Subject from metal halides

Torsional barriers for trimethylphosphine derivatives (63) have been obtained from Raman spectra.56 Vibrational spectra for the uranyl nitrate complex of (63a) have been published.66 Complexes of triarylphosphine derivatives (64) with iodine,67 and of (64b) with metal halides,68 have been the subject of thermodynamic67 and spectroscopic67 68 study. 

Organic electroreductive coupling reactions using transition-metal complexes as catalysts have been widely investigated. Reviews on the subject have been published [89, 90]. The method involving the most common transition-metal complexes (nickel, cobalt, palladium) appears to be a useful tool to synthetize heterocycles from organic halides via radical intermediates. Nickel catalyst precursors are nickel(II) salts that are cathodically reduced either to nickel(I) or to nickel(O) and cobalt catalyst... 

In comparison with classic Lewis acids derived from main group halides (e.g., B, Al, Sn), f-elements, and early transition metal halides, late transition metal Lewis acids often are more inert to ubiquitous impurities such as water, offer higher stability, tunable properties by ligand modification, and a well-defined structure and coordination chemistry, thus allowing detailed studies of reaction mechanisms, and a rational basis for catalyst optimization. Among this new class of late transition metal Lewis acids, ruthenium complexes - the subject of this chapter - display remarkable properties... 

The studies were carried out in a hermetic stainless steel vessel in helium at 750°C. As the melt container a nickel crucible was used. Alkali metal halides were carefully dehydrated by stepwise heating up to 650 C under vacuum followed by melting in an inert atmosphere. Potassium fluorotantalate was obtained from tantalum metal. Prior to conducting the experiments the melt was subjected to electrolysis with tantalum electrodes. The working specimens cut from nickel rolled stock (-10 or 5 x -50 x 0.4 mm) were treated in the (HNO3 +H2SO4+H3PO4) mixture. The reference electrode was a chemically polished tantalum rod. In the experiments PI-50-1.1 potentiostat and PDA-IA recorder were used. 

Apart from the arene substrate and an alkyl halide or acyl halide/acid anhydride, Friedel-Crafts alkylations and acylations most often involve a Lewis acid promoter in the form of a metal halide, like AlCl. Several species may function as the active electrophile, and both acyl halide/metal halide complexes and acylium ions have been observed experimentally. The complex forming ability of these metal halides complicates all mechanistic evaluations, and Friedel-Crafts reactions have rarely been the subject of quantum chemical mechanistic studies. 

In 1923 nothing was known about the properties of gaseous monomeric alkaU metal halides and Lewis wrote In my earliest speculations on this subject 1 thought of the molecule of sodium chloride as produced by the complete transfer of an electTOTi from the sodium atom to the chlorine atom. But would this be found to be the case if we should study more carefully the properties of sodium chloride in the gas phase [6]. We shall consider bonding in the Group 1 and 2 metal halides in Sects. 2 and 3, respectively. 

Metallic sodium. This metal is employed for the drying of ethers and of saturated and aromatic hydrocarbons. The bulk of the water should first be removed from the liquid or solution by a preliminary drying with anhydrous calcium chloride or magnesium sulphate. Sodium is most effective in the form of fine wire, which is forced directly into the liquid by means of a sodium press (see under Ether, Section II,47,i) a large surface is thus presented to the liquid. It cannot be used for any compound with which it reacts or which is affected by alkalis or is easily subject to reduction (due to the hydrogen evolved during the dehydration), viz., alcohols, acids, esters, organic halides, ketones, aldehydes, and some amines. 

The Ag electrodes were subjected to potential sweep ORCs at 10 mV s"1 in either 0.1 M KC1 or 0.1 M KBr from an initial potential of -0.30 V to more positive potentials. After ca. 30 mC cm-2 of anodic charge was passed, the direction of potential sweep was reversed to reduce the Ag halide surface to Ag metal. The roughened electrode was then removed under potential control at -0.30 V and immersed in the Pb2+-containing test solution for SERS studies. 

Alkyl azides are conveniently prepared from the reaction of alkali metal azides with an alkyl halide, tosylate, mesylate, nitrate ester or any other alkyl derivative containing a good leaving group. Reactions usually work well for primary and secondary alkyl substrates and are best conducted in polar aprotic solvents like DMF and DMSO. The synthesis and chemistry of azido compounds is the subject of a functional group series. ... 

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