Physical properties and structure of diethylaminodifluoroborane

Abstract

Diethylaminodifluoroborane has been characterised in the solid, liquid, and vapour phases, and in solution. The compound is dimeric in the crystalline state and in solution but ¹⁹F nuclear magnetic resonance studies on the molten phase reveal the presence of a temperature-dependent monomer–dimer equilibrium. The compound is entirely monomeric in the vapour phase, as shown by a comparison of its infrared spectrum with the newly reported spectra of the corresponding dichloro- and dibromo-analogues. When compared with the behaviour of dimethylaminodifluoroborane the results indicate that the increased steric congestion at the nitrogen atom inhibits but does not completely suppress the tendency of the diethylamino-compound to dimerise.