Abstract
Tetramethylaluminato/halogenido(X) ligand exchange reactions in half-sandwich complexes [Cp(R) La(AlMe(4) )(2) ] are feasible in non-coordinating solvents and provide access to large coordination clusters of the type [Cp(R) LaX(2) ](x) . Incomplete exchange reactions generate the hexalanthanum clusters [Cp(R) (6) La(6) X(8) (AlMe(4) )(4) ] (Cp(R) =Cp*=C(5) Me(5) , X=I; Cp(R) =Cp'=C(5) H(4) SiMe(3) , X=Br, I). Treatment of [Cp*La(AlMe(4) )(2) ] with two equivalents Me(3) SiI gave the nonalanthanum cluster [Cp*LaI(2) ](9) , while the exhaustive reaction of [Cp'La(AlMe(4) )(2) ] with the halogenido transfer reagents Me(3) GeX and Me(3) SiX (X=I, Br, Cl) produced a series of monocyclopentadienyl rare-earth-metal clusters with distinct nuclearity. Depending on the halogenido ion size the homometallic clusters [Cp'LaCl(2) ](10) and [Cp'LaX(2) ](12) (X=Br, I) could be isolated, whereas different crystallization techniques led to the aggregation of clusters of distinct structural motifs, including the desilylated cyclopentadienyl-bridged cluster [(μ-Cp)(2) Cp'(8) La(8) I(14) ] and the heteroaluminato derivative [Cp'(10) La(10) Br(18) (AlBr(2) Me(2) )(2) ]. The use of the Cp' ancillary ligand facilitates cluster characterization by means of NMR spectroscopy.