The multiple binding modes of [3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ]allow it to adjust to different coordinating or geometric demands. [3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ]can behave as a platform on which two types of coordinating moieties exist: the BH's and boron-or carbon-bonded elements with available lone pairs. Until now, no compounds containing Na + bonded to thioether ligands were known other than Na [7,8-The dithioether moiety in the latter compound is preorganized to favor chelation and produces a five-membered ring. This definitely assists in coordination to sodium. To avoid this preorganization and assess the independent strength of the C-S(thioether)-Na bond, the anionic nonpreorganized dithioetherligand was synthesized. The two cluster moieties have sufficient accessible rotamers to allow adequate metal coordination, but they do not preorganize. The synthetic procedure leading toimplied the formation of idealized meso and racemic forms. These forms behave differently toward Na + . In the meso form coordination to sodium is achieved via the two sulfur (C-S) and three oxygen elements in the exo cluster chain. In the racemic form coordination is achieved via the three oxygen elements in the exo cluster chain, with no thioether participation. The remaining Na + coordination sites are filled by oxygen atoms from ancillary ligands. These coordination environments were determined by the crystal structures of Na[1,1′-µ-{S(CH 2 CH 2 O) 3 CH 2 -CH 2 S}-3,3′-Co(1,2-C 2 B 9 H 10 ) 2 ]‚ (CH 3 ) 2 CO‚CHCl 3 ‚CH 2 Cl 2 (meso form) and Na[1,1′-µ-{S(CH 2 -CH 2 O) 3 CH 2 CH 2 S}-3,3′-Co(1,2-C 2 B 9 H 10 ) 2 ]‚2(CH 3 ) 2 CO (racemic form). Therefore, C-S(thioether)-Na coordination has been demonstrated for the first time with nonpreorganized ligands, although the cluster participation has been found necessary. A situation similar to that obtained with the racemic form of [1,1′-µ-{S(CH 2 CH 2 O) 3 CH 2 CH 2 S}-3,3′-Co(1,2-C 2 B 9 H 10 ) 2 ] -, having only three coordinating oxygen atoms, is also possible for [3, 9 H 11 )] -. This ligand does not have thioethers, and it was interesting to discover how the [3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ]moiety would behave with a low supply of coordination sites in a more flexible -O-CH 2 CH 2 -O-CH 2 CH 2 -O-CH 2 CH 3 arrangement. The structure of Na[3,3′-Co(8-{O(CH 2 CH 2 O) 2 CH 2 CH 3 }-1,2-C 2 B 9 H 10 )(1′,2′-C 2 B 9 H 11 )] shows that the chain contributes three oxygen atoms for coordination to Na + and, interestingly, the [3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ]moiety provides three extra B-H coordination sites.

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Regioselective monoalkylation and monoarylation in cobaltabisdicarbollide clusters has been achieved starting from Cs[8-I-3,3'-Co(1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))] by cross-coupling reactions between a B-I fragment and an appropriate Grignard reagent in the presence of a Pd catalyst and CuI. A considerable number of monoalkylated and monoarylated derivatives have been synthesized, which allowed study of the influence of boron in metallocene-type ligands and the effect of alkyl and aryl substituents on boron in boron anionic clusters. Experimental data from UV/Vis spectroscopy, E(1/2) measurements, and X-ray diffraction analysis, and supported by EHMO and ab initio analyses, indicate that the participation of metal d orbitals in the HOMO is less than that in typical metallocene complexes. This can be explained in terms of the lower electronegativity of boron compared to carbon. Related to this is the -I character of alkyl groups when bonded to boron in boron anionic clusters, contrary to the common belief that alkyl groups are generally electron-releasing moieties.

LSN862 is a novel peroxisome proliferator-activated receptor (PPAR)alpha/gamma dual agonist with a unique in vitro profile that shows improvements on glucose and lipid levels in rodent models of type 2 diabetes and dyslipidemia. Data from in vitro binding, cotransfection, and cofactor recruitment assays characterize LSN862 as a high-affinity PPARgamma partial agonist with relatively less but significant PPARalpha agonist activity. Using these same assays, rosiglitazone was characterized as a high-affinity PPARgamma full agonist with no PPARalpha activity. When administered to Zucker diabetic fatty rats, LSN862 displayed significant glucose and triglyceride lowering and a significantly greater increase in adiponectin levels compared with rosiglitazone. Expression of genes involved in metabolic pathways in the liver and in two fat depots from compound-treated Zucker diabetic fatty rats was evaluated. Only LSN862 significantly elevated mRNA levels of pyruvate dehydrogenase kinase isozyme 4 and bifunctional enzyme in the liver and lipoprotein lipase in both fat depots. In contrast, both LSN862 and rosiglitazone decreased phosphoenol pyruvate carboxykinase in the liver and increased malic enzyme mRNA levels in the fat. In addition, LSN862 was examined in a second rodent model of type 2 diabetes, db/db mice. In this study, LSN862 demonstrated statistically better antidiabetic efficacy compared with rosiglitazone with an equivalent side effect profile. LSN862, rosiglitazone, and fenofibrate were each evaluated in the humanized apoA1 transgenic mouse. At the highest dose administered, LSN862 and fenofibrate reduced very low-density lipoprotein cholesterol, whereas, rosiglitazone increased very low-density lipoprotein cholesterol. LSN862, fenofibrate, and rosiglitazone produced maximal increases in high-density lipoprotein cholesterol of 65, 54, and 30%, respectively. These findings show that PPARgamma full agonist activity is not necessary to achieve potent and efficacious insulin-sensitizing benefits and demonstrate the therapeutic advantages of a PPARalpha/gamma dual agonist.

Long-term performance assessment of nuclear waste repositories is affected by the ability of the outer barrier systems to retain radionuclides after possible corrosive leakage of waste containers. The mobility of the radionuclides released from the spent fuel depends strongly on the processes that take place in the backfill material. The interaction of steel corrosion products and radionuclides is part of such a scenario. In this work, the sorption of Th(IV) onto 2-line-ferrihydrite (FeOOH x H2O) and magnetite (Fe3O4), used as models for steel corrosion products, has been studied using EXAFS spectroscopy. Sorption samples were prepared in 0.1 M NaClO4 solutions at acidic pH (initial pH values in the range 3.0-4.2) either from undersaturation and supersaturation conditions with respect to amorphous ThO2. Two oxygen subshells, one at 2.37 A and another at 2.54 A, were observed in the first hydration sphere of Th in the case of the ferrihydrite samples. Th-Fe distances for the different ferrihydrite samples are approximately 3.60 A. These results indicate a corner sharing surface complex of Th(IV) ion onto the ferrihydrite surface where the Th atom shares one O atom with each of two coordinated octahedra. The longer Th-O distance accounts for coordinated water molecules. No significant changes in the structural environment of Th in terms of coordination numbers and distances were detected as a function of Th(IV) concentration. Magnetite samples sorbing Th(IV) also showed also a strong distortion of the O shell, but in contrast to ferrihydrite, two types of nearest Fe atoms were detected at 3.50 A and 3.70 A. These results indicate that Th(IV) ion sorbs onto the magnetite surface as bidentate-corner sharing arrangements to [FeO6] octahedra and [FeO4] tetrahedra.