Tetraphenylarsonium ions complexes

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. 

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). 

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... 

Iron halides react with halide salts to afford anionic halide complexes. Because iron(III) is a hard acid, the complexes that it forms are most stable with F and decrease in both coordination number and stability with heavier halides. No stable I complexes are known. [FeF5(H20)]2 is the predominant iron fluoride species in aqueous solution. The [FeF6]3 ion can be prepared in fused salts. Whereas six-coordinate [FeClJ3 is known, four-coordinate complexes are favored for chloride. Salts of tetrahedral [FeClJ can be isolated if large cations such as tetraphenylarsonium or tetraalkylammonium are used. [FeBrJ is known but is thermally unstable and disproportionates to iron(II) and bromine. Complex anions of iron(II) halides are less common. [FeClJ2 has been obtained from FeCl2 by reaction with alkali metal chlorides in the melt or with tetraethylammonium chloride in deoxygenated ethanol. 

The anionic thiocyanate complex of Mo forms ion-pairs with various organic cations, which are extractable from acid solutions into non-polar solvents. The most useful are tetraphenylarsonium [53] and tetraphenylphosphonium [54] ions, CTA (in the presence of SnCy [55], A-oclylbenzamidine [56], and thioacetanilide [57]. 

Niobium can be separated from Ta and other metals in HF or HCl media by extracting into CHCI3, CCI4, cyclohexane, 1,2-dichloroethane, or xylene the ion-associates, which are formed by Nb (and Ta) complexes with tetraphenylarsonium cation, TO A [8,9], DAM [10], or Aliquat 336 [11-13]. The thiocyanate complexes of Nb with triphenylphosphonium cation [14] or with amides [15] have also been extracted. 

The uranyl ion, (U02), forms yellow azido complexes that are stable in dilute (0.01 M) aqueous solutions in the presence of excess azide a cation structure [(U02)(N3)] has been established and was used in the analysis of uranium [137,138]. The anion tetraazido complex has been isolated as the tetraphenylarsonium salt, [As(Ph)4]2 [(U02)(N3)4], by admixing a solution of 1 g uranyl nitrate in 2 N nitric acid in nitrogen environment to a solution of 7 g sodium azide. At 80°C the red solution was precipitated with tetraphenylarsonium chloride to obtain yellow crystallites that decomposed at 171°C [139]. 

Clem and Huffman [210] studied the chemical structure of solutions containing Au(III) and azide ions. It was found that a tetraazidoaurate(III) anion, [Au (N3)4]", is formed when the molar ratio of Au(III) to azide is at least 1 to 10. The complex is light sensitive, especially in solution e.g., a tetrahydrofuran solution of the tetraphenylarsonium tetraazidoaurate(III), when exposed to daylight, is quantitatively reduced to the diazidoaurate(I) complex [139] ... 

Substoichiometric extraction of an ion associate is sometimes preferable to that of internal complex compounds, although the latter form very stable compounds in many cases. The substoichiometric isolation of Mn(VII), Au(III), Ta(V), Re(VII), and other elements in the form of ion associates with tetraphenylarsonium (TPA) or quarternary aimnonium base (QAB) is undoubtedly the most expedient from tlw viewpoint of selectivity. 

Recent x-ray powder data indicate that K2lr2(CO)4Ci4.s and presumably the bromo and iodo analogue are in fact K o-6lr(CO)2X2 with KX impurities (515). In 1970 Cleare and Griffith (94) reported that the reaction of concentrated hydrohalic and formic acids with hexachloroiridate(IV) results in the formation of diamagnetic needle crystals of [ 2(00)4X4]- stoichiometry which exhibit a metallic luster. In accord with the work of Malatesta and Canziani (283) they prepared the bromo complexes as well as complexes containing different cations. Table X. The chloro potassium salt exhibits Vco absorptions at 2115, 2080, and 1985 cm i while the bromo tetraphenylarsonium salt exhibits Vco absorbances at 2105,2085,2047, and 1957 cm-i. To account for the observed diamagnetism they proposed a planar tetranuclear structure, [Ir4-(CO)sX8]2", based on the structure of the isoelectronic Re4(CO) ion. 

Only a few data exist for the higher monosubstituted amides. Fuchs, Bear and Rodewald have measured heats of solution of several uniunivalent electrolytes in iV-ethylacetamide (NEA) including some tetraalkylammonium salts and others containing complex anions. They observe that for some salts, particularly tetraphenylarsonium chloride and sodium tetraphenylborate, the heat of solution varies markedly with concentration. While they suggest that the cause may be the result of ion-pair formation, they offer no convincing evidence. 

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