Synthesis of Tetrasilatetrathia[8]circulenes by a Fourfold Intramolecular Dehydrogenative Silylation of C−H Bonds

The first two examples of a tetrasilatetrathia[8]circulene were synthesized in two steps from a tetraiodotetrathienylene by using a fourfold intramolecular dehydrogenative silylation of C−H bonds as the key step. A single‐crystal X‐ray diffraction analysis revealed that tetrasilatetrathia[8]circulene contains a perfectly planar [8]radialene skeleton. The excited‐state dynamics of tetrasilatetrathia[8]circulene were evaluated by steady‐state and time‐resolved spectroscopic measurements, revealing an efficient intersystem crossing in the excited state. The first two examples of a tetrasilatetrathia[8]circulene were synthesized by using a fourfold intramolecular dehydrogenative silylation of C−H bonds as the key step. A single‐crystal X‐ray diffraction analysis revealed that tetrasilatetrathia[8]circulene contains a perfectly planar [8]radialene skeleton. The excited‐state dynamics were evaluated by steady‐state and time‐resolved spectroscopic measurements, revealing an efficient intersystem crossing in the excited state (see scheme).