Unexpected Dimerization of a Bis(fluorenyl)-bis(trimethylsilyl)-diallene to a Dihydroquatercyclopentadiene, an Octacyclic C36 Fragment Corresponding to 60% of C60: Reaction of the Diallene with Fe2(CO)9

The propargylallene 3,3′-biphenylene-1-trimethylsilyl-1-(9-trimethylsilylethynyl)-9H-fluorenylallene, 12, undergoes thermal rearrangement in refluxing THF to the corresponding s-trans-bis(fluorenylidene)bis(trimethylsilyl)diallene, 13. In contrast, when thermolyzed in refluxing toluene, 12 cyclizes to form a cyclopentenylidene carbene that dimerizes to furnish the tetrabenzodihydroquatercyclopentadiene 15. Moreover, treatment of 13 with NaF …