Arsenic and antimony halides

In the solid, liquid and gas states, ASF3 and ASCI3 have molecular, trigonal pyramidal structures. With an appropriate reagent, ASF3 may act as either an F donor or acceptor (equations 15.82 and 15.84) compare this with the behaviours of Brp3 (Section 9.10) and ASCI3 (equation 15.84) which finds some use as a non-aqueous solvent. 

ASF3 -h SbFj [AsF2]+[SbFfi]-2ASCI3 [AsCl2] -b [AsCU]- 

The reaction of ASCI3 with Mc2NH and excess HCl in aqueous solution gives [Me2NH2]3[As2Cl9] containing anion 15.36.  

Salts containing the [AsX4] (X = F, Cl, Br, I) ions include [AsF4][PtF5] and [AsCl4][AsF6] which are stable compounds. 

Ciunik, G. Bator and R. Jakubas (2002) Zeitschrift fiir anorganische und allgemeine Chemie, vol. 628, p. 516. 

Dalton Trans., p. 3761]. The bridge Sb F bonds in SbFs and [Sb2Fn] are 15 pm longer than the terminal bonds. Colour code Sb, silver As, red F, green I, yellow. 

We have already illustrated the role of SbF5 as an extremely powerful fluoride acceptor (e.g. reactions 8.44, 8.55, 14.65, 14.66 and 14.80), and similarly, SbCl5 is one of the strongest chloride acceptors known (e.g. reactions 14.69 and 14.86). Reactions of SbF5 and SbCls with alkali metal fluorides and chlorides yield compounds of the t5rpe M[SbFg] and 

AsFs -h KF K+[AsF4] ASF3 + SbFj [AsF2]+[SbFs] 2ASCI3 [AsClj] + [AsCl4]  

AsBr3 + BrOTeF5+ As(OTep5)5 — [AsBr4] [As(OTeF5)6] [OTeFs] acceptor 

Antimony pentafluoride (mp 280 K, bp 422 K) is prepared from SbF3 and F2, or by reaction 15.91. In the solid state, SbFs is tetrameric (Fig. 15.13a) and the presence of Sb F Sb bridges accotmts for the very high viscosity of the liquid. Antimony pentachloride (mp 276 K, bp 352 K) 

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The radii in the lowest row of the table were obtained by a number of approximate considerations. For instance, if we assume the bismuth radius to bear the same ratio to the interatomic distance in elementary bismuth as in the case of arsenic and antimony, we obtain (Bi) = 1.16— 1.47 A. A similar conclusion is reached from a study of NiSb and NiBi (with the nickel arsenide structure). Although the structures of the aurous halides have not been determined, it may be pointed out that if they are assumed to be tetrahedral (B3 or Bi) the interatomic distances in the chloride, bromide, and iodide calculated from the observed densities1) are 2.52, 2.66, and 2.75 A, to be compared with 2.19, 2.66, and 2.78 A, respectively, from pur table. 

The most important range for inorganio chemicals is between 1 40 and 1 70. But there are some substances, such as certain oxides and sulphides, whose indices lie well above this range, or even well above 2 0. Media which are liquid at room temperature and have such high refractive indices are not available, but certain mixtures of substances which solidify to glasses may be used. A little of the medium is melted on a microscope slide, the substance under examination is dusted into the melt, a cover-glass is pressed on, and the slide is then allowed to cool. Substances which have been used in this way are mixtures of piperine with arsenic and antimony tri-iodides (for indices 1 7-2 1), mixtures of sulphur and selenium (2-0-2-7)—for details, see Larsen and Berman (1934)—and mixtures of the halides of thallium (Barth, 1929). 

Stannoles differ significantly from other group 14 metalloles in their ability to undergo exchange reactions with boron, arsenic or antimony halides. Boroles563,76, arsoles and... 

The first cyclopentadienyl n complexes of phosphorus, arsenic, and antimony have been characterized only recently. The salt-like species LXXXV-LXXXVII containing a cationic n complex are prepared via halide ion abstraction from pentamethylcyclopentadienyl element halides according to Eq. (47) (248-250). 

From the dipole moments of the halides of phosphorus, arsenic and antimony it is possible to calculate the contributions of the ionic states in these... 

Lithium aluminum hydride reacts with metal halides of silicon, germanium, tin, arsenic, and antimony to form hydrides, which are flammable and toxic ... 

Arsenic and Antimony. Three studies of reaction mechanisms for tetrahedral antimony(v) compounds are reported. These are of the reaction of trimethylantimony sulphide (MegSbS) with alkyl halides, where a four-centre transition state seems possible, the reaction of R4Sb+ cations with alkoxide ions, and the ageing of antimonic acid in aqueous solution. Both thermal and photochemical decomposition of pentaphenylanti-mony have been investigated. Whereas the products of the photochemical reaction are numerous, though all derived from phenyl radicals, the... 

The Lewis-acidity of the halides of arsenic and antimony is high enough to allow the nucleophilic attack of 1 (Eq. 8). The reaction leads to the formation of the corresponding Cp ECl2 species 10 [8] and 11 [9] (E = As, Sb). 

Arsenic and antimony show a fairly strong affinity for sulphur. Halides RMCI2 (M = As, Sb) react with H S or NaSH to give oligomeric sulphides (RMS) and with thiols to yield RM(SR )2. Dithiols afford stable and relatively harmless products. This property was used to combat the notorious Lewisite. 

In contrast to these monohalides R4M X , the dihalides R3ASX2 and R3SbX2 (from R3M+X2) are covalent derivatives with five-co-ordinate arsenic and antimony and a planar arrangement of the groups R about As or Sb. Five-co-ordination persists in aqueous solutions of these halides, which on the basis of their Raman spectra are believed to contain cations [R3M(OH2)2f or [R3M(0H)(0H2)], w/ R3MOH+ or [R3MOMR3] + (cf. [R3Sn(OH2)2] ). 

The arsenic and the antimony halides, that have lone electron-pairs, too, form compounds similar to that of PC13, but less stable, and the bismuth halides do not react at all. The most probable explanation is that, in the series... 

Antimony(III) halides are chemically reactive, but less so than their phosphorus or arsenic analogues. Antimony(III) chloride forms a clear solution with water, and there is no evidence for Sb3+ ions dilution results in precipitation of insoluble oxychlorides of various compositions, e.g. SbOCl, Sb405a2, SbsOuCl2. Some reactions of SbCl3 are shown in Scheme 3. Antimony(III) fluoride is an important fluorinating agent. 

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