Potassium graphite compounds

Avdeev VV, Zharikov OV, Nalimova VA, Pal nichenko AV, Semenenko KN (1986) Superconductivity of the layered potassium-graphite compounds CgK and C4K. Pis ma Zh Eksp Teor Fiz 43 376—378... 

The first cyclotrisilene 48 is synthesized by the reduction of dibromochlorosilane 90 with potassium graphite. Compound 48 is isolated as air-sensitive dark red crystals in 65% yield 24... 

Reduction by Alkali Metals. This was the first reduction method successfully used it is particularly useful for reducing in liquid ammonia cyanides ( ), alkynyls (f 4 ), ammines (193) and ethylendiammines (192). The same reaction on phosphine compounds gives low yields because the reagents are insoluble in liquid ammonia (45). The zero valent nickel compounds with phosphites are obtained in good yield with the potassium graphite compound KCs (110). 

Analysis. The contents of a weighed ampoule are placed in an Erlenmeyer flask containing 50-70 ml. of ice-cold 2N H3SO4. The decomposed product is boiled for one half hour and the graphite is filtered off and washed. The alkali is determined as sulfate in an aliquot of the filtrate KOH is added to another aliquot, and the NH3 is distilled off and determined by volumetric analysis. The dried graphite is treated as described for potassium graphite compounds. 

Potassium Graphite. Potassium, mbidium, and cesium react with graphite and activated charcoal to form intercalation compounds CgM, C24M, C gM, C gM, and C qM (61,62). Potassium graphite [12081 -88-8] 8 P gold-colored flakes, is prepared by mixing molten potassium with graphite at 120—150°C. 

HEAVY ALKYNE ANION RADICALS The Only example of Compounds of this type, the anion radical of the valence isomer of distannyne 51-K, was recently synthesized by Power by the reduction of chlorostannylene 52 with potassium graphite in THF (Scheme 2.39). ... 

The story of the heavy analogs of 6jt-electron cyclopentadienyl anions has culminated in the latest synthesis of a compound containing three heavier group 14 elements (two Si and one Ge) in the ring. This aifionic species 69 Li+ was prepared by the reduction of the disilagermacyclopentadiene precursor 70 with potassium graphite KCg followed by the exchange of countercation from K+ to Li+ by treatment with LiBr (Scheme 2.66). ... 

The synthesis of metal graphite compounds is carried out by the reduction of layer graphite compounds and metal chlorides by using different reducing agents such as, for instance, solutions of aromatic anion radicals in THF, metallic sodium in liquid ammonia, complex boron and aluminum hydrides, and vapor or liquid potassium. As a result, the complex compounds containing one (Sn, Co, Mn, Cr, Mo, W, Pd) and two (Fe-Mo, Fe-W, or Mo W) metals were synthesized. 

Yang, M. H. and P. C. Eklund. 1988. Optical dielectric function of high-stage potassium graphite intercalation compounds Experiment and theory. Phys. Rev. B 38 3505-3516. 

Takahashi, T., H. Tokailin, T. Sagawa, and H. Suematsu. 1985. Angle-resolved ultraviolet photoemission study of potassium-graphite intercalation compound C8K. Synth. Metals 12 239-244. 

Quite recently, this most sought after prize was won A group ofworkers succeeded in synthesizing a stable compound containing a -Si Si- triple bond. Sekiguchi and cowork-ers isolated l,l,4,4-tetrakis[bis(trimethylsilyl)methyl]-l,4-diisopropyl-2-tetrasilyne from reaction of 2,2,3,3-tetrabromo-1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]- 1,4-diisopropyl-tetrasilane with four equivalents of potassium graphite in tetrahydrofuran (equation 6). ... 

The nature of platinum zerovalent derivatives was questioned by Chopoorian et al. (55) who considered them platinum(II) dihydrides. A new careful investigation (47, 133)j however, has confirmed that they are certainly zerovalent compounds. The nickel(0) derivatives with tertiary monophosphines can be obtained as well from NiBr2L2 and sodium tetrahydridoborate or ethanolic potassium hydroxide in the presence of an excess of the ligand 185) j while those with phosphites were prepared using potassium graphite 110) (CsK) as the reducing agent. By reduction with alkylmetals 199), zerovalent tetrasubstituted nickel (0) compounds with tertiary phosphine, arsines, and stibines have been obtained. 

Riidorff et al. 66, 72, 54) obtained the ammoniates in a pure state by the action of the blue solution of the alkali or alkaline earth metals on graphite. If the metal is in excess a deep blue graphite compound with the structure of stage 1 results. The strontium and barium compounds are violet at low temperatures. After washing with liquid ammonia and removal of the absorbed ammonia in a vacuum at 0°, the composition corresponds approximately to the formula CiaMeCNHsla- The potassium, rubidium, and cesium compounds may also be obtained by treating CgMe with liquid ammonia. 

According to Dzurus and Hennig 15) the free chlorine necessary for the occurrence of reaction between graphite and aluminum trichloride does not act catalytically, as Riidorff and Zeller first assumed, but is partly taken up in the lattice. Riidorff and Landel 61) found this to be true of the gallium trichloride-graphite compound also. For both compounds the ratio Me Cl is between 1 3.2 and 1 3.4 and the compounds therefore oxidize potassium iodide solution and cause iodine to separate. 

Reduction of compound 7 resulted in an incredible variety of products, depending on the reducing conditions. While the reduction of 7 with Na in toluene gave cyclotetrasilene 5 in 64% yield, the reduction with potassium graphite in THF below -40 °C afforded the first cyclotrisilene 8 in 67% yield [11], in addition to a small amount of the fascinating spiropentasiladiene 9 (Scheme 3) [12]. 

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