Tetracarbon

Many novel cluster compounds have now been prepared in this way, including mixed metal clusters. Further routes involve the oxidative fusion of dicarbon metallacarborane anions to give dimetal tetracarbon clusters such as (103) and (104) O (jjg insertion of isonitriles into inetallaborane clusters to give monocarbon meiallacarboranes such as (105) and the reaction of small ii/t/o-carboranes with alane adducts such as Et3NAlH3 to give the commo species (106) ... 

Tetracarbon monofluoride, 1362 Tetrachlorodiphosphane, 4171 Tetrachlorosilane, 4173 Tetraiododiphosphane, 4637 Thiazyl fluoride, 4306... 

In the first group of syntheses, three carbon substrates (e.g., d- and L-glyceraldehyde d- and L-lactaldehyde) and tetracarbon, (e.g., L-threose) are often elongated by addition reaction to the carbonyl group—Wittig or aldol reactions (Scheme 1)—and the products obtained are subsequently converted into required structures. 

Tetracarbon monofluoride, 1358 Tetrachlorodiphosphane, 4165 Tetrachlorosilane, 4167 Tetraiododiphosphane, 4632 Thiazyl fluoride, 4300... 

Figure S-15 Transition metal-promoted syntheses of tetracarbon carboranes.

An example illustrating the possibility of significantly different reactivity is pertinent here (see also Section 5). A comparison of the photon driven reaction of aUcynes with (CO)3Fe()]" -E4H4), E = C, BH (39) has been reported. The former yields substituted benzenes, whereas the latter generates predominantly carbon-rich carboranes, C H B4H4, n = 2, 4, 9, where the tetracarbon carborane is the primary product. 

The structure of tetracarbon monofluoride (C4F) has been discussed by Riidorff Riidorff (1947 6) and Riidorff (1959). While it cannot be unequivocally demonstrated from their X-ray powder diffraction data, they proposed that in C4F the carbon atom sheets were flat and that the fluorine atoms made close ca. 1.4 Af) contacts to the carbons. Their finding ofhigh electrical conductivity for C4Fj, j(HF)4 also supported their notion that the carbon atom sheets were planar. Recent work in these laboratories (Mallouk Bartlett 1983 Mallouk 1983) has established that chemical fluorination of graphite, to compositions C4.Fj, 5(HF),5, x > 2.3, may... 

Like carbon monofluoride, tetracarbon monofluoride is also very inert, though it is appreciably less stable thermally. It is completely stable in... 

When warmed above 100° tetracarbon monofluoride preparations begin to decompose and when rapidly heated they deflagrate—sometimes with flame—and leave a very finely divided soot. Decomposition also occurs when the compound is gradually heated to 200-300° in a stream of fluorine or of a fluorine-hydrogen fluoride mixture. Thus it is not possible to convert the compound to carbon monofluoride by further fluo-rination. 

Structural studies made up to the present lead to the generalization that in a graphite compoimd all C—C distances in the carbon layers, apart from lattice imperfections, are the same and that the layers are either plane or puckered, even when some of the carbon atoms have a different type of bonding. In carbon monofluoride and tetracarbon monofluoride the two possible structures for the carbon layers are realized. 

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