Synthesis, structure and stability of new Pt(II)-bis(N-heterocyclic carbene) complexes

The use of metal acetates has allowed the synthesis of NHC complexes without isolation of the free carbene. This route is very useful in cases where the metal acetates are readily available and has been used, for example, for the synthesis of bis(N-heterocyclic carbene) complexes of palladium(ii). In the case of platinum, however, the corresponding acetate is not commercially available and is difficult to synthesize. Previously published syntheses require either an external base (e.g. NaOAc or KOtBu) or a transmetalation step. Here we present a new general synthetic pathway for platinum-bis(carbene) complexes using platinum(ii) acetylacetonate as a commercially available metal precursor. Aromatic substituents greatly enhance the stability of the metal complexes against acidic media. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)