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 MeSiI and MeGeX (Cp* = CMe; 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*GdI(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.