3(1),3(2)-DIDEHYDRORHODOCHLORIN-15-ACETIC ACID TRIMETHYL ESTER

The structure of the title compound, methyl ethyl-3,7,12,17-tetramethy lporphyrin-2-propionate, C37H42N4O6, containing no solvent molecules o f crystallization, has been determined at 193 (2) K. The subrings A, B and C of the chlorin macrocycle are approximately in the least-square s plane defined by the four N atoms, The reduced ring D is distorted o wing to the steric repulsion between the C17 and C15 substituents. The crystal packing is dominated by pi-pi interactions between subrings A and C of adjacent molecules in a slipped parallel orientation.