Organoamido- and Aryloxo-lanthanoids. IX. Preparations and Structures of Tris(η²-3,5-diphenyl-pyrazolato)lanthanoid(III) Complexes With Triphenylphosphine Oxide and Tetrahydrofuran

Abstract

From reaction of lanthanoid metals with bis ( pentafluorophenyl )mercury and 3,5-diphenylpyrazole (HPh₂pz) in 1,2-dimethoxyethane ( dme ) and treatment of the products with triphenylphosphine oxide, the complexes [ Ln (η²-Ph₂pz)₃(OPPh₃)₂].( dme )n ( Ln = Er or Nd , n = 1; Ln = La, n = 0.6) have been isolated. An X-ray crystal structure shows that the erbium complex [monoclinic, space group C2, a 22.08(3), b 14.30(1), c 13.37(1) Ǻ, β 124.09(7)°, Z 2 2730 'observed' data refined to R 0.046] is monomeric , with eight coordination of the metal. There is a trigonal bipyramidal arrangement of the centre ( Cen ) of the N-N bonds of three η²-3,5-diphenylpyrazolate groups ( ΣCen-Er-Cen 360°; ( Er -N) 2.344 Ǻ) and the oxygens of two equivalent trans triphenylphosphine oxide ligands [O- Er -O 176(1)°; Er -O 2.207(9)Ǻ]. Unit cell data indicate that the neodymium analogue [monoclinic, space group C2, a 23.01(3), b 14.94(2), c 13.82(2) Ǻ, β 123.65(8)°] is isostructural with the erbium complex. An analogous reaction of lanthanum or neodymium metal, Hg(C₆F₅)₂, and HPh₂pz in tetrahydrofuran ( thf ) gives [ Ln (η²-Ph₂pz)₃( thf )₃]. thf ( Ln = La or Nd ). The X-ray crystal structure of the neodymium complex [orthorhombic, space group P2₁2₁2₁, a 14.009(9), b 16.280(8), c 22.640(16)Ǻ, Z 4, 2967 'observed' data refined to R 0.046 reveals a nine-coordinate monomer with three η²-Ph₂pz ligands [ Nd -N 2.420(10)-2.524(8)Ǻ] and three thf ligands [ Nd -O 2.497(8)-2.587(8)Ǻ]. There is a trigonal prismatic arrangement of the centres of the N-N bonds and the oxygen donor atoms.