Multimetallic Half-Sandwich Complexes of the Rare-Earth Metals

Multimetallic half-sandwich complexes of the paramagnetic lanthanides gadolinium, terbium, dysprosium, holmium, and erbium as well as of diamagnetic yttrium are readily accessible via AlMe /halogenido exchange reactions of Cp*Ln(AlMe ) with the mild halogenido transfer reagents Me SiI and Me GeX (Cp* = C Me ; X = Br, Cl). Depending on the rare-earth-metal center and halogenido ion size, complexes with distinct structural motifs and nuclearities are obtained, including dimeric compounds [Cp*Ln(AlMe )(μ -Cl)] for the smaller metal centers Ln = Ho, Er, iodido-bridged tetranuclear rings [Cp*Ln(μ -I) ] (Ln = Y, Tb, Dy, Ho, Er), and a heterobimetallic tetramethylaluminato-bridged gadolinium cluster [Cp* Gd I (AlMe )] . The tetranuclear dysprosium complex [Cp*Dy(μ -I) ] shows single-molecule magnet (SMM) behavior in zero applied field with an effective energy barrier of 164(10) cm .