UNUSUAL TRIGONAL-BIPYRAMIDAL COORDINATION OF GALLIUM BY AN AZA CROWN ETHER - SYNTHESIS AND MOLECULAR-STRUCTURE OF [GA(CH3)2][C12H25N2O4][GA(CH3)3]2

Reaction of diaza-18-crown-6, C12H2eN204, with trimethylgallium in a toluene/heptane mixture affords the crystalline complex [Ga(CH3)2] [C^H^NjOj [Ga(C-H3)3]2. The title compound contains two trimethylgallium units and one dimethylgallium unit. The dimethylgallium unit resides within the cavity of the aza crown with the gallium atom bonding to two oxygen atoms and a nitrogen atom in addition to the two methyl carbon atoms. As the gallium atom, the two carbon atoms, and the nitrogen atom constitute a basal plane while the two oxygen atoms of the crown are found to reside above and below the plane (O-Ga-0 bond angle 157.2 (2)°), the coordination of the core gallium atom may be described as distorted trigonal bipyramidal. © 1990, American Chemical Society. All rights reserved.