Noncovalent interactions in gold(iii) tetrakis(4-butoxyphenyl)porphyrinate structures

Abstract

Gold(III) porphyrinates have been extensively studied due to their high stability and anticancer activity. Less attention has been paid to the structural features of such compounds. In this work, a new gold(III) complex [Au(TBPP)][AuCl₄] (1) was synthesized in high yield starting from 5,10,15,20-tetrakis(4-butoxyphenyl)porphyrin (TBPPH₂). The compound was characterized by IR, ¹H NMR and UV-vis spectroscopy, ESI-MS, cyclic voltammetry and elemental CHN analysis. The crystal structure of 1 was determined using X-ray diffraction analysis. The crystalline phases [Au(TBPP)]₂[AuCl₄][AuCl₂]*2HOAc (1a) and [Au(TBPP)]₂[AuCl₄][AuCl₂] (1b) were also isolated. Analysis of all three crystal structures revealed the tendency of the [Au(TBPP)]⁺ cationic complex to form weak intermolecular Au⋯Au, Au⋯Cl, and Au⋯O interactions with [AuCl₄]⁻ anions, HOAc molecules, and neighboring [Au(TBPP)]⁺ cations. DFT calculations at the ωB97XD/DZP-DKH level of theory confirmed the noncovalent nature of these interactions.