Trivalent aluminium compounds are well known for their reactivity as Lewis acids/electrophiles, a feature that is exploited in many pharmaceutical, industrial and laboratory-based reactions Recently, a series of isolable aluminium(I) anions ("aluminyls") have been reported, which offer an alternative to this textbook description: these reagents behave as aluminium nucleophiles This minireview covers the synthesis, structure and reactivity of aluminyl species reported to date, together with their associated metal complexes The frontier orbitals of each of these species have been investigated using a common methodology to allow for a like-for-like comparison of their electronic structure and a means of rationalising (sometimes unprecedented) patterns of reactivity

/pdf/the-aluminyl-anion-a-new-generation-of-aluminium-nucleophile-1u8wlv6q11.pdf

The Aluminyl Anion: A New Generation of Aluminium Nucleophile

Since the groundbreaking discovery in 2018 that the synthesis of a bottleable nucleophilic aluminyl anion is feasible, a handful of derivatives have been developed to date, which are, however, limited to diamino- and dialkyl-substituted species. Herein, we report the synthesis of a cyclic (alkyl)(amino)aluminyl anion based on a five-membered framework. The dicoordinate aluminum center features both a lone pair of electrons and an unoccupied 3p orbital, thus genuinely making it isoelectronic with carbenes. We show the bond formation and bond activation at the Al sphere: thus, not only does it undergo electron redistribution with borane to furnish a heteroatomic group 13 ring exhibiting a σ-aromatic nature concomitant with a three-center two-electron AlB2 bond but also the ambiphilic nature allows for oxidative addition of Si-H, N-H, and even C-C bonds at the aluminum center.

Construction of σ-Aromatic AlB2 Ring via Borane Coupling with a Dicoordinate Cyclic (Alkyl)(Amino)Aluminyl Anion

Over the past few decades, β-diketiminate ligands have been widely used in coordination chemistry and are capable of stabilizing various metal complexes in multiple oxidation states. Recently, the chemistry of aluminum and gallium in their +1 oxidation state has rapidly emerged. NacNacM(i) (M = Al, Ga; NacNac = β-diketiminate ligand) shows a two coordinate metal center comparable with singlet carbene-like species. The metal center also possesses a formally vacant p-orbital. In this article we present an overview of the last 10 years for aluminum(i) and gallium(i) stabilized by β-diketiminate ligands that have been widely explored in bond breaking and forming species.

/pdf/the-unique-b-diketiminate-ligand-in-aluminum-i-and-gallium-i-51zrr07irt.pdf

The unique β-diketiminate ligand in aluminum(i) and gallium(i) chemistry.

Multigram syntheses of magnesium(I) compounds using alkali metal halide supported alkali metals as dispersible reducing agents

The monomeric molecular aluminium(I) complex 1 [{(ArNCMe)2CH}Al] (Ar = 2,6-di-iso-propylphenyl) reacts with a series of terminal and strained alkenes including ethylene, propylene, allylbenzene and norbornene to form alkene bound products. Remarkably all these reactions are reversible under mild conditions (298–353 K) with alkene binding being disfavoured at higher temperatures due to the positive reaction entropy. Van't Hoff analyses have allowed quantification of the binding events with . Calculations and single crystal X-ray diffraction studies are consistent with the alkene bound species being metallocyclopropane complexes. Alkene binding involves a reversible redox process with changes from the +1 to +3 aluminium oxidation state. Under more forcing conditions the metallocyclopropane complexes undergo non-reversible allylic C–H bond activation to generate aluminium(III) allyl hydride complexes. This represents a rare example of redox-based main group reactivity in which reversible substrate binding is followed by a further productive bond breaking event. Analysis of the mechanism reveals a reaction network in which alkene dissociation and reformation of 1 is required for allylic C–H activation, a realisation that has important implications for the long-term goal of developing redox-based catalytic cycles with main group compounds.

https://pubs.rsc.org/en/content/articlepdf/2019/SC/C8SC04865G

Jia Li

Papers

The chemistry of aluminum(I) with β-diketiminate ligands and pentamethylcyclopentadienyl-substituents: Synthesis, reactivity and applications