Tetrabutylammonium Hexafluoroarsenate

Initially, 3.97 g of potassium hexafluoroarsenate (17.4 mmol) in 36 mL of distilled water is added slowly to 140 mL of an aqueous solution that contains 6.42 g of tetrabutylammonium iodide [Alfa Inorganics] (17.4 mmol) at 60°. A pale yellow precipitate of tetrabutylammonium hexafluoroarsenate forms immediately. The mixture is stirred for 10 min and then allowed to cool to room temperature. The precipitate is removed by filtration and is washed with five 10-mL portions of distilled water. The crude product is recrystallized twice fix)m hot methanol. The yield is 5.77 g of white needles of [CH3(CH2)3]4N[AsFJ (13.4 mmol, 80%) (mp 245-248°). 

There are a few reports of poly(naphthalene) thin films. Yoshino and co-workers. used electrochemical polymerization to obtain poly(2,6-naphthalene) film from a solution of naphthalene and nitrobenzene with a composite electrolyte of copper(II) chloride and lithium hexafluoroarsenate. Zotti and co-workers prepared poly( 1,4-naphthalene) film by anionic coupling of naphthalene on. platinum or glassy carbon electrodes with tetrabutylammonium tetrafluoroborate as an electrolyte in anhydrous acetonitrile and 1,2-dichloroethane. Recently, Hara and Toshima prepared a purple-colored poly( 1,4-naphthalene) film by electrochemical polymerization of naphthalene using a mixed electrolyte of aluminum chloride and cuprous chloride. Although the film was contaminated with the electrolyte, the polymer had very high thermal stability (decomposition temperature of 546°C). The only catalyst-free poly(naphthalene) which utilized a unique chemistry, Bergman s cycloaromatization, was obtained by Tour and co-workers recently (vide infra). 

Polyselenophene (Fig. 16c) has been prepared. However, due to the difficulty in obtaining the monomer, the polymer has not been extensively investigated. Polymers of selenophene prepared electrochemically under appropriate conditions yield films with maximum conductivities of 10"- S cm [330,331]. Samples of p-doped selenophene produced chemically have conductivities on the same order of magnitude [332]. Applying 3-10 V between two electrodes in an electrolyte of 0.1 to 1 M lithium tetrafluoroborate or lithium perchlorate dissolved in benzonitrile or propylene carbonate gives polyselenophene films, as does the combination of tetrabutylammonium tetrafluoroborate in benzonitrile. However, other salts such as lithium hexafluoroarsenate, lithium hexafluorophosphate, tetrabutylammonium perchlorate, or silver perchlorate in combination with solvents such as acetonitrile or nitrobenzene were reported to produce either powders or no products at all [330,331,333]. 

---