STRUCTURE AND REACTIVITY OF YTTERBIUM BENZAMIDINATES

The ytterbium(II) benzamidinates [RC6H4C(NSiMe3)2]2Yb(THF)2 (1a: R = H, 1b: R = OMe) react with diaryl diselenides and ditellurides to give ytterbium(III) complexes of the type [RC6H4C(NSiMe3)2]2Yb(SeR')(THF) (2: R = H, R' = Ph; 3: R = H, R' = Mes) and [RC6H4C(NSiMe3)2]2Yb(TeR')(THF) (4: R = OMe, R' = Mes), respectively. The molecular structure of [PhC(NSiMe3)2]2Yb(SeMes)(THF) (3) has been determined by X-ray crystallography (triclinic, space group P1BAR, a 1064.9(3). b 1377.1(3), c 3690(3) pm, alpha 68.61(2), beta 89.46(3), gamma 72.82(1)-degrees, Z = 4, 10531 observed reflexions, R = 0.045). Moreover the strongly temperature-dependent H-1 NMR spectra of 2 and 3 are discussed and YB-171 NMR spectra of some ytterbium(II) chelate complexes are reported.