Can Bismuth Replace Mercury in Redox Transmetallation/Protolysis Syntheses from Free Lanthanoid Metals?

Tris(pentafluorophenyl)bismuth has been examined as a potential replacement for diarylmercurials in redox transmetallation/protolysis (RTP) syntheses of reactive rare earth compounds from free rare earth metals, HgAr2, and a proligand HL. Thus, the lanthanoid pyrazolates, [Ln(Ph(2)pz)(3)(thf)(3)) (Ph(2)pz = 3,5-diphenylpyrazolate; Ln = La, 1, Ce, 2, Nd, 3, Tb, 4; thf = tetrahydrofuran), [Ln(2)(Ph(2)pz)(4)(OMe)(2)(dme)(2)]center dot 2 dme (Ln = Ho, 5, Er, 6, Tm, 7, Lu, 8; dme =1,2-dimethoxyethane), [Ln(Ph(2)pz)(3)(dme)(2)] (Ln = Dy, 9, Sm, 10), [Ln(tBu(2)pz)(3)(thf)(2)) (tBu(2)pz = 3,5-di-tert-butylpyrazolate; Ln = La, 11, Ce, 12, Sm, 13, Gd, 14, Dy, 15, Ho, 16, Tm, 17, Yb, 18, Lu, 19), [Ln(ttfpz)(3)(thf)(3)] (ttfpz = 3-(2'-thienyl)-5-(trifluoromethyl)pyrazolate; Ln = La, 20, Sm, 21), and [Er(PhMepz)(3)(thf)(2)) 22 (PhMepz = 3-phenyl-5-methylpyrazolate) have been prepared in good yields by redox transmetallation/protolysis reactions employing lanthanoid metals and trispentafluorophenylbismuth [Bi(C6F5)(3)]center dot 0.5 diox (diox =1, 4-dioxane) in donor solvents. This is a new and efficient synthetic route in which Bi(C6F5)(3) replaces the commonly used Hg(C6F5)(2) or HgPh2, and provides proof of concept for the method. [Ln(2)(Ph(2)Pz)(4)(OMe)(2)(dme)(2)]center dot 2 dme (5-8) complexes are derived from C-O bond activation of dme on crystallization of the initial products from this solvent, and are dimeric methoxide-bridged species. Other structures are monomeric with re-bound pyrazolate ligands and nine-coordinate metal atoms for complexes 1-4,9-10 and 20-21, and eight-coordinate metal atoms for complexes 11-19 and 22.