Tetraalkylammonium salts, transition metal

Tetrailkylammonium hydroxide, 736 Tetraalkylammonium ozonide, 736 Tetraalkylammonium salts, transition metal peroxides, 1082... 

Group-IIIB element-transition-metal compounds have been synthesized by means of anionic metal bases and halide-free group-IIIB compounds. The carbonylate anions of Mn and Re interact with BHj to give [HjBMfCOlj]", which are best isolated as the tetraalkylammonium or phosphonium salts ... 

Most of the compounds listed in this class (Table 7) are tetraalkylammonium (R4N+) salts of metal dithiolene complexes. These salts generally exist in a 2 1 or 1 1 stoichiometry. The 2 1 salts, such as [ra-Bu4N]2[Cu(mnt)2]114) and [Et4N]2-[Cu(mnt)2]115,116) can exhibit interesting properties, but they will not be considered here since the transition-metal components are isolated from each other (d(M-M) > 5 A). 

Some homoleptic unsymmetrical (dmit/mnt, dmit/tdas) dithiolene nickel complex-based D-A compounds with D = TTF and EDT-TTF also exhibit metal-like conductivity (see Table I) (101). Their molecular structure is shown in Scheme 3. The unsymmetrical tetraalkylammonium salts [MLjLJ- (M = Ni, Pd, Pt) have been prepared by ligand exchange reaction between tetraalkylammonium salts of MLj and ML21 (128, 129) and the D-A compounds have been synthesized by electrooxidation. Among these complexes, only the Ni derivatives exhibit metallic-like properties, namely, TTF[Ni(dmit)(mnt)] (metallic down to --30 K), a-EDT-TTF[Ni(dmit)(mnt)] (metallic down to 30 K), TTF[Ni(dmit)(tdas)] (metallic down to 4.2 K), and EDT-TTF[Ni(dmit)(tdas)] (metallic down to --50 K) (see Table I). The complex ot-EDT-TTF-[Ni(dmit)(mnt)J is isostructural (130) to a-EDT-TTF[Ni(dmit)2)] [ambient pressure superconductor, Section II.B.2 (124)]. Under pressure, conductivity measurements up to 18 kbar show a monotonous decrease of the resistivity but do not reveal any superconducting transition (101). 

Schema 8.1 Electrochemical fabrication of nanosized transition metal colloids (the stabilizer is usually a tetraalkylammonium salt) [25],...

In another electrochemical approach we used inert electrodes and a transition metal salt such as PtCl2 as the source of metal [38]. Reduction of Pt at the cathode has to be compensated by some oxidative process at the anode. Therefore, we substituted tetraalkylammonium halides by the analogous acetates R4N CH3C02, hoping that they would fulfill three purposes, namely to function as the electrolyte, as the stabilizer and as the reductant (Kolbe-like) ... 

Another application concerns the fabrication of metallic and bimetallic nanostructures on surfaces by electron beam induced metallization of the RjN Br"-stabilized Pd and Pd/Pt colloids [48]. In a simple three-step process, namely dip-coating, electron beam writing of patterns (e.g. lines) and rinsing, lines having a thickness of only 30 nm were achieved. This technique is of potential interest in lithography and catalysis. Finally, tetraalkylammonium salt-stabilized transition... 

In an electrochemical way of making metal nanopartides, a solution of stabilizer e.g., tetraalkylammonium bromide in THF) is electrolyzed using an anode made of the metal of interest and an inert cathode.l Under the conditions of the electrolysis, dissolution of the anode material takes place via oxidation. The metal cations transfer to the cathode, where reduction, nucleation and finally stabilization occur. The size of thus-prepared nanopartides can be easily controlled by the current density. The method is applicable to many transition metals. Moreover, systems with two anodes of different metals result in the formation of bimetallic nanopartides. When oxidation of the anode metal is difficult, the metal of interest can be introduced as inorganic salt.h67] pd nanopartides, e.g., prepared via this method were found to be catalyticaUy active in the Heck reaction and the... 

Ethanol has also received considerable attention as a solvent over a long period of time. Data on this solvent, however, are rather few compared to methanol and very few systematic studies exist. Several solubility studies have been made since the publication of Seidell and Linke. Thomas has reported solubilities for the alkali metal iodides at 20 and 25°C, and observed a decrease in solubility with an increase in ionic radius of the cation. Deno and Berkheimer have reported the solubilities of several tetraalkylammonium perchlorates. In every case the solid phase was the pure salt. Solubilities for several rare earth compounds have been reported.Since all of these salts form solvates in the solid phase, the results cannot be used in thermodynamic calculations without the corresponding thermodynamic values for the solid phases. Solubilities of silver chloride, caesium chloride, silver benzoate, silver salicylate and caesium nitrate have been measured in ethanol, using radioactive tracer techniques. Burgaud has measured the solubility of LiCl from 10.2 to 57.6°C and observed that there is a transition from the four-solvated solid phase to the non-solvated phase at 20.4°C. 

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