Systematic and efficient syntheses of Ru6(CO)182-, Ru6C(CO)162-, Os6(CO)182-, and Os10C(CO)242-. Isolation and characterization of Os6C(CO)17

Article abstract of DOI:10.1021/ic00140a043

Treatment of Ru₃(CO)₁₂ or Os₃(CO)₁₂ with sodium in ether solvents at various reaction temperatures provides efficient preparations of several large anionic carbonyl clusters of ruthenium and osmium. The combination of Ru₃(CO)₁₂ and 1 equiv of sodium (Ru₃:Na = 1:1) affords Ru₆(CO)₁₈^2- in refluxing tetrahydrofuran (66°C) but Ru₆C(CO)₁₆^2- in refluxing diglyme (162°C). Under the latter conditions Ru₆(CO)₁₈^2- is converted quantitatively to Ru₆C(CO)₁₆^2-. Treatment of Os₃(CO)₁₂ with sodium (Os₃:Na = 1:1) in diglyme at 162°C yields Os₆(CO)₁₈^2-. Pyrolysis of Os₆(CO)₁₈^2- in triglyme (216°C) gives Os₁₀C(CO)₂₄^2- as the major product. The decanuclear compound also is formed from the direct reaction of Os₃(CO)₁₂ with sodium (Os₃:Na = 1.66:1 or 1:1) in tetraglyme at 230-260°C. Oxidation of Ru₆C(CO)₁₆^2- and Os₆(CO)₁₈^2- with aqueous ferric chloride in a carbon monoxide atmosphere produces Ru₆C(CO)₁₇ and Os₆(CO)₁₈ in good yields. A compound formulated as Os₆C(CO)₁₇ is isolated in low yield from the similar oxidation of reaction mixtures produced upon pyrolysis of Os₆(CO)₁₈^2-. This is suggested as evidence for the formation of Os₆C(CO)₁₆^2- under the conditions for conversion of Os₆(CO)₁₈^2- to Os₁₀C(CO)₂₄^2-.