Solid-State Structural Chemistry of Gold Corroles: Nonplanar Distortions, Crystal Packing, and Aurophilic Interaction

Abstract

Gold(III) corroles are often close to planar, the factors governing their deviations from planarity in the solid state remain poorly understood due to the limited number of available crystal structures. Herein, we report a combined single-crystal X-ray diffraction and density functional theory study of a series of meso-phenyl-substituted gold corroles bearing electron-donating and electron-withdrawing substituents. The structures exhibit modest out-of-plane distortions dominated by saddle-type deformations, with amplitudes and symmetry influenced by substituent identity, lattice environment, and asymmetric unit contents (Z′ > 1). Normal-coordinate structural decomposition and relaxed potential energy scans indicate that saddling corresponds to a shallow deformation mode, with planar and distorted conformers separated by < 0.3 kcal/mol and exhibiting nearly invariant force constants across the series. Notably, a short unsupported Au III •••Au III contact (< 3.55 Å) is observed exclusively for AuT[3,5-diOMe]PC; for which NBO and QTAIM analyses provide electronic evidence of a weak but stabilizing aurophilic interaction, representing the first such example in gold corroles. Molecular electrostatic potential analysis further shows that substituent-dependent polarization influences the preferred distortion pattern without significantly perturbing the frontier electronic structure, highlighting how peripheral substitution and crystal packing together shape the supramolecular organization of these metallomacrocycles.