Half-sandwich lanthanide (III) complexes coordinated by Two α-iminopyridine radical anions

Abstract

The reaction of ytterbocene (C5H4Me) 2Yb(THF) with 2 equiv of N-2,6-diisopropylphenylimino2-pyridine (Ipy) occurs with oxidative cleavage of one Yb-Cp bond and oxidation of the ytterbium(II) ion and affords the half-sandwich Yb(III) complex [Yb(C 5H4Me){(2,6-i-Pr2C6H 3NCH(C5H4N)•-}2], containing two Ipy radical-anions. The indenyl-containing analogue [Yb(C 9H7){(2,6-i-Pr2C6H 3NCH(C5H4N)•-}2] was unexpectedly obtained in the metathesis reaction of (C9H 7)2Yb(μ-Cl)2Li(Et2O)2 with an equimolar amount of [Ipy•-]K+ instead of the sandwich Yb(III) complex [Yb(C9H7)2{(2,6i- Pr2C6H3NCH(C5H4N) •-)]. The gadolinium complex [Gd(C5Me 5){(2,6-i-Pr2C6H3NCH(C 5H5N)•-}2] was synthesized by the metathesis reaction of (C5Me5)GdCl2(THF) 3 with a 2-fold molar excess of [Ipy•-]K+ in THF. The structures of all complexes were proved by the X-ray single-crystal diffraction studies. The investigation of magnetic properties of complexes [LnCp{(2,6-i-Pr2C5H3NCH(C5H 4N)•-}2] (Cp = C5H 4Me, C5Me5, C9H7; Ln = Yb, Gd) in the temperature region 2-300 K revealed the presence of two types of antiferromagnetic interactions between the paramagnetic centers: between the Ln3+ ion and both radicals and between two radicals. © 2009 American Chemical Society.