Isoelectronic Arduengo-Type Carbene Analogues with the Group IIIa Elements Boron, Aluminum, Gallium, and Indium

Boryllithium: Isolation, Characterization, and Reactivity as a Boryl Anion

“…2) (21,22). Also, the parent boryl anion 6 was predicted to realize aromatic stabilization by the fivemembered ring structure containing two nitrogen atoms (23,24). Large 2,6-diisopropylphenyl groups were introduced on the nitrogen atoms to prevent the boryl radical intermediates from dimerizing to diborane (5,(25)(26)(27).…”

Oxidative addition of an imidazolium cation to an anionic gallium(I) N-heterocyclic carbene analogue: Synthesis and characterisation of novel gallium hydride complexes

“…In both cases only the starting materials were recovered from the reaction mixture. Despite earlier theoretical studies which suggested the heterocycle's gallium centre should be electrophilic [4], this result is perhaps not surprising considering the overall anionic nature of the ring. Similarly, attempts to form complexes of [:Ga{[N(Ar)C(H)] 2 }] À with a range of unhindered strong Lewis bases, e.g.…”

“…However, whereas it is now widely accepted that the carbene centres of NHCs are very nucleophilic but poorly electrophilic due to significant overlap of both nitrogen p-orbital lone pairs with the carbene p-orbital [3], the gallium centre of [:Ga{[N(Ar)C(H)] 2 }] À has the potential to act as both a Lewis base and a Lewis acid. The reasoning behind this comes from theoretical studies which have shown that the electronegativity difference between Ga and N leads to little orbital overlap between these centres in a model of the heterocycle and that, to some extent, it can be regarded as a diamido-complex of a Ga + centre [4]. As a result, we were interested in investigating the reactivity of the gallium centre of [:Ga{[N(Ar)C(H)] 2 }] À towards strong nucleophiles, in particular NHCs.…”

Diborane heterolysis and P(v) reduction by Ph3PO coordination to magnesium

“…The chemistry of nucleophilic group 13-centred anions has been an area of interest for over 20 years. The viability of singlet lithium boryl anions (X 2 B-Li; X = F, Cl, O) was posited by Schleyer in 1995, 1 while the electronic structures of a range of model boron, aluminium, gallium and indium imidazolate anions (1)(2)(3)(4) were evaluated by Schoeller and co-workers a short time later. 2 Schmidbaur's realisation of the N-heterocyclic gallyl anion (5) in 1999, therefore, was a true landmark in group 13 element synthesis.…”

“…The viability of singlet lithium boryl anions (X 2 B-Li; X = F, Cl, O) was posited by Schleyer in 1995, 1 while the electronic structures of a range of model boron, aluminium, gallium and indium imidazolate anions (1)(2)(3)(4) were evaluated by Schoeller and co-workers a short time later. 2 Schmidbaur's realisation of the N-heterocyclic gallyl anion (5) in 1999, therefore, was a true landmark in group 13 element synthesis. 3 Although the chemistry of compound 5 was never exploited, Jones' subsequent exploration of the reactivity of the closely-related gallyl (6), 4 definitively established the potential of such species as gallium-centred nucleophiles and reducing agents.…”