Four-and five-co-ordinate lanthanide (II) aryloxides: X-ray structures of the bis(2,6-di-t-butyl-4-methylphenoxo)ytterbium(II) complexes [Yb(OAr)2(L)2] and [Yb(OAr)2(L′)3][ArC6H2But2-2,6-Me-4, L = tetrahydrofuran (thf) or OEt2, L′= thf]

Abstract

General methods for the preparation of hydrocarbon-soluble, monomeric ytterbium (II) aryloxides are described {Yb+2TIOAr, or [Yb(NR₂)₂(OEt₂)₂]+2ArOH;RSiMe₃, ArC₆H₂Bu^t₂-2,6-Me-4; crystalline [Yb(OAr)₂(thf)₃](thf = tetrahydrofuran)(1) has the unprecedented square-pyramidal Yb^II stereochemistry (one thf apical), whereas the complexes [Yb(Oar)₂(L)₂][L = thf (2) or OEt₂(3)] are tetrahedral, with <Yb–OAr> 2.207 (12)(1), 2.137(10)(2), or 2.154(28)Å(3); complex (3) with thf readily yields (1) or (2)}.