Ln4(CH2)4 Cubane-Type Rare-Earth Methylidene Complexes Consisting of "(C5Me4SiMe3)LnCH2" Units (Ln = Tm, Lu).

Tetranuclear cubane-type rare-earth methylidene complexes consisting of four "Cp′LnCH2" units, [Cp′Ln(μ3-CH2)]4 (4-Ln; Ln = Tm, Lu; Cp′ = C5Me4SiMe3), have been obtained for the first time through CH4 elimination from the well-defined polymethyl complexes [Cp′Ln(μ2-CH3)2]3 (2-Ln) or mixed methyl/methylidene precursors such as [Cp′3Ln3(μ2-Me)3(μ3-Me)(μ3-CH2)] (3-Ln). The reaction of the methylidene complex 4-Lu with benzophenone leads to C-O bond cleavage and C-C bond formation to give the cubane-type oxo complex [Cp′Lu(μ3-O)]4 and CH2-CPh2, while the methyl/methylidene complex 3-Tm undergoes sequential methylidene addition to the C-O group and ortho C-H activation of the two phenyl groups of benzophenone to afford the bis(benzo-1,2-diyl)ethoxy-chelated trinuclear complex [Cp′3Tmμ(μ2-Me)3{(C6H4)2C(O)Me}] (6-Tm). [ABSTRACT FROM AUTHOR]