Mercury bis(phenyltellurolate) as a precursor for the synthesis of binary and ternary nanoclusters

The reaction of Hg(TePh)2 with AgX (X = Cl, NO3) in the presence of PPh3 and PMePh2 in dimethylformamide (DMF) affords the cluster [Hg6Ag4(TePh)16] (1) at room temperature or [Hg6Ag4Te(TePh)14]2 (2) with heating. When Hg(TePh)2 is reacted with [Co(PPh3)2Cl2] or [Ni(PPh3)2Cl2], the clusters [Hg8Te(PhTe)12Cl4]Q [3; Q = [Co(DMF)6]2+ (3a), [Ni(DMF)6]2+ (3b)] are formed. The syntheses of 1 and 2 occur with the incorporation of AgI into the cluster, and the single-crystal analyses show that the two ternary clusters consist of Hg, Ag, and Te centers occupying well-defined positions. Compounds 3a and 3b do not show the incorporation of the metal into the cluster, but the CoII and NiII salts provide the Cl atom to generate the anionic cluster 3 stabilized by the [Co(DMF)6]2+ or [Ni(DMF)6]2+ ion.     

Copper-catalyzed sulfenylation of pyrroles with disulfides or thiols: directly synthesis of sulfenyl pyrroles

We present here the synthesis of sulfenyl pyrroles by copper-catalyzed sulfenylation of pyrroles with organic disulfides or thiols. The direct sulfenylation of pyrroles with organic disulfides has been accomplished in the presence of 3 mol % of CuI in DMSO at 110 °C under air atmosphere. In the other hand, sulfenylation of pyrroles with thiols were performed in the same solvent and temperature, however it is necessary 5 mol % of CuI and nitrogen atmosphere. Using these protocols we were able to produce 2-sulfenyl pyrroles in good to excellent yields and with high selectivity without use of any ligand or additive.     

Green synthesis of (−)-isopulegol from (+)-citronellal: application to essential oil of citronella

A simple green and efficient method has been developed for the synthesis of (−)-isopulegol from (+)-citronellal in the presence of a solid supported catalyst (SiO₂/ZnCl₂), under solvent-free conditions and MW irradiation. It was also found that the same technology is applicable to the direct preparation of (−)-isopulegol from the essential oil of citronella (Cymbopogon nardus, growing in southern Brazil) in excellent yield.     

Ion beam induced phase transformation in Fe–Mn bilayers: a Mössbauer study

Ion‐beam mixing of Fe–Mn bilayers induced by 100 keV krypton ions in the dose range (0.1-15)×10¹⁵ ions/cm²has been studied by means of conversion electron Mössbauer spectroscopy and X‐ray diffraction. The results indicate that a dose of about 1 ×10¹⁵ Kr⁺/cm² is sufficient to induce an appreciable mixing between the two atomic species. The α-Fe(Mn)solid solution presents a maximum at this dose, while at higher doses also the ? and γFe–Mn phases are formed in an appreciable amount. Heating of irradiated samples evidences the metastable character of ? phase and favours the growth of the terminal structures γ-Fe(Mn) and α-Mn(Fe) of the Fe–Mn equilibrium phase diagram.     

A new approach to the discretization of chaplygin’s method

5. Conclusion Chaplygin’s method is not convenient for the application in analytical form. However, the discretization of this method can be made successfully. The method of discretization described in this work is easy for the program-ming and, in some cases, gives better results than the Runge—Kutta method. Specifically, this happens when the steph is relatively small. It is highly un-likely that more than 6 iterations are necessary to achieve full accuracy, with 3 iterations being the most usual case. The fact that the upper and lower Chaplygin’s boundary functions be-come almost identical after several iterations (in the sense of the floating point representation of their values on the grid) did not produce noticeable problems, even though it means evident departure from the assumptions of Chaplygin’s Theorem (specifically, the solution of the differential equation ceases to be bounded by the lower and upper functions). Nevertheless, the definite conclusion on this subject requires further theoretical investigation.     

Metallation of Ligands with Biological Activity: Synthesis and X‐ray Characterization of the New Sulfathiazolato Complexes of Gold(I) and Silver(I): [(sulfathiazolato)AuPPh3] and [Ag(sulfathiazolato)]2 (sulfathiazole = N1‐2‐thiazolyl‐sulfanilamide)

Sulfathiazole reacts with [Ph₃PAu(CH₃COO)] in benzene and with Ag(CH₃COO) in methanol giving [(sulfathiazolato)AuPPh₃] ( 1 ) and {[Ag(sulfathiazolato)]₂}_n ( 2 ). While the lattice of 1 contains single molecules with linear N–Au–P bonds, compound 2 performs a polymeric, one‐dimensional assembling of [Ag(sulfathiazolato)]₂ dimers linked through intermolecular Ag···O=S=O interactions along the crystallographic axis b. The silver atoms achieve a tetrahedral configuration through Ag–Ag contacts which measure 2.8427(4) Å, considerably shorter than the normal bonding distance of metallic silver.     

Supramolecular Assembling of Complex Tellurium Salts: Synthesis and Crystal Structures of {Cs[PhTeCl4]·CH3OH} and Cs[PhTeBr4]

The direct reaction between PhTeCl₃ and CsCl in methanol affords {Cs[PhTeCl₄]·CH₃OH}. Cs[PhTeBr₄] was prepared by refluxing [2‐Br‐C₅NH₅][PhTeBr₄] and CsCl in ethanol in the presence of an excess of HBr. In {Cs[PhTeCl₄]·CH₃OH} the [PhTeCl₄]^— units form dimers by secondary Te···Cl bonds with methanol molecules bridging adjacent Cs⁺ cations. In both compounds, the alkali metal cation interacts secondarily with the chlorine and bromine Te‐ligands, achieving singular coordination polyhedrons and holding the lattices in supramolecular tridimensional assemblies. The new complexes, {Cs[PhTeCl₄]·CH₃OH} and Cs[PhTeBr₄], crystallize in the space groups P2₁/c and P2₁/n, respectively. Only one such structure has been reported before.     

Polymeric assembling through reciprocal metal-η-arene π-interactions: Synthesis and X-ray characterization of [Hg(RPhNNNPhR′)2Py]2 (R = NO2, R′ = F), an asymmetric bis diaryl-substituted triazenide-pyridinyl complex of Hg(II)

Hg(SCN)₂ reacts with 3-(2-fluorophenyl)-1-(4-nitrophenyl)triazene in tetrahydrofuran in the presence of triethylamine to give orange crystals of [Hg^II(RPhNNNPhR′)₂Py]₂ (R = NO₂, R′ = F), a new polymeric triazenide-pyridinyl complex of Hg(II) with reciprocal metal-η²-arene π-interactions. The crystal structure belongs to the triclinic space group , and the lattice of [Hg^II(RPhNNNPhR′)₂Py]₂ can be viewed as a supramolecular unidimensional assembling of tectonic [Hg^II(RPhNNNPhR′)₂Py] units linked through intermolecular metal-arene π interactions and non-classical C-H?O hydrogen bonding.     

Clean and atom-economic synthesis of octahydroacridines: application to essential oil of citronella

A green and efficient method for the synthesis of octahydroacridine (OHA) has been developed by a simple one-pot hetero-Diels-Alder reaction starting from (+)-citronellal and N-arylamines in the presence of a solid supported catalyst (SiO₂/ZnCl₂), under MW irradiation and without any solvent. The method was used in the direct preparation of OHA from citronella oil in good yield.