Rules Isolated Pentagon Rule

Isolated Pentagon Rule, 12 228 Isolated silanol groups, 22 380, 381 silica surface chemistry and, 22 373 Isolation... 

Similar calculations were made for the only possible isomer of C70 [11-13] that obeys the isolated pentagon rule [4, 6] and for some of the most stable isomers of the higher fullerenes [11, 14-16]. On the basis of their easily accessible LUMOs and high electron affinities, all stable members of the fullerene family were expected to display very rich cathodic electrochemistry. 

Cg4 can be any of 24 stable isomers that satisfy the isolated pentagon rule [4, 6] and possess closed-shell electronic configurations [15]. Before successful HPLC separation and characterization of major and some minor isomers was achieved [53, 55, 56], electrochemical studies of Cg4 involved a mixture of its two major isomers, D2(IV) and D2rf (I I), which at the time could only be isolated as a 2 1 mixture [50, 51, 60]. In solvents such as pyridine, PhCN, and DMF/PhMe, the mixture displayed multiple redox waves, making assignment difficult. In the first OSWV study of the separated isomers, D2-Cg4(IV) displayed four one-electron evenly spaced reductions in pyridine (see Table 8 and Fig. 5) [53]. However, the reduction potentials of the isomer reported as 02 (11) in that same study are now believed to correspond to one of the minor isomers of Cg4, the C2 (IV)... 

All fullerenes (C ) are composed of sp2 hybridized carbon atoms forming a 3-D network of fused (n - 20)/2 six-membered and 12 five-mem-bered rings. As enshrined in the Isolated Pentagon Rule (IPR), so far, none of the structures isolated have two pentagons fused together. The curvature of the cage results in some strain, and the three angles around a carbon atom sum to 348° instead of the ideal value of 360° for . The [6,6] fusions have most double-bond character and are invariably where complexation occurs. For there are 30 such equiva-... 

There is an infinity of ( 5,6, 3)-spheres that are 5Rq in fact, as die number of vertices goes to infinity, the proportion of such spheres amongst all ( 5,6, 3)-spheres tends to 1. Such fullerenes are said to satisfy the isolated pentagon rule in Chemistry ([FoMa95]>. 

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