Syntheses and structural characterization of a series of hydrido osmium–palladium carbonyl clusters: [Os₅Pd(CO)₁₆H_n+4(µ-Cl)_{2 –n}](n= 0–2), [{Os₃Pd(CO)₉(µ-H)₂(µ-Cl)}₂(µ-Cl)₂]·H₂O and [Os₄Pd(CO)₁₁(µ-H)₃(µ-Cl)₃(C₅H₅N)]·0.5C₆H₁₄

The unsaturated triosmium cluster [Os3(CO)10(µ-H)2] reacted with the complex trans-[Pd(py)2Cl2](py = pyridine) to give a range of complexes including [Os5Pd(CO)16(µ-H)6]1, [Os5Pd(CO)16-(µ-H)4H(µ-Cl)]2, [Os5Pd(CO)16(µ-H)4(µ-Cl)2]3, [{Os3Pd(CO)9(µ-H)2(µ-Cl)}2]4, [Os4Pd(CO)11(µ-H)3(µ-Cl)3(py)]5 and three known osmium clusters, [Os3(CO)10(µ-H)(µ-OH)], [Os3(CO)10(µ-H)(µ-Cl)] and [Os4(CO)13(µ-H)2]. All five mixed-metal clusters were characterized by IR, 1H NMR and mass spectroscopy and X-ray crystallography. Complexes 1–3 have similar metal dispositions but different combinations of bridging hydrides and chlorides. They can be viewed as a diosmium fragment connected to the palladium vertex of the Os3Pd tetrahedron through a number of bridging ligands. Complex 4 is dimeric with two Os3Pd tetrahedra tied together by two bridging chlorides in a planar fashion. Complex 5 consists of an Os3Pd tetrahedropn with a fourth osmium atom linked to the palladium vertex by three bridging chlorides. The pyridine ligand is co-ordinated to the singular osmium instead of the palladium atom.