Tetraphenylarsonium ions

The exchange between the ruthenium anions RuO and RuO " in aqueous hydroxide media has been found rapid. A limit for the rate coefficient at 0 °C of > 1.7x10 l.mole . sec has been proposed by Luoma and Brubaker. The isotopic method ( ° Ru), and separation procedures based on the precipitation of the Ru04 or RuOJ species with barium or tetraphenylarsonium ions, respectively, were used. Attempts to use an esr technique failed. 

Here, TPhAs and DPA denote tetraphenylarsonium ion and dipicrylaminate ion, respectively. 

Similarly, in 0.1 M hydrochloric acid or at pH 5.3 resolution from the wave of triphenylarsine oxide is not possible. At pH > 7 only the latter species is active. Thus, by choice of a suitable pH, specific determination of phenylarsonic acid, diphenylarsinic acid and triphenylarsineoxide in mixtures is possible. Inorganic arsenic(V) is electroinactive while the tetraphenylarsonium ion is reduced at much more negative potentials. Arsenic(III) species are reduced at more positive potentials. Polarography is thus of value for the quantitative speciation of organoarsenic samples. 

In the extraction-spectrophotometric methods, the ion-association complexes of dichromate ions (in dilute H2SO4 medium) with tribenzylamine, TOA or Aliquat 336 [4], tetraphenylarsonium ion [26], or 1-naphthylmethyltriphenylphosphonium ion [27] are extracted into CHCI3 or 1,2-dichloroethane. 

Gallium has been extracted from HCl media into chloroform in the presence of N-benzylaniline [3,4], n-octylaniline [5], and crown ethers (e.g., dicyclohexyl-18-crown-6) [6], and into o-dichlorobenzene in the presence of the tetraphenylarsonium ion [7]. Gallium has been separated from In and other metals by extraction into non-polar solvents in the form of its chelates with cupferron [8], HTTA [9], BPHA, p-diketones [10], and alkylphosphoric acids [11]. Gallium has been extracted also, from citric acid solutions of pH 2-3.5, into xylene solutions of Amberlit LA-2 [12] and Aliquat 336S [13]. 

Ruthenium can be separated from osmium by extraction as the ion-pair of perruthenate [Ru(VIII)] with tetraphenylarsonium ion [19] or with benzyltributylammonium chloride [20]. 

Values of A(i.G° for the alkali metal cations together with the value for the tetraphenylarsonium ion are given in table 4.6 for the solvents considered in this chapter. For the alkali metal ions, A(rG° is both positive and negative, the latter values indicating that the ion is more stable in the non-aqueous environment. In the case of the Na ion, varies from —17 kJ moP in hexamethylpho-... 

Similarly, the uranyl ion is extracted from aqueous nitrate solution into isobutanol by associating with two nitrate ions (U02 , 2N03 ), with the uranium probably being solvated by the solvent to make it solventlike. Permanganate forms an ion pair with tetraphenylarsonium ion [(C6H5)4As , Mn04"], which makes it organiclike, and it is extracted into methylene chloride. There are numerous other examples of ion-association extractions. 

Although aryl halides do not normally add to arsines, Chatt and Mann 159) found that bromobenzene and triphenylarsine yield, in the presence of aluminum trichloride, the tetraphenylarsonium ion. The reaction is believed to proceed by addition to an initially formed 1 1 complex 160). 

Chatt and Mann found that the tetraphenylarsonium ion could also be obtained from chlorophenylarsines (159). 

Complexes of the bisethoxydithiophosphinate ion [(C2HsO)2PS2] for all the lanthanides are readily obtained by adding the tetraphenylarsonium ion to an ethanolic solution of the ligand and the hydrated lanthanide chlorides (Pinkerton, 1974). Recrystallization from ethanol/iso-propanol mixtures yields the tetrakis complexes [(C6Hs)4As]RL4. The sodium salts can also be prepared although they... 

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