Reaction of [Os₃(u-H)₂(CO)₁₀] with fra/w-[Pd(NH₃)₂I₂]; molecular structures of [Os₆Pd(u-H)₈(CO)₁₈]

Reaction of the co-ordinatively unsaturated cluster [Osj(u-H)j(CO)10] with /rans-[Pd(NH3)2IJ afforded the complexes [Os6Pd(u-H)8(CO)18] 1, [Os4Pd(u-H)4(CO)12(u-I)J 2, [Os4Pd'(n-H),(CO)12(u-I)3] 3 and [Os3(CO)12] in moderate yields. Thermolysis of 2 in refluxing chloroform produced 3 and the linked cluster [{Os3Pd(u-H)3(CO)9-(u-I)}J 4. Complexes 1-4 were fully characterised by IR and 'H NMR spectroscopy, mass spectrometry, elemental analysis and X-ray crystallography. The structures of 1 and 2 are based on vertex-shared condensed polyhedra with the palladium atoms at the vertex-sharing sites. The molecular structure of complex 1 consists of a central palladium atom sandwiched between two triosmium units. Complexes 2 and 3 possess a similar metal disposition in which an {Os3Pd} tetrahedron bridges to a mononuclear 'Os(CO)3' moiety via two and three bridging iodide ligands respectively. Complex 4 is dimeric with two {Os3Pd} tetrahedra tied together by two bridging iodide ligands. .