The First Heterometallic Acetate-Bridged Pt(II)–Pd(II) Complex: Synthesis, Structure, and Formation of Bimetallic PtPd2 Nanoparticles

The reaction of platinum acetate blue, empirically described as Pt(OOCMe)2.50, with palladium(II) acetate Pd3(μ-OOCMe)6 gave the first heterometallic acetate-bridged platinum(II) and palladium(II) complex Pd2Pt(μ-OOCMe)6 (I) as co-crystallizates 17Pd2Pt(μ-OOCMe)6 ⋅ 4Pd3(μ-OOCMe)6 ⋅ 42C6H6 (IIa) and 17Pd2Pt(μ-OOCMe)6 ⋅ 4 Pd3(μ-OOCMe)6 (IIb). Single crystal X-ray diffraction (CIF files CCDC nos. 1568105 and 1852744), EXAFS, and quantum chemical studies (DFT and QTAIM) of complex I revealed a slightly distorted triangular structure similar to the structure of palladium(II) acetate Pd3(μ-OOCMe)6 and hypothetical platinum(II) complex Pt3(μ-OOCMe)6. The thermal decomposition of complex IIa gives the bimetallic alloy PtPd2. A combined X-ray diffraction and EXAFS study demonstrated that the obtained material consists of core (Pt)–shell (Pd) particles with an average size of ~28 nm and a minor amount of smaller (~5 nm) PdO nanoparticles on the surface. The obtained results are useful for the understanding of the nature and structure of the supported phase of heterogeneous Pt–Pd catalysts.