Halides hydration

When reacted with tetraalkylammonium halides, hydrated [Me2Sn(IV)], [Bu2Sn(IV)]2-",2 [Ph2Sn(IV)]2-", 5 and [EtPhSn(lV)]2-",2 ester derivatives of 2,6-pyridinedicarboxylic acid yield tetraalkylammonium diorganohalogeno(2,6-pyr-idinedicarboxylato)stannates. Both classes of compounds exhibit high in vitro antitumor activity. 

Rowley, A. T. et al., Inorg. Chem. Acta, 1993, 211(1), 77 Preparation of metal oxides by fusing metal halides with lithium oxide in a sealed tube leads to explosions if halide hydrates are employed, particularly lanthanide trihalide hydrates. The preparation succeeds with anhydrous halides. This will be purely a question of vapour pressure above an exothermic reaction the question is whether the vapour is water, or metal halide, and the reaction oxide formation, or hydration of lithium oxide. Like other alkali metal oxides, hydration is extremely energetic. 

A fair number of mixed solvates, compounds containing molecules of crystallization of two different solvents, are also known. Generally, these are obtained either by recrystallizing halide hydrates from a nonaqueous solvent, or by crystallizing a halide from an appropriate solvent mixture, such as an alcohol intentionally or unintentionally containing significant amounts of water. Examples include... 

Within the (M6Xi2) + (X = Cl, Br q = 2-4) cluster halides, the only series that cover all three oxidation states are the tantalum halide hydrates and the haloanions [(MsXi Xg] -. The isolation of [(Ta6Cli2)Cl2(PR3)4](PF6) (n = 1, 2) led to the first complete series of group VA cluster stabilized by an organic ligand. 

Preparation of metal oxides by fusing metal halides with lithium oxide in a sealed tube leads to explosions if halide hydrates are employed, particularly lanthanide trihalide... 

In a difference from the above, the majority of metal halides of secondary subgroups of Group I, II, and VII and lanthanides are low-soluble in the examined solvents, so synthesis of their complexes is carried out in comparatively high-polar solvents (water, alcohols, and aqueous-alcohol mixtures). To carry out syntheses in water, the corresponding conditions, necessary to obtaining soluble derivatives of organic compounds (for example, halide hydrates of amines or N-containing hetero-... 

Step 1 of the hydration mechanism is similar to the first step in the addition of HBr. The proton adds to the less substituted end of the double bond to form the more substituted carbocation. Water attacks the carbocation to give (after loss of a proton) the alcohol with the —OH group on the more substituted carbon. Like the addition of hydrogen halides, hydration is regioselective It follows Markovnikov s rule, giving a product in which the new hydrogen has added to the less substituted end of the double bond. Consider the... 

Covalent hahdes can be prepared by various synthetic routes. The simplest are direct reactions of elemental halogens (equation 9), or hydrogen halides with elements (equation 10) or oxides (equation 11). In other processes, the oxides are reacted with a halogen halide in the presence of carbon to combine with the oxygen (equation 12) or other reactive carbon-halides (equation 13). Exchange of halogens can also take place (equations 14 16). Anhydrous halides can also be obtained by dehydration of metal halide hydrates, using reactants such as thionyl halide, which react with the hydrated water (equation 17). 

Figure 1(a), (b), and (c) show the X-ray radial distribution functions (RDF) for the 10.6 m LiCl, 11.2 m LiBr, and 11.1 m Lil aqueous solutions, respectively, at the various temperatures. The first prominent peak observed at 3.1 - 3.6 A in the RDFs corresponds mainly to the halide-water interactions due to the halide hydration. The contribution of the water-water interactions within the primary hydration shell of Li also falls within this range. A characteristic feature of the RDFs with temperature is an appearance of a new peak centered at 4.3 A. The position of the peak does not depend on the halide ions the peak is gradually enhanced with lowering temperature. We have previously assigned this peak mainly to water-water interactions for the 11m aqueous LiCl solution. The quantitative analysis has been made by a least-squares fitting procedure, and the important structural parameter values finally obtained are summarized in Table 2. The evolution of the 4.3 A peak with lowering temperature is clearly seen in Fig. 

Halides, hydration nitmbers, 144 HalUwell and Nyburg the essence of their method, 109 and the individital properties of the proton,... 

An appropriate nickel(II) halide hydrate (1 mmol, X = Cl, Br or I) was dissolved in dry ethanol (10 ml), and tris(2-dimethylarsinophenyl)bismuthine (1 mmol) was added in dichloromethane. The resulting dark red solution was stirred briefly and then NaBPlu (0.35 g, 1 mmol) was added in ethanol (10 ml). The product [NiX(BiAr3)][BPli4] was precipitated by adding an excess of ether and recrystallized from dichloromethane-ethanol. Yield 60% [77JCS(D)711]. 

Dehydration of hydrated halides. Hydrated halides are usually obtained easily from aqueous solutions. They can sometimes be dehydrated by heating them in a vacuum, but often this leads to oxo halides or impure products. Various reagents can be used to effect dehydration. For example, SOCl2 is often useful for chlorides. Another fairly general reagent is 2,2-dimethoxy-... 

E. APPLICATIONS TO INORGANIC MATERIALS 1. Alkaline Earth Halide Hydrates... 

The alkaline earth halide hydrates and related salts have been studied by TG and other thermal techniques under a variety of atmospheric and instrumental conditions. Using the quasi-isothermal and quasi-isobaric techniques in different types of sample holders, Paulik et al. (61) found that various hydrate stoichiometries could be obtained. As shown in Figure 4.8, the inflection points in curve (/) indicate the presence of CaBr2-2H20 and CaBr2 H20. In curves (2)-(4), the inflection points correspond 10 CaBr2-3H20 and... 

We shall for the most part illustrate our general arguments by examples of typically ionic solids oxides, halides, hydrates, etc. However, it must be appreciated that factors important in determining the structures of ionic solids also decide the stereochemistry of discrete molecules and complex ions. We shall not, therefore, hesitate to discuss the stereochemistry of isolated molecules or complex ions in solution insofar as they are relevant to the general problem of the stereochemistry of metal ions. 

The structures of typical ligands were shown earlier in Figure 1.9 and will also be shown later in Figures 3.1 and 3.2. Complexes include some metal halides, hydrates, amines, amides and imides, such as Ti(NR2)4 (R is an alkyl group), oxides, H3B NR3 (a borane-amine adduct), Co(MNT)2 (MNT = maleonitrile dithiolate), Cupc (pc = phthalocyanine), Mo(CO)6, cluster carbonyls, and metal acetylacetonate derivatives. 

The lanthanide and actinide halides remain an exceedingly active area of research since 1980 they have been cited in well over 2500 Chemical Abstracts references, with the majority relating to the lanthanides. Lanthanide and actinide halide chemistry has also been reviewed numerous times. The binary lanthanide chlorides, bromides, and iodides were reviewed in this series (Haschke 1979). In that review, which included trihalides (RX3), tetrahalides (RX4), and reduced halides (RX , n < 3), preparative procedures, structural interrelationships, and thermodynamic properties were discussed. Hydrated halides and mixed metal halides were discussed to a lesser extent. The synthesis of scandium, yttrium and the lanthanide trihalides, RX3, where X = F, Cl, Br, and I, with emphasis on the halide hydrates, solution chemistry, and aspects related to enthalpies of solution, were reviewed by Burgess and Kijowski (1981). The binary lanthanide fluorides and mixed fluoride systems, AF — RF3 and AFj — RF3, where A represents the group 1 and group 2 cations, were reviewed in a subsequent Handbook (Greis and Haschke 1982). That review emphasized the close relationship of the structures of these compounds to that of fluorite. 

It is worth noting, in passing, that Mootz s work is predated by that of G. A. Jeffrey and coworkers who, in a series of papers [669, 670], have described an extensive series of quaternary ammonium halide hydrates with low-melting points. A number of these have been structurally characterised, but as they melt to give liquids that are not conprised solely of ions (indeed, they are aqueous solutions), they are only briefly mentioned in the following text. 

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