Dimerization of 1,2-bis(diisopropylamino)-1 ,2-dihydro-1,2-diborete (2) with palladium phthalocyanine quantitatively yields the eight-membered 1,2,5,6-tetrakis(diisopropylamino)-1,2,5,6-tetrahydro- 1,2,5,6-tetraborocine (3), which thermally or photolytically rearranges to give 2,4,6,8-tetrakis- (diisopropylamino)-2,4,6.8-tetrabora-tricyclo- [3,3,0,0 3,7 ]-octane (4). The X-ray structure analysis of the S 4 N 4 -like cage 4 exhibits long C-C-distances (1.67(1) Å ). 4 crystallizes in the space group F2dd with the lattice constants: a = 7.432(2), b = 24.802(6), c = 36.563(9) Å.