Graphite, intercalation compounds with metal halides

First metal halide-graphite intercalation compound made with FeCl.i. 

Layer misfit was first recognised in the structures of two metal chloride-graphite intercalation compounds. Intercalates of graphite with many other metal halides, including fluorides and bromides, have since been reported, but they seem to be of the CC type and are not discussed here. 

Biintercalation, an interleaving of different inserted species, has been studied in the case of inserted halide species " . Halogen-containing solvents, with metal chlorides, can also lead to ternary phases, such as graphite-FeCl3-C2H4Cl2 . A different approach to inserted halides is the intercalation compound with trimethyltin chloride . Finally, the intercalation of halides into carbon fibers is an area of increasing interest . ... 

At this time, no all-inclusive rule can be given that will predict whether a given compound will intercalate or not. Most of the information available seems to have been obtained empirically. Such analogies as similar chemical properties have been helpful. The many factors that infiuence the intercalation process have been surveyed by Herold (H14). In Tables II-VI are listed metal halides considered to intercalate into graphite, together with some structural information (S2J, i 9). Several general characteristics have been ascribed to intercalat-... 

The presence of the potassium atoms causes the distance between the layers of carbon atoms to increase from the value of 235 pm in graphite to 540 pm in C8K. When rubidium and cesium atoms are placed between the layers, the distances between the carbon layers are 561 and 595 pm, respectively. As would be expected for materials that contain atoms of an alkali metal, these materials are extremely reactive in air, and they react explosively with water. A large number of other intercalation compounds have been prepared that have halogens, interhalogens, or metal halides as the included substances. 

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