A novel trinuclear palladium cluster compound:: di-μ3-chloro-tris[chloro(triphenylphosphine-P)palladium] acetone solvate

The title triangular tripalladium cluster, [Pd3Cl5(C18H15P)(3)].- C3H6O, (I), has a trigonal-bipyramidal framework of Pd-3(mu(3)- Cl)(2), with the two Cl atoms in apical positions. Each Pd atom in the framework has two additional coordination sites to establish square-planar cis-PdL2(mu(3)-Cl)(2) geometry. Three P atoms are located on the same side of the plane defined by the Pd-3 triangle, which leads to a pseudo-C-3 nu symmetry for the core framework of Pd-3(mu(3)-Cl)(2)P3Cl3. The average Pd-Cl distance trans to PPh3 is 2.473 (8) Angstrom, which is significantly longer than the average Pd-Cl distance of 2.294 (4) Angstrom for those trans to terminal Cl, due to the strong trans effect of a P atom compared with a Cl atom. Compound (I) has 49 valence electrons and shows a rhombic electron-spin resonance signal, indicating an S = 1/2 ground state.