Bidentate amino- and iminophosphine ligands in mono- and dinuclear gold(I) complexes: Synthesis, structures and AuCl displacement by AuC6F5

Bidentate imino- and aminophosphine ligands were prepared by firstly a Schiff-base condensation reaction between 2-(diphenylphosphino)benzaldehyde and the corresponding primary amines to afford the imino derivatives and secondly reduction of the imines with NaBH4 to the aminophosphine ligands in satisfactory yields. The ligands readily reacted with chlorogold(I) compounds to produce new mononuclear iminophosphine- and dinuclear aminophosphine chlorogold(I) complexes. Further, reaction of the dinuclear chlorogold complex with C6F5Au(tht) (tht = tetrahydrothiophene) led to the displacement of one AuCl moiety by AuC6F5 forming a digold(I) mixed halogen/organometallic complex. Both digold(I) complexes displayed intramolecular Au⋯Au interactions, whilst the di(chlorogold) complex also showed an intermolecular Au⋯ Au interaction, as determined by X-ray crystallography. The displacement of only one of the two AuCl groups presumably relates to the strength of the Au–P bond (inert) vs. the weakness of the Au–N bond (labile), the latter being more easily broken.