1,3-dimethyl-2-(2-phenylethynyl)-1,3,2-diazaborolidine

1,3-dimethyl-2-[(trimethylsilyl)ethynyl]-1,3,2-diazaborilidine

2-[2-(1,3-dimethyl-1,3,2-diazaborolidin-2-yl)ethynyl]-1,3-dimethyl-1,3,2-diazaborolidine