The preparation of some new boron trihalide addition compounds with trimethylarsine and trimethylstibine

New 1 : 1 adducts of BBr3 and BI3 with (CH3)3As and (CH3)3Sb are reported. The (CH3)3As adducts are stable indefinitely at room temperature under an inert atmosphere while the (CH3)3Sb compounds slowly decompose at that temperature to form (CH3)3SbX2 (X = Br, I). Boron-11 and proton NMR data suggest that these species may exist as ions in chloroform solution.