Metal dependence of the contributions of low-frequency normal coordinates to the sterically induced distortions of meso-dialkyl-substituted porphyrins

Research was conducted to study the influence of central metals of various sizes on the macrocyclic structure of a series of 5,15-disubstituted metallophorphyrins. Methodologies used included X-ray crystallography, resonance Raman spectroscopy and molecular mechanics. The contributions of the ruf and dom deformations in the crystal structures of several metal complexes of the phorphyrins were found to be metal-dependent. Results indicate the quantitative validity of normal-coordinate structural decomposition.