A new strained germacycle, 3, 4-benzo-1, 1, 2, 2-tetraethyl-1, 2-digermacyclobut-3-ene (1), was thermally labile and readily underwent ring-opening polymerization to give the corresponding polymer (M n= 4.4× 105, M w= 7.4× 105, M w/M n= 1.7). On thermolysis at 160° C for 20 h, unexpectedly 1 gave two products, 4, 5-benzo-1, 2, 3-trigermacyclopent-4- ene 5 and 3, 4: 6, 6-dibenzo-1, 2, 5-trigermacyclohepta-3, 6-diene 6, in reasonable yields.
