Alkali metal fluoride complexes

Several alkali metal fluoride complexes withXeOF are known, such as 3KF XeOF [12186-19-5], 3RbF -2K.eO [12186-23-1], CsF XeOF ... 

When no catalyst is used or if KF and NaF are present as catalysts, CIF is the main by-product. When the more basic alkali metal fluorides, RbF and CsF, are used, CIF3 is the favored coproduct. The formation of CIF 3 rather than CIF is presumably associated with the more ready formation of C1F2 intermediates with RbF and CsF. Yields of CIF3O from CljO are rather variable and may be affected by the particular alkali fluoride present. Yields of over 40% have been consistently obtained and have reached over 80% using either NaF or CsF. Since NaF does not form an adduct with CIF3O (64), stabilization of the product by complex formation does not seem to influence the CIF3O yields strongly. 

Table 3 [18]Crown-6 Complexed Alkali Metal Fluoride Reactions (74JA2250)...

Fluorinations by alkali metal fluorides are often carried out in high-boiling solvents. Crown ethers have been used to solvate inorganic fluorides by complexation. 

Many chemical properties of beryllium resemble aluminum, and to a lesser extent, magnesium. Notable exceptions include solubility of alkali metal fluoride-beryllium fluoride complexes and the thermal stability of solutions of alkali metal beryllates. 

Unlike Sep4, which forms 1 1 ionic complexes containing the SeFs ion with alkali metal fluorides, only octahedral ions of the type [SeXe] are known for SeCU and SeBr4 (equation 30). 

Protaetinium(V) oetafluoro complexes, MgPaF, have been prepared (5, 35, 37, 59) by precipitation from aqueous hydrofluoric acid (M = Li, Na, and Rb), by heating the alkali metal fluoride with the corresponding heptafluoro complex in argon (M = K and Cs) or by fluorinating the product obtained by evaporation of a hydrofluoric acid solution containing 3 1 mixtures of MF and Pa(V). 

Consequently, in early 1953, research on these complex compounds was initiated to determine whether they were suitable for electrolytic aluminum deposition. The first trials ended in disappointment, because the electrolytes, employed as melts, yielded useless aluminum coatings containing large portions of alkali metal. Besides, the electrolytes showed a very low conductivity compared to aqueous systems. Attempts to improve the quality of the aluminum deposits by adding excess triethylaluminum led to unexpected observations. Hence, a detailed investigation of alkali metal fluoride-aluminum trialkyl systems was necessary. 

Complex Chemical Behavior of Coordination Complexes of Alkali Metal Fluorides and Aluminum It ialkyls... 

The fluorides of the alkali metals Na, K, Rb, and Cs, together with aluminum trialkyl, form two classes of complex compounds [118, 120, 135, 215, 217]. With a molar ratio of one for alkali metal/R3Al, complexes of the type MP3AIF] (1 1 complexes) result with a molar ratio of 0.5, complexes of the type M[RgAl2F] (1 2 complexes) are formed. 

Melts or solutions of the 1 1 complexes of alkali metal fluorides with aluminum trialkyls show only a moderate electrolytic conductivity of /c = 0.1 to 4 mS cm" at 100 °C. During electrolysis of these compounds, spongy cathodic deposits containing alkali metal are obtained [118, 217, 221]. 

The 1 2 complexes of alkali metal fluorides dissolve well in aromatic hydrocarbons, such as toluene or xylene, at least at higher temperatures. 

Ikble S. Melting points and specific conductivities of molten organo-aluminum 1 2 complexes of alkali metal fluorides [13S]. 

Defined 1 2 complexes with two different aluminum trialkyls in a stoichiometric ratio of 1 1 can be synthesized either from the individual components, i. e., alkali metal fluoride, AIR3 and AlRf or by reacting the 1 1 complex of a particular alkylaluminum with a stoichiometric amount of a second type of alkylaluminum. Alternatively, the varying complex formation tendency of the aluminum trialkyls can be exploited by displacing one of the alkylaluminum groups of the 1 2 complex by a stronger complexing alkylaluminum [118], for example... 

The observation that only dark gray, spongy aluminum containing alkali metal is deposited by electrolysis of 1 1 complexes of alkali metal fluorides with aluminum trialkyls made it seem useful to try to suppress alkali metal deposition by adding Eiluminum trialkyls to the 1 1 complexes [118]. It is well known that aluminum trialkyls react easily with alkali metals, for example with sodium, to give alkali metal tetraalkyl aluminates and aluminum metal [135]. 

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