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

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)][AuCl 4 ] ( 1 ) was synthesized in high yield starting from 5,10,15,20-tetrakis(4-butoxyphenyl)porphyrin (TBPPH 2 ). The compound was characterized by IR, 1 H 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 [AuCl 4 ][AuCl 2 ]*2HOAc ( 1a ) and [Au(TBPP)] 2 [AuCl 4 ][AuCl 2 ] ( 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 [AuCl 4 ] − 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. In this work, three new structures of gold( iii ) porphyrinate were obtained, in which multiple noncovalent interactions were revealed.