Organoamido- and Aryloxo-lanthanoids. IV. Synthesis and X-Ray Structures of Low-Coordinate [Yb(O-2,4,6-Bu^t₃C₆H₂)₃(thf)] and [Yb(O-2,4,6-Bu^t₃C₆H₂)₂(μ-OH)(thf)]₂ (thf = Tetrahydrofuran)

Abstract

Reaction of Yb ( Otbp )₂( thf )₃( tbp = 2,4,6 Bu^t₃C₆H₂; thf = tetrahydrofuran ) with TlOtbp in tetrahydrofuran at room temperature yields thallium metal and Yb( Otbp )₃( thf ) (1), which was also obtained by redox transmetallation between TlOtbp and ytterbium metal in refluxing tetrahydrofuran . Some [ Yb ( Otbp )₂( µ-OH) (thf)]₂ (2) was also isolated from the first synthesis and is derived from hydrolysis of Yb ( Otbp )₃( thf ) by traces of water. The X-ray crystal structure of (1) [triclinic, P1, a 21.78(1), b 13.89(2), c 10.461(4)Å , α; 109.03(5), β 99.03(3), γ; 98.34(5)º, Z 2, No = 4354 'observed' data refined to R 0.0711 shows novel distorted tetrahedral four coordination for ytterbium [0-Yb-0 angles 90.6(5)-121.8(4)º, which is bonded more strongly to the aryl oxide [Yb-0 1.97(1), 2.02(1), 2.09(1) Å ] than to thf [Yb-0 2.35(1) Å. The X-ray structure of (2) [triclinic, P1, a 15.61(1), b 13.84(2), c 11.085(4) Å, α 99.25(9),, β 94.46(4), γ 96.42(9), Z 1, No = 4718 'observed' data refined to R 0.050] indicates a centrosymmetric hydroxo -bridged dimer with a YbO₂Yb core. Ytterbium has irregular five coordination with two bridging hydroxide oxygens [Yb-0 2.217(6), 2.199(6) A; 0-Yb-0' 70.2(2)º, Yb-O-Yb, 109.8(3)º, non-bonding Yb…Yb 3.614(2) A], two phenoxide oxygens [2.047(7), 2.073(6) Å], and a more distant thf oxygen [2.363(8) Å ].