Formation of silicon triazacorrole and tetrabenzotriazacorrole by the ring contraction of the corresponding tetraazaporphyrin ligands

Silicon-inserted triazacorrole, its μ-oxo dimer, and tetrabenzotriazacorrole have been obtained by ring contraction when metal-free tetraazaporphyrin (TAP) and phthalocyanine (Pc), respectively, were reacted with trichlorohydrosilane (HSiCl3) in the presence of tributylamine in refluxing benzene. The triazacorrole has very sharp absorption at ca. 400 nm, which is suitable for blue-laser applications.