The exchange of substituents between 3,5-dibromo-1,2,4,3,5-trithiadiborolane ( 1 ) and 1,2,3-trimethyl-1,3,2-diazaborolidine ( 2 ) proceeds via formation of adducts as indicated by tetracoordinated boron atoms but definite products could not be isolated. However, a well defined ...