Resonance Raman studies of 1,2,3,4,5,6,7,8‐octamethylporphin, 1,3,5,7‐tetramethylporphin, and mesotetraphenylporphin and its Ni‐, Cu‐, and Pd‐chelates

Resonance Raman spectra are reported for 1,2,3,4,5,6,7,8‐octamethylporphin, 1,3,5,7‐tetramethylporphin and mesotetraphenylporphin and its Ni‐, Cu‐, and Pd‐chelates. Comparison of infrared and Raman data for the non‐metallo compounds provides evidence that mesotetraphenylporphin loses its centre of symmetry in the solid state while the other two molecules retain theirs. Depolarization ratio measurements for Ni‐tetraphenylporhin in CS2 solution reveal the presence of several anomalously polarized vibrations (ϱ > ¾). Evidence is presented to show that the symmetry of the molecule in solution has been reduced from D4h.