Silyl- and Germyl-Substituted Boranes: Synthesis and Investigation as Potential Atomic Layer Deposition Precursors.

Boranes featuring bulky hypersilyl or supersilyl groups and/or sterically unencumbered trimethylgermyl substituents were synthesized for investigation as potential precursors for atomic layer deposition (ALD) of elemental boron. The envisaged ALD process would employ a boron trihalide coreactant, exploiting the formation of strong silicon-halogen and germanium-halogen bonds as a driving force. The alkali metal silyl and germyl compounds hypersilyl lithium, {(MeSi)Si}Li(THF) (), supersilyl sodium, (BuSi)Na(THF) (, = 2-3), and trimethylgermyl lithium, {MeGeLi(THF)} (), were used for the synthesis of the silyl- and germyl-substituted boranes in this work.

Synthesis of Silyl Aluminum Reagents: Relevance Toward Atomic Layer Deposition of Metal Silicides and the Serendipitous Synthesis of a Novel Al-Hydride Cluster.

The novel mono-silyl [(RSi)AlX], di-silyl [(RSi)AlX], tri-silyl (RSi)Al·EtO, and -ate-complex [(RSi)Al]·Li(EtO) have been synthesized by reaction of AlX (X = Cl, Br) with silyl lithium reagents (BuMeSiLi, EtSiLi) in EtO. Treatment of these compounds with MeN yields the corresponding amine-coordinated silyl aluminum complexes (RSi)AlX·NMe, (RSi)AlX·NMe, and (RSi)Al·NMe. An intramolecular amine-coordinated mono-silyl aluminum complex MeN(CH)(BuMeSi)SiAlCl was prepared by the reaction of MeN(CH)(BuMeSi)SiLi with AlCl in EtO.

[Tenofovir-associated Fanconi`s syndrome and rickets in a HIV infected girl].

Unlabelled: Tenofovir (TDF) is an inhibitor of reverse transcriptase nucleotide analogue, although it has good tolerability and high anti-retroviral activity, its effect on the kidney has been a concern.

Objective: To describe a girl infected with HIV who presented Fanconi syndrome during antiretroviral therapy with TDF.

Clinical Case: We describe a HIV-1-infected girl, who after 18 months treatment with TDF presented loss of strength and pain of the lower extremities with functional impairment.

Synthesis, structural characterization and thermal properties of copper and silver silyl complexes.

The synthesis of copper and silver silyl complexes containing either N-heterocyclic carbenes or nitrogen donors is described. Alterations made to both the neutral donor ligands as well as the silyl group provided access to a number of different compounds. Many of the complexes synthesized were studied in the solid state and the effect of the donor ligand on the final structure of the complexes was examined.

Kinetic and thermodynamic analysis of processes relevant to initiation of olefin metathesis by ruthenium phosphonium alkylidene catalysts.

Initiation processes in a family of ruthenium phosphonium alkylidene catalysts, some of which are commercially available, are presented. Seven 16-electron zwitterionic catalyst precursors of general formula (H(2)IMes)(Cl)(3)Ru=C(H)P(R(1))(2)R(2) (R(1) = R(2) = C(6)H(11), C(5)H(9), i-C(3)H(7), 1-Cy(3)-Cl, 1-Cyp(3)-Cl, 1-(i)Pr(3)-Cl; R(1) = C(6)H(11), R(2) = CH(2)CH(3), 1-EtCy(2)-Cl; R(1) = C(6)H(11), R(2) = CH(3), 1-MeCy(2)-Cl; R(1) = i-C(3)H(7), R(2) = CH(2)CH(3), 1-Et(i)Pr(2)-Cl; R(1) = i-C(3)H(7), R(2) = CH(3), 1-Me(i)Pr(2)-Cl) were prepared. These compounds can be converted to the metathesis active 14-electron phosphonium alkylidenes by chloride abstraction with B(C(6)F(5))(3).

Fetal bovine serum concentration affects delta9 desaturase activity of Trypanosoma cruzi.

Fetal bovine serum (FBS) is an important factor in the culture of Trypanosoma cruzi, since this parasite obtains and metabolizes fatty acids (FAs) from the culture medium, and changes in FBS concentration reduce the degree of unsaturation of FAs in phosphoinositides. When T. cruzi epimastigotes were cultured with 5% instead of 10% FBS, and stearic acid was used as the substrate, (9) desaturase activity decreased by 50%.

Generation and spectroscopic characterization of ruthenacyclobutane and ruthenium olefin carbene intermediates relevant to ring closing metathesis catalysis.

The reaction of phosphonium alkylidenes [(H2IMes)RuCl2=CHPR3]+[A]- (R = C6H11, A = OTf or B(C6F5)4, 1-Cy; R = i-C3H7, A = ClB(C6F5)3 or OTf, 1-iPr) with 1 equiv of ethylene at -78 degrees C, in the presence of 2-3 equiv of a trapping olefin substrate, yields intermediates relevant to olefin metathesis catalytic cycles. Dimethyl cyclopent-3-ene-1,1-dicarboxylate gives solutions of a substituted ruthenacyclobutane 3 of relevance to ring closing metathesis catalysis. 1H and 13C NMR data are fully consistent with its assignment as a ruthenacyclobutane, but 1JCC values of 23 Hz for the CalphaH2-Cbeta bond and 8.

Mechanistic studies on 14-electron ruthenacyclobutanes: degenerate exchange with free ethylene.

The phosphonium alkylidene [(NHC)Cl2Ru=CH(PCy3)]+[B(C6F5)4]-, 1, (NHC = N-heterocyclic carbene, Cy = cyclohexyl, C6H11) reacts with 2.2 equiv of ethylene at -50 degrees C to form the 14-electron ruthenacyclobutane (NHC)Cl2Ru(CH2CH2CH2), 2. NMR spectroscopic data indicates that 2 has a C2v symmetric structure with a flat, kite shaped ruthenacyclobutane ring with significant Calpha-Cbeta agostic interactions with the Ru center.

Direct observation of a 14-electron ruthenacyclobutane relevant to olefin metathesis.

The 14-electron ruthenium phosphonium alkylidene complex [(IH2Mes)Cl2Ru=CH(PCy3)][B(C6F5)4], 1b, a highly active olefin metathesis catalyst, reacts with stoichiometric quantities of ethylene at -50 degrees C in CD2Cl2 to generate the ruthenacyclobutane complex [(IH2Mes)Cl2RuCH2CH2CH2], 2, and [CH2=CH(PCy3)][B(C6F5)4] in quantitative yield by NMR spectroscopy. 1H and 13C NMR spectroscopies on 2 and 2-13C3 are consistent with a symmetrical C2v structure, providing the first experimental information concerning this crucial intermediate in ruthenium-mediated olefin metathesis. At -50 degrees C, exchange with free ethylene takes place on the chemical time scale.