Abstract
The molecular structure of enigmatic "poly(aluminium-methyl-methylene)" (first reported in 1968) has been unraveled in a transmetalation reaction with gallium methylene [Ga(8) (CH(2) )(12) ] and AlMe(3) . The existence of cage-like methylaluminomethylene moieties was initially suggested by the reaction of rare-earth-metallocene complex [Cp*(2) Lu{(μ-Me)(2) AlMe(2) }] with excess AlMe(3) affording the deca-aluminium cluster [Cp*(4) Lu(2) (μ(3) -CH(2) )(12) Al(10) (CH(3) )(8) ] in low yield (Cp*=C(5) Me(5) ). Treatment of [Ga(8) (CH(2) )(12) ] with excess AlMe(3) reproducibly gave the crystalline dodeca-aluminium complex [(CH(3) )(12) Al(12) (μ(3) -CH(2) )(12) ] (MAM-12). Revisiting a previous approach to "poly(aluminium-methyl-methylene" by using a (C(5) H(5) )(2) TiCl(2) /AlMe(3) (1 : 100) mixture led to amorphous solids displaying solubility behavior and spectroscopic features similar to those of crystalline MAM-12. The gallium methylene-derived MAM-12 was used as an efficient methylene transfer reagent for ketones.