Other Chloride Complexes

Righellato and Davies (S34) postulated in 1930 that most uni-bivalent salts must be considered as incompletely dissociated even in dilute solutions. It may be expected then that ion association will occur for many bi-univalent salts. This would seem to be particularly true of the doubly charged transition metals. Zinc chloride is one such salt which has been shown to form many complexes. The complexing tests described earlier in this chapter are applied to manganous chloride, cobalt chloride, nickel chloride, and cupric chloride. 

Libus and Tialowska (OlO) presented the following stability constants at 25°C  

They found that the activity coefficient quotient dependence on the perchlorate molality differed for the CoCI complex from the dependence shown by the CuCl, MnCI and ZnCl complexes. As a careful spectrophotometric study they did indicated that the CuCl complex existed primarily as the inner-sphere complex [ CuCKOHj) 51. they speculated that the difference was that the CoCr complex was an outer-sphere complex [ CoCOHj ] cr.  

An examination of the thermodynamic data tables of the National Bureau of Standards (1) and Russian Academy of Science (2) present different pictures of the solution composition. The NBS table does not point to any ion pairing while the Russian table indicates the existence of the CoCl complex. The free energy values and resulting formation constant for 25° C from the Russian table are  

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There appear to be at least two zinc chloride complexes of pyridine, one of m.p. 207 and composition 2CsH,N,ZnCh, sind the other of m.p. 152° and probable composition 2C,H,N,ZnClt,HCl. The former is slightly soluble in water and in hot ethyl alcohol the latter passes into the former in aqueous solution, is readily soluble in hot absolute ethanol and can therefore be readily recrystaUised from this solvent. 

Ai lepiesents an aiyl group. Diaiyl products are obtained after long reaction times. Other Friedel-Crafts catalysts, eg, ZnCl2, FeCl2, FIF, and BF, can also be used. In most cases, stoichiometric amounts of the catalyst ate requited. Flowever, strong complexation of the phosphine by the catalyst necessitates separation by vacuum distillation, hydrolysis, or addition of reagents such as POCl to form more stable aluminum chloride complexes. Whereas yields up to 70—80% are possible for some aryl derivatives, yields of aliphatic derivatives are generally much less (19). 

The volatile chlorides ate collected and the unreactedsohds and nonvolatile chlorides ate discarded. Titanium tetrachloride is separated from the other chlorides by double distillation (12). Vanadium oxychloride, VOCl, which has a boiling point close to TiCl, is separated by complexing with mineral oil, reducing with H2S to VOCI2, or complexing with copper. The TiCl is finally oxidized at 985°C to Ti02 and the chlorine gas is recycled (8,11) (see also... 

The advantages of titanium complexes over other metallic complexes is high selectivity, which can be readily adjusted by proper selection of ligands. Moreover, they are relative iaert to redox processes. The most common synthesis of chiral titanium complexes iavolves displacement of chloride or alkoxide groups on titanium with a chiral ligand, L ... 

In the presence of Eriedel-Crafts catalysts, gaseous ethyl chloride reacts with ben2ene at about 25°C to give ethylben2ene, three diethylben2enes, and other more complex compounds (12) (see Xylenes and ethylbenzene). Aromatic compounds can generally be ethylated by ethyl chloride in the presence of anhydrous aluminum chloride (see Eriedel-Crafts REACTIONS). Ethyl chloride combines directly with sulfur trioxide to give ethyl chlorosulfonate,... 

The next step in the calculations involves consideration of the allylic alcohol-carbe-noid complexes (Fig. 3.28). The simple alkoxide is represented by RT3. Coordination of this zinc alkoxide with any number of other molecules can be envisioned. The complexation of ZnCl2 to the oxygen of the alkoxide yields RT4. Due to the Lewis acidic nature of the zinc atom, dimerization of the zinc alkoxide cannot be ruled out. Hence, a simplified dimeric structure is represented in RTS. The remaining structures, RT6 and RT7 (Fig. 3.29), represent alternative zinc chloride complexes of RT3 differing from RT4. Analysis of the energetics of the cyclopropanation from each of these encounter complexes should yield information regarding the structure of the methylene transfer transition state. 

The complexes are 1 1 electrolytes in solution. Other such complexes can be made by a similar route or by halide (or carboxylate) exchange. The first monomeric system Ru2C1(02C.C4H4N)4 (thf), where the ruthenium at one end of the lantern is bound to a thf and the other to a chloride, has recently been made [97], [Ru2Cl(02CBut)4(H20)] and [R Cl CPr thf)] are also monomeric [98],... 

According to these previous studies, the most dominant dissolved states of Au and Ag in ore fluids are considered to be bisulfide and chloride complexes, depending on the chemistry of ore fluid (salinity, pH, redox state, etc.). However, very few experimental studies of Au solubility due to chloride complex and Ag solubility due to bisulfide complexes under hydrothermal conditions of interest here have been conducted. Thus, it is difficult to evaluate the effects of these important species on the Ag/Au of native gold and electrum. Other Au and Ag complexes with tellurium, selenium, bismuth, antimony, and arsenic may be stable in ore fluids but are not taken into account here due to the lack of thermochemical data. 

A monodentate palladium(II) complex trans-[Pd(py)2(H202)]2+ hydrolyzes Met-Aa amide bonds with a rate comparable with that promoted by [Pd(H20)3(0H)]+. Unlike Pd(H20)3(0H)]+, //chelated complex containing temed (A,A,AAA -tctramcthylcthylenediamine) hydrolyzes Met-Aa amide bonds with hydrolytic rate controlled by temed release. The action of the other two complexes, c -[Pd(ED-TA)C12] (EDTA = ethylene diaminetetraacetic acid) and cis-1,2-bis(2-formylglycinebenzene-sulfenyl)ethane Pd11 chloride differs from the action of similar complexes of U,v-[Pd(en)Cl2] and cw-[Pd(dtco-3-OH)Cl2] (dtco-3-OH = l,5-dithiacycooctan-3-ol).448... 

Controlled alkylation of phosphorus oxychloride may also be accomplished using a modification of this approach. Reaction of alkyl-aluminum dichloride with phosphorus oxychloride generates the aluminum chloride complex of the alkylphosphonodichlori-date,54 which may be isolated as the simple compound or directly used in reaction to generate other derivatives of the alkylphospho-nic acid. 

The transuranium elements are also separated from each other by these means (115), (122), (136) and their order of elution from the columns, which, like the rare-earths, is a function of their atomic number, has been used as important evidence of the identity of the new elements (123). Separation from the rare-earths is not possible, however, as their elution peaks coincide with those of the actinides. This separation can be made, however, using hydrochloric acid as the elutriant. The actinides form anionic chloride complexes more readily than the rare-earths and are consequently more readily removed from the cationic resin (114). 

While hydrosilylation of 1-alkenes and HSiCl3 with platinum catalysts provides linear products (1-trichlorosilylalkanes), palladium chloride modified with phosphines gives products carrying the trichlorosilyl group at the secondary carbon. This is highly remarkable because all other metal complexes studied so far lead to 1-substituted products. This regioselectivity leads to the possibility to carry out asymmetric hydrosilylation. 

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