A Stable Calcium Alumanyl

Abstract

A seven‐membered N,N′‐heterocyclic potassium alumanyl nucleophile is introduced and utilised in the metathetical synthesis of Mg−Al and Ca−Al bonded derivatives. Both species have been characterised by experimental and theoretical means, allowing a rationalisation of the greater reactivity of the heavier group 2 species implied by an initial assay of their reactivity.

Recent advances in low oxidation state aluminium chemistry

“…The Al-K bond of length (3.4549(5)Å) was slightly longer than the sum of the covalent radii, 3.28Å, and much shorter than observed in 17, 32 and 44. 38,45,51 The Al-C bond lengths in 49 were longer than in 48 and the C-Al-C bond angle was wider, indicating a less electropositive Al centre. DFT analysis revealed the HOMO to be the lone pair of electrons centred mainly on the aluminium and the lowest unoccupied molecular orbital (LUMO) to be comprised of the p* orbitals of the potassium coordinated toluene molecules.…”

“…In related work by Hill and co-workers, this class of nucleophilic aluminium reagents was expanded to include a sevenmembered N,N 0 -heterocyclic potassium alumanyl species (44), which does not contain a bonding moiety in the ligand backbone. 51 Compound 44 was synthesised analogously to 32, via reduction of the aluminium iodide 43 over a potassium mirror (Fig. 14).…”

Boosting Low‐Valent Aluminum(I) Reactivity with a Potassium Reagent

“…[11] Subsequent work of the groups of Coles and Hill led to similar dimeric bis-amido Al I complexes, IV and V, respectively. [12,13] Most recently, Yamashita and co-workers isolated a highly reactive monomeric anionic bis-alkyl Al I complex (VI), while the group of Kinjo reported a monomeric Al I anion analogue to the CAAC-carbene ligand. [14] Some of these anionic Al I complexes are considerably more reactive than ( DIPP BDI)Al (II), which does not react with benzene.…”

The Aluminyl Anion: A New Generation of Aluminium Nucleophile

“…Superficially, both 7 and 8 possess similar structures to 6 : both are dimeric in the solid state featuring interactions between the flanking aryl rings of the bulky diamido ligands and the potassium cations. 7 features a 6‐membered aluminium‐containing heterocycle, with a N‐Al‐N angle of 103.89(8)°, [29] while the 7‐membered ring in 8 (not surprisingly) makes the corresponding unit somewhat wider (108.84(9)°) [30] . Both of these angles however are considerably smaller than that in 6 (128.11(9)°) [27] …”

“…One of the foremost points of novelty of aluminyl anions is their ability to react as aluminium‐centred nucleophiles. All of the reported aluminyl anions have shown nucleophilic behaviour to some extent, with 6 , 8 and 10 showing evidence for nucleophilic substitution chemistry [27, 30, 32, 37, 38] …”