Synthesis and characterization of a new class of divalent lanthanide complexes {[C5H4(CMe2Ph)]4Ln2(μ-X)2}[Li(DME)3]2 (Ln=Sm, X=I; Ln=Yb, X=Cl; DME=dimethoxyethane)

Synthesis and characterization of a new class of ion-pairs complexes [Ln2(PhMe2CC5H4)4(μ-X)2][Li(DME)3]2 (Ln=Sm, X=I; Ln=Yb, X=Cl) are described. The reaction of SmI2(THF)2 (THF=tetrahydrofuran) with two equivalents of PhMe2CC5H4Li(DME) in THF affords the Sm(II) complex [Sm2(PhMe2CC5H4)4(μ-I)2][Li(DME)3]2 (1), while the Na–K alloy reduction of (PhMe2CC5H4)2YbCl, which was formed in situ by the reaction of YbCl3 and PhMe2CC5H4Li in 1:2 molar ratio, gives Yb(II) complex [Yb2(PhMe2CC5H4)4(μ-Cl)2][Li(DME)3]2 (2). The single-crystal structural analyses of 1 and 2 reveal that they both comprise two Li+(DME)3 cations and a new class of dianion, {[C5H4(CMe2Ph)]4Ln2(μ-X)2}2−, in which two [C5H4(CMe2Ph)]2Ln were bridged together by two iodine atoms for Sm and two chlorine atoms for Yb. The coordination geometry of the central metal is best described as a distorted tetrahedral.