Ga–C and Ga–Ga bond formation using a NON-ligated gallyl nucleophile

Abstract

We report an improved synthesis of the NON-donor stabilized potassium gallyl dimer [K{Ga(NON)}]2 (NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethyl-xanthene) from (NON)GaI and potassium naphthalenide that avoids issues associated with over-reduction of the metal centre. The use of [K{Ga(NON)}]2 in the synthesis of Ga–E bonds has been explored through its reactions with a range of electrophiles. The reaction with (NON)GaI to give {Ga(NON)}2 via Ga–Ga bond formation mirrors the behaviour of the corresponding aluminyl compound, while Ga–C bond formation via nucleophilic attack on 1-bromopentane to give (NON)Ga(n-pentyl) avoids the retention of KBr often encountered in the formation of (more Lewis acidic) AlIII compounds. Attempted formation of a Mg–Ga bond, e.g. via the reaction of [K{Ga(NON)}]2 with (NacnacMes)MgI(OEt2), generates instead the unsymmetrical digallane(4), (NacnacMes)Ga(μ2-N,N'-NON)GaI, consistent with enhanced lability of Ga (over Al) within the NON-ligand scaffold.