dolicocéfala y eumétrica. Se estudiaron los parámetros productivos y reproductivos, así como la calidad de canal y carne de los tipos de cordero lechal, ternasco y pastenco, confirmando su viabilidad comercial. La caracterización genética mostró una raza homogénea, con niveles altos de variabilidad genética y bajos de consanguinidad. Finalmente, se han creado bancos de semen y embriones, estando representados los distintos genotipos de resistencia a Scrapie. La evolución positiva del censo en los últimos 10 años, añadida a la viabilidad de sus productos comerciales, garantiza la preservación de la Churra Tensina y de determinados sistemas ganaderos ligados a la tierra.This work aims to present the research activities in the Churra Tensina sheep breed, raised on the mountain area of Huesca Pyrenees. The population structure was prospected and the farming system was characterized through surveys to farmers. The animal morphology was studied through zoometric measurements and phaneroptic characters assessment of the individuals belonging to the breeders' Association (ATURA), showing a mediolineous, dolicocephalous and eumetric breed. The productive and reproductive parameters were analysed, and the commercial value of the suckling, light and heavy lamb categories was confirmed. The genetic studies showed that Churra Tensina is an homogeneous breed, with high genetic variability and low inbreeding. This breed was self-genetic differentiated, and has no crossbreeding with other Churro group populations. Finally, semen and embryos banks were established, being the different Scrapie resistance genotypes represented. The increasing census evolution in the past 10 years and the observed commercial viability assure the long term maintenance of this breed in their original location.Financiado por los proyectos INIA RZ2004-028, RZP2004-0008 y RTA2003-031

Efecto de la suplementación con vitamina E en los ácidos grasos poliinsaturados y en la expresión de genes relacionados con el metabolismo lipídico en L. Thoracis de corderos ligeros

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