Mono- and bi-nuclear gold(I), gold(II), and gold(III) perhalogenoaryl complexes with the ligand bis(diphenylphosphino)amine. Crystal and molecular structure of µ-[bis(diphenylphosphino)amine]-dichlorobis(pentafluorophenyl)digold(II)

Abstract

Addition of bis(diphenylphosphino)amine (dppa) to neutral or cationic gold(I) and gold(III) complexes containing weakly co-ordinating neutral ligands leads to the formation of complexes of the following types: [RAu(dppa)AuR], [Au2(dppa)2][ClO4]2, [AuR3(dppa)], and [AuR2Cl(dppa)](R = C6F6 or C6Cl5). Oxidative-addition of halogens X2(X = Cl or Br) to the gold(I) complexes leads to the gold(II) derivatives [RXAu(dppa)AuXR] and [XAu(dppa)2AuX][ClO4]2 which can be further arylated with Ag(C6F5) to give [R2Au(dppa)AuR2] and [RAu(dppa)AuR][ClO4]2. Mixed gold(III)–gold(I) derivatives can also be synthesized either by the spontaneous isomerization of the gold(II) complexes or from mononuclear gold(III) derivatives. The structure of the complex [(C6F5)ClAu(dppa)AuCl(C6F5)] has been determined by single-crystal X-ray diffraction: space group C2/c, a= 18.009(3), b= 17.033(2), c= 18.420(3)A, β= 103.79(2)°, Z= 4, and R= 0.035 for 4 000 unique observed reflections. The molecule possesses crystallographic two-fold symmetry, with Au–Au 2.576(2)A; this is the shortest reported Au–Au bond. The unit cell also contains eight di-isopropyl ether and four water molecules, which are well ordered and form a hydrogen bonding network with the amine N-H group.