Water-Soluble and Water-Stable Organometallic Gold(II) Complexes

The dicationic digold(II) complexes [Au2{μ-(CH2)2PPh2}2(P)2](OTf)2, where P are the water-sol-uble phosphine ligands 1,3,5-triaza-7-phosphaadamantane (TPA), 3,7-diacetyl-1,3,7-triaza-5-phosphabi-cyclo[3.3.1]nonane (DAPTA), and mono-, di-, and trisulfonated triphenylphosphines (TPPMS, TPPDS, TPPTS), were prepared by a metathesis reaction from [Au2Cl2{μ-(CH2)2PPh2}2] with the silver(I) salts [Ag(OTf)(P)]. The complexes where fully characterized by spectroscopic methods and, in the case of [Au2{μ-(CH2)2PPh2}2(TPA)2](OTf)2, by X-ray diffraction. The complexes containing sulfonated tri-phenylphosphine ligands are very water soluble (up to 75 g/L) and also are stable in water. The catalytic activity of [Au2{μ-(CH2)2PPh2}2(TPPDS)2](OTf)2 in the addition of MeOH to phenyl acetylene in an aqueous medium was tested; however the complex was found to be a poor catalyst for this reaction under these conditions.