Synthesis and structural studies of heteroleptic complexes of ytterbium(III) involving aryloxy- or alkoxy- and cyclopentadienyl ligands
摘要:
Treatment of tris-cyclopentadienyl-ytterbium in thf with one equivalent of 2,6-di(tert-butyl)phenol, N,N-dimethyl-2-aminoethanol or N,N-diethyl-2-aminoethanol resulted in substitution of one cyclopentadienyl ligand and formation of [YbCp2(O-C6H3'Bu-2,6)(thf)] (1), [{YbCp2(mu-OCH2CH2NMe2)}(2)] (2) or [{YbCp2(mu-OCH2CH2NEt2)}(2)](.)(thf)(2) (3), respectively. All compounds were characterised by spectroscopic and X-ray crystallographic techniques, the latter two also being studied by variable temperature H-1 NMR spectroscopy. Compound (1) is mononuclear with the Yb centre bound by two eta(5)-cyclopentadienyl ligands one O-bound thf and an O-bound phenoxy ligand. Compounds (2) and (3) are centrosymmetric dimers with the Yb centre bound by two eta(5)-cyclopentadienyl ligands, while the bidentate ligands chelate the metal centre and also bridge to the adjacent Yb through the alkoxy oxygen atom. Variable temperature H-1 NMR studies on compounds (2) and (3) show a solution-state equilibrium between the dimeric solid-state structure and one with the nitrogen atoms non-bound to Yb. (C) 2003 Elsevier B.V. All rights reserved.