Organoamido- and Aryloxo-Lanthanoids. II. Preparation of Tris(2,6-diphenylphenoxo)-lanthanoid(III) Complexes and the X-Ray Structures of Low-Coordinate [Yb(O-2,6-Ph2C6H3)3] Containing an Intramolecular Chelate Yb…π-Arene Interaction, and [Yb(O-2,6-Ph2C6H3)3(thf)2].thf (thf = Tetrahydrofuran)

Bulky monomeric lanthanoid(III) aryl oxides Ln(Odpp)3(Odpp = 2,6- diphenylphenoxide; Ln = Nd, Sm, Er, Yb or Lu) have been prepared by reaction between the lanthanoid metal, Hg(C6F5)2, and HOdpp in tetrahydrofuran (thf), and Yb(Odpp)3 has also been obtained from an analogous reaction of (PhCC)2Hg. Cleavage of Ln(η5-C5H5)3 (Ln = Nd or Yb) with HOdpp also yields Ln(Opdd)3. The aryl oxides have been isolated as [Ln(Odpp)3(thf)2] (Ln = Nd, Sm or Yb) or as the homoleptic complexes Ln(Odpp)3 (Ln = Nd, Er, Yb or Lu). The X-ray crystal structure of [Yb(Odpp)3(thf)2].thf [crystals monoclinic, space group P21/n, a 11.009(4), b 32.134 (7), c 15.498(6)Ǻ, β 96.72(3)°, Z 4; 2785 data refined to R 0.039] shows the complex to have distorted square pyramidal stereochemistry with apical and transoid basal Odpp ligands, (Yb-Odpp) 2.078(9)Ǻ, and transoid basal thf ligands, {Yb-O(thf)} 2.305(8)Ǻ. Similarly, Yb(Odpp)3 [crystals triclinic, space group Pī, a 15.934(2), b 13.563(1), c 10.968(2)Ǻ, α 116.71(1), β 92.90(2), γ 103.38(1)°, Z 2; 6236 data refined to R 0.031] was shown to have a trigonal pyramidal arrangement of oxygen donor atoms [{Yb-O} 2.065(4) Ǻ;{O-Yb-O} 117.5(1)°], a novel intramolecular chelate Yb…π-arene interaction, {Yb...C} 2.978(6)Ǻ, and an agostic Yb…CH interaction.