Fingerprinting petroporphyrin structures with vibrational spectroscopy: II. Resonance Raman marker bands for the exocyclic rings of nickel tetrahydrobenzoporphyrins and nickel cycloalkanoporphyrins

The Q-band excited (568.2 nm) resonance Raman (RR) spectra are reported for a series of geologically significant nickel(II) complexes of etio-, cycloalkano-, and tetrahydro-benzoporphyrins in the frequency range from 600 to 1200 cm−1. Several patterns in the RR spectra of these complexes can be utilized as signatures for each petroporphyrin family. Useful marker bands for these classes of petroporphyrins are identified and distinguishing features of the spectra are given which can differentiate closely related isomers within a given class.