Widely contrasting outcomes from the use of tris(pentafluorophenyl)bismuth or pentafluorophenylsilver as oxidants in the reactions of lanthanoid metals with N,N '-diarylformamidines

Guo, Zhifang, Blair, Victoria L., Deacon, Glen B., and Junk, Peter C. (2020) Widely contrasting outcomes from the use of tris(pentafluorophenyl)bismuth or pentafluorophenylsilver as oxidants in the reactions of lanthanoid metals with N,N '-diarylformamidines. Dalton Transactions, 49. pp. 13588-13600.

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Abstract

Reactions of lanthanoid metals with tris(pentafluorophenyl)bismuth or pentafluorophenylsilver and two widely disparate formamidines, N,N'-bis(2,6-difluorophenyl)formamidine (DFFormH) and N,N'-bis(2,6-diisopropylphenyl)formamidine (DippFormH) have been investigated as possible redox transmetallation/protolysis (RTP) syntheses of lanthanoid formamidinates. Thus, (Ln(DFForm)(3)(thf)) (Ln = Lu, 1, Yb, 2, Tm, 3, Er, 4, Ho, 5, Dy, 6; thf = tetrahydrofuran), [Ln(DFForm)(3)(thf)(2)] (Ln = Tb, 7, Gd, 8, Sm, 9, Nd, 10), and (Yb(DippForm)(2)(thf)(2)]center dot 2thf (11) complexes were obtained from an excess of lanthanoid metals, [Bi(C6F5)(3)]center dot 0.5diox (diox = 1,4-dioxane) and the appropriate formamidine. Reaction of neodymium and [Bi(C6F5)(3)]center dot 0.5diox with the bulkier DippFormH in thf resulted in C-F activation and formation of (Nd(DippForm)(2)F(thf)(2)] (12) and o-HC6F4O(CH2)(4)N(Dipp)CH=N(Dipp) (Dipp = 2,6-di-isopropylphenyl). Although the reaction of erbium and [Bi(C6F5)(3)]center dot 0.5diox with DippFormH was not complete after one week (by 19F NMR), use of [Hg(C6F5)(2)] instead of [Bi(C6F5)(3)]center dot 0.5diox resulted in C-F activation and formation of [Er(DippForm)(2)F(thf)) (13) and o-HC6F4O(CH2)(4)N(Dipp)CH=N(Dipp) in two days. Attempted RTP reactions between lanthanoid metals, AgC6F5 and DFFormH in thf gave [Ag-2(DFForm)(2)]center dot 3thf (14), except in the case of ytterbium. All other lanthanoid metals required activation by 12 (2%) before lanthanoid complex formation could be achieved. From these reactions, lanthanoid formamidinates, [Ln(DFForm)(2)(solv)I] (Ln = Lu, 15, Tm, 16, Er, 17, Tb, 18, Gd, 19), (Ln(DFForm)(3)(py)] = Er, 17a, Tb, 18a; py = pyridine), and (Nd(DFForm)(3)(thf)(2)]center dot thf (10) were obtained. Where two types of lanthanoid formamidinates [Ln(DFForm)(3)(pY)] and [Ln(DFForm)(2)(solv)I] were obtained from the Ln metals activated by 12, they could not be separated on preparative scale. From Yb, the peroxide-bridged complex, [Yb-2(DippForm)(2)(O-2)(2)(py)(4)] (20) was surprisingly isolated. Thus [Bi(C6F5)(3)]center dot 0.5diox has potential as an oxidative replacement for diarylmercurials in RTP syntheses of lanthanoid formamidinates but [AgC6F5(py)] does not.

Item ID: 64888
Item Type: Article (Research - C1)
ISSN: 1477-9234
Copyright Information: © The Royal Society of Chemistry 2020
Funders: Australian Research Council (ARC)
Projects and Grants: ARC DP190100798
Date Deposited: 28 Oct 2020 07:45
FoR Codes: 34 CHEMICAL SCIENCES > 3402 Inorganic chemistry > 340203 F-block chemistry @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%
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