278608-73-4Relevant articles and documents
Reactions of an Aluminum(I) Reagent with 1,2-, 1,3-, and 1,5-Dienes: Dearomatization, Reversibility, and a Pericyclic Mechanism
Bakewell, Clare,Crimmin, Mark R.,Gar?on, Martí,Kong, Richard Y.,O'Hare, Louisa,White, Andrew J. P.
, (2020)
Addition of the aluminum(I) reagent [{(ArNCMe)2CH}Al] (Ar = 2,6-di-iso-propylphenyl) to a series of cyclic and acyclic 1,2-, 1,3-, and 1,5-dienes is reported. In the case of 1,3-dienes, the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene-containing products. This mechanism has been examined by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4 + 1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4 + 1) cycloaddition includes styene, 1,1-diphenylethylene, and anthracene. In these cases, the diene motif is either in part, or entirely, contained within an aromatic ring and reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2-cyclononadiene or 1,5-cyclooctadiene, complementary reactivity is observed; the orthogonal nature of the Ca? C ?-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavor a (4 + 1) cycloaddition. Rather, reaction pathways are determined by an initial (2 + 1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further Ca? C ?-bond, leading to complex organometallic products that incorporate fused hydrocarbon rings.
Theory and X-ray absorption spectroscopy for aluminum coordination complexes - Al K-edge studies of charge and bonding in (BDI)Al, (BDI)AlR2, and (BDI)AlX2 complexes
Altman, Alison B.,Pemmaraju,Camp, Clément,Arnold, John,Minasian, Stefan G.,Prendergast, David,Shuh, David K.,Tyliszczak, Tolek
, p. 10304 - 10316 (2015)
Polarized aluminum K-edge X-ray absorption near edge structure (XANES) spectroscopy and first-principles calculations were used to probe electronic structure in a series of (BDI)Al, (BDI)AlX2, and (BDI)AlR2 coordination compounds (X = F, Cl, I; R = H, Me; BDI = 2,6-diisopropylphenyl-β-diketiminate). Spectral interpretations were guided by examination of the calculated transition energies and polarization-dependent oscillator strengths, which agreed well with the XANES spectroscopy measurements. Pre-edge features were assigned to transitions associated with the Al 3p orbitals involved in metal-ligand bonding. Qualitative trends in Al 1s core energy and valence orbital occupation were established through a systematic comparison of excited states derived from Al 3p orbitals with similar symmetries in a molecular orbital framework. These trends suggested that the higher transition energies observed for (BDI)AlX2 systems with more electronegative X1- ligands could be ascribed to a decrease in electron density around the aluminum atom, which causes an increase in the attractive potential of the Al nucleus and concomitant increase in the binding energy of the Al 1s core orbitals. For (BDI)Al and (BDI)AlH2 the experimental Al K-edge XANES spectra and spectra calculated using the eXcited electron and Core-Hole (XCH) approach had nearly identical energies for transitions to final state orbitals of similar composition and symmetry. These results implied that the charge distributions about the aluminum atoms in (BDI)Al and (BDI)AlH2 are similar relative to the (BDI)AlX2 and (BDI)AlMe2 compounds, despite having different formal oxidation states of +1 and +3, respectively. However, (BDI)Al was unique in that it exhibited a low-energy feature that was attributed to transitions into a low-lying p-orbital of b1 symmetry that is localized on Al and orthogonal to the (BDI)Al plane. The presence of this low-energy unoccupied molecular orbital on electron-rich (BDI)Al distinguishes its valence electronic structure from that of the formally trivalent compounds (BDI)AlX2 and (BDI)AlR2. The work shows that Al K-edge XANES spectroscopy can be used to provide valuable insight into electronic structure and reactivity relationships for main-group coordination compounds.
Reactions of Fluoroalkenes with an Aluminium(I) Complex
Bakewell, Clare,White, Andrew J. P.,Crimmin, Mark R.
supporting information, p. 6638 - 6642 (2018/05/05)
A series of industrially relevant fluoroalkenes react with a monomeric AlI complex. These reactions break strong sp2 and sp3 C?F bonds, and result in the formation of a diverse array of organoaluminium compounds. Mechanistic studies show that two mechanisms are likely in operation: 1) direct oxidative addition of the C?F bond to AlI occurs with retention of alkene stereochemistry, and 2) stepwise formation and decomposition of a metallocyclopropane intermediate occurs with inversion of alkene stereochemistry. As part of this mechanistic analysis, we have isolated the first aluminium metallocyclopropane complex from oxidative addition of an alkene to AlI. Remarkably this reaction is reversible and reductive elimination of the alkene occurs at higher temperature reforming AlI. Furthermore, in selected cases the organoaluminium products are susceptible toward β-fluoride elimination to yield a double C?F activation pathway.
Oxidative addition of σ Bonds to an Al(I) center
Chu, Terry,Korobkov, Ilia,Nikonov, Georgii I.
, p. 9195 - 9202 (2014/07/08)
The Al(I) compound NacNacAl (1, NacNac = [ArNC(Me)CHC(Me)NAr]- and Ar = 2,6-Pri2C6H3) reacts with H-X (X = H, Si, B, Al, C, N, P, O) σ bonds of H2, silanes, borane (HBpin, pin = pinacolate), allane (NacNacAlH2), phosphine (HPPh2), amines, alcohol (PriOH), and Cp H (Cp* = pentamethylcyclopentadiene) to give a series of hydride derivatives of the four-coordinate aluminum NacNacAlH(X), which are characterized herein by spectroscopic methods (NMR and IR) and X-ray diffraction. This method allows for the syntheses of the first boryl hydride of aluminum and novel silyl hydride and phosphido hydride derivatives. In the case of the addition of NacNacAlH 2, the reaction is reversible, proving the possibility of reductive elimination from the species NacNacAlH(X).
Unprecedented reactivity of an aluminium hydride complex with ArNH 2BH3: Nucleophilic substitution versus deprotonation
Harder, Sjoerd,Spielmann, Jan
, p. 11945 - 11947 (2011/12/01)
Reaction of DIPPnacnacAlH2 with DIPPNH2BH3 did not give the anticipated deprotonation but nucleophilic substitution at B was observed instead. The product DIPPnacnacAl(BH4)2 was isolated and structura
Synthesis and structures of monomeric divalent germanium and tin compounds containing a bulky diketiminato ligand
Ding, Yuqiang,Roesky, Herbert W.,Noltemeyer, Mathias,Schmidt, Hans-Georg,Power, Philip P.
, p. 1190 - 1194 (2008/10/08)
Reaction of the β-diketiminato lithium salt Li(OEt2)[HC(CMeNAr)2] (Ar = 2,6-i-Pr2C6H3) with GeCl2·(dioxane) and SnCl2 in diethyl ether provided the monomeric complexes [HC-(CMeNAr)2]MCl (M = Ge (2), Sn (3), respectively) with a three-coordinated metal center. The reductive dehalogenation reactions of 3 with C8K and LiAlH4 afforded [HC(CMeNAr)2]2Sn (7) and [HC(CMeNAr)2]AlH2, respectively. The metathesis reactions of 3 with t-BuLi, AgSO3-CF3, and NaN3 resulted in the formation of [HC(CMeNAr)2]Sn(t-Bu) (4), [HC(CMeNAr)2]-Sn(OSO2CF3) (5), and [HC(CMeNAr)2]SnN3 (6), respectively. Compounds 2, 3, 5, and 7 were characterized by single-crystal X-ray structural analysis. The structures indicate that the β-diketiminato backbone is essentially planar and the metal centers reside in distorted-tetrahedral environments with one vertex occupied by a lone pair of electrons. The bond angles at the metal center are in the range 85.2(8)-106.8(2)°, and the most acute angle is associated with the bite of the chelating ligand.
