Structural characterisation of dimethylgallium tetrahydroborate and its adducts with diethyl ether and tetrahydrofuran

Abstract

The structures of dimethylgallium tetrahydroborate and its 1∶1 adducts with diethyl ether and tetrahydrofuran have been investigated by single crystal X-ray diffraction at low temperatures. The structure of dimethylgallium tetrahydroborate has been shown to consist of discrete GaMe₂(BH₄) units in which each BH₄ group exhibits bidentate ligation to a single Me₂Ga unit, but in which there are long-range interactions between the Ga and the terminal hydrogen atom of a BH₄ group in each of two neighbouring molecules. The structures of the adducts show that they are composed of molecules in which the Ga is 5-coordinate and asymmetrically bound to a bidentate BH₄ unit. The adducts display enhanced thermal stability compared to that of uncoordinated GaMe₂(BH₄), but reversibly dissociate in the gas phase at ambient temperature. The infrared spectra of the compounds are discussed on the basis of their structures.