Thumbnail Image

Synthesis and Characterisation of Cycloaurated Gold(III) Complexes with Bidentate (O,O), (N,S) and (S,S) Chelating Ligands

The reaction of C,N-coordinated gold(III) dihalides; BpAuCl₂ (Bp = 2 benzylpyridyl), AnpAuCl₂ (Anp = 2 anilinopyridyl) and TypAuCl₂ (Typ = 2 tolylpyridyl) with catecholate ligands in hot methanol and trimethylamine produced metallacycles with structural isomers of the general formula (C,N)Au{O,O}. Similarly, BpAuCl₂ and AnpAuCl₂ were reacted with thiourea ligands to form complexes giving high yield and good purity with the general formula (C,N)Au{PhNCSNR₂}+, by means of the addition of BPh₄- for precipitation. X-ray crystal structures of the compounds [AnpAu{PhNCSNMe₂}]BPh₄ and [AnpAu{PhNCSNCy₂}]BPh₄ confirmed the coordination of the thiourea to the gold centre through the N and S atoms. In both cases the geometry around the gold atom is square-planar with complex [AnpAu{PhNCSNCy₂}]BPh₄ showing a slightly more puckered conformation than [AnpAu{PhNCSNMe₂}]BPh₄ due to the sterically bulky cyclohexyl groups attached. Some thiourea derivatives were tested against P388 murine leukaemia cells with complex [AnpAu{PhNCSNHPh}]BPh₄ showing promising anti-tumour activity. When thiourea ligands were replaced by dithiophosphinate and dithiophosphate ligands the reaction proceeded at room temperature without the need for the presence of a base. Relatively low yields of impure metallacycles with the general formula (C,N)Au{S₂PR₂}+ were obtained on the addition of BPh₄- or BF₄-. Attempts to improve purity by varying batches of starting materials, anion and solvents used were unsuccessful. X-ray crystal data from a single crystal of [(C,N)Au{S₂PPh₂}]BPh₄ shows the reduction of gold(III) to gold(I) forming a known polymeric gold(I) dithiophosphinate complex. In order to extend this study the synthesis of complexes with the general formula R₂PS₂AuCl₂ was attempted, but no new compounds were characterised. Where possible, all new compounds reported in this thesis were characterised by ES-MS, IR, NMR, melting point and micro-elemental analysis.
Type of thesis
Smith, T. S. (2012). Synthesis and Characterisation of Cycloaurated Gold(III) Complexes with Bidentate (O,O), (N,S) and (S,S) Chelating Ligands (Thesis, Master of Science (MSc)). University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/6512
University of Waikato
All items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.