Synthesis and characterization of octaaryltetraazaporphyrins containing group 14 elements

Abstract Octaaryltetraazaporphyrins substituted at the para position of the peripheral benzene rings and containing group 14 elements (Si(IV), Ge(IV), and Sn(IV)) were synthesized and characterized, and their properties were compared specifically with those of a group 15 element (P). Tert-butyl or fluorine-substituted compounds exhibit the Q, CT, and Soret bands in ascending energy, and the position and intensity of the former two bands appear to change due to configuration interaction between their states. Consequently, strongly electron-donating diphenylamino-substituted compounds exhibited the CT, Q, and Soret bands in ascending energy. Among compounds with the same substituent, those containing elements situated at a higher level in the periodic table exhibited spectra with a stronger electron-withdrawing property. Namely, the Q and CT bands of the Si complex appeared at shorter wavelengths than those of the Ge and Sn compounds. The spectra of the Sn complexes resemble those of the P compound in terms of shape and position. Molecular orbital calculations broadly supported these observations. Single crystal X-ray diffraction analysis unambiguously elucidated two compounds containing tert-butyl substituents and Si or Sn to maintain a tetravalent, hexacoordinated metal representation.