[PT6(CO)12]2- AND [PT9(CO)18]2- SUPPORTED ON MGO - SYNTHESIS AND SPECTROSCOPIC CHARACTERIZATION

[Pt6(CO)12)]2- and [Pt9(CO)18)]2- were synthesized from [Pt(acaC)2] on the surface of MgO powder and characterized by infrared spectroscopy. When the reaction was carried out in the presence of CO at 100 atm, [Pt9(CO)18]2- was formed in high yield. When the reaction was carried out under these conditions with [Re2-(CO)10] also present on the surface, [Pt6(CO)12]2- was formed in high yield. The platinum carbonyl anions were extracted into solution by cation metathesis and characterized spectroscopically. The carbonyl stretching bands of [Pt6(CO)12]2- on MgO were shifted about 10 cm-1 to higher energy relative to those of the cluster in tetrahydrofuran solution, indicating weak ion pairing with the Mg2+ ions of the MgO surface; in contrast, the lack of such shifts characterizing [Pt9(CO)18)]2- on MgO indicates the lack of significant ion pairing of this cluster on the surface. In the presence of traces of air, the platinum carbonyl clusters on MgO were converted into small particles of Pt metal.