Polyhalides mixed

The preparative utility of such reactions is, however, rather limited, and neither ICl or IBr has been much used except to form various mixed polyhalide species. Compounds must frequently... 

The halides participate as terminal and bridge ligands and can be included in inner and external spheres of this kind of complex. A few examples of compounds with such terminal ligands are the boron ammines [BX3 NH3], [BX2(NH3)2]X, BX(NH3)3]X2, and [B(NH3)4]X3 (X = F, Cl, Br, I). Halides form part of many mixed-ligand carbonyl complexes, for example, Fe(CO)4I2 and polyhalide anions with various elements [4], In this respect, the structure of the anion [Re2Clx]2 provides important information the Re — Re bond is present and the chlorine atoms have a bridge function [4]. 

Many polyhalides of alkali metals are known, the most important being the tri-iodides and the very stable mixed halides of the type MICl. Lithium... 

Rubidium and caesium also form tribromides, and mixed trihalides, particularly of the MIClg type, are known in these the (Cl—I—Cl) ion is linear. The compounds KIBrCl and CsIBrF have also been isolated. All the alkali metals form stable orange-red polyhalides of the type MICI4, containing a square complex ion (p. 127). 

In the preparation of hydrocarbons an alkyl, aryl, or aralkyl halide is mixed with an excess of an aromatic hydrocarbon, and anhydrous aluminum chloride is added in small portions. The reagents must be free from moisture. If the reactants are not liquid or the reaction is very vigorous, a solvent is used. Benzene, nitrobenzene, carbon disulfide, or o-dichlorobenzene may be employed as solvents. When polyhalides are used, more than one molecule of the hydrocarbon may react. For example, benzene with chloroform yields triphenylmethane, and benzene with carbon tetrachloride gives triphenylmethyl chloride ... 

Mixed polyhalides. A mixture of l-chloro-l,2-difluoroethylene, sulfur tetrafluoride, and lead dioxide heated 2 hrs. at 100° in an autoclave 1-chloro-1,1,2,2-tetrafluoroethane. Y 95.8% conversion 89.2%.—This method affords higher yields under conditions which are somewhat milder than those previously reported. F. e. s. E. R. Bissell and D. B. Fields, J. Org. Ghem. 29, 1591 (1964). 

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