Synthesis and solid-state structure of [Pd6Ru6(CO)24]2–. Electrochemistry and 13C nuclear magnetic resonance spectra of [Fe6Pd6H(CO)24]3– and [Pd6Ru6(CO)24]2–

Abstract

The cluster [Pd₆Ru₆(CO)₂₄]^2– was obtained in good yield from the reaction of [Ru₃H(CO)₁₁]^– with [Pd(NCPh)₂Cl₂]. The salt [NEt₄]₂[Pd₆Ru₆(CO)₂₄] crystallized in the triclinic space group P(no. 2) with a= 11.514(5), b= 11.602(5), c= 11.933(5)Å, α= 73.01 (3), β= 78.25(3), γ= 65.26(4)°, Z= 1. Data were collected at room temperature, giving 5968 unique reflections. The structure was solved by direct methods. The final discrepancy indices were R= 0.024 and R′= 0.026 for 4129 independent reflections with I > 3σ(I). The metal skeleton consists of a trigonally distorted octahedron of palladium atoms, capped by six ruthenium atoms with twelve terminal, six edge- and six face-bridging carbonyl ligands. This ruthenium–palladium cluster adopts the same metallic polyhedron as [Fe₆Pd₆H(CO)₂₄]^3– but possesses two valence electrons less. The solution ¹³C NMR spectra of both anions are in agreement with the solid-state structures and electrochemical analysis shows that they produce labile congeners: [Pd₆Ru₆(CO)₂₄]^2– undergoes a one-electron oxidation with formation of the relatively stable monoanion; [Fe₆Pd₆H(CO)₂₄]^3– can be oxidized and reduced, to give corresponding anions with charges of 2– to 5–.