Synthesis, characterisation, supramolecular aggregation and biological activity of phosphine gold(I) complexes with monoanionic thiourea ligands

A series of phosphine gold(I) complexes containing monoanionic thiourea ligands has been synthesised by reaction of the appropriate precursor chloro complex, Ph3PAuCl, Cy3PAuCl, dppf(AuCl)2 [dppf = Fe(η5-C5H4PPh2)2] or dppe(AuCl)2 (dppe = Ph2PCH2CH2PPh2) with the thiourea and Me3N base in methanol solution. The complexes have been fully characterised by elemental analysis, NMR spectrometry, electrospray mass spectrometry, and in several cases, by single-crystal X-ray diffraction studies. The crystallographic studies show that the ligands coordinate as a thiolate in each case with systematic variations in geometric parameters being readily ascribed to the influence of the N-bound substituents. In four of the structures, discernable supramolecular aggregation patterns are evident, leading to loosely associated dimers or chain motifs, the latter mediated by either Au⋯S, N–H⋯N or C–H⋯O interactions. Cytotoxicity data, against the P388 leukemia cell line, and anti-microbial data are also reported.