Method for producing aqueous preparations of complexes of platinum group metals

The invention relates to a method for producing aqueous preparations of complexes of platinum group metals (PGM) Pt, Pd, Rh and Ir having the general formula [M A /M B /M C (L) a (H 2 O) b (O 2 —) c (OH − ) d] (OH—) e (H + ) f , wherein M A =Pt II or Pd II , M B =Pt IV , M C =Rh or Ir, L is a neutral monodentate or bidentate donor ligand, and a is an integer between 1 and 4 (or 2) and/or between 1 and 6 (or 3), b is an integer between 0 and 3 (or 5), c is an integer between 0 and 3 (or 4), d is an integer between 0 and 3 (or 5), e is an integer between 0 and 2 (or 3 or 4) and f is an integer between 0 and 4 (or 5). In the method according to the invention, the hydroxo complexes H 2 P d (OH) 4 (in the case of M A =Pd II ), H 2 Pt(OH) 6 (in the case of M A =Pt II and M B =Pt IV ) or H 3 M C (OH) 6 (for M C =Rh III Ir III ) are converted in the presence of the donor ligands, wherein at least one hydroxo group of the hydro complex is exchanged. Preferably, the reaction occurs at temperatures in the range of 40 to 110° C. with a reaction time of between 2 and 24 hours, wherein, where MA=PtII, the conversion additionally occurs in the presence of a reduction agent. The method optionally further comprises an exchange of OH anions bound outside of the complex sphere with other anions (e.g. hydrogen carbonate or carbonate anions). The aqueous preparations contain PGM complexes such as [Pt(en) 2 ](OH) 2 , [Pt(EA) 4 ](OH) 2 or [Rh(NH 3 ) 6 ](OH) 3 and are used to produce electroplating baths, heterogeneous catalysts or metal powders, for example.