Main group complexes incorporating 1,3-bis(furyl)-1,1,3,3-tetramethyldisilazide ligands

The lithium salt of the bis-furyl substituted disilazide anion, Li{i} [{i} = N(SiMe₂R)₂ where R = 2-methylfuryl] has been examined as a ligand transfer reagent for the synthesis of group 2 (magnesium) and group 13 (aluminium) compounds. Salt metathesis between Li{i} and AlMe₂Cl afforded the expected dimethyl species, Al{i}Me₂ (1), which was isolated as a colourless oil. In contrast the corresponding aluminium dichloride, synthesized from Li{i} and AlCl₃, gave crystalline products as both the THF adduct Al{i}Cl₂(THF) (2a) and the base-free derivative, Al{i}Cl₂ (2b). The homoleptic magnesium bis(amide) Mg{i}₂ (3) was also synthesized. X-ray crystallographic analysis of 2a reveals a four-coordinate distorted tetrahedral metal, in which neither of the furyl-substituents interact with the metal. In contrast, the aluminium in the base-free dichloride 2b is five-coordinate, containing the first structurally characterized example in which the amide binds with a κ¹N,O,O′-bonding mode, involving coordination of both furyl-substituents at the N-bound metal.