Aminolysis of 1,2-(Cl2B)2C6H4 with R2NH (R = Me2CH throughout this abstr.) gave 1,2-[(R2N)(Cl)B]2C6H4 which on NaK8 mediated coupling gave title compd. I. Cryst. I is thermally stable; an x-ray crystallog. structure detn. for which has been carried out. In concd. soln., reaction of 1,2-[(R2N)(Cl)B]2C6H4 with sodium/potassium alloy predominantly leads to the formation of the tetraborocine II by dimerization. In the presence of (phthalocyaninato)palladium as catalyst I reacts with 2 equiv of di-Me acetylenedicarboxylate to give the benzo-annulated diborocine III.