Reactions of Fused Polycyclic 1,2-Dithiins with Transition Metals: Synthesis of Heteroacenes via Desulfurization

Bis(thieno[3,2-b]thiophene)-fused 1,2-dithiin reacts
with a stoichiometric amount of Ni(cod)2/2PPh3 to produce a
dimeric Ni(II) complex via the oxidative addition of the disulfide
bond in the 1,2-dithiin skeleton to the Ni(0) center. An X-ray
crystal structure analysis revealed that this complex has a
dimeric structure in which one sulfur atom derived from the
disulfide bond bridges two metal centers. The resultant Ni
complex undergoes desulfurization at elevated temperature to
produce a fully fused thiophene-based heteroacene.