Tetraphenylporphyrins with varying degree of β-ethyl substitution were reduced with diimide to the respective chlorins. Increasing nonplanarity of the parent porphyrins led to successively more instable chlorins and the most nonplanar chlorins that could be isolated, were based on a tetra-β-ethyl-tetra-meso-phenyl-macrocycle. Depending on the substituent pattern different isomers were formed and crystal structure analysis showed the chlorins to possess varying degrees of conformational distortion depending on the degree of peripheral substitution and the localization of the pyrrolenine ring. Highly substituted free base chlorins exhibited a larger degree of ring distortion than their parent porphyrins.