A Tetraorganyl-Alumaborane with An Al–B σ-Bond and Two Adjacent Lewis-Acidic Centers

Kurumada, Satoshi; Yamashita, Makoto

doi:10.1021/jacs.2c01580

Cited by 16 publications

(18 citation statements)

References 55 publications

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“…Für einen Einblick in die Farbe von Verbindung 5 wurden experimentelle UV/Vis-Spektren in Et 2 O aufgenommen, welche zwei schwache Banden im sichtbaren Bereich bei 425 nm und 520 nm aufweisen (Schema 4). TD-DFT [17] 15), Al1À C9 2.016(2), Al1À C20 2.0045( 18), Al1À B1 2.1481 (19), C1À B1 1.564( 2), C11À B1 1.569( 2), C9À Al1À B1 88.72( 8), C10À C9À Al1 109.44 (13), C10À C1À B1 118.34 (15), C1À B1À Al1 102.23 (11). energie der AlÀ B-Bindung mit ΔE = 382 kJ mol À 1 ermittelt.…”

Section: Ergebnisse Und Diskussionunclassified

“…Ein sehr aktuelles Beispiel von Yamashita verwendet zur Herstellung von Alumaboran H ein anionisches Aluminium-Nukleophil mit einem Bor-Elektrophil. [11] Trotz der Bedeutung der berichteten Verbindungen BÀ H für die Bor-Chemie, wurde die Reaktivität von elektronspezifischen AlÀ B-Bindungen nur wenig untersucht. Lediglich für das jüngste Alumaboran H führten Reaktionen mit Dimethylsulfoxid und Kohlenmonoxid zur Desoxygenierung dieser beiden Substrate unter gleichzeitiger Bildung des AlÀ OÀ B-Strukturmotivs.…”

Section: Introductionunclassified

“…Mit umgekehrter Funktionalität reagieren neutrale Al I −Nukleophile mit Bor‐Elektrophilen unter Bildung der Al−B‐Bindung, wie von Braunschweig ( F ) [9] und Nikonov ( G ) [10] berichtet wurde. Ein sehr aktuelles Beispiel von Yamashita verwendet zur Herstellung von Alumaboran H ein anionisches Aluminium‐Nukleophil mit einem Bor‐Elektrophil [11] . Trotz der Bedeutung der berichteten Verbindungen B−H für die Bor‐Chemie, wurde die Reaktivität von elektronspezifischen Al−B‐Bindungen nur wenig untersucht.…”

Section: Introductionunclassified

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Reduktive Bildung von Al−B σ‐Bindungen in Alumaboranen: Einfache Spaltung polarer Mehrfachbindungen

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Es wird ein einfacher Zugang zu einer Alumaboran-Spezies mit elektronenpräziser AlÀ B σ-Bindung vor-gestellt. Die reduktive Umlagerung von 1-(AlI 2 ), 8-(BMes 2 )-Naphthalin (Mes = 2,4,6-Me 3 C 6 H 2 ) ermöglicht die Bildung der Alumaboran-spezies cyclo-(1,8-C 10 H 6 )-[1-Al(Mes)(OEt 2 )-8-B(Mes)] mit einer ko-valenten AlÀ B σ-Bindung. Diese AlÀ B σ-Bindung bewirkt die reduktive Spaltung von Mehrfachbindungen: S=C-(NiPrCMe) 2 ergibt die naphthalinverbrückende Struktur BÀ SÀ Al(NHC), NHC = N-Hetero-cyclisches Carben, während O=CPh 2 desoxygeniert wird, um eine BÀ OÀ Alverbrückende Spezies zu erhalten, bei der das verbliebene = CPh 2 -Fragment in das Naphthalingerüst eingebaut wird. Die Re-aktion mit Isonitril Xyl-N�C (Xyl = 2,6-Me 2 C 6 H 4 ) erfolgt über eine vorgeschlagene (Aminoboryl-)Carben-Spezies, die ein weiteres Äquivalent Isonitril hinzufügt, um die AlÀ NÀ B-verbrückende Spezies cyclo-(1,8-C 10 H 6 )-[1-Al(Mes)-N(Xyl)-8-B{C(Mes) = CÀ N-Xyl}] unter voll-ständiger Spaltung der C�N-Dreifachbindung zu bilden. Die letztgenannte Reaktion wird anhand isolierter Zwischenstufen sowie durch DFT-Berechnungen unterstützt.

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Section: Ergebnisse Und Diskussionunclassified

Section: Introductionunclassified

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Reduktive Bildung von Al−B σ‐Bindungen in Alumaboranen: Einfache Spaltung polarer Mehrfachbindungen

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“…[8] With the inverted reagent functionality, neutral Al I nucleophiles reacted with boron electrophiles with formation of the AlÀ B bond as demonstrated by Braunschweig (F) [9] and Nikonov (G). [10] A very recent example reported by Yamashita employed an anionic aluminum nucleophile with a boron electrophile to produce alumaborane H. [11] Despite the importance of the reported compounds BÀ H in the chemistry of boron, the reactivity of electron precise AlÀ B-bonds has only marginally been studied. Only for the recent alumaborane H, reactions with dimethyl sulfoxide and carbon monoxide gave deoxygenation of these two substrates with concomitant formation of the AlÀ OÀ B structural motif.…”

Section: Introductionmentioning

confidence: 99%

Reductive Al−B σ‐Bond Formation in Alumaboranes: Facile Scission of Polar Multiple Bonds

et al. 2022

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We present facile access to an alumaborane species with electron precise AlÀ B σ-bond. The reductive rearrangement of 1-(AlI 2 ), 8-(BMes 2 ) naphthalene (Mes = 2,4,6-Me 3 C 6 H 2 ) affords the alumaborane species cyclo-(1,8-C 10 H 6 )-[1-Al(Mes)(OEt 2 )-8-B(Mes)] with a covalent AlÀ B σ-bond. The AlÀ B σ-bond performs the reductive scission of multiple bonds: S=C(NiPrCMe) 2 affords the naphthalene bridged motif BÀ SÀ Al(NHC), NHC = N-heterocyclic carbene, while O=CPh 2 is deoxygenated to afford an BÀ OÀ Al bridged species with incorporation of the remaining �CPh 2 fragment into the naphthalene scaffold. The reaction with isonitrile Xyl-N�C (Xyl = 2,6-Me 2 C 6 H 4 ) proceeds via a proposed (amino boryl) carbene species; which adds a second equivalent of isonitrile to ultimately form the AlÀ NÀ B bridged species cyclo-(1,8-C 10 H 6 )-[1-Al(Mes)-N(Xyl)-8-B{C(Mes)=CÀ NÀ Xyl}] with complete scission of the C�N triple bond. The latter reaction is supported with isolated intermediates and by DFT calculations.

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“…59 The reaction between E-1.4 and dimesitylboron fluoride was found to give an oxidative addition product E-1.21, which could undergo a subsequent reaction with trimethylsilyl triflate to yield neutral complex E-1.22 containing an Al-B bond. 60 Moreover, coordination was observed between aluminyl C Dipp -1.3 and triphenyl borane to give C Dipp -1.23, which also contains an Al-B interaction. 46 The preparation of a trimetallic coinage metal complex from A-1.3 and CuI(PPh3) was shown to proceed through the desired "A-Cu-PPh3" intermediate via salt metathesis, followed by coordination of another equivalent of A-1.3 and dissociation of PPh3 to give A-1.24.…”

Section: Accessing Al-m Bimetallic Systems Using Potassium Aluminyls ...mentioning

confidence: 99%

Synthesis and Reactivity of an Aluminyl Anion

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The work detailed in this thesis describes the synthesis and reactivity of an N-heterocyclic aluminyl anion ([Al(NONDipp)]–, NONDipp = [O(SiMe2NDipp)2]2–, Dipp = 2,6-iPr2-C6H3) charge-balanced by an alkali metal cation. As a low-valent aluminium(I) nucleophile, the chemistry of the aluminyl anions is versatile and remains a rapidly developing area of chemistry. Chapter One provides a comprehensive literature review on the different aluminyl anion systems and their general structure and reactivity. Commonly isolated as potassium salts, the aluminyl anions can be used to access a range of other bimetallic systems that contain novel Al–M bonds that have demonstrated the reduction of carbon dioxide and other heteroallenes. The potassium aluminyls are by far the most well studied, displaying a rich chemistry that exploits the reduction potential and nucleophilicity of the Al(I) centre. Several modes of reactivity have been identified, including oxidative addition, reductive coupling, cycloaddition, and oxidation reactions. A key finding is the synergistic interactions between the Al and K metal centres which influence the outcome of a reaction. Chapter Two extends the chemistry of the potassium aluminyls to the other alkali metals via reduction of the iodide precursor, Al(NONDipp)I. Three main structural classes were identified, depending on the coordination sphere of the alkali metal. Contacted dimeric pairs were isolated in absence of coordinating solvents, where cations were held between flanking aryl interactions of the Dipp substituents. Monomeric ion pairs could be accessed from the addition of monodentate or bidentate ligands to the corresponding contacted dimeric pairs, rendering discrete Al–M bonds. Separated ion pairs were formed on the addition of suitable polydentate donors to the corresponding contacted dimeric pairs, giving a naked aluminyl with no interactions between the cationic and anionic components. Chapter Three investigates the oxidative addition chemistry of the alkali metal aluminyls towards polar acidic, polar basic, and non-polar E–H bonds. In each instance, the E–H bonds add across the Al centre to give the corresponding anionic aluminium(III) hydride complexes. The installed Al–H bonds are highly polar and were shown to reduce carbon dioxide under ambient conditions to give formate complexes. Hydroboration of these formate complexes was attempted and shown to yield the corresponding anionic aluminium(III) alkoxide complexes. Chapter Four details the reduction of ethene and propene by a potassium aluminyl complex. For ethene, a highly strained metallacycle was formed that was shown to engage in C–H activation and ring expansion reactions. Of note is the carbonylation of ethene, which successfully installs the desired C=O functionality to grow a C3-chain. Clear synergistic effects were observed in this reaction, where the contacted dimeric pair and monomeric ion pair formed different products. For propene, only C–H activation was observed due to the acidity of the allylic proton. Chapter Five explores the homologation and reductive coupling of CO and isonitriles by the alkali metal aluminyls. A range of chain-growth products were formed in these reactions, from the C3 → C4 → C5 homologation of CO, which was found to be dependent on the alkali metal cation. To understand this process in more detail, the isonitriles were reacted with the potassium aluminyl and shown to give C2 → C3 products. The results in this chapter further highlight cooperation between the aluminium and alkali metals in these systems, where the aluminyl complexes are capable of cleaving extremely strong bonds.

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A Tetraorganyl-Alumaborane with An Al–B σ-Bond and Two Adjacent Lewis-Acidic Centers

Cited by 16 publications

References 55 publications

Reduktive Bildung von Al−B σ‐Bindungen in Alumaboranen: Einfache Spaltung polarer Mehrfachbindungen

Reduktive Bildung von Al−B σ‐Bindungen in Alumaboranen: Einfache Spaltung polarer Mehrfachbindungen

Reductive Al−B σ‐Bond Formation in Alumaboranes: Facile Scission of Polar Multiple Bonds

Synthesis and Reactivity of an Aluminyl Anion

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