Crystal structure of 5-tert-butyl-10,15,20-triphenylporphyrin

Abstract

In the title free base porphyrin, C42H34N4, the neighbouring N...N distances in the center of the ring vary from 2.818 (8) to 2.998 (8) Å and the phenyl rings are tilted from the 24-atom mean plane at angles varying between 62.42 (2)–71.63 (2)°. The NH groups are involved in intramolecular bifurcated N—H...(N,N) hydrogen bonds. The Ca—Cm—Ca angles vary slightly for the phenyl rings, between 124.19 (18)–126.17 (18)°. The largest deviation from the mean plane of the 24-atom macrocycle is associated with the meso carbon at the substituted tert-butyl position, which is displaced from the mean plane by 0.44 (2) Å. The free base porphyrin is characterized by a significant degree of ruffled (B1u) distortion with contributions from domed (A2u) and wave [Eg(y) and Eg(x)] modes. In the crystal, molecules are linked by a number of weak C—H...π interactions, forming a three-dimensional framework. The structure was refined as a two-component inversion twin.

Keywords

• crystal structure
• unsymmetrical porphyrins
• free base porphyrin
• non-planar porphyrins.