Photochemical functionalization of C-60 with cyclosilanes and cyclogermane

The photochemical reaction of 3,4-benzo-1,2-disilacyclobutene 1 with C-60 afforded stable 1:1 adduct 2 with C-2v symmetry. The photochemical reaction of cyclotetrasilane 4a with C-60 afforded adducts 5a and 6a, the latter was obtained from a rearrangement of the cyclotetrasilane unit. Similarly, cyclotetragermane 4c, gave 5c and the rearranged product 6c. In the case of cyclotetrasilane 4b, only the rearranged product 6b was obtained in high yield. The structures of all compounds were determined by spectroscopic methods, including Si-29-H-1 HMBC hetero nuclear shift correlation experiments. (C) 1996 Elsevier Science Ltd