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

The structures of dimethylgallium tetrahydroborate and its 1 : 1 adducts wi th diethyl ether and tetrahydrofuran have been investigated by single cryst al 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, bu t in which there are long-range interactions between the Ga and the termina l hydrogen atom of a BH4 group in each of two neighbouring molecules. The s tructures 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. Th e adducts display enhanced thermal stability compared to that of uncoordina ted GaMe2(BH4), but reversibly dissociate in the gas phase at ambient tempe rature. The infrared spectra of the compounds are discussed on the basis of their structures.