The Vibrational Spectra of Pyrrole and Some of Its Deuterium Derivatives

The Raman spectra of pyrrole, pyrrole-N-d, symmetrical pyrrole-d4, and pyrrole-d5 have been studied with a high speed grating spectrograph. The infra-red absorption spectra of the same compounds have been investigated in the liquid state in the region 750–1900 cm−1. With the help of the selection principles and Teller's product rule, these spectra have been analyzed for a molecule of C2v symmetry. The analysis yields values for all but one of the twenty-four fundamental frequencies, and this one has been estimated. The spectra indicate clearly a C2v structure for pyrrole, although a Cs (non-planar) structure cannot yet be rigorously excluded.