Organoamido- and Aryloxo-lanthanoids. X. Tris(η²-3,5-di-t-butylpyrazolato)lanthanoid(III) Complexes and the X-Ray Crystal Structure of Er(η²-Bu^t₂pz)₃(thf)₂

Abstract

The complexes Ln (Bu^t₂pz)₃( thf )₂ ( Ln = Y, La, Pr, Nd , Sm, Gd, Dy , Er , Yb, Lu; Bu^t₂pz- = 3,5-di-t-butylpyrazolate; thf = tetrahydrofuran ), and [ Ln (Bu^t₂pz)₃(OPPh₃)₂].( dme )n ( Ln = La, n = ⅔ ; Ln = Er , n = 1; dme = 1,2-dimethoxyethane) have been prepared by reaction of the lanthanoid metal with bis ( pentafluorophenyl )mercury and the corresponding pyrazole in either thf , or in dme in the presence of triphenylphosphine oxide. The X-ray crystal structure of Er (η²-Bu^t₂pz)₃( thf )₂ [monoclinic, space group P2₁ (No. 4), a 9.738(4), b 19.602(4), c 11.636(4) Ǻ, β 99.42(3)°, R 0.0374 for 3667 observed reflections] shows the complex to be an eight-coordinate monomer with three chelating Bu^t₂pz ligands . The arrangement of centres ( Cen ) of the N-N bonds of the Bu^t₂pz ligands [< Er -N> 2.336 Ǻ; Cen-Er-Cen 140.1(4)°, 110.3(4)° and 109.6(4)°] and the thf oxygen atoms [< Er -O> 2.351 Ǻ; O- Er -O 140.1(4)°] is intermediate between trigonal bipyramidal and square pyramidal. The other Ln (Bu^t₂pz)₃( thf )₂ complexes and Ln (Bu^t₂pz)₃(OPPh₃)₂ are considered to have similar structures.