Reactions of diazocyclopentadiene and NBS at appropriate stoichiometries give 2, 5- dibromodiazocyclopentadiene and 2, 3, 5-tribromodiazocyclopentadiene in 40% and 30% yields, respectively, after chromatography. These react with BrRe (CO) 5 or BrMn (CO) 5 (80° C, CF3C6H5) to give (η5-1, 2, 3-C5H2Br3) M (CO) 3 (3; M= a, Re; b, Mn) and (η5- C5HBr4) M (CO) 3 (4a, b) in 75–85% yields. In the case of 4a, the intermediate η1- ...
