Nonplanar, noninnocent, and chiral: a strongly saddled metallocorrole

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Crystallography

Background:

• Metallocorrole complexes typically exhibit planar macrocycle conformations in their solid-state structures.
• Understanding the structural diversity of corrole macrocycles is crucial for developing new functional materials.

Purpose of the Study:

• To determine the first crystal structure of a copper beta-octabromo-meso-triarylcorrole.
• To investigate the factors contributing to nonplanar macrocycle conformations in corrole complexes.

Main Methods:

• Single-crystal X-ray diffraction analysis was employed to elucidate the three-dimensional structure.
• Density functional theory (DFT) calculations were performed to analyze electronic and steric effects.

Main Results:

• The crystal structure revealed a significantly saddled corrole macrocycle, with adjacent pyrrole rings tilted by 60-80 degrees.
• This pronounced nonplanarity contrasts sharply with the generally planar structures of other metallocorroles.
• DFT calculations identified ligand noninnocence and peripheral overcrowding as key contributors to the observed conformation.

Conclusions:

• The study presents the first crystallographic evidence of a uniquely saddled copper corrole macrocycle.
• Ligand noninnocence and peripheral overcrowding synergistically induce significant nonplanarity in this corrole complex.
• These findings offer insights into the conformational flexibility of corrole macrocycles and their substituent effects.