Lanthanoid Pseudo-Grignard Reagents: A Major Untapped Resource

Safaa H. Ali, Glen B. Deacon, Peter C. Junk, Shima Hamidi, Michal Wiecko, Jun Wang

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Pseudo-Grignard reagents PhLnI (Ln=Yb, Eu), readily prepared by the oxidative addition of iodobenzene to ytterbium or europium metal at −78 °C in tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME), react with a range of bulky N,N′-bis(aryl)formamidines to generate an extensive series of LnII or more rarely LnIII complexes, namely [Eu(DippForm)I(thf)4]⋅thf (1), [{EuI2(dme)2}2] (2), [Eu(XylForm)I(dme)2]⋅0.5 dme (3 a), [Eu(XylForm)I(dme)(μ-dme)]n (3 b), [{Eu(XylForm)I(μ-OH)(thf)2}2] (4), [Yb(DippForm)I(thf)3]⋅thf (5 a), [Yb(DippForm)I2(thf)3]⋅2 thf (5 b), [{Yb(MesForm)I(thf)2}2] (6), [{Yb(XylForm)I(thf)2}2] (7 a), and [Yb(XylForm)2I(dme)]⋅dme (7 b) {(Form=ArNCHNAr; XylForm (Ar=2,6-Me2C6H3), MesForm (Ar=2,4,6-Me3C6H2), DippForm (Ar=2,6-iPr2C6H3)}. Reaction of PhEuI and MesFormH in DME consistently gave 2, and reaction with XylFormH in THF gave 4. Europium complexes 1 and 3 a are seven-coordinate divalent monomers, whilst 3 b is a seven-coordinate dme-bridged polymer. Complex 5 a of the smaller YbII is a six-coordinate monomer, but the related 6 and 7 a are six-coordinate iodide-bridged dimers. 4 is a trivalent seven-coordinate hydroxide-bridged dimer, whereas complexes 5 b and 7 b are seven-coordinate monomeric YbIII derivatives. A characteristic structural feature is that iodide ligands are cisoid to the formamidinate ligand. To illustrate the synthetic scope of the pseudo-Grignard reagents, [Yb(Ph2pz)I(thf)4] (Ph2pz=3,5-diphenylpyrazolate) was oxidised with 1,2-diiodoethane to afford seven-coordinate monomeric pyrazolato-ytterbium(III) iodide [Yb(Ph2Pz)I2(thf)3] (8) in high yield, whilst metathesis between [Yb(Ph2pz)I(thf)4] and NaCp (Cp=C5H5) gave [Yb(C5H5)(Ph2pz)(thf)]n (9), a nine-coordinate η55-Cp-bridged coordination polymer. Reaction of the pseudo-Grignard reagent MeYbI with KN(SiMe3)2 gave [K(dme)4][Yb{N(SiMe3)2}3] (10) with a charge-separated three-coordinate homoleptic [Yb{N(SiMe3)2}3] anion, a complex that could be obtained in high yield by deliberate synthesis from YbI2 and KN(SiMe3)2 in DME.

Original languageEnglish
Pages (from-to)230-242
Number of pages13
JournalChemistry - A European Journal
Volume24
Issue number1
DOIs
Publication statusPublished - 2 Jan 2018

Keywords

  • europium
  • formamidines
  • LnLX-type complexes
  • organolanthanoid complexes
  • X-ray diffraction
  • ytterbium

Cite this

Ali, Safaa H. ; Deacon, Glen B. ; Junk, Peter C. ; Hamidi, Shima ; Wiecko, Michal ; Wang, Jun. / Lanthanoid Pseudo-Grignard Reagents : A Major Untapped Resource. In: Chemistry - A European Journal. 2018 ; Vol. 24, No. 1. pp. 230-242.
@article{e80756f95e3a4b4bafb0b9a2a4de4851,
title = "Lanthanoid Pseudo-Grignard Reagents: A Major Untapped Resource",
abstract = "Pseudo-Grignard reagents PhLnI (Ln=Yb, Eu), readily prepared by the oxidative addition of iodobenzene to ytterbium or europium metal at −78 °C in tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME), react with a range of bulky N,N′-bis(aryl)formamidines to generate an extensive series of LnII or more rarely LnIII complexes, namely [Eu(DippForm)I(thf)4]⋅thf (1), [{EuI2(dme)2}2] (2), [Eu(XylForm)I(dme)2]⋅0.5 dme (3 a), [Eu(XylForm)I(dme)(μ-dme)]n (3 b), [{Eu(XylForm)I(μ-OH)(thf)2}2] (4), [Yb(DippForm)I(thf)3]⋅thf (5 a), [Yb(DippForm)I2(thf)3]⋅2 thf (5 b), [{Yb(MesForm)I(thf)2}2] (6), [{Yb(XylForm)I(thf)2}2] (7 a), and [Yb(XylForm)2I(dme)]⋅dme (7 b) {(Form=ArNCHNAr; XylForm (Ar=2,6-Me2C6H3), MesForm (Ar=2,4,6-Me3C6H2), DippForm (Ar=2,6-iPr2C6H3)}. Reaction of PhEuI and MesFormH in DME consistently gave 2, and reaction with XylFormH in THF gave 4. Europium complexes 1 and 3 a are seven-coordinate divalent monomers, whilst 3 b is a seven-coordinate dme-bridged polymer. Complex 5 a of the smaller YbII is a six-coordinate monomer, but the related 6 and 7 a are six-coordinate iodide-bridged dimers. 4 is a trivalent seven-coordinate hydroxide-bridged dimer, whereas complexes 5 b and 7 b are seven-coordinate monomeric YbIII derivatives. A characteristic structural feature is that iodide ligands are cisoid to the formamidinate ligand. To illustrate the synthetic scope of the pseudo-Grignard reagents, [Yb(Ph2pz)I(thf)4] (Ph2pz=3,5-diphenylpyrazolate) was oxidised with 1,2-diiodoethane to afford seven-coordinate monomeric pyrazolato-ytterbium(III) iodide [Yb(Ph2Pz)I2(thf)3] (8) in high yield, whilst metathesis between [Yb(Ph2pz)I(thf)4] and NaCp (Cp=C5H5) gave [Yb(C5H5)(Ph2pz)(thf)]n (9), a nine-coordinate η5:η5-Cp-bridged coordination polymer. Reaction of the pseudo-Grignard reagent MeYbI with KN(SiMe3)2 gave [K(dme)4][Yb{N(SiMe3)2}3] (10) with a charge-separated three-coordinate homoleptic [Yb{N(SiMe3)2}3]− anion, a complex that could be obtained in high yield by deliberate synthesis from YbI2 and KN(SiMe3)2 in DME.",
keywords = "europium, formamidines, LnLX-type complexes, organolanthanoid complexes, X-ray diffraction, ytterbium",
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year = "2018",
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language = "English",
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journal = "Chemistry - A European Journal",
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Lanthanoid Pseudo-Grignard Reagents : A Major Untapped Resource. / Ali, Safaa H.; Deacon, Glen B.; Junk, Peter C.; Hamidi, Shima; Wiecko, Michal; Wang, Jun.

In: Chemistry - A European Journal, Vol. 24, No. 1, 02.01.2018, p. 230-242.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Lanthanoid Pseudo-Grignard Reagents

T2 - A Major Untapped Resource

AU - Ali, Safaa H.

AU - Deacon, Glen B.

AU - Junk, Peter C.

AU - Hamidi, Shima

AU - Wiecko, Michal

AU - Wang, Jun

PY - 2018/1/2

Y1 - 2018/1/2

N2 - Pseudo-Grignard reagents PhLnI (Ln=Yb, Eu), readily prepared by the oxidative addition of iodobenzene to ytterbium or europium metal at −78 °C in tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME), react with a range of bulky N,N′-bis(aryl)formamidines to generate an extensive series of LnII or more rarely LnIII complexes, namely [Eu(DippForm)I(thf)4]⋅thf (1), [{EuI2(dme)2}2] (2), [Eu(XylForm)I(dme)2]⋅0.5 dme (3 a), [Eu(XylForm)I(dme)(μ-dme)]n (3 b), [{Eu(XylForm)I(μ-OH)(thf)2}2] (4), [Yb(DippForm)I(thf)3]⋅thf (5 a), [Yb(DippForm)I2(thf)3]⋅2 thf (5 b), [{Yb(MesForm)I(thf)2}2] (6), [{Yb(XylForm)I(thf)2}2] (7 a), and [Yb(XylForm)2I(dme)]⋅dme (7 b) {(Form=ArNCHNAr; XylForm (Ar=2,6-Me2C6H3), MesForm (Ar=2,4,6-Me3C6H2), DippForm (Ar=2,6-iPr2C6H3)}. Reaction of PhEuI and MesFormH in DME consistently gave 2, and reaction with XylFormH in THF gave 4. Europium complexes 1 and 3 a are seven-coordinate divalent monomers, whilst 3 b is a seven-coordinate dme-bridged polymer. Complex 5 a of the smaller YbII is a six-coordinate monomer, but the related 6 and 7 a are six-coordinate iodide-bridged dimers. 4 is a trivalent seven-coordinate hydroxide-bridged dimer, whereas complexes 5 b and 7 b are seven-coordinate monomeric YbIII derivatives. A characteristic structural feature is that iodide ligands are cisoid to the formamidinate ligand. To illustrate the synthetic scope of the pseudo-Grignard reagents, [Yb(Ph2pz)I(thf)4] (Ph2pz=3,5-diphenylpyrazolate) was oxidised with 1,2-diiodoethane to afford seven-coordinate monomeric pyrazolato-ytterbium(III) iodide [Yb(Ph2Pz)I2(thf)3] (8) in high yield, whilst metathesis between [Yb(Ph2pz)I(thf)4] and NaCp (Cp=C5H5) gave [Yb(C5H5)(Ph2pz)(thf)]n (9), a nine-coordinate η5:η5-Cp-bridged coordination polymer. Reaction of the pseudo-Grignard reagent MeYbI with KN(SiMe3)2 gave [K(dme)4][Yb{N(SiMe3)2}3] (10) with a charge-separated three-coordinate homoleptic [Yb{N(SiMe3)2}3]− anion, a complex that could be obtained in high yield by deliberate synthesis from YbI2 and KN(SiMe3)2 in DME.

AB - Pseudo-Grignard reagents PhLnI (Ln=Yb, Eu), readily prepared by the oxidative addition of iodobenzene to ytterbium or europium metal at −78 °C in tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME), react with a range of bulky N,N′-bis(aryl)formamidines to generate an extensive series of LnII or more rarely LnIII complexes, namely [Eu(DippForm)I(thf)4]⋅thf (1), [{EuI2(dme)2}2] (2), [Eu(XylForm)I(dme)2]⋅0.5 dme (3 a), [Eu(XylForm)I(dme)(μ-dme)]n (3 b), [{Eu(XylForm)I(μ-OH)(thf)2}2] (4), [Yb(DippForm)I(thf)3]⋅thf (5 a), [Yb(DippForm)I2(thf)3]⋅2 thf (5 b), [{Yb(MesForm)I(thf)2}2] (6), [{Yb(XylForm)I(thf)2}2] (7 a), and [Yb(XylForm)2I(dme)]⋅dme (7 b) {(Form=ArNCHNAr; XylForm (Ar=2,6-Me2C6H3), MesForm (Ar=2,4,6-Me3C6H2), DippForm (Ar=2,6-iPr2C6H3)}. Reaction of PhEuI and MesFormH in DME consistently gave 2, and reaction with XylFormH in THF gave 4. Europium complexes 1 and 3 a are seven-coordinate divalent monomers, whilst 3 b is a seven-coordinate dme-bridged polymer. Complex 5 a of the smaller YbII is a six-coordinate monomer, but the related 6 and 7 a are six-coordinate iodide-bridged dimers. 4 is a trivalent seven-coordinate hydroxide-bridged dimer, whereas complexes 5 b and 7 b are seven-coordinate monomeric YbIII derivatives. A characteristic structural feature is that iodide ligands are cisoid to the formamidinate ligand. To illustrate the synthetic scope of the pseudo-Grignard reagents, [Yb(Ph2pz)I(thf)4] (Ph2pz=3,5-diphenylpyrazolate) was oxidised with 1,2-diiodoethane to afford seven-coordinate monomeric pyrazolato-ytterbium(III) iodide [Yb(Ph2Pz)I2(thf)3] (8) in high yield, whilst metathesis between [Yb(Ph2pz)I(thf)4] and NaCp (Cp=C5H5) gave [Yb(C5H5)(Ph2pz)(thf)]n (9), a nine-coordinate η5:η5-Cp-bridged coordination polymer. Reaction of the pseudo-Grignard reagent MeYbI with KN(SiMe3)2 gave [K(dme)4][Yb{N(SiMe3)2}3] (10) with a charge-separated three-coordinate homoleptic [Yb{N(SiMe3)2}3]− anion, a complex that could be obtained in high yield by deliberate synthesis from YbI2 and KN(SiMe3)2 in DME.

KW - europium

KW - formamidines

KW - LnLX-type complexes

KW - organolanthanoid complexes

KW - X-ray diffraction

KW - ytterbium

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DO - 10.1002/chem.201704383

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SN - 1521-3765

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