Synthesis of New Tetraphenylporphyrin Molecules Containing Heteroatoms Other than Nitrogen. I. Tetraphenyl-21,23-dithiaporphyrin

A new and general synthesis of tetraphenylporphyrin analogs is described. The tetraphenyl-21,23-dithiaporphyrin was prepared in a pure form. Its electronic spectrum, as well as preliminary X-ray measurements, suggests that the central sulfur and nitrogen atoms are somewhat out of the plane of the molecule, facilitating attainment of a smaller angle between the phenyl groups and the porphin plane than is found in tetraphenylporphyrin. The chemical shift of the β-pyrrole hydrogens as found in the ¹H NMR spectrum at room temperature is almost identical with that found for tetraphenylporphyrin at −80°. Protonation is seen to occur at the nitrogen atoms and the optical spectrum of the conjugate acid is qualitatively similar to that of the conjugate acid of tetraphenylporphyrin.