Copper(I), silver(I) and gold(I) complexes with the ligand 1-(diphenylphosphino)-2-(2-pyridyl)ethane (ppye) of general formula M(ppye)₂PF₆ have been prepared and characterized by means of IR and multinuclear (¹H, ¹³C and ³¹P) NMR spectroscopy. The copper(I) and silver(I) complexes are bis(chelate) with a tetrahedral geometry around the metal atom. On the contrary, the gold(I) derivative exhibits a digonal structure with monodentate P-bound ppye ligands co-ordinated to the metal centre. The complex [Au(ppye-P)₂]PF₆ has been characterized in the solid state by X-ray diffraction analysis. Crystal data: triclinic, space group P, a= 9.972(1), b= 10.299(2), c= 10.521(2)Å, α= 69.90(2), β= 66.03(1), γ= 78.51(1)°, Z= 1, R= 0.039. The gold atom, which lies on a symmetry centre, is linearly co-ordinated by the P atoms of ppye (P–Au–P, 180°). Variable-temperature NMR studies show that the [M(ppye-P,N)₂]⁺ species rearrange in solution by inversion at the tetrahedral metal centre. Furthermore, all three ppye derivatives undergo ligand-exchange processes. The reactions of the cations [M(ppye-P,N)₂]⁺ and [Au(ppye-P)₂]⁺ with ppye have been investigated.