Springer Online Journal Archives 1860-2000
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Abstract Tetrapalladium clusters containing dppa or dppa and dppm bridging ligands were prepared by condensation of dinuclear units. Reaction of [Pd2Cl2(μ-dppa)2] with [Cu(PPh3)]PF6 (generated in situ in THF) yielded [Pd4(μ-Cl)2(μ-dppa)4] (PF6)2 (4) in a virtually quantitative yield but [Pd4(μ-Cl)2(μ-dppm)2(μ-dppa)2] (PF6)2 (6) was best prepared in CH2Cl2 from [Pd2Cl2(μ-dppm)2] and [Pd2(MeCN)2(μ-dppa)2](PF6)2 (2). The structure of 6·2(CH3)2CO·2H2O was determined by X-ray diffraction. It consists of a planar, centrosymmetric 10-membered ring structure. The four bridging diphosphine ligands are of two types: two dppa ligands support the Pd Pd bonds [2.6055(4) Å], whereas the two dppm ligands bridge between two palladium atoms separated by 3.722(4) Å, which are also bridged by a chloride ligand.
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