Search results for "halides"
showing 10 items of 33 documents
Magnetic Properties of a New Hexahalorhenate(IV) Compound and Structural Comparison with Its Hexahaloplatinate(IV) Analog
2020
Adducts of 1,4-diazabutadienes with group IIB metal halides
1981
Abstract The reactions of 1,4-diazabutadienes (or α-diimines) RNC(R′)C(R″)NR, DAB, (R = p -C 6 H 4 OMe, R′ = R″ = H, DAB I ; R = p -C 6 H 4 OMe,R′ = H, R″ = Me, DAB II ; R = p -C 6 H 4 OMe, R′= R″ = Me; DAB III ; R = CMe 3 , R′ = R″ = H, DAB IV ) with MX 2 M = Zn, Cd, Hg; X = CI, Br) yield in general 1/1 adducts. These species are assigned a monomeric configuration with a σ,σ′-N,N′, chelating DAB ligand for M = Zn, Hg, whereas the CdCl 2 adducts have polymeric structures with terminal and/or bridging chlorides. In the reactions of CdCl 2 with DAB I or DAB IV polymeric species [(CdCl 2 ) 2 (DAB)] x are obtained in which all chlorides are bridging. Spectrophotometric dissociation equilib…
Proton sponge lead halides containing 1D polyoctahedral chains
2021
Hybrid one-dimensional lead halides, containing the protonated 1,8-bis(dimethylamino)naphthalene moiety (C14H19N2, monoprotonated "proton sponge"), were prepared by simple one-pot methods and investigated in terms of crystal structure, morphology, thermal stability and electronic properties. The as-precipitated (C14H19N2)PbBr3 and (C14H19N2)PbI3 species are isostructural and crystallize in the orthorhombic Pbca space group, resulting in 1D crystal phases with ([PbX3](-))(infinity) chains (built by face-sharing [PbX6] octahedra; X = Br, I), among which the (C14H19N2)(+) cations are inserted. The two compounds display complete miscibility in the solid state: both (C14H19N2)PbI2Br and (C14H19N…
Making by Grinding: Mechanochemistry Boosts the Development of Halide Perovskites and Other Multinary Metal Halides
2019
Mechanochemical synthesis has recently emerged as a promising route for the synthesis of functional lead halide perovskites as well as other (lead‐free) metal halides. Mechanochemical synthesis presents several advantages with regards to more commonly used solution‐based processes such as an inherent lower toxicity by avoiding organic solvents and a finer control over stoichiometry of the final products. The ease of implementation, either through the use of a simple mortar and pestle or with an electrically powered ball‐mill, and low amount of side products make mechanochemical synthesis appealing for upscaling the production of halide perovskites. Due to the defect tolerance of lead halide…
The Antimicrobial Action of Silver Halides in Calcium Phosphate
2014
Silver halides represent a yet unexplored avenue for imparting antimicrobial activity to calcium phosphates. Negtively charged silver halide colloids (AgI, AgBr and AgCl) were added to synthesized amorphous calcium phosphate. Concurrent melting of silver halides and crystallization to carbonated apatite at 700 oC increased the silver halide surface area available to bacteria and formed a lower solubility apatite. The effect of the matrix solubility on antimicrobial response could then be investigated. Pseudomonas aeruginosa was more sensitive to silver iodide and silver bromide than Staphylococcus aureus. Silver iodide demonstrated greater activity than silver bromide. Silver chloride did n…
Palladium-Catalysed Intermolecular Direct C–H Bond Arylation of Heteroarenes with Reagents Alternative to Aryl Halides: Current State of the Art
2022
Abstract: This unprecedented review with 322 references provides a critical up-to-date picture of the Pd-catalysed intermolecular direct C–H bond arylation of heteroarenes with arylating reagents alternative to aryl halides that include aryl sulfonates (aryl triflates, tosylates, mesylates, and imidazole-1-sulfonates), diaryliodonium salts, [(diacetoxy)iodo]arenes, arenediazonium salts, 1-aryltriazenes, arylhydrazines and N’-arylhydrazides, arenesulfonyl chlorides, sodium arenesulfinates, arenesulfinic acids, and arenesulfonohydrazides. Particular attention has been paid to summarise the preparation of the various arylating reagents and to highlight the practicality, versatility, and limit…
Direct catalytic cross-coupling of alkenyllithium compounds
2015
A catalytic method for the direct cross-coupling of alkenyllithium reagents with aryl and alkenyl halides is described. The use of a catalyst comprising Pd-2(dba)(3)/XPhos allows for the stereoselective preparation of a wide variety of substituted alkenes in high yields under mild conditions. In addition (1-ethoxyvinyl) lithium can be efficiently converted into substituted vinyl ethers which, after hydrolysis, give readily access to the corresponding methyl ketones in a one pot procedure.
Palladium-catalysed direct cross-coupling of secondary alkyllithium reagents
2014
Palladium-catalysed cross-coupling of secondary C(sp(3)) organometallic reagents has been a long-standing challenge in organic synthesis, due to the problems associated with undesired isomerisation or the formation of reduction products. Based on our recently developed catalytic C-C bond formation with organolithium reagents, herein we present a Pd-catalysed cross-coupling of secondary alkyllithium reagents with aryl and alkenyl bromides. The reaction proceeds at room temperature and on short timescales with high selectivity and yields. This methodology is also applicable to hindered aryl bromides, which are a major challenge in the field of metal catalysed cross-coupling reactions.
Secondary minerals from halite caves in the Atacama Desert (Chile)
2017
In the past 15 years several expeditions by French, American and especially Italian cavers have surveyed over 15 km of salt cave passages in the Cordillera de la Sal, close to San Pedro de Atacama village (Atacama Desert, Northern Chile). Over 50 caves have been explored up to now at an elevation around 2,500 m asl. These karst systems are characterized by in-cave temperature of around 17 °C and a relative humidity always very low, with a maximum of 15%. This extreme aridity is due to the severe conditions of the area with only a couple millimeters annual rainfall and several years without rain. Currently the rare precipitation events are enough to allow the dissolution of the salt rock and…
Dissolved silica in the Garonne River waters : changes in the weathering dynamics
2000
The major ion chemistry of the Garonne River is indicative of seasonal variations in the weathering dynamics of the drainage basin. Using the geochemical model MEGA for calculation of the contribution of atmospheric CO2 to the total bicarbonate fluxes exported by the Garonne River allows estimations of the concentrations of the major dissolved elements that originate from silicate- and carbonate-rock weathering. The molecular ratio SiO2/Al2O3 was calculated for the 1989–1992 period to identify the main type of weathering in the Garonne River, and montmorillonite was shown to be the major mineral occurring in the weathering products. The seasonal variations of the SiO2/Al2O3 ratio also showe…