Graphite intercalation compounds alkali metal

Alstrom, P. 1986. Electronic properties of first-stage heavy alkali metal graphite intercalation compounds. Synth. Metals 15 311-322. 

Intercalation compounds Alkali metals react with graphite in such a way that they get between the layers of graphite and cause the layers to expand. Intercalation compounds are commonly composed of the alkali metals, bromine, or some electron donor molecules such as amines or organometallic compounds. This is found in lithium ion batteries, for example. 

Graphite reacts with alkali metals, for example potassium, to form compounds which are non-stoichiometric but which all have limiting compositions (for example K C) in these, the alkaU metal atoms are intercalated between the layers of carbon atoms. In the preparation of fluorine by electrolysis of a molten fluoride with graphite electrodes the solid compound (CF) polycarbon fluoride is formed, with fluorine on each carbon atom, causing puckering of the rings. 

Cj(K prepared — the first alkali metal-graphite intercalation compound. 

Figure 8.16 Layer-plane sequence along the c-axis for graphite in various stage I -5 of alkali-metal graphite intercalation compounds. Comparison with Fig. 8.15 shows that the horizontal planes are being viewed diagonally across the figure. /,. is the interlayer repeat distance along the c-axis.

Alkali, Alkaline Earth, and Rare Earth Metal Graphite Intercalation Compounds... 

Saito, M. and A. Oshiyama. 1986. Self-consistent band structures of first-stage alkali-metal graphite intercalation compounds. J. Phys. Soc. Jpn. 55 4341-4348. 

Gunasekara, N., T. Takahashi, F. Maeda, T. Sagawa, and H. Suematsu. 1988. Angle-resolved ultraviolet photoemission study of first stage alkali-metal graphite intercalation compounds. Z. Phys. B 70 349-355. 

The reaction of various carbonaceous materials with steam to yield CO, CO2, and H2 has been intensively studied. Of special interest has been the catalysis of this reaction by various alkali metal containing compounds, most notably potassium carbonate (32-37). Various mechanisms have been proposed, some including alkali metal atoms (37) or even graphite intercalation compounds (38) as intermediates. 

Graphite intercalate compounds have also been used to catalyse Fischer-Tropsch reactions. Although alkah-metal intercalates are active,the yield of hydrocarbons can be markedly improved by replacing the alkali metal with a transition-metal chloride complex or an alkali-metal/transition-metal chloride intercalate. 

W.J. Stead, I.P. Jackson, J.McCaf ey J.W. White (1988). J. Chem. Soc, Faraday Trans. II, 1988, 84, 1669-1682 Tuimelling of hydrogen in alkali-metal-graphite intercalation compounds. A systematic study of C24Rb(H2)x and its structural consequences. 

The endohedral metallofullarenes just described (and the alkali metal fullerides described on p. 285) are all formally examples of metal carbides, M cCy, but they have entirely different structure motifs and properties from the classical metal carbides and the more recently discovered metallacarbohedrenes (metcars) on the one hand (both to be considered in Section 8.4) and the graphite intercalation compounds to be discussed in Section 8.3. Before that, however, we must complete this present section on the various forms of the element carbon by describing and comparing the chemical properties of the two most familiar forms of the element, diamond and graphite. 

The alkali metals form only ionic carbides, mostly simple ionic salts of acetylene, M2C2, which liberate acetylene on reaction with moisture. There has been much recent interest in permetalated and hypermetalated hydrocarbon species, or methanides . Most studied in this respect has been lithium, presumably because of its volatility and amenability to calculation. Mass spectrometric and calculational evidence has been presented for CLie, CLis, and C2Li4, but real samples of CLi4, C3Li4, and C5Li4 are preparable. All are pyrophoric powders. The heavier metals form another class of carbide , the graphite intercalation compounds, but as the electron has not been totally freed from the metal, these were considered in the previous section. 

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