Silylenes fullerenes

When 2,2-bis(2,6-diisopropylphenyl)-l,l,l,3,3,3-hexamethyltrisilane (90), a silylene precursor of Dip2Si , was photolyzed with a low pressure mercury lamp in a toluene solution of Ceo thermally stable sUiranes, (Dip2Si)Cgo (91) and (Dip2Si)2Ceo (92) were formed, in 58 and 27% yields, respectively, together with other polyadducts, which evidently arose from addition of the silylene across the C=C double bond between the two six-membered rings of the fullerene (Scheme 14.45)." ... 

More recently, the same research group showed that the same silylene, Dip2Si , added in a similar manner to the C70 fullerene to yield the related silacyclopropane202. 

It is noteworthy that silylenes have been employed in the derivatization of fullerenes. Bis(2,6-diisopropylphenyl)silylene adds regiospecifically to a jr-bond localized at a 6-ring,... 

Fullerene silacyclopropane derivative (102) was prepared in 58% yield by photolysis of trisilane (101) in the presence of C60. The spectral data for the product was consistent with a silacyclopropane of C2v symmetry, which would arise from addition of the silylene across the six-ring-six-ring junction (Scheme 34) <93JA1605>. 

Ando and coworkers fonnd that the silylene Dip2Si 382 (Dip = 2,6-di-i-propylphenyl), formed on photolysis of the trisilane 382 in the presence of Ceo, gave an adduct assigned the structure of the silacyclopropane 384 which evidently arose from addition of the silylene across the C=C between two six-membered rings of the fullerene. A segment of the structure of 384 is shown in equation 47. 

The chemistry of 50 and other fiillerenes has developed rapidly since the first preparative-scale Isolation of this molecule in 1990 (7). The new field of fullerene chemistry is leading to many novel derivatives some of which may have extraordinary optical and electronic properties. The many Ceo derivatives reported so far include transition metal complexes, (2--, complexes with aromatic rings (4), Diels-Alder products (5), addition compounds with carbenes (d), silylene (7) or oxygen (8) and other organic derivatives (P). Several polymers of C60 have also been reported (JO-75). 

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