Synthesis and Properties of an Unusual New High-Symmetry Osmium−Palladium Carbonyl Cluster Complex

The new tetrahedral complex Os₄(CO)₁₂[Pd(PBu^t₃)]₄, 3, was obtained from the reaction of Os₃(CO)₁₂ with Pd(PBu^t₃)₂ in octane solution at reflux. Compound 3 was characterized by IR, ¹H and ³¹P NMR spectroscopy, mass spectroscopy, and single-crystal X-ray diffraction analysis. The electronic structure of 3 was evaluated by Fenske–Hall molecular orbital analysis. Compound 3 is electronically unsaturated and reacts with hydrogen at room temperature to yield the known compound Os₄(CO)₁₂(μ-H)₄, 4.