Observation of an unusual amine oxidation reaction during the oxidation and hydrolysis of [ [formula omitted]: molecular structures of [ [formula omitted] and [formula omitted](OPPh 3)

Abstract

Reaction of [( tBu) 2Ga(μ-Cl)] 2 with Li( o-C 6H 4NMe 2) yields [ ( t Bu) 2 Ga(o- C 6 H 4 NMe 2)] 2 ( 1). The atmospheric oxidation/hydrolysis of 1 results in the isolation of ( t Bu) 2 Ga(o- C 6 H 4 ▪ Me 2] ( 2). The structure of compound 2 (as determined by X-ray crystallography) consists of a gallium dimer in which one of the ortho-(dimethylamino)phenyl ligands is oxidized and the other exhibits strong intramolecular O3·N hydrogen bonding ( ΔG ‡ = 57.3 kJ mol −1 ) to the hydroxide bridge. A pathway for the formation of 2 is proposed. Reaction of compound 1 with OPPh 3 results in the formation of the Lewis acid-base complex [ ( t Bu) 2 Ga(o- C 6 H 4 NMe 2 )(OPPh 3) ( 3), whose structure has been confirmed by X-ray crystallography.