Hydrogenation of carbon monoxide by tetranuclear rare earth metal polyhydrido complexes. Selective formation of ethylene and isolation of well-defined polyoxo rare earth metal clusters

The reaction of the tetranuclear rare earth metal polyhydrido complexes {Cp′Ln(μ-H)2}4(THF) (Cp′ = C5Me4SiMe3, Ln = Y (1a), Lu (1b)) with carbon monoxide (1 atm) yielded ethylene and the corresponding tetraoxo cubane complexes (Cp′Ln)4(μ3-O)4 (Ln = Y (5a), Lu (5b)). Stepwise formation of some key reaction intermediates, such as oxymethylene complexes (Cp′Ln)4(μ-OCH2)(μ-H)6(THF) (Ln = Y (2a), Lu (2b)), enolate species (Cp′Y)4(OCH=CH2)(μ-O)(μ-H)5(THF) (3), and dioxo complex (Cp′Y)2(μ3-O)2(μ-H)4(THF) (4), was confirmed. The molecular structures of 2a, 4, and 5b were determined by X-ray diffraction studies. Copyright © 2006 American Chemical Society.