Rare‐Earth‐Metal Dialkynyl Dimethyl Aluminates

Nieland, Anja; Mix, Andreas; Neumann, Beate; Stammler, Hans‐Georg; Mitzel, Norbert W.

doi:10.1002/chem.201300465

Cited by 10 publications

(11 citation statements)

References 56 publications

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“…1 HNMR spectroscopy revealed that the aluminabenzene and 2,4-ditert-butylpentadienyl ligands remained intact showing only slightly shifted proton signals,i na ddition to the CH 3 /C 6 F 5 exchange.T his was also confirmed by XRD measurements, along with the routine U-conformation of the pentadienyl ligand. In the solid state,t he two C 6 F 5 moieties coordinate either terminally,f acing upwards and away from the aluminabenzene ligand, or bridge the yttrium center via the orthofluorine atom F1 (Figure 3).The terminal and bridging C 6 F 5 groups could also be assigned by a 19 F- 19 FC OSY NMR experiment ( Figure S28). B(C 6 F 5 ) 3 -promoted CH 3 /C 6 F 5 exchange at the Lewis acidic aluminum center has been observed before.…”

Section: Angewandte Chemiementioning

confidence: 99%

“…Thed imeric 4,4'-bipyridine complex 3d is dark-red colored and is one of only few yttriumbipyridine complexes reported to date and the first with flanking organometallic moieties. [13] In complex 4,the aluminum atom is markedly bent out of the C1-C2-C4-C5-plane (0.824 )due to the steric demand of the C 6 F 5 ligands.Asaresult, the Y···Al distance of 3.071 (2) is much larger than that in the parent complex 1-Y.T he C À C distances within the aluminabenzene ring, however,d on ot deviate remarkably from those in 1-Y.T he Y···F distance (2.413(9) )lies in between literature-known Y···F distances for bridging (2.217(5) ) [14] and weakly coordinating (2.786-(2) ) [15] fluorine atoms.A si ndicated by av ariable-temperature 19 FNMR experiment, an Y···F interaction seems to emerge in solution at lower temperatures ( Figure S29), since signals assigned to the bridging C 6 F 5 ligand started to broaden considerably at temperatures below À40 8 8C. 1 HNMR spectroscopy revealed that the aluminabenzene and 2,4-ditert-butylpentadienyl ligands remained intact showing only slightly shifted proton signals,i na ddition to the CH 3 /C 6 F 5 exchange.T his was also confirmed by XRD measurements, along with the routine U-conformation of the pentadienyl ligand.…”

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confidence: 94%

“…TheC -Al-C-Y four-membered metallacycle involving the vinylic carbon atom C5 and the acetylido carbon atom C29 deviates markedly from an ideal plane (torsion angle Y-C5-Al-C29 = À14.798 8). [16][17][18][19] TheC ÀCdistances within the bridging,S-shaped 2,4-di-tert-butylpentadienediyl ligand confirm the h 3 -allylic h 1 -bridging bonding mode,asthe distances for C1-C2 (1.417 (3) )a nd C2-C3 (1.381 (3) )a re typical for conjugated double bonds,C 3-C4 (1.499 (3) )i si nt he region for single bonds,a nd C4-C5 (1.348 (3) )i sc learly indicative of ad ouble bond. Thed istances between the yttrium metal center and the bridging carbon atoms (Y-C5 2.577(2) ;Y-C29 2.524 (2) )are in the range typical of such complexes.…”

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Formation and Reactivity of an Aluminabenzene Ligand at Pentadienyl‐Supported Rare‐Earth Metals

et al. 2018

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The half-open rare-earth-metal aluminabenzene complexes[(1-Me-3,5-tBu 2 -C 5 H 3 Al)(m-Me)Ln(2,4-dtbp)] (Ln = Y, Lu) are accessible via as alt metathesis reaction employing Ln(AlMe 4 ) 3 and K(2,4-dtbp). Treatment of the yttrium complex with B(C 6 F 5 ) 3 and tBuCCH gives access to the pentafluorophenylalane complex [{1-(C 6 F 5 )-3,5-tBu 2 -C 5 H 3 Al}{m-C 6 F 5 }Y{2,4-dtbp}] and the mixed vinyl acetylide complex [(2,4-dtbp)Y(m-h 1 :h 3 -2,4-tBu 2 -C 5 H 4 )(m-CCtBu)-AlMe 2 ], respectively.Since the 1980s it has been known that pentadienyl ligands impart as tabilizing environment for the organometallic chemistry of alkali, alkaline-earth, transition, and rare-earth metals. [1] In comparison to the ubiquitous cyclopentadienyl congeners these "open variants" actively engage in distinct reaction paths,t he most prominent being the formation of metallabenzenes.T he feasibility of such metallacycles was initially shown for osmium by Elliot and co-workers in 1982 and later extended to the transition metals molybdenum, iridium, ruthenium, and nickel by the research groups led by Roper, Ernst, and Salzer. [2] In contrast to these aromatic transition-metal derivatives and the well-established borabenzene chemistry, [3] such ac ompound was only recently described for the Group 13 metal aluminum. In fact, the first isolation and subsequent characterization of the anionic aluminabenzene Li[1-Mes-2,6-C 5 H 3 Al] (Mes = 2,4,6-trimethylphenyl) was accomplished by Yamashita et al. in 2014 through as ophisticated reaction pathway employing asilyl-substituted diyne,DIBAL-H, and mesityllithium. [4] The same group also utilized the aforementioned aluminabenzene derivative in reactions with CpZrCl 3 ,C p*ZrCl 3 ,a nd ZrCl 4 , yielding distinct chlorido-bridged aluminabenzene-bearing complexes but at the expense of losing aromaticity in the aluminacycle to some degree. [5] Furthermore,n onbridged aluminabenzene complexes of the transition metals rhodium and iridium were published very recently by the Yamashita group as was az witterionic zirconium complex derived from an aluminacyclohexadiene and homoleptic benzyl ZrBn 4 . [6] These complexes also showed promising performances in C À Hb orylation and ethylene polymerization, respectively.Here we wish to report the formation of ad ianionic aluminabenzene ligand at rare-earth-metal centers according to an unprecedented reaction path, exploiting an alkylaluminate-mediated pentadienyl deprotonation and ring closure.A ccordingly,w hen we reacted the potassium salt of 2,4-di-tert-butylpentadiene K(2,4-dtbp) [1f] with rare-earthmetal tetramethylaluminates Ln(AlMe 4 ) 3 (Ln = Y, Lu) [7] at ambient temperature,w ew ere able to isolate the unusual "half-open" sandwich complexes [(1-Me-3,5-tBu 2 -C 5 H 3 Al)(m-Me)Ln(2,4-dtbp)] (1-Y,L n= Y) and 1-Lu (Ln = Lu) in high yields (Scheme 1). Complexes 1-Ln bear one 2,4-di-tertbutylpentadienyl ligand and one methyl-bridged 3,5-di-tertbutylaluminabenzene ligand, thus displaying another member of this rare family of metal-coordinated aluminabenzenes,...

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Section: Angewandte Chemiementioning

confidence: 99%

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confidence: 94%

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confidence: 99%

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Formation and Reactivity of an Aluminabenzene Ligand at Pentadienyl‐Supported Rare‐Earth Metals

et al. 2018

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“…All of these compounds were characterized by NMR spectroscopy, X-ray crystallography, and by elemental analysis. NMR spectroscopic studies of the series of paramagnetic compounds Ln(AlMe 4 ) 3 and Ln[(-C≡CPh) 2 AlMe 2 ] 3 have also been performed [105].…”

Section: Heterobimetallic Organolanthanide Complexesmentioning

confidence: 99%

Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2013

Edelmann

2015

Coordination Chemistry Reviews

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“…[58] Addition of 1equiv.o ftBuCCH to this mixture at room temperature does not generate detectable quantities of the aluminated product tBuCCAlEt 2 or the alkynylaluminate. [59] Instead, heating the reaction mixture to 60 8Ca ffords tBuCCÀ AlEt 2 and ethane and reforms 1 Y (Scheme 5).…”

Section: Mechanistic Studiesmentioning

confidence: 99%

Rare‐Earth Catalyzed C−H Bond Alumination of Terminal Alkynes

Kanbur

Sadow

2020

Chemistry A European J

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Organoaluminum reagents' application in catalytic CÀHbond functionalization is limited by competitive side reactions, such as carboalumination andh ydroalumination. Herein, rare-earth tetramethylaluminate complexes are shown to catalyzet he exclusive CÀHb ond metalation of terminal alkynes with the commodity reagents trimethyl-, triethyl-, and triisobutylaluminum.K inetic experiments probing alkyl-group exchange between rare-earth aluminates and trialkylaluminum, CÀHb ond metalation of alkynes,a nd catalytic conversionsr eveal distinct pathways of catalytic aluminationsw ith triethylaluminum versus trimethylaluminum. Most significantly,k inetic data point to reversible formation of au nique [Ln](AlR 4 ) 2 ·AlR 3 adduct, followed by turnover-limiting alkyne metalation. That is, CÀHb ond activation occurs from am ore associated organometallic species, rather than the expected coordinatively unsaturated species. These mechanistic conclusions allude to an ew general strategy for catalytic CÀHb ond alumination thatm ake use of highly electrophilic metal catalysts. representsanonlinear least-squares fit to the equation d[tBuCCAlEt 2 ] = dt = A[AlEt 3 ] = {[AlEt 3 ]+ +B}, where A = k 2 [1 Y ][tBuCCH] and B = (k -1 + +k 2 [tBuC CH]) = k 1 .[ AlEt 3 ] = 0.194-1.419 m;[tBuCCH] = 0.096 m;[1 Y ] = 0.012 M.All manipulations were carried out under inert conditions, either using Schlenk techniques or in gloveboxes under an itrogen at-Caution:T rialkylaluminum and alkynyldialkylaluminum compounds are pyrophoric liquids and must be handled under inert atmospheres. The terminal alkyne and trialkylaluminum reactants were added via syringe to as olution of the catalyst (3 mol %) in [D 6 ]benzene at room temperature, and the reaction mixture was placed in aT eflon-sealed JY oung-style NMR tube. The NMR tube 1 HNMR ([D 6 ]benzene): d = 7.40 (m, 2H, m-C 6 H 5 ), 6.91 (vt, 3 J HH = 7.5, 1H, p-C 6 H 5 ), 6.81 (vt, 3 J HH = 7.5, 2H, o-C 6 H 5 ), 1.50 (t, 3 J HH = 8.1 Hz, 6H,A lCH 2 CH 3 ), 0.64 (q, 3 J HH = 8.1 Hz, 4H,A lCH 2 CH 3 ). 13 C{ 1 H} NMR

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Rare‐Earth‐Metal Dialkynyl Dimethyl Aluminates

Cited by 10 publications

References 56 publications

Formation and Reactivity of an Aluminabenzene Ligand at Pentadienyl‐Supported Rare‐Earth Metals

Formation and Reactivity of an Aluminabenzene Ligand at Pentadienyl‐Supported Rare‐Earth Metals

Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2013

Rare‐Earth Catalyzed C−H Bond Alumination of Terminal Alkynes

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