A Series of Cyclopentadienyl Lanthanum Complexes with Metalloid Germanium Clusters

A series of cyclopentadienyllanthanum complexes with the disilylated metalloid germanium cluster [Ge 9 (Hyp) 2 ] 2-[Hyp = Si(SiMe 3 ) 3 ] has been prepared and fully characterized.The synthetic procedure is based on the salt metathesis reaction of two different c yclopentadienyllanthanum diiodides CpLaI 2 (Cp: Cp*, pentamethylcyclopentadienyl; Cp ttt , 1,2,4-tri-tert-butylcyclopentadienyl) with K 2 [Ge 9 (Hyp) 2 ] in tetrahydrofuran (THF) with a subsequent extraction with n-hexane.The composition of the obtained compounds and the mode of coordination of the germanium cluster to the rare-earth metal are strongly influenced b y t he s teric d emand o f t he c yclopentadienyl l igands and the crystallization conditions.The centrosymmetric dimeric compounds with the common formula [CpLa(solv)( 2,3 -Ge 9 (Hyp) 2 )] 2 [1, Cp = Cp*, solv-THF; 2, Cp = Cp ttt , solv-NCCH 2 C(M e)NSiM e 3 ] have been isolated by the slow evaporation of a n-hexane solution, while a mononuclear complex [Cp ttt La(THF) 2 ( 3 -Ge 9 (Hyp) 2 )] (4) was found by crystallization from THF.The repeated recrystallization of 1 from n-hexane afforded the asymmetric dimer [Cp*La(THF)( 2,3 -Ge 9 (Hyp) 2 )][Cp*La( 2,3 -Ge 9 (Hyp) 2 )] (3) with only one coordinated THF molecule.