Chlorination of trimethylamine borane. Synthesis of trimethylamine dichloroborane

Abstract Trimethylamine borane can be chlorinated with a variety of halides and oxyhalides under mild conditions. Reactivity decreases in the order SbCl5∼ SO2Cl2 > SbCl3 > SOCl2 > HgCl2 > HCl > (CH3)3 NH . HCl, and correlates well with thermodynamic properties of the halogenating agents. Reactivity towards chlorination in the amine boranes decreases in the order (CH3)3NBH3>(CH3)3NBH2Cl>(CH3)3NBHCl2, and correlates well with B stretching frequencies and nmr shifts. Trimethylamine dichloroborane was synthesized and characterized for the first time. The weaker halogenating agents appear to react via a polar hydride transfer mechanism whereas the strongest ones are likely to halogenate by a free radical chain mechanism.