Noncovalent interactions determine the conformation of aurophilic complexes with 2-mercapto-4-methyl-5-thiazoleacetic acid ligands

Abstract

We report the synthesis of three gold(I) complexes [Au(H₂-mmta)₂]Cl·3H₂O (1), Na₃[Au(mmta)₂]·6H₂O (2) and Na₃[Au(mmta)₂]·10.5H₂O (3) (H₂-mmta = 2-mercapto-4-methyl-5-thiazoleacetic acid) in which the Au(I) centre is incorporated either in cationic or anionic units of the [Au(SR)₂]^+/− type depending on the protonation state of the ligand. All structures were characterized by single crystal X-ray analysis and found to exhibit unsupported aurophilic interactions leading to the formation of dimeric [Au₂(H₂-mmta)₄]²⁺ and [Au₂(mmta)₄]⁶⁻ species. By applying several ab initio interpretative techniques we examine the character of the intermolecular interactions stabilizing the eclipsed arrangement of the aurophilic dimers formed in 1–3.