Structure and bonding in gold(I) compounds. Part 4. A phosphorus-31 nuclear magnetic study of the structure of some gold(I) phosphine complexes in solution
Abstract
The addition of PEt3 to dichloromethane solutions of [Au(PEt3)2][PF6] or [Au(PEt3)Cl] at 175 K leads to the formation in solution of three- and four-co-ordinate gold(I) complexes. These are of the type [AuLn]+(n= 3 or 4) and there is no evidence in the case of [Au(PEt3)Cl] for the presence of the undissociated species [AuLnCl](n > 1) under these conditions. When P(OEt)3 is added to solutions of the above complexes, mixed species of the type [Au(PEt3)n{P(OEt)3}4-n]+(n= 1–3) are formed. If the amount of P(OEt)3 added is such as to give a total ligand : gold ratio of <4 : 1 the two- and three-co-ordinate complexes which are present contain only PEt3. In no case has free ligand [PEt3 or P(OEt)3] been observed to be present until the ligand : gold ratio exceeded 4 : 1. At >213 K, ligand exchange is rapid on the n.m.r. time scale in all the systems studied.