Primary amido and amine adduct complexes of gallium: synthesis and structures of [t-Bu 2Ga(μ-NHPh)] 2 and t-Bu 3Ga·NH 2Ph

Abstract

Reaction of t-Bu 2GaCl with LiNHPh in toluene/diethylether (4 : 1) at −78°C gives the dimeric primary amido complex [t-Bu 2Ga(μ-NHPh)] 2 ( 1) in 60% yield. The reaction of t-Bu 3Ga with NH 2Ph at −78°C in toluene gives the adduct t-Bu 3Ga·NH 2Ph ( 2) in 75% yield. The structures of both compounds have been determined by X-ray crystallography. The molecular geometry of 1 consists of a dinuclear unit with two bridging NHPh groups and two terminal t-Bu groups bound to each gallium atom. The coordination geometry of both the gallium and nitrogen atoms is distorted tetrahedral. The molecular geometry of 2 involves a fairly long dative N→Ga donor bond [2.246(9) Å] and the configuration of the amine is distorted from an idealized tetrahedral geometry due to steric repulsions. Crystallographic data for both 1 and 2 suggest the presence of close interactions between the NH hydrogen atoms and the gallium atoms (NH … Ga).