Synthesis and First Structural Characterization of Lanthanide(II) Aryls:  Observation of a Schlenk Equilibrium in Europium(II) and Ytterbium(II) Chemistry

and, Gernot Heckmann; Niemeyer, Mark

doi:10.1021/ja993494c

Cited by 120 publications

(99 citation statements)

References 25 publications

(28 reference statements)

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“…Dimeric [Yb{C(SiMe 3 ) 2 (SiMe 2 X)}I(OEt 2 )] 2 (X = CH= CH 2 ,O Me, Me) compounds, reported by Smith and co-workers, were prepared by the addition of C(SiMe 3 ) 2 (SiMe 2 X)I to ytterbium metal in diethyl ether [12,13] and, notably, monomeric cis-[Yb(C 6 H 3 Ph 2 -2,6)I(thf) 3 ]w as isolated. [14] The chemistry of "RLnX" is complicated by oxidationt oL n III for Ln = Sm, Eu, and Yb, and the existence of Schlenke quilibria in both oxidation states. [15,16] Of the alkaline-earthm etal ions, Ca 2 + has comparable ion size to Yb 2 + (CN = 6: Yb 2 + :1 .02 ;C a 2 + :1 .00 ) [17] and often displays analogous chemistry.…”

Section: Introductionmentioning

confidence: 99%

“…In the case of the reaction with DippFormH, the 171 Yb NMR spectrum at 30 8Cs hows ad oublet with ac hemical shift of d = 552 ppm attributable to 5a,a sw ell as as harp singlet at d = 460 ppm for [YbI 2 (thf) 4 ] ( Figure 1). [14,15,28] Coupling of the hydrogen on the backbone carbon( NC(H)N) with the 171 Yb (spin 1 = 2 )i sotope gives rise to ad oublet in the 171 Yb NMR spectrum, with ac oupling constant of 51 Hz, similart ot he couplingc onstant found in the 1 HNMR spectrum of isolated 5a (44 Hz). Resonances were not observed forc ompound 5b as it is paramagnetic.…”

Section: Introductionmentioning

confidence: 99%

“…spectrum.T he third component [Yb(DippForm) 2 (thf) 2 ]i s known [29] ( Figure 2). [14,15,28] When the temperature was progressivelyl owered from 30 8Ct oÀ30 8C, at À15 8Ct he signal of [Yb(XylForm) 2 (thf) 2 ]w as split into at riplet ( 3 J (YbH) = 40 Hz). On furtherlowering the temperature,t he resonances of the solvated bis(formamidinato)ytterbium complex did not undergo any dramatic changes in chemical shift (at À30 8C: ab road resonance at d = 677 ppm).…”

Section: Introductionmentioning

confidence: 99%

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Lanthanoid Pseudo‐Grignard Reagents: A Major Untapped Resource

Ali

Deacon

Junk

et al. 2017

Chemistry A European J

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Pseudo-Grignardr eagents PhLnI (Ln = Yb, Eu), readily prepared by the oxidative addition of iodobenzene to ytterbium or europium metal at À78 8Cint etrahydrofuran (THF) or 1,2-dimethoxyethane (DME), react with ar ange of bulky N,N'-bis(aryl)formamidines to generate an extensive series of Ln II or more rarely Ln III complexes,n amely [Eu(Dipp-, and [Yb(XylForm) 2 I(dme)]·dme (7b){ (Form = ArNCHNAr;X ylForm (Ar = 2,6-Me 2 C 6 H 3 ), MesForm (Ar = 2,4,6-Me 3 C 6 H 2 ), DippForm (Ar = 2,6-iPr 2 C 6 H 3 )}. Reaction of PhEuI and MesFormH in DME consistently gave 2, and reactionw ith XylFormH in THF gave 4.E uropium complexes 1 and 3a are seven-coordinate divalent monomers, whilst 3b is as even-coordinate dme-bridged polymer.C omplex 5a of the smaller Yb II is as ix-coordinate monomer,b ut the related 6 and 7a are six-coordinatei odide-bridged dimers. 4 is at rivalent seven-coordinate hydroxide-bridged dimer,w hereas complexes 5b and 7b are seven-coordinate monomeric Yb III derivatives. Ac haracteristic structural feature is that iodide ligands are cisoid to the formamidinate ligand.T oi llustrate the synthetic scope of the pseudoGrignardr eagents,[ Yb(Ph 2 pz)I(thf) 4 ]( Ph 2 pz = 3,5-diphenylpyrazolate) was oxidised with 1,2-diiodoethane to afford seven-coordinate monomeric pyrazolato-ytterbium (III)

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Lanthanoid Pseudo‐Grignard Reagents: A Major Untapped Resource

Ali

Deacon

Junk

et al. 2017

Chemistry A European J

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“…It is notable that similar, although even larger, displacements in the range 0.75 to 1.50 have been observed for the aryl lanthanides [Ln(Dpp) 2 (thf) 2 ] (Dpp = 2,6-Ph 2 C 6 H 3 ), which also contain highly polar MÀC bonds. [17] Perhaps the most striking features in the solid-state structures of 3-5 are the additional metal-p-arene interactions [18] with the pendent arms of the biphenyl and terphenyl groups in the triazenide ligands. These arene rings apparently compete with THF to bind the M II cations, thus allowing the isolation of solvent-free derivatives.…”

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confidence: 99%

Stabilization of Aryl–Calcium, –Strontium, and –Barium Compounds by Designed Steric and π‐Bonding Encapsulation

et al. 2005

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In the last decade a major theme of organometallic chemistry has been the design and development of alternative ligand systems capable of stabilizing monomeric metal complexes while provoking novel reactivity. Exploration of this field is driven by the potential use of these complexes in catalysis and organic synthesis. Examples of monoanionic chelating Ndonor ligands that have received much recent attention (Scheme 1) include the b-diketiminate (I) [1] and the amidinate (II) [2] ligand systems. Much less attention has been given to the closely related triazenides (III). [3, 4] This may be attributed to the lack of suitable ligands that are sterically crowded enough to prevent undesirable ligand redistribution reactions and allow better control of the electronic and steric properties at the metal center.Triazenides are weaker donors than the isoelectronic amidinates and the related b-diketiminates, and should induce greater electrophilicity at a bonded metal atom. [5] This is reflected by the results of an NBO (natural bond orbitals) analysis of the energy-minimized structures [6] of the model anions 1,3-diphenyl-1,3-diketiminate (I M ), 1,3-diphenyl-1,3-diazaallyl (II M ), and 1,3-diphenyltriazenide (III M ) (see Supporting Information), which shows an NPA (natural population analysis) charge for the chelating N atoms of À0.54, À0.60, and À0.38, respectively.We recently succeeded in the preparation of aryl-substituted, sterically crowded triazenes. Ligands of this type may be synthesized in excellent yields by the reaction of different substituted 2-lithiobiphenyls with the m-terphenyl azide 1, followed by hydrolysis (Scheme 2).In a first attempt to test their properties, we have used the obtained triazenes to stabilize pentafluorophenyl compounds of the heavier alkaline-earth metals calcium, strontium, and barium. The heteroleptic pentafluorophenyl triazenides are accessible in tetrahydrofuran as solvent by a convenient onepot transmetalation/deprotonation [7] reaction from the triazene 2 a (HN 3 ArAr'), bis(pentafluorophenyl)mercury, and the corresponding alkaline-earth metal (Scheme 3). After crystallization from n-heptane, either the THF-free compounds [M(C 6 F 5 )(N 3 ArAr')] (M = Sr (4), Ba (5)) or the solvate [Ca(C 6 F 5 )(N 3 ArAr')(thf)] (3) were isolated in good yields. It is remarkable that attempts to replace the pentafluorophenyl substituents by a second triazenide ligand have not been successful so far. Apparently, the steric bulk of the latter prevents further substitution or ligand redistribution and therefore formation of the homoleptic complexes. [8] Solutions of 4 or 5 in aromatic or aliphatic solvents show considerable thermal stability and can be stored at ambient

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“…112 In Yb(Dpp)I(THF) 3 (Figure 90b), the metal is bonded to the ipso-carbon atom of the terphenyl group, to the terminal iodo substituent, and to three THF molecules. Eu(Dpp) 2 (THF) 2 shows an Eu center in a distorted tetrahedral coordination environment.…”

Section: Divalent Alkyl Lanthanide Complexesmentioning

confidence: 99%

Scandium, Yttrium & The Lanthanides: Organometallic ChemistryBased in part on the article Scandium, Yttrium & The Lanthanides: Organometallic Chemistry by R. D. Köhn, G. Kociok‐Köhn, & H. Schumann which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

Schumann

Fedushkin

2005

Encyclopedia of Inorganic Chemistry

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The group 3 metals scandium and yttrium and the 4f elements lanthanum to lutetium build up a big variety of organometallic compounds, in general with the metal in the oxidation state +3. Most of them are sandwich complexes Cp 3 Ln, Cp 2 LnX, and CpLnX 2 containing unsubstituted or substituted cyclopentadienyl ligands. In addition, cyclopentadienyl‐free organo rare earth compounds, like alkyl or aryl derivatives, alkenyl, allyl, alkynyl, hydrido, and carbene complexes, and organolanthanide compounds with indenyl, fluorenyl, cyclooctatetraenyl, or with heterocyclic ligands are described. Samarium, europium, and ytterbium form reasonable stable organic compounds in the oxidation state +2, whereas only a few rare earth organometallics with the metal in the oxidation state 0, +1, and +4 are known. All organo rare earth complexes are extremely sensitive to oxygen and water. The development of various synthetic methods as well as intensive single‐crystal X‐ray structure investigations made these highly reactive organometallic compounds available for use as organic synthons, efficient catalysts for polymerization, hydrogenation, hydroamination, and hydrosilylation as well as precursors for Metal Organic Chemical Vapor Deposition (MOCVD) and other material science applications.

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Synthesis and First Structural Characterization of Lanthanide(II) Aryls: Observation of a Schlenk Equilibrium in Europium(II) and Ytterbium(II) Chemistry

Cited by 120 publications

References 25 publications

Lanthanoid Pseudo‐Grignard Reagents: A Major Untapped Resource

Lanthanoid Pseudo‐Grignard Reagents: A Major Untapped Resource

Stabilization of Aryl–Calcium, –Strontium, and –Barium Compounds by Designed Steric and π‐Bonding Encapsulation

Scandium, Yttrium & The Lanthanides: Organometallic ChemistryBased in part on the article Scandium, Yttrium & The Lanthanides: Organometallic Chemistry by R. D. Köhn, G. Kociok‐Köhn, & H. Schumann which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

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