Carbon−Carbon Bond Formation and Cleavage in the Dimerization of a Nickelacycle

Addition of 1,12-dilithiotriphenylenediyl to
L2NiCl2 (L = PEt3) gives the nickelacycle L2Ni(1,12-triphenylenediyl), which decomposes to a dimer (L2Ni2C36H20) containing two coupled triphenylene moieties
with a new C−C bond. Thermolysis of the dimer
completes the coupling, yielding a chiral tetraphenylene, while alkyne addition leads to cleavage of the
newly formed C−C bond of the dimer and cycloaddition
of the alkyne to the triphenylene fragment.