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, HgAr 2 , 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 ] ⋅ 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( t Bu 2 pz) 3 (thf) 2 ] ( t Bu 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(C 6 F 5 ) 3 ] ⋅ 0.5 diox (diox=1, 4‐dioxane) in donor solvents. This is a new and efficient synthetic route in which Bi(C 6 F 5 ) 3 replaces the commonly used Hg(C 6 F 5 ) 2 or HgPh 2 , and provides proof of concept for the method. [Ln 2 (Ph 2 pz) 4 (OMe) 2 (dme) 2 ] ⋅ 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 η 2 ‐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 .