Rare-earth-metal half-sandwich complexes incorporating methyl, methylidene, and hydrido ligands.

Complexes Cp* 3 Ln 3 (μ 2 -CH 3 ) 3 (μ 3 -CH 2 )(μ 3 -H)(thf) 3 (Ln = Y, Dy; Cp* = C 5 Me 5 ) are formed via elimination of CH 4 and C 2 H 4 from the respective trinuclear polymethyl complexes [Cp*Ln(μ 2 -CH 3 ) 2 ] 3 , involving the methyl/methylidene complex Cp* 3 Ln 3 (μ 2 -CH 3 ) 3 (μ 3 -CH 2 )(μ 3 -CH 3 )(thf) 2 as an intermediate. Compound Cp* 3 Y 3 (μ 2 -CH 3 ) 3 (μ 3 -CH 2 )(μ 3 -H)(thf) 3 displays "Schrock-type" nucleophilic carbene reactivity, converting ketones into the corresponding terminal alkenes. Treatment of Cp* 3 Y 3 (μ 2 -CH 3 ) 3 (μ 3 -CH 2 )(μ 3 -H)(thf) 3 with [D 4 ]methanol proved accessibility of all small-group functionalities as indicated by the simultaneous formation of deuterated HD and deuterated methanes CH 3 D and CH 2 D 2 .