Guo, Zhifang, Blair, Victoria, Deacon, Glen B., and Junk, Peter C. (2018) Can bismuth replace mercury in redox transmetallation/protolysis syntheses from free lanthanoid metals? Chemistry: a European journal, 24 (66). pp. 17464-17474.

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Abstract

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(Ph2pz)3(thf)3] (Ph2pz=3,5‐diphenylpyrazolate; Ln=La, 1, Ce, 2, Nd, 3, Tb, 4; thf=tetrahydrofuran), [Ln2(Ph2pz)4(OMe)2(dme)2]⋅2 dme (Ln=Ho, 5, Er, 6, Tm, 7, Lu, 8; dme=1,2‐dimethoxyethane), [Ln(Ph2pz)3(dme)2] (Ln=Dy, 9, Sm, 10), [Ln(tBu2pz)3(thf)2] (tBu2pz=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]⋅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. [Ln2(Ph2pz)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 η2‐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.

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