Treatment of an aqueous solution of sodium tetrachloroaurate (I) with an excess of tris(hydroxymethyl)phosphine (II) causes the reduction from gold(III) to gold(I) oxidation state, with concomitant complexation with the phosphine to produce the target tetrakis(phosphine) gold complex. (1,2)
In an alternative method, triphenylphosphinegold(I) chloride (I) is complexed to tris(hydroxymethyl)phosphine (II) to furnish the title compound.