Reactivity of a cationic square-planar palladium(II) chloro complex containing bis[2-(diphenylphosphino)ethyl]amine: chloro substitutions by anionic ligands and formation of neutral digold(I) compounds possessing linear PAuX fragments. The X-Ray crystal structure of Au2[Ph2P(CH2)2N(NO)(CH2)2PPh2]Cl2

Abstract

The interaction of sodium tetrachloropalladate(II) with the potentially tridentate aminophosphine bis[2-(diphenylphosphino)ethyl]amine (PNHP) in 1∶1 molar ratio leads to the formation of the four-coordinate complex [Pd(PNHP)Cl]Cl (1). Complex 1 undergoes chloro substitution reactions with NaX (X = Br, I), CuCl, AgNO₃, the amino acid N-acetyl-L-cysteine (AcCysSH) and the tripeptide reduced glutathione (γ-L-Glu-L-Cys-Gly, GSH) affording [Pd(PNHP)X]X′ [X = X′ = Br (2), I (3), NO₃ (4); X = Cl, X′ = CuCl₂ (1a); X′ = Cl, X = RS = AcCysS (8), GS (9)]. However, gold(I) induces abstraction of the aminophosphine from the ionic complexes 1 and 2 to produce the neutral compounds Au₂(PNHP)X₂ [X = Cl (5), Br (6)]. The dinuclear complex Au₂(PN(NO)P)Cl₂ (5a), containing the ligand bis[2-(diphenylphosphino)ethyl]nitrosylamine, was formed by reaction of 4 with gold(I) in the presence of traces of nitrosyl chloride. Addition of one molar equivalent of PNHP to 1 results, by a ring-opening process, in the formation of [Pd(PNHP)₂]Cl₂ (7) in which the palladium is five-coordinate. The ionic complexes 1, 2 and 4 were shown by X-ray diffraction to be distorted square-planar and complex 2 has a N–H⋯Br bond of 2.371 Å with the ligand adopting a boat conformation. The X-ray crystal structure of the novel neutral compound 5a shows linear P–Au–Cl arrangements with intermolecular Au⋯Au interactions of 3.0412(9) Å.